Conference Agenda

Overview and details of the sessions of this Conference. Please select a date or location to show only sessions at that day or location. Please select a single session for detailed view (with abstracts and downloads if available).

Please note that all times are shown in the time zone of the conference. The current conference time is: 18th May 2022, 04:17:33am BST

Session Overview
Date: Saturday, 10/July/2021
9:00am - 4:00pmSource apportionment of mine pollution in watersheds: An introduction to the tracer dilution and synoptic sampling approach
Session Chair: Patrick Byrne
Overview Need for the workshop. Pollution from abandoned and active mines is recognised as a major cause of failure to achieve water quality objectives around the world. As such, identification and remediation of mine pollution sources is one of the major challenges facing environmental managers. Developed by the U.S. Geological Survey, the tracer dilution and synoptic sampling approach has been used extensively in the USA to inform remediation under the Abandoned Mine Lands Initiative. The approach provides streamflow estimates across a watershed by measuring the dilution of a conservative tracer injected into the stream. Combined with synchronous (or synoptic) water quality measurements, the approach provides spatially detailed assessments of pollutant loads and sources for remediation decision-making. Target audience. The target audience for this workshop includes practitioners and researchers who are interested in understanding the sources and impacts of mine pollution in watersheds. Specifically, the workshop will appeal to those interested in locating sources of mine pollution and quantifying the relative importance of different sources at the watershed-scale. Professionals who might be interested in this workshop include hydrologists, hydrogeologists, water quality scientists, ecologists, environmental engineers, and mine site remediation and rehabilitation scientists. Outline. The workshop will follow the format of previous successful knowledge exchange workshops delivered to UK practitioners and scientists as part of a UK research council (NERC) funded project. The programme will run from (approximately) 0900 to 1600 and include five sessions: an introduction (0900-0930), three technical sessions (0930-1530), and a final discussion (1530-1600). Each of the three technical sessions will include a 30 minute presentation followed by a 60 minute practical activity. The sessions topics are: ‘Preparing for a tracer dilution experiment’, Executing a tracer dilution experiment’ and ‘Analysis and communication of tracer dilution data’. Outcomes and benefits. The overall aim of the workshop is to build the capacity of environmental managers, scientists and engineers to monitor and remediate mine pollution in watersheds. At the end of the workshop, participants will be able to: (i) design a tracer dilution and synoptic sampling experiment; (ii) understand how to conduct a tracer dilution experiment; (iii) perform a mine pollution source apportionment analysis; and (iv) evaluate potential water quality improvements from hypothetical remediation scenarios. This workshop will benefit practitioners and researchers interested in understanding and mitigating the impacts of mine pollution in the environment. Environmental managers and remediation scientists in particular will benefit from understanding how to locate and discern the relative importance of different mine pollution sources across a watershed, and to evaluate the benefits of remedial alternatives. Materials. The technical sessions outlined above will be structured around a case study of the Nant Cwmnewyddion stream in central Wales. The publication can be accessed here. For each of the three technical sessions, workshop participants will receive an excel spreadsheet containing case study data and a handout with instructions on how to perform different analyses. Participants will receive all of the presentation slides in pdf format.
9:00am - 4:00pm"PITLAKQ" Modelling Pit Lakes: Modelling Hydrodynamics and Water Quality of Pit Lakes with PITLAKQ
Session Chair: Mike Müller
Overview Modelling pit lakes is a complex task. The open-source software PITLAKQ ( allows one to model hydrodynamic processes in pit lakes including temperature stratification. Furthermore, transport of constituents and a variety of chemical and biological reactions can be modelled. PITLAKQ combines the abilities of CE-QUAL-W2 ( and PHREEQC ( Participants need to be familiar with the topic of pit lakes and their water quality. Basic hydro-geo-chemical knowledge is assumed. Preferably, participants should have modelling experience with CE-QUAL-W2, PHREEQC or comparable models. They also need to have basic knowledge of important pit lake processes. Solid PC handling abilities are necessary. Participants will get login data to an online teaching system, consisting of a video conferencing system and a modelling environment (JupyterHub). This system has been used by Python Academy for nearly a year (see attachment for details). After the course, participants can install PITLAKQ on their own computers and used the same tools they learn in the course. PITLAKQ provides new features such as distributed groundwater exchange, treatment of the lake water with chemicals, and accounting for the impact of bank erosion on lake water quality. This workshop introduces PITLAKQ with a hands-on tutorial of setting up and running models. It covers: Getting familiar with the teaching system Python basics for running models Setting up and running a hydrodynamic model Interpreting and presenting hydrodynamic results Setting up and running a water quality model Interpreting and presenting water quality results Varying the water quality processes PITLAKQ solves complex problems and offers many more features than can be covered in the workshop. The presenter will be glad to answer questions that go beyond the content described above. Each participant will receive a comprehensive course handout (PDF) and the PITLAKQ software. After the course, participants will be able to set up and run PITLAKQ models.
9:00pm - 10:30pmIMWA EC Meeting
Session Chair: Christian Wolkersdorfer
Date: Sunday, 11/July/2021
9:00am - 3:30pmBiotechnologies for the treatment of mining and metallurgical wastewater on the context of metal recovery
Session Chair: Denys Villa Gomez
This course will provide a complete insight on the currently bio-based alternatives for mine wastewater treatment, including biological sulphate/sulphur reduction, biosorption, or enzymatic reductive precipitation among others. The application of these technologies is a step forward from using chemicals, eliminating the costs associated with the acquisition of reagents, and in the case of biological sulphate reduction, it uses a pollutant usually present in metal-containing wastewaters (i.e. sulfate) and it allows the production of sulfide on-site, thus avoiding transportation of hazardous chemicals. Currently, an increasing number of mining companies are evaluating these technologies, either in their processes or in wastewater treatment applications. The application of these microorganisms offers the potential for enhanced metal recovery and a sustainable strategy for handling water and solid wastes. The effect on the water sector through this course is a change of thinking from considering treatment of mine-impacted water as a cost, to consider it as a resource that can provide revenue. This, by overcoming the barriers on lacking know-how of the process and the further adaptation of these technologies case by case to receive a more widespread implementation of these technologies. The knowledge and application of these microbial-based technologies are an important way to green up the industry, reducing environmental risks and improving the efficiency and the economy of mine water treatment through metal recovery. At the completion of this course you should be able to: Describe the fundamental principles and commonly applied biotechnologies to recover metals from various wastewater streams, including the advantages, disadvantages and typical application area of each technology; Set a design basis for the different metal recovery technologies, conduct preliminary reactor sizing and calculate performance predictions; Identify opportunities, challenges and research needs for metal recovery from other streams in terms of environmental and economic benefits.
9:00am - 3:30pmPractical Guide to Open Pit and Underground Mine Water Management
Session Chair: Simon James Sholl
Overview This one day course aims to provide those currently working in the development or operation of mining projects with an introduction to the main elements of mine water management at open pit and underground operations. Following on from an initial introduction of how to define and quantify mine water management requirements, the course will focus on practical examples of water management techniques applied at mine sites located in a variety of hydro(geo)logical settings across the globe. The course will cover all aspects of water management from mine dewatering and pore-pressure control, surface water conveyance, water quality prediction, control and treatment and site-wide water balance optimization. Module 1: Open pit mine water management (1.5 hrs) Starting with an overview of how water affects mining, including operational and cost implications, this module will provide an introduction to the general principles of mine water control, before providing practical examples of dewatering methods (including passive water control), surface water control and reviewing dewatering versus depressurisation. Methods for predicting dewatering rates will be reviewed, including the use and applicability of numerical models, before the design and analysis of monitoring data as a means of measuring the operational effectiveness of implemented dewatering strategies is assessed. Module 2: Underground mine water management(1.5 hrs) This module will focus on water management strategies for underground operations, including the specific requirements needed where underground operations develop either beneath exiting open pit operations, or where block caving is the mining method. The module will be based on practical examples of operations which have implemented pumping and/or grouting/freezing approaches to groundwater control underground. Focus will be placed on the criticality of the design execution, including development of a robust feedback loop as part of operations, to ensure that design-implementation-verification are constantly reviewed to maintain safe underground operations. Module 3: Mine water chemistry (1.5 hrs) This module will focus on the increasingly challenging issue of management of mine contact water. The module will encompass approaches to the prediction of contact water quality, the design of mine water management systems to optimize water quality and the key technologies applicable to the mining sector for the treatment of mine water. The module will be structured to consider all stages of the mine life cycle from pre-construction design to closure. Practical examples will be provided from a spectrum of climatic and geological settings, with successes and/or causes of failure highlighted as appropriate. Module 4: Mine water management as part of the site wide water balance (1.5 hrs) The final module in this course demonstrates how a site-wide water and chemical mass balance model allows the pit and/or underground and geochemistry aspects of mine management to be integrated. With the inclusion of additional mine-site water management requirements, such as process circuits, TSFs and waste rock dumps, a water balance provides an important tool for both short-term decision making and life of mine planning. Probabilistic simulations using GoldSim allow alternative water management strategies to be simulated and their relative risks included in trade off studies.
9:00am - 4:00pm"PITLAKQ" Modelling Pit Lakes: Modelling Hydrodynamics and Water Quality of Pit Lakes with PITLAKQ
Session Chair: Mike Müller
This course will provide a complete insight on the currently bio-based alternatives for mine wastewater treatment, including biological sulphate/sulphur reduction, biosorption, or enzymatic reductive precipitation among others. The application of these technologies is a step forward from using chemicals, eliminating the costs associated with the acquisition of reagents, and in the case of biological sulphate reduction, it uses a pollutant usually present in metal-containing wastewaters (i.e. sulfate) and it allows the production of sulfide on-site, thus avoiding transportation of hazardous chemicals. Currently, an increasing number of mining companies are evaluating these technologies, either in their processes or in wastewater treatment applications. The application of these microorganisms offers the potential for enhanced metal recovery and a sustainable strategy for handling water and solid wastes. The effect on the water sector through this course is a change of thinking from considering treatment of mine-impacted water as a cost, to consider it as a resource that can provide revenue. This, by overcoming the barriers on lacking know-how of the process and the further adaptation of these technologies case by case to receive a more widespread implementation of these technologies. The knowledge and application of these microbial-based technologies are an important way to green up the industry, reducing environmental risks and improving the efficiency and the economy of mine water treatment through metal recovery. At the completion of this course you should be able to: Describe the fundamental principles and commonly applied biotechnologies to recover metals from various wastewater streams, including the advantages, disadvantages and typical application area of each technology; Set a design basis for the different metal recovery technologies, conduct preliminary reactor sizing and calculate performance predictions; Identify opportunities, challenges and research needs for metal recovery from other streams in terms of environmental and economic benefits.
Date: Monday, 12/July/2021
8:30am - 9:10amOpening Ceremony
Location: Main Room
Main Room 
9:10am - 10:00amMorning Session Monday
Location: Main Room
Session Chair: Christian Wolkersdorfer
Main Room 

Overview of Metal & Coal Mines in Wales

Peter Brabham

Cardiff University, United Kingdom

New Developments in Tailings Dam Monitoring

Kym Lesley Morton

KLM Consulting Services, South Africa

10:00am - 10:10amHealth Break
10:10am - 12:15pmMine Drainage Chemistry
Location: Meeting Room 1
Session Chair: Christopher James Satterley
Meeting Room 1 
10:10am - 10:35am

Offscreen-Break Due to No-show or Last Minute Cancellation

IMWA 2021 Organizers

International Mine Water Association

10:35am - 11:00am

REE Enrichment Pattern in Acid Mine Drainage and Overburden from Coal Mine in Indonesia

Abie Badhurahman, Rudy Sayoga Gautama, Ginting Jalu Kusuma

Department of Mining Engineering, Institut Teknologi Bandung, Indonesia

Geochemical characteristics of REE in AMD and overburden from PT Bukit Asam coal mine, Indonesia were investigated from 11 AMD samples and 24 overburden samples.

Similarity between enrichment type of AMD and overburden samples shows that processes controlling REE enrichment in AMD is somewhat relate to the source of REE. Further study on the mechanism of REE enrichment from overburden to AMD to determine whether the mechanism is controlled by the source of REE or the geochemical characteristics of AMD is needed to obtain more information of processes of REE enrichment in AMD.

11:00am - 11:25am

Natural Tracers For Mine Water Fingerprinting – A First Step To A Hydrogeochemical Monitoring Plan For Risk Assessment During Mine Water Rebound In The Ruhr District Area, Germany

Henning Jasnowski-Peters, Christian Melchers

Research Center of Post Mining, Technische Hochschule Georg Agricola - University, Bochum, Germany

Bromide as natural tracer in combination with hydrochemistry and isotope geochemistry has been applied to distinguish regional aquifers from mine water derived from Upper Carboniferous hosted former hard coal mining area in the Ruhr District, Germany. The hydrogeochemical dataset successfully identified different origins of salinity, i.e. halite dissolution vs. seawater evaporation. Cl/Br ratios and molar Na/Cl ratios of mine water differ significantly compared to groundwater in Upper Cretaceous host rocks consisting of Coniacian-Santonian and Cenomanian-Turonian fractured aquifers. The bromide tracer has the potential to be used for risk management purposes during mine water rebound in order to verify containment.

11:25am - 11:50am

Simulation of Column Leach Tests using Reactive Transport Modelling

Yuan Tian1, Johan Fourie2, Brent Usher2

1Golder Associates, Australia; 2Klohn Crippen Berger , Australia

Reactive transport modelling has become an increasingly powerful tool to assist the mining industry for assessing the long-term geochemical behaviour of mine waste materials during operation and post-closure periods.The reactive transport models were developed in this study to model the key geochemical processes that control sulfide oxidation and subsequent chemical reactions (e.g. dissolution/precipitation) for lab scale column leach tests. The models were refined to allow calibration of kinetic rates of several of the waste rock minerals based on leachate data. The reactive transport models form the basis of the predictive model of drainage water quality for full-scale mine waste facilities.

11:50am - 12:15pm

Application of Multivariate Statistical Analysis in Mine Water Hydrogeochemical Studies of the Outcropped Upper Carboniferous, Ruhr Area, Germany

Tuan Quang Tran1,2, Andre Banning1,3, Stefan Wohnlich1

1Hydrogeology Department, Faculty of Geosciences, Ruhr University Bochum, Germany; 2Hydrogeology Department, Faculty of Geosciences and Geoengineering, Hanoi University of Mining and Geology, Vietnam; 3School of Biological, Earth and Environmental Sciences, University College Cork, Ireland

This study aimed to identify the processes controlling geochemical characteristics of adit mine waters using correlation analysis and multivariate statistical techniques.

Hierarchical cluster analysis classified water samples into 5 geochemically distinct clusters. HCO3- and Ca2+ were the dominant ions in 4 clusters indicating carbonate dissolution, while a Na+ dominated cluster suggests processes of rock weathering and ion exchange.

In PCA, a total of three principal components accounted for 82.95% of the total variance, interpreted to represent general water-rock-interaction processes and more local and geological effects.

This study demonstrated the usefulness of multivariate statistical analysis in hydrogeochemistry.

10:10am - 12:15pmMine Water Treatment
Location: Meeting Room 2
Session Chair: Devin Sapsford
Meeting Room 2 
10:10am - 10:35am

Steel Slag-Limestone Reactor with Resistance to Fe: Laboratory and Pilot Scale Evaluations of Mn Treatment Efficiency

Duk-Min Kim1,2, Youn-Soo Oh2,3, Hyun-Sung Park2, Dae-Gyu Im1, Woong-Lim Lim1, Hye-Rim Kwon1, Joon-Hak Lee2,4

1Sangji University, Republic of Korea; 2Korea Mine Reclamation Corporation (MIRECO), Republic of Korea; 3Department of Earth and Environmental Sciences, Korea University, Republic of Korea; 4Department of Earth Resources and Environmental Engineering, Hanyang University, Republic of Korea

Mixed substrate of steel slag and limestone were applied in reactors to evaluate resistibility to Fe. Steel slag mixed with limestone could decrease Mn from 32–46 mg L-1 to <3 mg L-1 with addition of 4.5–24.4 mg L-1 of Fe in the bench-scale experiment. In the pilot-scale experiments in five mines in South Korea, 95–99% of Mn was removed during the maximum test period of 4 years. Precipitation as Fe and Mn carbonates may have contributed to the Mn removal and resistibility to Fe.

10:35am - 11:00am

Offscreen-Break Due to No-show or Last Minute Cancellation

IMWA 2021 Organizers

International Mine Water Association

11:00am - 11:25am

Magnetic Coagulation Technology For Coal Gasification Wastewater Treatment

Jianlei Gao1, Yan Liu1, Yixin Yan1, Wenhao Wang2

1School of Ecology and Environment, Zhengzhou University 450001, Henan, China; 2Zhengzhou University Design and Research Institute Co.Ltd., China

Coal gasification wastewater is refractory for its high colority, complex water quality components, heavy toxicity and poor biochemical purification ability. This study focused on the wastewater treatment of coal gasification in a coal chemical enterprise by magnetic coagulation technology. Under the optimum condition, the removal rate of COD, turbidity and solube SiO2 were 27.6%, 97.0% and 68.4%, respectively. And the average recovery of magnetic powder was up to 97.38%. This paper provides technical guidance for the engineering application of the magnetic coagulation in coal gasification wastewater.

11:25am - 11:50am

Final Treatment Trials On Cwm Rheidol - Ystumtuen Mines Discharges, Wales, Using Sono-electrochemistry (Electrolysis With Assisted Power Ultrasound)

Peter Clive Stanley1, Chris Bullen2

1Natural Resources Wales, United Kingdom; 2Power & Water

Results of the successful 2019 Sono-electrochemistry Soneco© final pilot trials using a magnesium electrode are presented. The preferred pH range was 8.8 to 9.0 removing 90.0%, 95.7% and 95.1% total lead, zinc and cadmium.

Full-scale treatment plant would utilise 3.1 kW/m3/h, a clarification area of 57m2 (enabling the lamella to fit in the existing filter beds) generating a sludge volume of 4.8m3/day at 2% w/w (further dewaterable by press). CapEx for a comparable high-density sludge process has an appealing ratio of 1:3. Reducing electrode costs will make OpEx more competitive whilst planned process enhancements will lower CapEx and OpEx further.

11:50am - 12:15pm

Scale-up of Electrochemical Units for Mining Waters Treatment

Maria Mamelkina, Ritva Tuunila, Antti Häkkinen

LUT University, Finland

Mining industry is getting more attracted to developing water treatment technologies. The ease with which technology is brought from lab to industrial scale, along with minimizing the time consumption and costs, is influenced by several factors. Some of these depend on the reactor, removal mechanisms, volumes and operating conditions. While others are affected by external factors such as the maximum size of the equipment, treatment costs of established or alternative technologies. Scale-up is mainly employed to see if the technology meets the market requirements and expectations. This study focuses on transferring an electrocoagulation process from lab scale to pilot plant.

10:10am - 12:15pmWaste Rock
Location: Meeting Room 3
Session Chair: Trystan James
Meeting Room 3 
10:10am - 10:35am

Effects of pH on arsenic mineralogy and stability in Poldice Valley, Cornwall, United Kingdom

Julian Tang1, Eric Oelkers2, Julien Declercq1, Rob Bowell1

1SRK Consulting, 17 Churchill Way, Cardiff, CF10 2HH, UK; 2University College London, Gower Street, London, WC1E 6BT, UK

Many abandoned mine sites in Cornwall, UK, are characterised by elevated concentrations of arsenic (As), which can cause contamination of surrounding soil and water resources. These sites have important historical value that requires access to be maintained, despite exposure of humans to toxins that may lead to health issues including hyperpigmentation keratosis (including skin cancers) and liver fibrosis. The abandoned mine tailings at Wheal Maid has been assessed for As-bearing mineralogy and stability taking into account the public footpaths made by the local council to areas of potential contamination.

10:35am - 11:00am

Mobilization Of Environmentally Hazardous Elements Dressing Tailings Of Loparite Ores Under Atmospheric Precipitation

Eugenia Krasavtseva1,2, Dmitry Makarov1, Vladimir Masloboev1, Victoria Maksimova1,2, Anton Svetlov1

1Institute of the industrial ecology problems of the North, Kola Science Center RAS, Russian Federation; 2Laboratory of Nature-Inspired Technologies and Environmental Safety of the Arctic of the Federal Research Centre “Kola Science Centre of the Russian Academy of Sciences”

The paper investigates the mobilization of environmentally hazardous elements from loparite ore concentration tailings when exposed to atmospheric precipitation. A sulfuric acid solution simulating acid rain and distilled water were used as model solutions. When exposed to a weak sulfuric acid solution, a manifold increase in the decomposition rate of the tailings was observed. The concentrations of non-ferrous metals in the resulting solutions, when the test material was moistened with an acid solution, many times exceeded the maximum permissible concentrations for fishery water bodies. An intense transfer to the solution of rare earth elements was observed.

11:00am - 11:25am

Variability in Mine Waste Mineralogy and Water Environment Risks: a Case Study on the River Almond Catchment, Scotland.

Simon Haunch1, Alan MacDonald2, Christopher McDermott3

1Scottish Environment Protection Agency, 231 Corstorphine Road, Edinburgh; 2British Geological Survey, Research Avenue South, Edinburgh; 3School of Geoscience, Grant Institute, James Hutton Road, Edinburgh

The River Almond catchment contains coal, oil shale and ironstone mine waste and displays widespread surface water metals pollution. Mineralogical investigations and geochemical modelling at four mine waste sites identified pyrite oxidation and jarosite, siderite and aluminosilicate dissolution reactions as the primary sources of metal pollutants (Fe, Mn, Al). Carbonate dissolution reactions control drainage pH. Pyrite is absent in burnt oil shale waste, however, trace content in unburnt shale horizons is implicated as a source of Fe in drainage waters. Site specific water quality and load assessments indicate pyrite bearing coal and ironstone sites present the greatest water environment risks

11:25am - 11:50am

🎓 Assessing Heavy Elements In Tailings Water Around A Uranium Mine In Namibia

Vera Uushona1,2, Manny Mathuthu1

1North-West University (Mafikeng), South Africa; 2National Radiation Protection Authority of Namibia, Ministry of Health and Social Services, Harvey Street, Namibia

The study investigated the concentration of heavy elements in ground water and process water from the tailings of a uranium mine in Namibia. Inductively Coupled Plasma Mass Spectrometry was used to evaluate the concentration of heavy metals. Tailings water had higher average concentration of elements compared to ground water. The concentration of uranium in the ground water was above 15 µgl-1 and 30 µgl-1 as set by WHO and USEPA This shows that the ground water near the uranium mine is toxicologically not fit for human consumption.

11:50am - 12:15pm

The Use of Industrial Alkaline Wastes to Neutralise Acid Drain Water from Waste Rock Piles

Nikolay Maksimovich, Vadim Khmurchik, Olga Meshcheriakova, Artem Demenev, Olga Berezina

Natural Science Institute of Perm State University, Russian Federation

Around 100 piles of waste rock are located in the Kizel coal basin, Western Urals, Russian Federation. A lot of metals and metalloids are transported with drain water from waste piles to soil, groundwater and the nearest river systems and pollute them. We studied the capability of industrial alkaline wastes, covered waste rock piles, to neutralise drain water, formed during rainfalls. The most effective alkaline reagent for drain water neutralization was soda plant’s waste. The investigation revealed that organic substances addition increased the efficiency of waste rock piles treatment with alkaline wastes used.

12:15pm - 1:00pmLunch
1:00pm - 3:30pmMine Drainage Chemistry
Location: Meeting Room 1
Session Chair: Peter Clive Stanley
Meeting Room 1 
1:00pm - 1:25pm

Design, Operation, and Preliminary Findings from a Field Acid Rock Drainage (ARD) Study at the Bagdad Copper Mine in Arizona

Madhumitha Raghav1, Jessica Szaro1, Trika Graham2, Brent Callen2

1Freeport-McMoRan, Inc.; 2Freeport-McMoRan Bagdad, Inc.

A field test pad study is ongoing at the Bagdad mine in Arizona to understand acid rock drainage (ARD) and metal leaching (ML) potential of development rock and leached ore stockpiles under field conditions. Seepage oxidation-reduction potential (ORP) and dissolved oxygen (DO) data indicate test pads conditions are not oxygen limited and hence, are likely to promote sulfide oxidation. Seepage pH has remained in the circumneutral range for development rock pads. Seepage flow response suggests development of preferential flow paths within the pads. Study results will be used to support on-going mine planning and permitting processes at the Bagdad mine.

1:25pm - 1:50pm

Trace Element (As, F, U) Contamination and Hydrogeochemistry in the Vicinity of a Mexican Ore Mine

Andre Banning1,2, Desiree Schwertfeger1, Sócrates Alonso Torres3, Antonio Cardona Benavides4

1Hydrogeology Department, Faculty of Geosciences, Ruhr University Bochum, Germany; 2School of Biological, Earth and Environmental Sciences, University College Cork, Ireland; 3Postgraduate Program in Minerals Engineering, Faculty of Engineering, Universidad Autónoma de San Luis Potosí, Mexico; 4Earth Sciences Department, Faculty of Engineering, Universidad Autónoma de San Luis Potosí, Mexico

Dissolved fluoride (F), arsenic (As) and uranium (U) concentrations in ground and surface waters around the San Antonio el Grande Mine (Chihuahua/Mexico) exceed drinking water guidelines in 72.8%, 64.0% and 58.4% of all samples, thus threatening the most important drinking water source in the region.

To address the question of trace element origin and underlying mobilisation and transport processes, 125 water samples were analysed and evaluated.

Lithology is dominated by acidic igneous rocks and limestones with numerous mineralisation zones.

Solution processes were identified as the main driver for increased concentrations mainly depending on pH value and temperature.

1:50pm - 2:15pm

Effect of Mining to Water Quality in Chua and Revué Rivers, Mozambique

Clemencio Nhantumbo1, Estevao Pondja1, Dinis Juizo1, Antonio Cumbane1, Nelson Matsinhe1, Bruno Paqueleque1, Miguel Uamusse1, Gretchen Gettel2, Mário Franca2,3, Paolo Paron2

1Univerisidade Eduardo Mondlane, Mozambique; 2IHE-Delft Institute for Water Education; 3Delft University of Technology

Anthropogenic activities, particularly artisanal and industrial gold mining, have been affecting water resources in Manica Province, in Mozambique. Evaluation of water pollution in Révue and Chua rivers due to gold mining was done through field observations and laboratory analysis. This investigation revealed that water quality is being affected by activities developed in the river basin. Turbidity (200-5600 NTU) and concentration of sulfate (25-56 mg/L) are the most affected parameters. pH values measured were below 6.5 in two monitoring points. Although, agriculture is also present in the studied area, gold mining is likely to be the main source of water pollution.

2:15pm - 2:40pm

Efficacies of Pervious Concrete and Zero-valent iron as Reactive Media for Treating Acid Mine Drainage

Ayanda Nomaswazi Shabalala

University of Mpumalanga, South Africa

Batch reactor tests using pervious concrete (PervC) made at 0.27 water /cement ratio by mixing granite aggregate and Portland cement CEM I 52.5 R were performed to compare the use of PervC versus zero-valent iron (ZVI) for treatment of Acid Mine Drainage (AMD). The removal rates for Ca, Mg, Al, Fe, Mn, SO4 and Cu were greater for AMD samples that were treated with PervC reactive media relative to those treated with ZVI. The pH- driven metal precipitation and adsorption of precipitates onto the surface of PervC and gypsum by-product are the main mechanisms of removal of metals from AMD.

2:40pm - 3:05pm

🎓 Prediction Of Water Quality Parameters Using Unmanned Aerial Vehicle Multispectral Imagery In Acidic Water Bodies In The Iberian Pyrite Belt (Tharsis, SW Spain)

Melisa Alejandra Isgró1,2, María Dolores Basallote1, Luis Barbero2

1Department of Earth Sciences, Research Center on Natural Resources, Health and the Environment (RENSMA), University of Huelva, Campus El Carmen s/n, 21071 Huelva, Spain; 2Department of Earth Sciences, University of Cádiz, Campus Universitario de Puerto Real, 11510 Puerto Real, Cádiz, Spain

This study presents a novel approach of using high-resolution multispectral data acquired by an unmanned aerial system (UAS) combined with in situ chemical data to assess water quality parameters at 12 relatively small water bodies located in the Tharsis complex, an abandoned mining area highly affected by acid mine drainage (AMD) pollution. The spectral data jointly with water physicochemical data were used to estimate water quality parameters using regression analysis. Parameters including pH, ORP, EC, Al, Cu, Fe, Mn, S, Si, and Zn were estimated with high accuracy levels while Ba, Ca, and Mg showed low accuracy.

1:00pm - 3:30pmMine Water Treatment & Benefits Enhancement
Location: Meeting Room 2
Session Chair: Rhys John Savage
Meeting Room 2 
1:00pm - 1:25pm

Process For The Subsoil Treatment Of Acidified Groundwater Through Microbial Sulfate Reduction

Ralph Schöpke1, Manja Walko2, Konrad Thürmer3

1Brandenburgische Technische Universität Cottbus-Senftenberg, Germany; 2Lausitzer und Mitteldeutsche Bergbau-Verwaltungsgesellschaft mbH; 3Institut für Wasserwirtschaft, Siedlungswasserbau und Ökologie (IWSÖ GmbH)

Sulphate and the acidity formed mainly from ferrous iron ions are the main contaminants of groundwater affected by mining. The Chair of Wassertechnik & Siedlungswasserbau at BTU Cottbus-Senftenberg has developed a subsurface rehabilitation method using microbial sulfate reduction. The basis for dimensioning this technology is now available after a successful demonstration test in the Lusatian mining district. The used substrate guarantees complete implementation and does not trigger any further damaging effects. Nutritional supplements (N, P) are kept to a minimum. The concentration of hydrogen sulfide in equilibrium with the precipitated iron sulfides limits the treatment effect in the incorporation phase.

1:25pm - 1:50pm

Solvent Extraction To Recover Copper From Extreme Acid Mine Drainage

Amir Nobahar1,2, Alemu Melka1,2, Jorge Carlier1, Maria Clara Costa1,2

1Centre of Marine Sciences (CCMAR), University of the Algarve, Gambelas Campus, 8005-139 Faro, Portugal; 2Faculty of Sciences and Technology, University of the Algarve, Gambelas Campus, 8005 139 Faro, Portugal

This study evaluated the application of a solvent extraction process from an extreme Acid Mine Drainage (AMD) (with 5.3 ± 0.3 g/L Cu). The extractant Acorga M5640 showed high copper selectivity and 30% (v/v) of this extractant, extracted ~96% of this metal with a maximum loading capacity of ~16 g/L in the organic phase. Then, 2M sulfuric acid solution stripped ~99% of copper and through successive striping steps the concentration of copper was raised up to ~46 g/L, which is suitable for the electrowinning process. Recyclability of the organic phase was also confirmed in five successive extraction and stripping cycles.

1:50pm - 2:15pm

Enhancing Biological Nitrogen Removal from Mine Site Water in Cold Climate

Piia Juholin1, Kirsi-Marja Haanpää1, Elena Torresi2, Fernando Morgan-Sagastume2

1AFRY Finland Oy; 2AnoxKaldnes - Veolia Water Technologies AB

Biological nitrogen removal from cold mine water can be challenging due to low biological activity of the biomass, which may increase the size of the treatment unit and lead to increased costs. This paper introduces some design solutions that may improve the usability of biological nitrogen removal in cold climate. These solutions include taking advantage of warmer seasons and the thermal energy of underground mine water, heating and reuse of waste heat produced in concentration plants, treating a specific water stream with a considerable nitrogen load, and pretreating the influent.

2:15pm - 2:40pm

Innovative Adaptation of Mining Hydrogeology Practices during a Pandemic

Sofia Nazaruk, Grace Yungwirth, Jessica Nicholls, Gareth Digges La Touche

Golder Associates (UK) Limited

Traditional mining hydrogeology practices during site characterisation programmes have relied heavily on the availability of experienced practitioners to travel to mine sites. This was not possible during the COVID-19 pandemic and adaptations of previously established workflows were required. This paper aims to outline an approach for the remote oversight of field programmes by experienced practitioners and outlines the relative risks, rewards and key limitations to the approach developed.

2:40pm - 3:05pm

Employment Of A Double Continuum Model To Characterize Groundwater Flow In Underground Post-Mining Setups: Case Study Of The Ibbenbüren Westfield

Diego Bedoya-Gonzalez1,2, Timo Kessler2, Maria-Theresia Schafmeister2

1Department of Geography and Geology, University of Salzburg, Austria; 2Institute for Geography and Geology, University of Greifswald, Germany

Underground hard coal mining usually disrupt the mechanical equilibrium of the geological media, creating fractured zones in the bedrock. The present study employs a Double-Continuum model to assess the influence of the fractured and porous media on the percolation process at the Ibbenbüren Westfield. Model results displayed good agreement with measured mine water discharges. While fractured continuum reacts readily to heavy precipitations, water is released slowly from the matrix. This behavior generates a gradual decrease in the discharge over the dry season. Findings obtained from this approach can be integrated into reactive transport models to predict long-term evolution of mine drainages.

1:00pm - 3:30pmWaste Rock
Location: Meeting Room 3
Session Chair: Andrew Barnes
Meeting Room 3 
1:25pm - 1:50pm

The Relationships Between Negative Pore-water Potential, Water Content, Relative Humidity and Sulfide Oxidation in Waste Rock -- a Case Study

Eben Dy1, Kidus Tufa1, Elizabeth Fisher1, Zhong-Sheng {Simon} Liu1, Kevin Morin2, Michael O'Kane3, Tim O'Hearn4, Cheng Huang1, Qu Wei1

1National Research Council Canada; 2Minesite Drainage Assessment Group; 3O’Kane Conultants Inc.; 4Bureau Veritas

Acid rock drainage from mine waste is caused by the oxidation of sulfide minerals in moisture and air. In a test column filled with waste rock, oxidation was measured by oxygen consumption, moisture by weight, and negative pore-water potential indirectly by relative humidity. The results show an interesting correlation between the three.

In waste rock piles, moisture can reach areas not accessed by seepage of meteoric or ground water through vapour transport. Rocks retain/release moisture based on their water retention characteristics. This will in turn influence the relative humidity of the surrounding air space and sulfide oxidation rate.

1:50pm - 2:15pm

Numerical Modelling of Transient Groundwater Flow and Contaminant Transport at the Myra Falls Mine Site

Mahmoud Hussein1, Paul Ferguson1, Christoph Wels1, Nicole Pesonen2

1Robertson GeoConsultants Inc. (RGC), Canada; 2Nyrstar Myra Falls, Campbell River, Canada

The Myra Falls mine is an underground lead-zinc mine on Vancouver Island, British Columbia, Canada. The mine site has been operated since the 1970s and is affected by Acid Rock Drainage (ARD) generated by sulphide-bearing waste rock in the historic waste rock dumps. A numerical groundwater flow and transport model was developed using the software MODFLOW/MT3D to simulate the movement of groundwater and the transport of zinc in the Myra Valley Aquifer (MVA) and to predict Zn loads to Myra Creek during an emergency shutdown of the site-wide SIS.

2:15pm - 2:40pm

Quantification of Environmental Risk of U and Th in Witwatersrand Gold-Mine Tailings, South Africa

Robert Neill Hansen

Univeristy of the Free State, South Africa

This study explores the most likely mineral hosts and geochemical behaviour of U and Th in Witwatersrand gold tailings facilities with the purpose of quantifying environmental risk. U occurs in the mineral uraninite of which the dissolution is enhanced by the oxidation of pyrite, primarily in the oxidation zone of the tailings facility. U concentrations in tailings pore water may be controlled by secondary U-mineral phases in the tailings zones below the oxidation zone. Th is shown to be insoluble and the phase in which it occurs to be irrelevant in terms of environmental risk of Th leaching.

2:40pm - 3:05pm

A Multicomponent Reactive Transport Modeling Toolbox for Prediction of Drainage Quality from Mine Waste Facilities

Muhammad Muniruzzaman1, Teemu Karlsson2, Päivi M. Kauppila2

1Water Management Solutions, Geological Survey of Finland, Finland; 2Circular Economy Solutions, Geological Survey of Finland, Finland

This study presents a new multiphase multicomponent mine-waste simulator, which is capable of capturing variably saturated water flow, multicomponent advective-dispersive transport both in aqueous and gaseous phase, and chemical reactions (solved with PHREEQC, utilizing PhreeqcRM module) including thermodynamic databases. We particularly emphasize on the Nernst-Planck and Maxwell-Stefan based formulations for the aqueous and gaseous transport, respectively, to explicitly resolve the multilevel process coupling, driven by solute/surface charge or gaseous pressure, across and within different phases. This framework radically goes beyond the state-of-the-art of classical mine-waste models, which exclusively rely on Fickian transport and capture only a subset of governing processes.

5:00pm - 6:30pmGeneral IMWA Assembly
Session Chair: Christian Wolkersdorfer
IMWA Members have received login details for this Zoom meeting previously.
Date: Tuesday, 13/July/2021
8:45am - 9:40amMorning Session Tuesday
Location: Main Room
Session Chair: Robert Vaughan
Main Room 

Tools to Assess the Benefits of Mine Water Management: Economic and Social Valuation of Ecosystem Services

Mike Christie

Aberystwyth University, United Kingdom

Creating Opportunities from the UK’s Mining Legacy

Lisa Pinney

Coal Authority, United Kingdom

9:40am - 9:50amHealth Break
9:50am - 12:20pmCultural & Benefits Enhancement
Location: Meeting Room 1
Session Chair: Louise Siddorn
Meeting Room 1 
9:50am - 10:15am

Tailings dam failure: Estimation of Outflow Volume

Amir Keshtgar

GHD, Australia

The supernatant water in the pool and the dry density of tailings play important roles in defining the sediment concentration and type of outflow fluid duaring a failre event. It is evident that the tailings breach volume is heavily dependent upon the post failure slope of the tailings. This study proposes a method to consider the geometrical model of the storage area alongside the geotechnical characteristics and hydraulic of the tailings and sediment concentration for each facility in order to estimate the release volume from the tailings dam rather than using a simplified release volume equation.

10:15am - 10:40am

Cultural Aspects Constraining Mine Water Supply Chain Management In Asal Areas Of Kitui County, Kenya

Erastus Kiswili Nyile1,2, Joash Kibet Kirwah2

1Taita Taveta University, Kenya; 2Jomo Kenyatta University of Agriculture and Technology

Kitui County receives low levels of rainfall annually thus considered as Arid and Semi-Arid (ASAL) area. The community has formed many cultural imaginations about water ensuing from scarcity and insufficiency of the commodity in the area. This study sought to establish how community livelihood, beliefs, norms and customs, poverty, rituals and gender involvement constrained mine water supply chain management. The findings showed that there is difficulty in accessing water and the quantity and quality available do not match community domestic needs. Consensus building and factoring in of cultural aspects is key in ensuring success of mining and extraction activities.

10:40am - 11:05am

🎓 Youth Participation and Inclusivity in Mine Water Sustainability in Kitui County, Kenya

Erastus Kiswili Nyile1,2, Joash Kirwah Kibet2

1Taita Taveta University, Kenya; 2Jomo Kenyatta University of Agriculture and Technology, Kenya

Water is a crucial and scarce resource in Kitui County posturing a sense of responsibility amongst the youth in the county to managing the available water resources towards sustainability. Notwithstanding, youths remain marginalized and excluded from participation in mine water sustainability decisions. The findings of this study indicated that youth participation and inclusivity in mine water sustainability was wanting in the county. This research recommends that youth should be on the forefront to spearhead mine water sustainability efforts and be given an opportunity to have their opinions and voices heard, and to take active part in mine water decision-making.

11:05am - 11:30am

Developing Integrated Water Management Models To Address Water Related Risks And Provide Resilience In The Mining Industry

Scott Gregory Anderson, Tyler Tinkler

GHD, Australia

Integrated Water Management models comprises a spatially lumped representation of the components of a mine water management system and their interactivity including water supply and conveyance infrastructure, hydrological and hydrogeological processes, ore processing, water treatment and waste disposal. The model can be used to assess different operational and/or expansion scenarios and their evolution over a mine’s life to provide probabilistic outputs of impacts to the water system and identify areas where capacity is constrained and optimisation opportunities exist. We examine the potential benefits and limitations through case studies in both underground and open cut operations, throughout the mine life cycle.

11:30am - 11:55am

Utilization Of Mine Waste To Produce Sustainable Housing Materials For Artisanal Miners And The Surrounding Communities -A Case Study Of Mkuki, Taita Taveta County, Kenya

Phillis Mutheu Mbinda



Artisanal mining in Kenya contributes 60% of the gemstone mining revenue. In spite of this, the poverty levels among the artisanal miners remain high. Most of the artisanal miners live in shacks. Poor living conditions contribute to poor mental and physical health. This study sought to utilize mine water, mine waste-overburden and rocks to make sustainable housing bricks. Provide solutions to better housing and provide additional sources of income to the artisanal miners and the surrounding communities.

11:55am - 12:20pm

🎓 Application of Artificial Intelligence Systems in Mine Water Management – An Introduction to two Effective Predictive Models

Kagiso Samuel More, Christian Wolkersdorfer

Tshwane University of Technology (TUT), South Africa

This work presents a summary of machine learning techniques that are effective in predicting acid mine drainage (AMD). Machine learning can be divided into different categories such as supervised, unsupervised and reinforcement learning. In this study, a supervised learning method will be explored. In this technique, a model has input variables and an output value, and uses an algorithm to learn the mapping function from the input to the output. Predictive analysis is the key focus in this study. Therefore, regression supervised learning techniques will be investigated, and this includes artificial neural networks (ANN) and random forest.

9:50am - 12:20pmCleaning Up
Location: Meeting Room 2
Session Chair: Robert Vaughan
Meeting Room 2 
9:50am - 10:15am

A UK progress overview of Metal Mine Remedial Work

Peter Clive Stanley1, Potter Hugh2

1Natural Resources Wales, United Kingdom; 2Environment Agency, United Kingdom

10:15am - 10:40am

A GIS-Based Prioritisation Of Coastal Legacy Mine Spoil Deposits In England And Wales For Effective Future Management

Alex L. Riley1, Patrizia Onnis2, Elin Jennings2, Richard A. Crane2, Karen A. Hudson-Edwards2, Sean D.W. Comber3, Ian T. Burke4, Patrick Byrne5, Catherine J. Gandy6, Adam P. Jarvis6, William M. Mayes1

1Department of Geography, Geology and Environment, University of Hull, Hull, HU6 7RX, UK; 2Environment & Sustainability Institute and Camborne School of Mines, University of Exeter, Penryn, TR10 9DF, UK; 3School of Geography, Earth and Environmental Sciences, Plymouth University, Plymouth, PL4 8AA, UK; 4School of Earth and Environment, University of Leeds, Leeds, LS2 9JT, UK; 5School of Biological and Environmental Sciences, Liverpool John Moores University, Liverpool, L3 3AF, UK; 6School of Engineering, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK

Increases in coastal flooding and erosion due to climate change threaten many coastal mine waste deposits in the UK. As such, a robust approach to prioritising sites for management is required. A spatial dataset of 9094 mine spoil deposits in England and Wales was analysed against coastal erosion and flood projections to identify deposits most at-risk. Of these, 58 were at risk of tidal flooding and 33 of coastal erosion over the coming century. Within the 10 highest-priority deposits, 426,283 m3 of spoil was at risk of release by erosion, with Blackhall Colliery (County Durham) being the largest predicted contributor.

10:40am - 11:05am

Emerging Opportunities for Improving Legacy Metal Mine Water Pollution Driven by Changing Regulatory Environments and Outputs of Novel Fieldwork in the Southern Uplands of Scotland.

Alan Yendell1, Patrick Byrne2

1Scottish Environment Protection Agency, United Kingdom; 2Liverpool John Moores University, United Kingdom

The Wanlock Water is polluted by relicts of a former lead mining and processing industry. The problem is well known but it has been difficult to justify funding bids for remediation due to uncertainty about the scale of the water quality improvement remediation works could deliver. Utilising opportunities created by a regulatory shift at SEPA, source apportionment work has been undertaken. Application of tracer injection and synoptic sampling in the Wanlock Water improved the understanding of key sources. Water quality improvements achievable by remediation have been estimated and the data now supports collaboration to develop potential solutions with multiple benefits.

11:05am - 11:30am

Challenges of Watershed Mine Drainage Characterisation and Remediation at Scale: Force Crag Base Metal Mine, Cumbria, UK

Catherine J Gandy1, Adam P Jarvis1, Nick Cox2, Stephen Lofts3, John Malley4, Arabella M L Moorhouse-Parry2, Katherine S Neate1, Barbara Palumbo-Roe5, Hugh A B Potter6

1Newcastle University, United Kingdom; 2The Coal Authority, United Kingdom; 3UK Centre for Ecology & Hydrology, United Kingdom; 4National Trust, United Kingdom; 5British Geological Survey, United Kingdom; 6Environment Agency, United Kingdom

The challenges of watershed mine drainage characterisation and remediation are reported. Whilst the substantial benefits of point source remediation under low flow conditions are demonstrated, the dominance of diffuse sources on instream zinc flux at higher flows limits the overall improvement in downstream water quality. A watershed approach to remediation is therefore required with consideration given to remediation of diffuse, as well as point, sources. The design and installation of infrastructure, such as flow-monitoring devices and boreholes, throughout the Force Crag mine watershed has enabled a comprehensive investigation of the nature and importance of the various pollution sources.

11:30am - 11:55am

Numerical Modelling of Mine Pollution to Inform Remediation Decision-making in Watersheds

Patrick Byrne1, Patrizia Onnis1,2, Robert L Runkel3, Ilaria Frau1, Sarah F L Lynch4, Aaron M L Brown5, Iain Robertson5, Paul Edwards6

1Liverpool John Moore's University, United Kingdom; 2University of Exeter, United Kingdom; 3U.S. Geological Survey, USA; 4AECOM Ltd. United Kingdom; 5Swansea University, United Kingdom; 6Natural Resources Wales

Prioritisation of mine pollution sources for remediation is a key challenge facing environmental managers. This paper presents a numerical modelling methodology to evaluate potential improvements in stream water quality from remediation of important mine pollution sources. High spatial resolution synoptic sampling data from a Welsh watershed were used to calibrate the OTIS solute transport model. Simulation of mine pollution remediation scenarios using OTIS revealed decreases in stream Zn concentrations between 9% and 62% under mean streamflow conditions. Remediation scenarios under low streamflow conditions were less effective (<1% to 17% decrease in Zn concentrations), due to diffuse and metal-rich groundwater inflows.

11:55am - 12:20pm

🎓 Source Apportionment of Trace Metals at the Abandoned Nantymwyn Lead-Zinc Mine, Wales

Aaron Martin Lawrence Brown1, Iain Robertson1, Rory P.D. Walsh1, Patrick Byrne2, Paul Edwards3, Tom Williams3

1Swansea University, United Kingdom; 2School of Biological and Environmental Sciences, Liverpool John Moores University, Liverpool L3 3AF, UK; 3Natural Resources Wales, Faraday Building, Swansea University, Swansea SA2 8PP, UK

Abandoned metal mines cause longstanding stream pollution problems. The two streams at Nantymywn, Wales, the Nant y Bai and the Nant y Mwyn, cause the River Tywi to fail WFD standards for Zn for 35 km. In this study NaBr tracer dilution and synoptic water sampling, followed by ICP-MS laboratory analysis, were carried out in baseflow conditions along the Nant y Bai to identify and quantify sources of metals at high spatial resolution. Preliminary results enable Zn sources to be located, including one representing 34% of the stream Zn load, as well as areas of diffuse sources and attenuation.

9:50am - 12:20pmPassive Treatment
Location: Meeting Room 3
Session Chair: William Timothy Perkins
Meeting Room 3 
9:50am - 10:15am

Lake Kepwari: Western Australia’s First Successfully Relinquished Mine Lake.

Cherie McCullough

Mine Lakes Consulting, Australia

Mine pit lakes typically present significant mine closure liabilities in perpetuity though large volumes of contaminated waters. Lake Kepwari represents a significant achievement in mine closure planning as the first successfully rehabilitated and relinquished pit lake in Western Australia.

Lake Kepwari uses seasonal flow to remediate water quality and provide ecological connectivity to the broader catchment. State government endorsed the approach with a formal opening on December 2020 with significant infrastructure developments. Lake Kepwari demonstrates pit lake planning that presents a significant local opportunity for the mining town with regional benefits to state tourism and recreational opportunities too.

10:15am - 10:40am

Passive Treatment Of AMD Using a Full-Scale Up-Flow Mussel Shell Reactor, Bellvue Coal Mine, New Zealand

Dave Trumm, James Pope, Hana Christenson

Verum Group, New Zealand

This work presents the results of the first full-scale up-flow mussel shell reactor to treat AMD reported in the literature. In an up-flow configuration, the theory suggests that reducing conditions would be prevalent throughout the reactor, resulting in sulfate reduction and formation of sulfides rather than hydroxides which can reduce permeability with time in downflow reactors. The system raises the pH of the AMD from a median of 2.74 to a median of 6.94 and lowers metal concentrations by 97.2% (Fe), 99.8% (Al), 98.2% (Zn) and 97.0% (Ni). The benefits and challenges of up-flow reactors are discussed.

10:40am - 11:05am

Full-scale Compact Passive Treatment System for a Japanese AMD by Aerobic Bioreactor for Fe Removal and Sulfate Reducing Bacteria Bioreactor for Zn Removal

Kentaro Hayashi, Tsubasa Washio, Yusei Masaki, Takaya Hamai, Takeshi Sakata, Naoki Sato

Japan Oil, Gas and Metals National Corporation, Japan

Full-scale compact passive treatment system (flow rate: 100 L/min) was started at an abandoned mine site in Japan. AMD containing iron (35 to 40 mg/L) and zinc (15 to 20 mg/L) was treated in two biological steps: aerobic bioreactor with iron oxidizing bacteria and anaerobic reactor with sulfate reducing bacteria (SRB). In the aerobic reactor, iron was treated to below the wastewater standards by using a water transfer method such as a cascade. In the anaerobic bioreactor, two process utilizing rice bran and ethanol respectively, SO4 reduction and zinc removal were performed.

11:05am - 11:30am

Successful Passive Treatment of Sulfate Rich Water

James Donald Fraser Robinson1, Ian Andrews2, Jason Dodd3

1SLR Consulting Limited, United Kingdom; 2SLR Consulting Limited, United Kingdom; 3SLR Consulting Limited, United Kingdom

A passive sulfate reduction system was used to treat elevated sulfate within leachate from an old landfill and bench scale trials were established in 2019. This used of Biochemical Reactors to culture sulfate reducing bacteria. The resulting treated leachate was then passed through different iron media types to remove sulfide generated by the bacteria. An aerobic wetland used to polish the effluent. The success of the bench scale project led to a pilot scale system being constructed in 2020 providing insights into management of the system particular in winter months.

11:30am - 11:55am

Mobilization of Bound Arsenic and Antimony from Peat used for the Treatment of Mining-Affected Waters

Uzair Akbar Khan1, Vera Luostarinen1, Aileen Ziegelhöfer1,2, Katharina Kujala1

1University of Oulu, Finland; 2University of Applied Sciences FH Aachen, Germany

Mining-affected waters need to be purified for their safe discharge into water bodies. In Finland, peatlands are frequently used in the polishing phase of water treatment. Changes to inflow water quality to the treatment peatlands can trigger release of previously bound contaminants from the peat. A laboratory column experiment was designed to simulate leaching of arsenic and antimony from peat by transition from highly contaminated wastewater to less contaminated water. Inflow water composition change led to leaching and redistribution of bound arsenic and antimony in the peat column. Peak of bound arsenic/antimony shifted towards the outlet during the leaching phase.

12:20pm - 1:00pmLunch
1:00pm - 3:05pmLegacy Mine Impacts
Location: Meeting Room 1
Session Chair: Diana Brookshaw
Meeting Room 1 
1:00pm - 1:25pm

Investigating the sulfidation and high-temperature (100 °C – 200 °C) dissolution of As2O3 stored at the Giant Mine, NWT, Canada

Evelyn Tennant, Tom Al

University of Ottawa, Canada

The former Giant Mine, NWT, generated 237 000 tonnes of As2O3-rich dust as a by-product of gold mining. As2O3 is a relatively soluble form of As and is currently stored beneath the mine, posing a threat of contamination to the adjacent Great Slave Lake. This research investigates the potential for permanent remediation of the Giant Mine As2O3 through sulfidation. This research will contribute to the understanding of As2O3 solubility above 100 °C, and it explores the potential for applying high temperature-pressure dissolution as a preliminary step toward sulfidation of the As2O3 -rich mine waste.

1:25pm - 1:50pm

🎓 Effects of Coal Mining on the Lower Zambezi Basin, Tete Province, Mozambique

Vibeke Johansson1, Estêvão Pondja2, Kenneth M. Persson1

1Division of Water Resource Engineering, Lund University, Lund, Sweden; 2Chemical Engineering Department, Eduardo Mondlane University, Maputo, Mozambique

Recent discoveries of coal in Mozambique have attracted international mining companies to the area. Large amounts of groundwater and surface water are abstracted for coal mining drainage and coal processing. All wastewater is discharged to tributaries of the Zambezi River, which are used for irrigation, domestic purposes, and drinking water supply. A water quality assessment was done of two mines in the Zambezi basin through observations, chemical analysis and measured field parameters. Fieldwork was conducted in April 2019, revealing that both mines lack sufficient treatment of wastewater and one of tailing storage as it is led straight to the tributary.

1:50pm - 2:15pm

Treatability Trials To Remove Zinc From Abbey Consols Mine Water, Wales, UK

Tom Williams1, Julia Dent2, Thomas Eckhardt2, Matt Riding2, Devin Sapsford3

1Natural Resources Wales; 2WSP Ltd; 3Cardiff University

Abandoned metal mines are a principal cause of European Union Water Framework Directive (WFD) standards failures in Wales, with 1,300 mines affecting over 700 km of rivers. Abbey Consols lead-zinc mine discharges ≈3 kg day-1 of zinc to the River Teifi, causing WFD failures for at least 14 km. This paper presents results of laboratory and field trials to identify an effective method to remove zinc from Abbey Consols mine water. Sodium carbonate (Na2CO3) dosing to raise pH and facilitate precipitation is shown to offer an efficient and cost effective treatment solution, achieving >90% reduction in dissolved zinc concentrations.

2:15pm - 2:40pm

Passive Mine Water Treatment Trials of Dispersed Alkaline Substrate at Two Emblematic Mine Sites in Wales

Tobias Stefan Roetting1, Gareth Digges La Touche1, Iain Hall2, Louise Siddorn3, Peter Clive Stanley3, José Miguel Nieto4, Francisco Macías Suárez4, Alba Gómez Arias5,6, Julio Castillo6

1Golder Associates UK Ltd, 20 Eastbourne Terrace, London, W2 6LG, UK; 2Golder Associates UK Ltd, Citibase Edinburgh Gyleview, Gyleview House, 3 Redheughs Rigg, Edinburgh West Office Park, South Gyle, EH12 9DQ, UK; 3Natural Resources Wales, 29 Newport Road, Cardiff CF24 0TP, Wales; 4Department of Earth Sciences & Research Center on Natural Resources, Health and the Environment (RENSMA), University of Huelva, Avenida Tres de Marzo s/n, 21071 Huelva, Spain; 5Office for Research Commercialisation, University of the Free State, PO Box 339, Bloemfontein 9300, Republic of South Africa; 6Department of Microbiology and Biochemistry, University of the Free State, PO Box 339, Bloemfontein 9300, Republic of South Africa

Mine drainage from abandoned mines is a serious environmental legacy in Wales. Passive treatment is an attractive remediation strategy, but it has often failed due to premature clogging or passivation of the systems.

The Dispersed Alkaline Substrate (DAS) treatment system was developed to overcome these problems and is successfully deployed full-scale at two sites in SW Spain. In Wales the system is being tested at two emblematic metal mine sites, Parys Mountain and Cwm Rheidol.

The preliminary results from the trial at Cwm Rheidol and initial results from the column tests completed on Parys Mountain mine water are presented here.

2:40pm - 3:05pm

Should Irrigation With Mine-Affected Water Be Considered Part Of The Long-Term Strategy To Manage Acid Mine Drainage In The Witwatersrand Goldfields?

John George Annandale, Meiring du Plessis, Phil Tanner, Sarah Heuer

University of Pretoria, South Africa

Due to South Africa’s mining legacy, large volumes of acid mine drainage (AMD) threaten the quality of water resources. Treatment technologies exist, but are expensive and energy intensive. In the Witwatersrand Goldfields, three High Density Sludge water treatment facilities were established as emergency measure to neutralise large volumes of AMD in the Eastern, Central and Western Basins. These have been effective short-term measures, but sustainable long-term solutions are sought. Productive, cost-effective use can be made of these waters if used for irrigation, and livelihoods will be created. It is worthwhile to attempt to address any potential concerns with this option.

1:00pm - 3:05pmMine Water Treatment
Location: Meeting Room 2
Session Chair: Sudhagar Pitchaimuthu
Meeting Room 2 
1:00pm - 1:25pm

Refurbishment Of Water Treatment Plant Borna-West – From Lab Over Pilot Scale To Operation Plant Modification

Tim Aubel1, Falk Thürigen1, Roland Mayer1, Andre Hertzsch2

1G.E.O.S. Ingenieurgesellschaft mbH, Germany; 2Lausitzer und Mitteldeutsche Bergbau-Verwaltungsgesellschaft mbH, Germany

In this paper the refurbishment of the water treatment plant Borna-West in Germany is presented.

Experimental resulting from lab tests and a several months lasting on-site pilot test combined with the consideration for other necessary changes in plant operation. This led to the integration of an additional process step and a refurbishment of the plant, while ongoing operation.

1:25pm - 1:50pm

In-situ Hydrogen Peroxide Dosing Trials To Design Semi-Passive Treatment Schemes

Michael Alan Cox, Christopher Satterley, Waqas Ahmed, Benjamin Cordier

The Coal Authority, United Kingdom

The oxidation kinetics of ferrous iron in coal mine water can be increased using hydrogen peroxide solution. To determine hydrogen peroxide demand the Coal Authority used desk top modelling based on a presumption that all mine waters had a similar behaviour for iron oxidation kinetics.

During the early stages of project design trials of hydrogen peroxide dosing were undertaken to study the behaviour in-situ of real mine water rather than in a laboratory with synthetic water. Both trials demonstrated the benefits of using actual mine water because it allowed for efficient and cost effective, semi-passive treatment schemes to be designed.

1:50pm - 2:15pm

Osmodialysis - the Future of Oil Production Water Treatment

Matthias Fuhrland, Thomas Griessler

fluvicon GmbH, Austria

With Osmodialysis, the Austrian company fluvicon GmbH has developed a continuously operating, extremely robust membrane process based on forward osmosis that is capable of cleanly separating oil and salt water. Fouling and scaling - the two major problems of membrane separation technology - play no role. That enables extremely long membrane service lives despite high oil loads and water hardness. The range of applications extends from the treatment of produced waters, condensate and seepage water in the oil and gas industry, to the purification of contaminated seawater after tanker accidents, shipwrecks and well disasters.

2:15pm - 2:40pm

Prevention of Siltation in Artisanal Small-scale Mining

Esther Takaluoma1, Tatiana Samarina1, Antti Peronius2

1Kajaani University of Applied Sciences, Finland; 2Hangasojan Kulta Oy, Consulting company, Finland

Silting of waterbodies caused by sluicing in artisanal small-scale mining is a consquence of sluicing directly into receiving waterbodies. Silting lowers the acceptancy of mining activities by locals. Utilizing flocculants and/or coagulants in circulation ponds quickly reduces the amount of silt and colloids in the water. The flocculant can be applied with low-cost methods and the overall process is economical. The process has been tested in a 3-4 m3/h pilot in the Finnish Lapland.

2:40pm - 3:05pm

Mintek’s Integrated cloSURE(TM) Technology for Treatment of Acid Mine Drainage

Kerri du Preez

Mintek, South Africa

Mintek has developed cloSURETM for treatment of AMD. The process consists of two stages, biological sulfate reduction followed by oxidation for sulfide removal and biosulphur production. The process was demonstrated at laboratory scale and achieved sulfate reduction rates of 196 g/m3/d with 87% sulfate removal, and up to 98% sulphide removal. The pH level increased to 7.5 and metals were found to be within South African target water quality limits for irrigation. The results of the research show that cloSURETM is a potential solution for sustainable treatment of point sources of AMD.

1:00pm - 3:05pmMine Hydrogeology
Location: Meeting Room 3
Session Chair: Edward Austin
Meeting Room 3 
1:00pm - 1:25pm

Investigating Subvertical Dewatering Well Potential At An Open Pit Mine

Patrick Moran, Joe Ross, Ramsey Way, Rod Williams

Iron Ore Company Of Canada (IOC) / Rio Tinto, Canada

Groundwater is an operational risk at the Iron Ore Company of Canada (IOC). Orebodies being mined are currently dewatered via borefields comprised of vertical wells. While vertical wells are a proven technology, and have enabled mining to progress below water table, they are not an optimal solution. Subvertical wells are an optimal alternative. Two subvertical pilot holes were recently drilled at IOC. Both intersected favourable geological, geotechnical, and hydrogeological characteristics and are therefore interpreted as viable well targets. This paper presents investigative drilling results, in the context of well theory, and advocates for the construction of subvertical wells at IOC.

1:25pm - 1:50pm

Slope Depressurisation at Sishen Mine, Northern Cape, South Africa

Travis Hamilton White, Marnus Bester, Richard Carey

Anglo American Kumba Iron Ore, South Africa

Prior to 2014, the dewatering program at Sishen Mine focused exclusively on the deep fractured aquifer and neglected the upper shallow aquifer. In November 2014, increased pore pressures in the shallow aquifer led to slope instability with subsequent slope remediation measures costing more than USD9 million. This initiated the development of an active depressurisation program in its largest pit (GR80), to alleviate pore pressures. The system is an excellent example of the value of an effective depressurisation system which enabled slope design optimisation unlocking substantial value through a 24 million ton reduction in waste stripping and reduced production delays.

1:50pm - 2:15pm

The Use of Mineral Exploration Drilling to Kickstart Hydrogeology Data Collection for Pre-Feasibility Mining Studies and Beyond.

Kym Lesley Morton

KLM Consulting Services, South Africa

Groundwater information can be collected very inexpensively during exploration drilling, with holes used to create an early monitoring network. Information on water intersections, circulation losses, water chemistry and rest water levels can be collected by the contractor and site geologist.

Collection of basic information significantly reduces the cost of the initial hydrogeological study for the pre -feasibility reports. Decision criteria are provided for the use of the hole after drilling to optimise information and reduce risk when mining commences.

2:15pm - 2:40pm

Application Of Detailed Interval Flow Data Measured In Drillholes With PFL Tool In Hydrogeological Conceptualization And Numerical Flow Modelling For Mine Feasibility Scoping

Elias Pentti, Eero Heikkinen, Tiina Vaittinen

AFRY Finland Oy, Finland

Hydraulic drillhole measurements with the Posiva Flow Logging method have been performed at a planned open pit mining site in Northern Finland to acquire input data for numerical groundwater modelling. The high spatial resolution and low detection limit of the method enabled determining the hydraulic conductivity of bedrock, its depth dependence, and differences between two pit locations on a level sufficient for the numerical modelling. Separate FEFLOW models for two planned open pits were compiled and used to calculate groundwater inflow into the pits and effects on the water table in projected mining phases.

2:40pm - 3:05pm

Spatial and Temporal Changes of Physico-Chemistry Aspects of Mine Water, Due to Post-Closure Water Management

Lee M Wyatt, Jack Cropper, Ian A Watson

Coal Authority, United Kingdom

This paper describes how data collected from shaft sampling and electrical conductivity logging has been used to aid the assessment of complex mine systems. The paper focuses on sets of data from 4 coal mine shafts in the northeast of England, where sampling and logs have been undertaken from 2000 to 2020. The sites show both mine water level rise and ongoing mine water pumping to control the water level and prevent pollution. The paper shows how the mine water has changed over time, and also how pumping has influenced the water stratification in the shafts.

3:20pm - 5:00pmPoster
Location: Exhibition

The Effects Of Using Hydrogen Peroxide To Provide An Improved HDS Process

Jodie Evans1, Richard Morgan1, Richard Coulton2

1Siltbuster Ltd, United Kingdom; 2Materials Recovery Systems Ltd, United Kingdom

HDS treatment plants are effective active AMD remediation processes, comprising of two-stage systems using aeration as the oxidant. In this paper, the practicality of using H2O2 as an alternative oxidant to reduce to a single-stage HDS plant was assessed. Comparative trials were conducted (two-stage (conventional HDS) and single-stage processes) on a bench-scale HDS rig, treating a continuous flow of 150 mg/L Fe net alkaline synthetic mine water. Results demonstrate that HDS treatment plants can be modified to a single stage when using H2O2 without compromising water quality or dewatering capabilities (42% dewatered solid content) of the HDS process.

Distribution of Metals and Toxic Elements Between Carbonate, Sulfate, and Oxide Mineral Precipitates

Julie J. Kim1, Satish C.B. Myneni2, Catherine A. Peters1

1Department of Civil and Environmental Engineering, Princeton University, USA; 2Department of Geosciences, Princeton University, USA

Immobilization of toxic elements from pH adjusted sulfidic mine waters via coprecipitation in carbonate minerals was studied. To design toxic metal mitigation efforts and to assess permanence, it is important to know how trace elements distribute between mineral precipitates of different reactivity and stability under environmental conditions. Experiments using synthetic mine waters were conducted and various imaging and analytical approaches were coupled to image and quantify trace element uptake in precipitated mineral phases. In the copresence carbonate and oxide minerals, or carbonate and sulfate minerals, cadmium and zinc concentrations were consistently higher in calcium carbonate phases and demonstrated patterns of coprecipitation.

Geochemical sources and long-term implications of mine waste weathering, Cwmystwyth Mine, Wales

Rob Bowell2,3, Yulieth Marquinez1,2, Tim Jones2, Peter Braham2

1Palatine House, United Kingdom; 2Cardiff University, United Kingdom; 3SRK Consulting, United Kingdom

Evaluation of the distribution and leaching potential of lead, cadmium, and zinc from the Cwmystwyth Mine has been undertaken and demonstrated that metal leaching neutral mine drainage is being generated. Discharge water from mine workings, waste materials and outcrop generated some variations in terms of pH and metal concentration, with most samples showing alkaline results but higher metals from water that flows through the mine. The mine contributes a high metal load to the Ystwyth catchment. Contamination in the river is attributed to the water discharge and perhaps seepage from different mine tailings, adits and underground workings.

It is very unlikely that the site will be remediated by cover or removal of mine waste or by using passive treatment due to its topographical complexity, and the sensitive nature of the site, being within a protected Site of Special Scientific Interest (SSSI). Moreover, the data suggests that there have not been any improvements in terms of dissolved metals in the water when data was compared to historic values; hence the mine remains a potential source of metals to the catchment.

Modelling the Geochemical Behaviour of Desulfurized Tailings as a Moisture-Retaining Layer in Insulation Covers with Capillary Barrier Effects using MIN3P-THCm

Asif Qureshi, Bruno Bussière

Institut de recherche en mines et environnement (IRME), Université of Québec in Abitibi-Témiscamingue, Canada

A column laboratory experiment was performed to assess the hydrogeological, thermal, and geochemical behaviour of an insulation cover with capillary barrier effects (ICCBE) made of desulfurized tailings as the moisture-retaining layer and non-acid generating crushed rocks as the protective and the capillary break layer. The ICCBE was represented in a numerical model developed using MIN3P-THCm. The model simulated the thermal-hydrogeological-geochemical behaviour of the tested ICCBE. The laboratory tests and short-term modelling showed that the tested desulfurized tailings do not generate contaminants at a concentration higher than the regulatory limits and that they can be used as cover material in a typical arctic climate. The preliminary long-term modelling results also suggest that the column will not generate acidity and maintain a leachate quality below the regulatory limits.

Assessment of the Chemical and Ecological Recovery of the Frongoch Stream Following Remediation at Frongoch Lead and Zinc Mine, Mid Wales

Paul John Edwards1, John F. Murphy2, J. Iwan Jones2, Chloe Morgan1, Rory P.D. Walsh3, Julie Gething1

1Natural Resources Wales, United Kingdom; 2Queen Mary University of London, United Kingdom; 3Swansea University, United Kingdom

Diversion of Frongoch Stream in 2011 reduced inflows to Frongoch Mine, increasing streamflow and diluting contaminants. This, together with subsequent surface water management, capping, hydroseeding and revegetation from 2013-2018, led to overall decreases of 87%, 93% and 87% for dissolved Zn, Pb and Cd respectively. Residual discharges, however, still cause the stream to fail to comply with Water Framework Directive standards and there is only modest evidence of biological recovery to date. Sediment metal concentrations in 2020 indicate that ecological recovery may be impaired by enduring bed-sediment contamination, even where erosion and sediment transport of mine waste is successfully managed.

Numerical Groundwater Flow Modelling In Support Of Mine Water Supply In An Endoreic Groundwater System, Tasiast Mine, Mauritania

Martin Boland1, Florent Boddaert1, Geoff Beale1, Glen Hein2, Pieter Labuschagne3, Ryan Cox4

1Piteau Associates, United Kingdom; 2Kinross Gold Corporation; 3GCS; 4GEM Ltd

Tasiast Mine is located on the western margin of the Sahara Desert. Water for mine operations is supplied from a wellfield located 60 km west of the mine site and 25 km from the Atlantic coast. Since 2012 a 3D numerical groundwater flow model has been used, and updated annually, as part of regulatory compliance. Unlike most groundwater systems, natural groundwater elevations at the wellfield are below mean sea level, and simulating the interaction between abstraction at the wellfield and the groundwater system at the coast is challenging, requiring the ocean to act as a recharge boundary rather than a discharge zone. A 1D SEEP-W model was developed to quantify the recharge deficit developed over time in the coastal plain, together with determining the depth below which evaporation stops. These outputs were incorporated into a 2D numerical model transect, representing 5km of the coastal plain, which determined the interaction between sea water intrusion and evaporation. Evaporation from the coastal plain becomes the dominant driver within the local water balance, with the upward flux from the coastal flats balancing the inflow rate from the ocean.

"Extension Of Measuring Points Network For The Upper Aquifers Of RAG Aktiengesellschaft Through The Drilling Pferdekamp"

Christine von Kleinsorgen

RAG Aktiengesellschaft, Germany

Before the planned rise of mine water, the existing measurement profiles "Tiefe Pegel Mitte" and "Tiefe Pegel Ost" of RAG Aktiengesellschaft needs to be expanded. Measuring points to monitor the hydrogeological status and the hydrochemistry in different groundwater levels, were created with which the water level before, during and after a rise in the mine water is monitored. For this purpose, the drillings Pferdekamp 1, 2 and 3 with depths of 780m, 355m and 90m respectively were created in Marl, Germany at the former location of the Auguste Victoria mine shaft 8.

Methods of Environmental Bioindication of Rivers Prone to Technogenic Salinization

Mikhail Baklanov1, Pavel Mikheev1,2, Olga Mikheeva3, Tatiana Sheina1, Elena Khayrulina1

1Federal State Autonomous Educational Institution of Higher Education “Perm State National Research University”, Perm, Perm, Russia; 2Khabarovsk Branch of the Federal State Budget Scientific Institution “Russian Federal Research Institute of Fisheries and Oceanography” (“KhabarovskNIRO”), Khabarovsk, Russia; 3Perm Branch of the Federal State Budget Scientific Institution “Russian Federal Research Institute of Fisheries and Oceanography” (“PermNIRO”), Perm, Russia

Indication of technogenic salinization in freshwater water bodies is an important tool for the detection of environmental degradation. Studies of the chemical composition of rivers of the Kama River basin prone to salinization were supplemented by an analysis of cyanobacterial-algal cenoses and communities of zooplankton, macrozoobenthos, and fish. In the most saline sections of the rivers, halophilic and euryhaline species of diatoms, zooplankton, and zoobenthos dominate; fish are absent. Moreover, we have tested the parasitological and haematological analysis of fish for the possibility of using it in the bioindication of lower and intermediate levels of salinization. The results show the possibility of using new markers of salinity found by means of parasitological and haematological analyses. The development and application of new methods of bioindication of technogenic salinization of rivers, along with the traditional chemical and biological techniques, are important for the assessment of the impact of anthropogenic stress factors on the biota.

Systematic Approach in Environmental Geochemistry as Part of a Mining Project Roadmap

Päivi Picken, Anneli Wichmann, Eeva-Leena Anttila, Kirsi-Marja Haanpää, Elin Siggberg

AFRY Finland Oy, Finland

Geochemistry data gaps often result from insufficient consideration of site-specific circumstances or poor conceptualisation. Whoever plans the first mine site soil sampling or analysis of process trial residues, must understand the many future uses of the data. Misconceptions of other data users´ requirements disable future assessments and cause delays in project schedule. A systematic approach in environmental geochemistry enables better assessments and better environmental risk management. The successful project toolkit includes a combination of tools like conceptualisation, repetitive risk assessment, knowledge base management, gap analysis, roadmap, action plan and sampling and analysis plan.

Repurposing Mine Sites For The Well-being Of Future Generations: Innovative Examples And Case Study Of Developing Post Mining Remedial Work In Wales

Peter Clive Stanley1, Trystan James1, Bob Vaughan1, Steven Pearce2

1Natural Resources Wales, United Kingdom; 2Mine Environment Management Ltd.

The Well-being of Future Generations (Wales) Act 2015 introduced “sustainability” into legislation for the first time anywhere in the world aiming to improve the social, economic, environmental and cultural well-being of Wales. Seven case studies are described showing how Natural Resources Wales acted “in accordance with the sustainable development principle” revealing how public bodies must act in a manner seeking to ensure the needs of the present are met without compromising the ability of future generations to meet their own needs. Public bodies undertaking substantial capital spending have a duty to ensure they embrace community well-being by applying their Well-being objectives.

Selective Recovery of Copper and Cobalt from Mine Effluent

Esther Takaluoma1, Tatiana Samarina1, Gershom Mwandila2, Leonard Kabondo2, Kawunga Nyirenda2, Phenny Mwaanga2

1Kajaani University of Applied Science, Ketunpolku 1, FI-87100 Kajaani, Finland; 2Copperbelt University, School of Mines and Mineral Sciences, 4662 Jambo Drive, Riverside, Kitwe, Zambia

Adsorption is a powerful tool to remove contaminants ions from water. In here, two major limitations of adsorption technique (the accumulation of exhausted waste-adsorbent and poor selectivity) are overcome by time-dependent selectivity and cycling of adsorbent by selective desorption. Real mine effluent containing 917 ± 92 mg Cu/L and 36,9 ± 3,7 mg Co/L was used as a real-life sample to demonstrate the ability to separate Cu and Co by means of adsorption on MgO with subsequent recovery copper by leaching and cobalt as sulfide. The sorption-desorption cycle was repeated 12 times, with little loss of capacity. A brief economic evaluation suggests, that the approach will become suitable after optimization of parameter.

Integrated Dynamic Mine Water Balance Modelling with EcoBalance Model Libraries

Kirsi-Marja Haanpää1, Jacobus J. Van Blerk2, Jacobus J.P. Vivier3, Eric K. Howell4, Rodolfo Avila4

1AFRY, Finland; 2AquiSim Consulting Pty Ltd; 3Artesium Consulting Services (Pty) Ltd; 4AFRY, Sweden

Integrated water balance modelling is a tool that assists in the critical mining industry task of water management planning. The process starts with conceptualisation, which includes identification and description of all relevant site water management structures and usually involves the introduction of simple water balance modelling spreadsheets. Irrespective of their complexity, these models are usually analytical and utilise a deterministic approach. For more flexible modelling and a better understanding of the water management scenarios, dynamic water balance models are applied. This paper presents how the Ecolego® software tool is used for integrated dynamic mine water balance modelling.

Evaluation Of Preferential Pathways For An Effective Dewatering And Depressurization Of The Aitik Open-Pit, Norrbotten, Sweden

Florent Boddaert1, Hannington Mwagalanyi2, Simon Sholl1, Geoff Beale1

1Piteau Associates, United Kingdom; 2Boliden Mineral AB, Boliden Aitik, Sweden

Boliden’s Aitik mine in northern Sweden has a mine plan which will deepen the pit to 850 mbgl by the end of mine life. The control on pit slope pore pressures becomes critical to ensure stable slopes and a safe operation. This often requires numerical groundwater modelling to support the geotechnical analysis. Following industry best practice, a multi-disciplinary approach has been adopted over different campaigns of characterisation to improve the understanding of source zones, pathways and magnitudes of water reaching the pit wall and floor. This enabled the construction of a detailed conceptual model, with a high level of confidence, that served as a basis for the construction of a 3D numerical groundwater flow model.

Utilisation Of Mine Water From Abandoned Mines - Example “Anthracite Mine Ibbenbüren”, Germany

Marion Maria Stemke, Georg Wieber

Johannes Gutenberg-Universität Mainz, Germany

Sustainable and environmentally friendly extraction of raw materials for energy and materials is playing an increasingly important role in security of supply. The European Union compiles a list of critical raw materials at regular intervals. On this basis, mine water from the Ibbenbüren coal mine were examined. The results show that critical elements occur in the mine water. The concentration increases with depth. For the flooded Westfeld, the elements Al, B, Co, Li, Mg, Sr and Zn could be determined in the outflow and the loads determined. The calculation of the geothermal potential shows that about 900 single-family homes could be supplied with heat from the freely discharging mine water.

Study on Mechanism Analysis and Treatment Measures of Karst Water Disaster in Mines

Weitao Liu, Lifu Pang, Yanhui Du

Shandong University of Science and Technology, China, People's Republic of

According to the theory of rock mechanics and fracture mechanics combined with the actual geological conditions of the coal seam floor, the coupling of water and rock is analyzed, and it is believed that the karst pore water pressure has a greater influence on the strength of the floor rock. The method of numerical simulation is used to analyze the stress change of the floor and the failure of the plastic zone during mining at a water pressure of 1-8 MPa. It is believed that when the water pressure is greater than 4 MPa, the floor has a greater impact.

Characterization of Arsenical Mud from Effluent Treatment of AU Concentration Plants, Minas Gerais – Brazil

Mariana Lemos1, Teresa Valente1, Paula Marinho1, Rita Fonseca3, José Gregório Filho2, José Augusto Dumont2, Juliana Ventura2, Itamar Delben4

1Institute of Earth Sciences, Pole of University of Minho, University of Minho, Portugal; 2Anglogold Ashanti, Mining & Technical, COO International, Brazil; 3Institute of Earth Sciences, Pole of University of Évora, University of Évora, Portugal; 4Microscopy Center, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil.

The determination of the general properties of arsenical mud was carried out in effluent treatment plant of an Au metallurgical facility, located in Nova Lima, Minas Gerais, Brazil. This effluent, which comes from the calcination stage, is treated via Fe-coprecipitation / lime-neutralization and thus mud with high As concentration is generated. Instrumental methods were applied to investigate physical-chemical characteristics, such as pH, in addition to the forms of occurrence of As and its associations. The results indicated that the mud has an alkaline pH (» 8.5), particles with grain size below 20 µm, and As, Fe, S and Al concentrations above 5%. The element As is essentially associated with Fe, Ca, S, and Al, forming phases with wide compositional variation as major and minor constituents generically classified as "complex sulfates" and "compounds with S". The obtained results could assist optimization of the treatment routes in the plant and even to consider the potential reuse of this arsenic mud as a potential valuable product.

Mobility of Uranium in Groundwater-surface Water Systems in a Post-mining Context (Central Portugal)

Margarida Horta Antunes1, Paula Carvalho2, Teresa Albuquerque3, António Santos4

1University of Minho, Portugal; 2University of Coimbra, MARE – Marine and Environmental Science Centre, Department of Life Sciences, Coimbra, Portugal; 3Instituto Politécnico de Castelo Branco | CERNAS | QRural and ICT | Universidade de Évora; Portugal;; 4GeoBioTec, Department of Geosciences, University of Aveiro, Aveiro, Portugal

In uranium abandoned mine areas, particularly with mine tailings and open-pit lakes, the mobility of potentially toxic elements still acts as a source of surface and groundwater contamination. The water of open-pit lakes from Ribeira de Bôco mine and associated groundwater and surface water from the area is neutral and with low metal contents. However, some water samples are contaminated with Cd, Cr, Cu, Fe, Mn, As, and U and should not be used for human consumption or in agricultural activities. The baseline uranium threshold is considerably high for groundwater, which is supported by geogenic features and mining activities.

Overflow Estimation: A Study of MWN Pit Lake on East Borneo

Fahmi Syaifudin1, Yogi Pratama1, Karina Sujatmiko2

1PT Kaltim Prima Coal, Indonesia; 2Kansai University, Japan

The MWN pit lake was formed as a result of open-pit mining activities in one of the biggest coal mining companies in East Borneo, Indonesia. Forecasting the duration of pit lake filling and the subsequent overflow is important for a sustainable pit closure plan. This paper analyzes and predicts filling duration and overflow estimation using three different methods. Direct monitoring showed that the pit lake filling time is longer than the rational method and water balance calculation. The RSME between the direct calculation and water balance method is 4.71, while it is 14.6 with the rational method. Our result showed that the water balance method is a better approach for overflow forecasting. It showed that adjustment on input calculation parameter and calculation calibration is needed to get a precise estimation.

Hydrogeochemistry and Mineralogy of a River System in a Mining Region with a Cu-world-class Deposit in Mongolia

Soyol-Erdene Tseren-Ochir1,2, Teresa Maria Valente3, Tsermaa Kh2,4, Enkhdul T1,5, Munkhzul Davaadorj2,6,7, Boldbaatar Goosh2,6,8, Maria Amália Sequeira Braga3

1Department of Environmental and Forest Engineering, National University of Mongolia; 2Laboratory of Environmental Chemistry and Geochemistry, National University of Mongolia; 3Institute of Earth Sciences – pole of University of Minho, University of Minho, Braga, Portugal; 4Engineering Faculty, German Mongolian Institute for Resources and Technology, Nalaikh, Mongolia; 5Laboratory of Environmental Engineering and Clean technology, National University of Mongolia; 6Department of Chemical and Biological Engineering, National University of Mongolia; 7Water Agency, Ministry of Environment and Tourism, Mongolia; 8Water Supply and Sewerage Authority, Ulaanbaatar city Governance, Mongolia

The present work reports the environmental conditions of the Khangal River, under the influence of one of the biggest Cu mines in the world: the Erdenet mine, in North Central Mongolia. The results show that this River suffers the influence of the mining works and waste accumulations of the Erdenet Cu mine, although the neutral pH. The presence of calcite neutralizes the acidity of sulfides. In such alkaline conditions and in the absence of mineralogical control, elements such as Mo and As have high mobility, contaminating the ecosystem and preventing the use of water, either for consumption or for irrigation.

Acid Mine Drainage Precipitates At The Nanometric Scale – Properties And Environmental Role

Teresa Valente1, Ana Barroso1, Isabel Margarida Antunes1, Patricia Gomes1, Rita Fonseca2, Catarina Pinho2, Jorge Pamplona1, Maria Amália Sequeira Braga1, Juliana P.S. Sousa3

1Universidade do Minho, Portugal; 2Universidade de Évora; 3International Iberian Nanotechnology Laboratory

The mineral-water interactions responsible for mobilization of dissolved toxic elements in mine drainage often generate colloids that commonly occur at the nanometric scale. This study presents typical properties of these materials, mostly composed by iron-rich products. The samples were obtained in a variety of contexts, representing mine waters as well as natural acid rock drainage. Mineralogical results seem to confirm ferrihydrite forming nanoprecipitates at high pH and retaining arsenic. Further, the water properties could control the morphology and mineralogy of this very fine material, and consequently its environmental role.

Shear Behaviour of Compacted Gold Mine Tailings and Gold Mine Tailings Composite for Possible Use in Mine Backfilling.

Sisanda Prudence Gcasamba1, Koena Ramasenya1, Viswanath Vadapalli1, Stephen Ekolu2, Sammy Nyale1

1Council for Geoscience, South Africa; 2University of Johannesburg, South Africa

Utilisation of gold mine tailings (GMT) in mine reclamation requires a thorough understanding of its geotechnical characteristics. In this paper, a detailed experimental study carried on compacted gold mine tailings and gold mine tailings composite of varying curing ages is presented. Strength characteristics were investigated using consolidated drained (CD) and consolidated undrained (CU) triaxial tests under different confining pressures. The results obtained from the test showed that GMT composites exhibited higher strengths compared to untreated tailings. CD shear test revealed that GMT has a moderate capacity to withstand shear stress while the CU test showed an occurrence of static liquefaction.

Efficient Methodologies in the Treatment of Acid Water from Mines with Recovery of Byproducts

Osvaldo Aduvire1, Mayra Montesinos2, Nereyda Loza3

1SRK Consulting Peru, Peru; 2Pontifical Catholic University of Peru, Peru; 3SRK Consulting Peru, Peru

In general, the treatment of acid mine water is done via a one-stage process, at a determined pH level (Direct Treatment). In this article, a staged treatment methodology is presented (Staged Treatment), that makes the recovery of byproducts with economic value possible, as well as benefiting the environment by reducing contamination. This is achieved because we diminish the amount of non-usable slurry. For this reason, we will present the obtained results in Direct Treatment compared to those the Staged Treatment had, plus which byproducts were collected at different pH levels in the Staged Treatment. Finally, we will show flow.

Piloting a Sulfate Reduction System Using Chemical Precipitation for Wild Rice Waters

Lucinda Johnson, Meijun Cai, Shashi Rao, Adrian Hanson, ChanLan Chun, Sara Post, Alelxis Ward

University of Minnesota, United States of America

The Minnesota Pollution Control Agency (MPCA) has established a restrictive standard for sulfate of 10 mg/L in wild rice waters. Meeting this water quality standard is a special challenge for wastewater treatment facilities. Existing technologies (e.g., reverse osmosis; ultrafiltration) can achieve this standard, but are expensive and generate significant waste products. We are testing a chemical precipitation technology for removing sulfate cost-effectively, while also reducing the need for significant waste handling. Sulfate removal via barite precipitation has recently gained attention, as sulfate readily precipitates with barium salts as insoluble barium sulfate. It is not clear whether this application can be used cost effectively for municipal wastewater treatment, because that waste is dilute relative to other industrial waters (generally < 200 mg/L). We have previously demonstrated use barium chloride to precipitate sulfate (barite method) to levels below 10 mg/L. This led to a trailer-based demonstration system which will be tested at two wastewater treatment plants for two seasons. We discuss the results of our initial lab scale testing, as well as the results of the initial pilot scale deployment. Results are relevant to the mining industry, primarily for secondary treatment for polishing, following implementation of traditional treatment technologies.

Groundwater Nitrate Bioremediation of a Fractured Rock Aquifer System in South Africa

Paul Lourens1, Mariana Erasmus2, Robert Hansen3, Amy Allwright1

1Institute for Groundwater Studies, Faculty of Natural and Agricultural Sciences, University of the Free State; 2Saense Platform, Department of Microbial Biochemical and Food Biotechnology, Faculty of Natural and Agricultural Sciences, University of the Free State; 3Department of Geology, Faculty of Natural and Agricultural Sciences, University of the Free State

Due to the importance of groundwater in South Africa, the University of the Free State has successfully developed a zero waste bioremediation technology to treat nitrate pollution in water. Groundwater nitrate pollution of a fractured rock aquifer arose due to the storage of fertilizer effluent in unlined quarries. Numerical model simulations indicates that the proposed remediation removes the nitrate from the aquifer in a shorter timescale than the predicted natural attenuation. Treating the polluted water on site with the zero-waste bioremediation technique, and then re-injecting the treated water into the aquifer provides a holistic and sustainable solution to nitrate pollution.

Biological Treatment of Mining-Influenced Waters at Low Temperature

Hanna Heidi Anniina Virpiranta, Sanna Taskila, Tiina Leiviskä, Ville-Hermanni Sotaniemi, Jaakko Rämö, Juha Tanskanen

University of Oulu, Finland

Biological sulfate reduction is a widely studied treatment method for mining effluents containing sulfate and metals, especially at moderate temperatures. However, it is important to develop an efficient method for cold conditions also, as several mines operate in the Arctic region. In our previous study, consortia of sulfate-reducing bacteria (SRB) were enriched from a sediment sample collected from a mining area in northern Finland. After cold acclimation, the consortia were able to reduce sulfate at 6 °C with succinate as a carbon source. In a follow-up study, we used the consortia for sulfate reduction with low-cost carbon sources – whey from cheese manufacturing, natural peat, and conditioned sewage sludge – of which the sewage sludge was the most efficient. Further, we exploited the enriched SRB in a continuously operated up-flow bioreactor. The reactor was operated at near-neutral pH (7.0­–7.5) for the treatment of actual and synthetic acidic (pH 3.0±0.3) liquid streams containing sulfate and metals. Truly high sulfate reduction rate at temperature of 11.7±0.2°C was achieved. The SRB consortia have also been successfully tested for bio-regeneration of sulfate-laden anion exchangers.

UNEXMIN and UNEXUP Projects: Submersible Robots for Survey of Flooded Underground Mines. Showcasing Ecton Mine

Stephen Henley1,2

1Resources Computing International Ltd, United Kingdom; 2Ecton Mine Educational Trust

Submersible robots have been developed in the EU-funded UNEXMIN and UNEXUP projects, for surveying and exploration of flooded underground mines. They carry cameras and instrumentation to determine physical and chemical properties of wall rocks and water. On-board water samplers allow further laboratory analysis of the water.

Trials have been carried out at mines around Europe. Extensive dives yielded much new data on geology and archaeology, as well as the water which in one mine had been almost undisturbed since flooding to river level in the late 1850s. Some information is also presented on an important current project.

A short video shows tests of the first UNEXMIN robot at Ecton Mine, Staffordshire, UK

Floodplain Reconnection Stream Restoration In A Longwall Mining Region, Pennsylvania, USA

Natalie A Kruse Daniels1, Annika Gurrola1, Jordan Pazol1, Jacob South1, Nora Sullivan1, Jen Bowman1, Nicole Kirchner1, Ephraim Zimmerman2, Dave Goerman3

1Ohio University, United States of America; 2Western Pennsylvania Conservancy; 3Pennsylvania Department of Environmental Protection

This study tracks restoration projects in a longwall mine subsidence zone in western Pennsylvania, USA, that was completed using floodplain reconnection techniques rather than a more standard natural stream channel design. The restored sections are characterized by shallow, sinuous stream channels that readily inundate the adjacent floodplain wetlands. Floodplains are characterized with wetland microtopography with primarily wetland obligate and wetland functional plant communities. Upland tributaries are recontoured with lower maximum slope to reduce sediment transport and to reduce stream power into the main restored sections. Hydraulics, hydrology, sediment flux, and nutrient cycling and flux are being tracked simultaneously at quarterly intervals alongside deployed piezometers in both stream and wetland sections monitoring ongoing hydrology of the restored systems. Long-term water level data shows high frequency of floodplain inundation and channel flow and system discharge measurements show that there is a proportion of water that flows in the floodplain or hyporheic zone. This transient water storage can support dampened flood response when compared to the ‘flashy’ nature of most area streams, inundated floodplain wetland conditions driving nutrient cycling in the wetlands, and sustained perennial flow. These results suggest floodplain reconnection methods could be an alternative to natural channel design.

Scaling Passive Treatment Using Biopolymers for Lead and Zinc Removal from Metal Mine Pollution

Alice Lucy Slattery1, Tegan Imogen Allen1, Chris Hughes2, Luke Morgan3, Alex Finlay3, Hugh Christopher Greenwell1

1Department of Earth Science, Mountjoy Site, Durham University, United Kingdom DH1 3LE; 2X-Ray Minerals Ltd, Colwyn Bay, Conwy, Wales, United Kingdom LL29 7EF; 3Chemostrat Ltd, Buttington Cross Enterprise Park, Welshpool, United Kingdom SY21 8SL

Alginic acid is a polycarboxylated carbohydrate found in many species of seaweed, and has a very high affinity for dissolved metals. Whereas many small-scale experiments have been undertaken using alginic acid to trap dissolved metals, very little has been done to undertake scale-up to treat mine water discharge at significant flow rates. Here, data is presented from intermediate-scale trials with passive filter beds upto 1000 L bed volume, treating adit discharge waters of the Pugh's Adit, Cwmystwyth Mine, Wales, UK to remove Pb2+, Zn2+ and Cd2+. The inlet waters had concentrations of ca 300-800 ppb for Pb2+, and 18-22 ppm of Zn2+, with filters run for for periods of several weeks with a retention time of approximately 20 minutes. Metal removal and operational performance data for the trials are presented.

5:00pm - 7:00pmSocial Online Gathering
Join Zoom Meeting: | Meeting ID: 821 7945 3639 | Passcode: 946445
Date: Wednesday, 14/July/2021
8:45am - 9:40amMorning Session Wednesday
Location: Main Room
Session Chair: Carl Banton
Main Room 

Biotechnologies for the Treatment of Mining and Metallurgical Wastewater on the Context of Metal Recovery

Denys Villa Gomez

University of Queensland, Australia

Passive Mine Water Treatment in the UK – a view from Wales

William Timothy Perkins

Aberystwyth University, United Kingdom

9:40am - 9:50amHealth Break
9:50am - 11:55amEcology
Location: Meeting Room 1
Session Chair: Paul John Edwards
Meeting Room 1 
9:50am - 10:15am

The Effects Of Storm Events On Sediment, Nutrient, And Biofilm Dynamics In A Stream Recovering From Acid Mine Drainage

Natalie A Kruse Daniels1, Jennie Brancho1, Morgan L Vis2

1Environmental Studies Program, Voinovich School of Leadership and Public Affairs, Ohio University, United States of America; 2Environmental and Plant Biology Department, Ohio University, United States of America

This study quantified changes in nutrients, sediment transport, and algal biomass during normal and storm conditions in a treated acid mine drainage stream. Nitrate, sulfate, total reactive phosphorous (TRP), sediment deposition and total suspended solids (TSS) were measured during each sampling event. Biological response was measured by comparing algal biofilm biomass. Antecedent precipitation index (API) was an indicator of runoff potential. As API increased TSS increased, while chlorophyll a, conductivity, and sulfate decreased. TSS, nitrate, and sediment deposition were higher overall during storm events. TRP remained low at all sites during the sample period, suggesting phosphorous limitation.

10:15am - 10:40am

Effects of Vegetation on Erosion in Technosols Produced from Coal Waste

Daniel Campos Moro, Jéssica Weiler, Ivo André Homrich Schneider

Universidade Federal do Rio Grande do Sul, Brazil

The aim of this study was to evaluate soil loss by water erosion considering different technosols configurations produced from fine and coarse coal waste and an agricultural soil. All substrates were amended with sewage sludge to obtain 3% organic matter. The study considered two precipitation levels and the presence, or not, of the Medicago sativa (alfafa) and grass. Calculations were carried using the Revised Universal Soil Loss Equation. In terms of erosion control, the best configuration was attained with the mixture of coarse and fine waste. The presence of vegetation reduces in almost 100 times soil loss due rainfall.

10:40am - 11:05am

Biodiversity Benefits Of Coal Mine Water Remediation Schemes For Bird Life

Rosie O. Jaques1, Arabella M.L. Moorhouse-Parry2, Richard Carline2, William M. Mayes1, Susan L. Hull1

1University of Hull, United Kingdom; 2The Coal Authority, United Kingdom

Lagoons and reedbeds are established components of mine water treatment systems for iron-rich coal mine drainage. This study coupled British Trust for Ornithology Bird Survey monitoring with habitat survey to assess the presence and usage of two UK coal mine water treatment systems by bird species. Over thirty species were documented at the two sites including four red listed, eight amber listed and eighteen green listed species (under the BTO Birds of Conservation Concern designation). There were statistically significant associations of bird group with habitat types suggesting that a mosaic of habitats at coal mine treatment systems benefits bird diversity.

11:05am - 11:30am

Long-time Effect of Ancient Salt Production (Perm Krai, Russia)

Elena Khayrulina, Natalya Mitrakova

Perm State National Research University, Russian Federation

On the territory of the outflow of ancient brine wells in the valley of the Usolka River, soils and vegetation, transformed under the long-term impact of highly mineralized waters on the soil pore, were studied. Brines from ancient brine-lifting wells flow in streams along the soil surface and flow into the Usolka River determining its Na–Cl composition. The study area is characterized by the presence of salt-tolerant plants. Long-term influence of sodium-chloride waters on alluvial soils of the Usolka River led to the formation of a secondary gley sulfate-chloride solonchak (Gleyic Fluvic Solonchak (Loam, Salic)).

11:30am - 11:55am

Passive treatment of Acid Mine Drainage at Parys Mountain (Wales): column experiment results

Jose Miguel Nieto1, Tobias Rötting2, Peter Stanley3, Louise Siddorn3, Francisco Macías1, José María Fuentes1, Rafael León1, Riccardo Millán1

1University of Huelva, Spain; 2Golder Associates, United Kingdom; 3Natural Resources Wales, United Kingdom

Two sets of column test have been run for the design of a passive treatment of AMD at Parys Mountain. After 5 weeks of test runs, the two DAS system sets tested promote total metal removal of Fe, Al, Zn and Cu, and high retention / removal of Mn, As, Cd, Co, Cr and Ni by adsorption/coprecipitation processes. Sulfate removal was only efficient in one of the set-up. From the incoming 2340 mg/l of sulfate, the output solution concentration was 543 mg/l. No loss of permeability has been observed during the experiments.

9:50am - 11:55amPassive Treatment & Mine Closure
Location: Meeting Room 2
Session Chair: Carl Banton
Meeting Room 2 
9:50am - 10:15am

🎓 Performances of a semi-passive field-pilot for bioremediation of As-rich Acid Mine Drainage at the Carnoulès mine (France)

Camila Diaz-Vanegas1,2, Corinne Casiot1, Liming Lin3, Laurent De Windt4, Adam Djibrine2,3, Amandine Malcles3, Marina Héry1, Angelique Desoeuvre1, Odile Bruneel1, Fabienne Battaglia-Brunet2, Jerome Jacob2

1HydroSciences Montpellier, University of Montpellier, CNRS, IRD, Montpellier, France; 2French Geological Survey (BRGM), Water, Environment, Process and Analyses Division, Orléans, France; 3France LGEI (Laboratoire de Génie de l’Environnement Industriel), Institut Mines-Télécom Alès, Alès, France; 4MINES ParisTech, PSL University, Centre de Géosciences, Fontainebleau, France

Passive and semi-passive treatment systems show great potential to treat AMD originating from abandoned mines. The aim of this study was to determine iron and arsenic removal yields of two field treatment devices, which were designed to optimize natural process of bio-oxidation and co-precipitation to clean-up mine waste water. Almost one year of monitoring showed efficiency and stability of the treatment under environmental and operational variations. Using assisted aeration and bacterial support in the devices, average arsenic and iron removals of 67% and 43% were achieved. Additional steps will be considered to reach water quality and sludge disposal requirements.

10:15am - 10:40am

Performance Of The Hybrid Linear Flow Channel Reactor: Effect Of Reactors In Series For Enhanced Biological Sulphate Reduction And Sulphur Recovery

Tynan Steven Marais1, Rob John Huddy1, Rob Paul van Hille2, Susan Therese Largier Harrison1

1University of Cape Town, South Africa; 2Moss Group

Acid rock drainage (ARD) is a global crisis that will have long-lasting environmental consequences. The application of semi-passive biological sulfate reduction (BSR) is a potential solution for the remediation of persistent low-volume ARD effluents. However, major challenges of BSR, including slow reaction kinetics and management of the generated sulfide, still need to be addressed. The development of a hybrid Linear Flow Channel Reactor (LFCR) has shown promise for remediation of sulfate-rich effluents. In this study, the operation of two hybrid LFCRs connected as a dual reactor system was assessed for the improved removal of residual sulfide and COD.

10:40am - 11:05am

Saline Pit Lakes – What Biodiversity Values Can They Offer At Closure And Beyond?

Mark Lund, Melanie Blanchette

Mine Water and Environment Research Centre, Edith Cowan University, Australia

Closure of saline pit lakes is problematic as they are considered to have few prospects for future uses. In 2019, we assessed limnology and biodiversity of a two saline pit lakes (≈3.2-10.5 mS cm-1) from each of Australia’s main coal regions (Hunter Valley and Bowen Basin), one of which was rehabilitated.

Quarterly concentrations of nutrients, metal/metalloids and major ions were measured top and bottom with physico-chemical profiles throughout the water column. Aquatic biodiversity was assessed through macroinvertebrates, diatoms, and plankton communities.

Lakes were temperature but not salinity stratified and had limited metal/metalloid concentrations of concern. Salinity did not appear to limit biodiversity.

11:05am - 11:30am

Recharge-driven Underground Dewatering And Post-closure Groundwater Recovery

Simon Sholl1, Stephen Wheston2, Geoff Beale1

1Piteau Associates, Canon Court West, Abbey Lawn, Shrewsbury SY5 8AN, United Kingdom; 2Tembusu Ltd, 1 Killastafford Cross, Cashel, Co Tipperary, Ireland

Lisheen Mine, located in Tipperary, Ireland, was operational between 1999 and 2015. Through most of mine life, dewatering rates were typically within a seasonal range of 60 to 90 MLD, and rapidly changed with precipitation, which reflected the low storage of the limestone bedrock. After closure, groundwater levels in the mine workings rose over 120 m in the first three months, further demonstrating the low storage of the bedrock. Full recovery of the workings was confirmed in early 2018, 2 years after closure, when the natural seasonal variation in groundwater levels had re-established.

11:30am - 11:55am

Finite-element Modelling Approach To Study Flow Processes During Groundwater Rebound In Abandoned Underground Hard Coal Mines

Timo Kessler, Maria-Theresia Schafmeister

University of Greifswald, Germany

Groundwater rebound is one of the key challenges for the renaturation of underground mines. Numerical models can support the computation of rebound curves and the identification of long-term groundwater levels after steady-state conditions are reached. The present finite-element model case was to test the combination of different flow types and parameter configurations inside mine workings in order to optimally represent the flow patterns in cavity volumes and fractured rock masses. The approach may be an alternative to common pond-and-pipe models, particularly, if estimated cavity volumes of mine workings are uncertain or if groundwater levels in the surroundings are precarious.

9:50am - 11:55amMine Hydrogeology
Location: Meeting Room 3
Session Chair: Andrew Clifford Johnstone
Meeting Room 3 
9:50am - 10:15am

Using Data Science and Machine Learning to Improve Site Hydrogeological Conceptual Models

Tim Robert Ezzy, John Fortuna

Principal Hydrogeologist, Golder Associates, Brisbane, Queensland, Australia

A key goal of many mining groundwater investigations is to identify the main geological features, hydraulic boundaries and connection pathways that will materially influence: a) operations of a project, and b) the natural resources connected to the groundwater system. Exploratory data science techniques such as machine learning provide the experienced mining hydrogeologist opportunities to accelerate understanding of the role of key features within a site hydrogeological conceptual model (HCM) that may affect groundwater management. This has implications for both regulatory approval processes and operational efficiency.

10:15am - 10:40am

Open Pit-Mine Water Management In Equatorial Area

Yogi Pratama, Fahmi Syaifudin, Kris Pranoto


PT Kaltim Prima Coal, currently the largest open-pit coal mining company in Indonesia, is located in East Kalimantan. A province passed by the equator experiences heavy rainfall throughout the year. Annual average rainfall is recorded at 2,152mm. Controlling water inflow quantity is the most important thing in water management to have decent water quality. Proper design configuration consists of dry dam as flow detention and labyrinth pond for quality adjustment. Water discharge reduction up to 90% in average brings enormous benefit for water management system. Also, the design becomes the most feasible option in post mining.

10:40am - 11:05am

A Set of New Technology and Equipment of Advanced Water Detection and Drainage in Coal Mining Face with Borehole Geophysical Exploration

Qiang Wu1, Yifan Zeng1, Chunsheng Liu2, Honglei Liu1, Shouqiang Liu1, Fangpeng Cui1, Jingchuan Ma1

1China University of Mining and Technology,Beijing,China, China, People's Republic of; 2Wuhan Changsheng Coal Security Technology Co., Ltd., Wuhan 430312, China

In this paper, the latest research and challenges of the technologies and methods for water detection and drainage in coal mining faces in China are analyzed systematically. Through the comparison of two traditional water detection and drainage technologies, underground geophysical exploration technologies and pre-drilling technology, a new set of advanced water detection and drainage method based on borehole geophysical exploration is proposed. The equipment for borehole geophysical exploration technology is developed, including borehole radar advanced water detector and advanced electromagnetic sounder for wireless tomography while drilling.

11:05am - 11:30am

Influence of Coal Mining on Water Environment and Ecology in the Yellow River Basin

Fawang Zhang1, Zhiqiang Zhang1,2,3

1Chinese Academy of Geological Sciences, Beijing 100037, China; 2Hefei University of Technology, Hefei 230009, China; 3Hebei GEO University, Shijiazhuang 050031, China

The upper and middle reaches of the Yellow River are important coal production bases in China, and the current situation of "more coal and less water" has been the main factor restricting its economic development. Based on the coal resources in the upper and middle reaches of the Yellow River and the history of the Yellow River’s dry-up, this article puts forward the main environmental problems faced by the Yellow River. The impact of coal mining on the natural water cycle, water environment, soil erosion, and water-sediment relationship is systematically analysed, and the coordinated development proposal was finally put forward.

11:30am - 11:55am

Incorporating 2D Analytical Results into 3D Graphical and Multidisciplinary Mining Models.

Hannah Redfern, James Catley, Grace Yungwirth

Golder Associates (UK) Ltd

Front end mining studies inform the project development process by assessing key risks and developing an increased understanding of the available site data. 2D analytical models can be appropriate to support hydrogeological assessments during early studies given the level of data available, and the level of confidence required. Incorporating these results into a 3D model can transform a simple methodology into a visual representation which can be integrated with other aspects of multi-disciplinary studies. This methodology incorporates groundwater flow analyses into a 3D surface within standard industry software, Leapfrog Works™, to support an assessment for a proposed open pit mine.

11:55am - 12:40pmLunch
12:40pm - 2:45pmMine Drainage Chemistry & Passive Treatment
Location: Meeting Room 1
Session Chair: Arabella Mary Louise Moorhouse-Parry
Meeting Room 1 
12:40pm - 1:05pm

🎓 Seasonal Geochemical Variation of Sediments in the Sabie River, Mpumalanga, South Africa

Rudzani Lusunzi1,2, Frans Waanders2, Robert Khashane Tshishonga Netshitungulwana1

1Council for Geoscience, South Africa; 2North West University, South Africa

There was no significant variation observed in terms of metal dispersion (Cr, Zn, Cu, Ni, Pb, As) during wet and dry seasons respectively. The mineralogy of sediments indicated that acid-producing minerals hematite and jarosite found in mine wastes are potential sources of pollution to the Sabie River. The CF, PLI and Igeo showed that sediments were unpolluted to extremely polluted by As. Acid-neutralizing mineral dolomite found in the sediments can act as buffers for potential acid. There was no evidence of metal dispersion from the Nestor tailings storage facility to the adjacent water resources, Klein-Sabie and Sabie River respectively.

1:05pm - 1:30pm

Evaluation Of A Short Period Increasing Water Influx In A Mine Drainage Facility Of A Former Hard Coal Mine

Birgitta Wiesner

RAG AG, Germany

RAG AG currently operates a mine drainage facility at the abandoned coal mine Amalie in the city of Essen, Germany. Throughout April 2020 a short-term increased water influx occurred at this mining site at one dam. To identify on-going processes in the mining plant water chemistry was analysed and investigated. One result was, that the break of a dam lead to a new water influx into the water system of the mine. This new water influx resulted in a permanently higher amount of water entering the mine and a significantly change in water composition by increased amounts of dissolved salts.

1:30pm - 1:55pm

Recovering Rare Earth Elements from Acid Mine Drainage with Mine Land Reclamation

Chin-Min Cheng, Tarunjit Butalia, John Lenhart, Jeffrey Bielicki

The Ohio State University, United States of America

In this study, we demonstrated a trap-extract-precipitate (TEP) process that effectively recovers rare earth elements (REEs) from coal mine drainage (CMD). This three-stage TEP process uses environmentally benign industrial by-products to retain CMD REEs from CMD. It then applies an extraction/precipitation procedure to produce a concentrate feedstock (>7.5 wt. % of total REEs) that can be economically processed to produce marketable rare earth oxides. We envision the TEP process can be integrated with abandoned mine land reclamation to create a commercially viable approach to mitigate CMD and restore lands that are adversely impacted by historical mining.

1:55pm - 2:20pm

Distributions of Rare Earth Elements in Coal Mine Drainages

Chin-Min Cheng, Tarunjit Butalia, John Lenhart, Jeffrey Bielicki

The Ohio State University, United States of America

In the U.S., rare earth elements (REEs) are reported to be closely associated with coal deposits, especially in the Appalachian Basins. Historical coal mining in the Northern Appalachian Coal field of the United States has produced significant amount of coal drainage (CMD). In this study, we investigated 29 abandoned CMDs in eastern Ohio, USA. The main objective of this study is to understand the geochemical behavior of REEs in CMD. Results obtained from this study provide the knowledge that will form the basis of a reactive transport model, which can be used to predict REE retention and recovery.

2:20pm - 2:45pm

Passive Solar Photocatalytic Treatment in Mining Process-affected Water

Jeffrey Thomas Martin1, Tim Leshuk1,2, Brad Wilson1,3, Zac Young1, Frank Gu1,2

1H2nanO Inc., 151 Charles St. W., Suite 299, Kitchener, ON, Canada; 2University of Toronto, Department of Chemical Engineering and Applied Chemistry, 200 College St., Toronto, ON, Canada; 3Stantec, 100-300 Hagey Boulevard, Waterloo, ON, Canada

H2nanO Inc. has developed SolarPass, a floating reactive barrier comprised of buoyant photocatalyst beads that provides a passive, light-activated treatment process for target contaminants, while simultaneously blocking volatile emissions. Recently, H2nanO validated the efficacy of SolarPass for in-situ treatment of mining tailings water through an outdoor pilot-scale system in Alberta, Canada. Under natural sunlight illumination, target contaminants were degraded, including volatile sulfurous compounds and organics, while simultaneously reducing emissions by >70%. These results demonstrate that the novel SolarPass process can address diverse challenges with mining-influenced waters and provides an effective solution for passive tailings and process water management and remediation.

12:40pm - 2:45pmMine Water Treatment
Location: Meeting Room 2
Session Chair: Tobias Stefan Roetting
Meeting Room 2 
12:40pm - 1:05pm

History of Passive Treatment Technology Development in the United States

Jeff Skousen

West Virginia University, United States of America

The concept of passive treatment of AMD was conceived in the early 1980 based on the observations of scientists in Ohio and West Virginia. They noted that the quality of AMD was improved after passing through a natural aerobic wetland and they postulated that oxidation reactions and settling of sludge particles caused the improvement. Among the first to construct and report on constructed wetlands were researchers at the US Bureau of Mines (Kleinmann, Hedin, Nairn, Watzlaf) but many others reported designs and results. By 1989, more than 150 wetlands had been constructed for mine drainage treatment.

1:05pm - 1:30pm

Full-scale Reducing And Alkalinity Producing System (RAPS) For The Passive Remediation Of Polluted Mine Water From A Flooded Abandoned Underground Coal Mine, Carolina, South Africa

Gloria Dube1, Tebogo Mello1, Viswanath Vadapalli1, Henk Coetzee1, Kefyalew Tegegn1, Rudzani Lusunzi1, Shadung Moja1, Mafeto Malatji1, Munyadziwa Ethel Sinthumule2, Rudzani Ramatsekisa2

1Council for Geoscience, South Africa; 2Department of Mineral Resources and Energy

This paper documents the application of a reducing and alkalinity producing system (RAPS) named CaroRap implemented for coal mine water remediation in South Africa. RAPS combines the mechanisms of anaerobic treatment wetlands and anoxic limestone drains. These systems improve water quality by processes, amongst others, of calcite dissolution and sulfate reduction through sulfate-reducing bacteria (SRB). Results from the system, which became operational in January 2021, show an increase in pH from an average of 2.9 to that of 5.6 coupled with an increase by 35.8 mg/L in alkalinity .

1:30pm - 1:55pm

A Strategy to Stimulate and Manage Indigenous Bacterial Communities to Effectively Remediate Mine Drainages

Gerhard Potgieter1, Errol Cason2, Mary Deflaun3, Estariëthe van Heerden1

1iWater (pty) (ltd); 2University of the Free state; 3Geosyntec Consultants

Drainages from mining operations frequently contain elevated levels of contaminants of concern (CoC). The unique adapted bacterial communities are characterized and their ability to reduce many CoC are showcased. Each contaminated site consists of a distinct prokaryotic community that in turn requires a specific C:N:P balanced environments to contribute to site remediation. This balanced bioremedial strategy are managed both for in situ or fix-filmed bioreactors, using hydraulic retention times, electron donor selection and ratios, and redox potential. These communities can effectively treat elevated levels of hexavalent chromium (10 mg/L), nitrate (110 mg/L), and sulfate (1 250 mg/L) in a one-pot balanced.

1:55pm - 2:20pm

🎓 On-site XRF Analysis of Metal Concentrations of Natural Waters

Tommi Tiihonen1, Tuomo Nissinen2, Joakim Riikonen1, Pertti Sarala3, Vesa-Pekka Lehto1, Bruno Lemière4

1Dept. of Applied Physics, University of Eastern Finland, FI-70210 Kuopio, Finland; 23AWater Oy, FI-70210, Kuopio, Finland; 3Geological Survey of Finland, FI-96101 Rovaniemi, Finland; 4BRGM, France

Real-time and on-site analysis of metals in waters is not routinely carried out for environmental monitoring. Laboratory analyses are used instead, which require sampling on-site, shipping to a laboratory and analysis making them expensive and slow. A novel analytical technique based on nanotechnology enhanced preconcentration and portable X-ray fluorescence was developed in this study. The analysis system was calibrated for Mn, Ni, Cu and Zn between concentrations of 50 µg/l and 10 mg/l and fast on-site analysis was demonstrated for two mining related sites.

2:20pm - 2:45pm

Gravel Bed Reactors: Semi-Passive Water Treatment Of Metals and Inorganics

Silvia Mancini1, Rachel James1, Evan Cox1, James Rayner2

1Geosyntec Consultants Inc, Canada; 2Geosyntec Consultants Ltd, United Kingdom

Diffuse impacts to surface waters are a critical issue facing mining industries, given rigorous environmental quality standards. Many conventional treatment technologies are expensive and difficult to comply with discharge criteria. Gravel Bed Reactors (GBR™) are a versatile semi-passive treatment technology capable of addressing a variety of water quality issues through altering the geochemistry of extracted mine water. GBRs™ offer simpler, cost-effective alternatives to water treatment facilities, packed or fluidized bed reactors and the possibility to re-use waste rock as packing media. GBRs™ allow installation of smaller systems in remote, challenging environments and the potential to treat mine water at source.

12:40pm - 2:45pmLegacy Mine Impacts
Location: Meeting Room 3
Session Chair: Julia Dent
Meeting Room 3 
12:40pm - 1:05pm

Assessment of the Constraints on Sustainable Urban Drainage Systems Due to Rising Mine Water and Mine Water Management

Lee M Wyatt1, Ian A Watson1, Sally Gallagher2, Joanne Grantham2

1Coal Authority, United Kingdom; 2Environment Agency, United Kingdom

Many urban areas of the UK have underground mine workings, which were dewatered during mining. Cessation of pumping and resultant rising mine water changes the natural and post mining hydrogeological properties of the subsurface. Sustainable drainages systems are the promoted common approach to manage surface water. Groundwater changes can either be influenced by these systems or their presence can influence effectiveness; leading to an increased flooding risk and contrary to the aims of sustainable drainage. This paper describes a trial screening tool developed to help assess the suitability and site specific design of sustainable drainage now and in the future.

1:05pm - 1:30pm

Site Specific Optimisation Assessment Of Circum-neutral Water Treatment Using a Cost-treatability Curve Assessment

James Marsden1, Steven Pearce1, Tim Sambrook1, Julia Dent2, Andrew Barnes3

1Cambrian Environmental Technologies Ltd., 1a Gower Street, Cardiff, Wales, CF24 4PA; 2Mine Environment Management Ltd., 3a Vale Street, Denbigh, Wales, LL16 3AD; 3Geochemic Ltd., Lower Race, Pontypool, Wales, NP4 5UH, United Kingdom

Pollutant load reduction from operational and legacy mine water can pose a financial burden. Many mine sites globally generate discharges in the circum-neutral range. Recent regulatory and social pressures have increased focus on improving discharge quality for these sites. Because treatment of circum-neutral drainage depends on site specific conditions, and is sensitive to water quality targets, an assessment methodology based around a modular approach to water treatment has been developed. This methodology assesses treatment options to meet a range of water quality targets with respect to cost, allowing generation of a cost-treatability curve based on site specific factors or “levers”.

1:30pm - 1:55pm

Evaluating Circum-neutral Mine Drainage: Case Studies of Advanced Testing Methods Generating Representative Empirical Data

Steven Richard Pearce1, Diana Brookshaw1, Seth Mueller2, Andrew Barnes3

1Mine Environment Management Ltd, United Kingdom; 2Boliden Mineral AB, Boliden, Sweden; 3Geochemic Ltd, United Kingdom

Standard acid mine drainage (AMD) characterisation testing methods focus on acidity and can underestimate risks posed by circum-neutral mine drainage. For circum-neutral sites, amended testing methods are required to provide representative empirical data. Case studies of where such amended testing methods have been used to refine assessments of discharge quality from circum-neutral drainage sites are discussed.

1:55pm - 2:20pm

Algae Bioaccumulation Capacity for Metals in Acid Mine Drainage (AMD)-a Case Study in Frongoch Mine, the UK

Tianhao Du1, Anna Bogush2, Paul Edwards3, Peter Stanley3, Luiza C Campos1

1Department of Civil, Environmental & Geomatic Engineering, Faculty of Engineering, University College London, London, WC1E 6BT, United Kingdom; 2Centre for Agroecology, Water and Resilience, Coventry University, Coventry, CV8 3LG, United Kingdom; 3Natural Resources Wales, 29 Newport Road, Cardiff CF24 0TP, United Kingdom

Algae living in the AMD water around the Frongoch Mine, the UK, were collected and identified by microscope. Metals’ concentration was evaluated in AMD water and algae in two seasons (June and October) in 2019 to assess the bioaccumulation capacity of algae. Two types of algae, Ulothrix sp. and Oedogonium sp., were found to be the main species at the Frongoch mine, and they revealed a high capacity of metals bioaccumulation. Concentrations of metals in AMD water from higher to lower were Zn>>Pb>Cd>Fe>Cu. Study results identified the bioaccumulated metals concentrations in algae from higher to lower were Fe>Pb>Cu>Cd>Zn.

2:20pm - 2:45pm

UNEXMIN and UNEXUP Projects: Development of Submersible Robots for Survey of Flooded Underground Mines

Stephen Henley

Resources Computing International, United Kingdom

Submersible robots have been developed in the EU-funded UNEXMIN and UNEXUP projects, for surveying and exploration of flooded underground mines. They carry cameras and instrumentation to determine physical and chemical properties of wall rocks and water. On-board water samplers allow further laboratory analysis of the water.

Trials have been carried out at mines around Europe. Extensive dives yielded much new data on geology and archaeology, as well as the water which in one mine had been almost undisturbed since flooding to river level in the late 1850s. Some information is also presented on an important current project.

3:00pm - 5:00pmVirtual Tours
Date: Thursday, 15/July/2021
8:45am - 9:40amMorning Session Thursday
Location: Main Room
Session Chair: John George Annandale
Main Room 

Brief Notes from Two Decades of Mine Waste and Mine Water Research

Devin Sapsford

Cardiff University, United Kingdom

PCBs in the Mining Environment – From Silver Bullet to Dirty Dozen

Christian Wolkersdorfer

Tshwane University of Technology (TUT), South Africa

9:40am - 9:50amHealth Break
9:50am - 11:55amMine Drainage Chemistry & Passive Treatment
Location: Meeting Room 1
Session Chair: Ian Jones
Meeting Room 1 
9:50am - 10:15am

A Comparison Of Be And W In Mine Drainage Downstream Two Different Repositories Storing Tailings From A Skarn Ore

Lina Hällström, Lena Alakangas

Luleå University of Technology, Sweden

The geochemical behaviour of beryllium (Be) and tungsten (W) in neutral mine drainage (NMD) downstream of two skarn tailings repositories (Smaltjärnen and Morkulltjärnen) was studied. Surface water was sampled monthly during 2018, with epilithic water diatoms used as bioindicators. Smaltjärnen (1918-1963) has been open to the atmosphere for over 30 years, while Morkulltjärnen (1969-1989) was covered and water-saturated directly after closure. NMD with high concentrations of dissolved Be from Smaltjärnen and dissolved W from Morkulltjärnen had negative environmental impacts as far as 5 km from the Yxsjöberg mine site. Re-mining could be a potential remediation method.

10:15am - 10:40am

Alternative Reagents for the Treatment of Pb-Zn Mine Drainage in Wales

Joe Dean, Ban Alkhazraji, Devin Sapsford

Cardiff University, United Kingdom

This paper presents the results of a laboratory-scale dosing experiment to test the efficacy of four low-cost / alternative reagents to removed dissolved Zn, Cd, and Pb from contaminated mine water. Hydrogen phosphate (Na2HPO4) achieved >95% Pb removal, but lower Zn and Cd removal. Sodium metasilicate (Na2SiO3) and sodium bicarbonate (NaHCO3) did not achieve suitable metal removal. A 99-244 mg/L dose of sodium carbonate (Na2CO3) removed high levels of Zn (99% ±0.2), Cd (95% ±3), and Pb (88% ±3). Sodium carbonate dosing of Zn-Cd-Pb-contaminated mine water could form the basis of a new, low cost, and low input treatment process.

10:40am - 11:05am

🎓 Dewatering, Flooding and Stratification of Nikolaus-Bader small-scale Gold Mining Shaft in Austria

Elke Mugova1, Christian Wolkersdorfer2

1Technische Hochschule Georg Agricola, Germany; 2Department of Environmental, Water and Earth Sciences, Tshwane University of Technology, South Africa

To investigate density stratification in flooded underground mines, the 10 m deep Nikolaus-Bader shaft in Biberwier/Tyrol, Austria was pumped out and the subsequent flooding process was observed. After a short time, a density stratification developed which collapsed in late autumn and built up again in spring. By means of data loggers measuring pressure, temperature and electrical conductivity in four different depths of the flooded shaft, a long-term monitoring of the water body is possible, from which conclusions can be drawn about temporal factors for the formation and collapse of density stratification

11:05am - 11:30am

Justification For Modification Of The NAG Test Method To Suit Varied Mining Waste Geochemical Characteristics On A Site-Specific Basis

Andrew Barnes1, Steven Pearce2, Diana Brookshaw2, Mark Roberts1, Seth Mueller3

1Geochemic Ltd, Lower Race, Pontypool, NP4 5UH. United Kingdom; 22Mine Environmental Management Ltd, Vale Street, Denbigh, Denbighshire, LL16 3AD. United Kingdom; 3Boliden AB, Sweden

The Net Acid Generation (NAG) test is generally carried out using a consistent method, irrespective of the site or the geochemical properties of material being tested. There are significant risks posed by utilising standard methods to assess processes which are inherently site specific like AMD. This can lead to misleading interpretations of results which is particularly true where the NAG liquor is being used to give an indication of elemental mobility during sulfide oxidative weathering. Examples include an average 3 pH unit increase between pre and post boiling, and greater than 60% reduction in nickel release to the NAG liquor.

11:30am - 11:55am

Photoelectrochemical Concurrent Hydrogen Generation and Materials Recovery from Acidic Mine Water

Sudhagar Pitchaimuthu1,2, Ben Jones2, Katherine R. Davies2

1Heriot-Watt University, United Kingdom; 2Swansea University, United Kingdom

Hydrogen is a promising future energy carrier for carbon-free transport and electrification due to its high gravimetric energy density (142 MJ kg−1) and non-polluting nature. The solar hydrogen fuel generation from water using semiconductors has received profound attention since the Honda–Fujishima effect was first demonstrated in 1972.

Our results encourage AMD water as a feedstock for PEC water splitting hydrogen generation and material recovery. A simultaneous water pollutant treatment at a photoanode and solar fuel generation at the cathode along with a material recovery open new pathways beyond the water-splitting process.

9:50am - 11:55amMine Hydrogeology
Location: Meeting Room 2
Session Chair: Catherine Hughes
Meeting Room 2 
9:50am - 10:15am

Groundwater Source Determination of an Underground Diamond Mine Utilizing Water Chemistry and Stable Isotope Analysis

Paul Lourens1, Adriaan Pretorius1, Danie Vermeulen2

1Institute for Groundwater Studies, Faculty of Natural and Agricultural Sciences, University of the Free State; 2Faculty of Natural and Agricultural Sciences, University of the Free State

An underground diamond mine historically experienced periodic groundwater inflow into the underground workings of the mine, resulting in unsafe working conditions. A conceptual model was developed to better the understanding of the groundwater situation at the mine. Water samples were collected at various points. The samples were analysed for major and minor chemical constituents and the stable isotopes of hydrogen and oxygen. Three sources of groundwater inflow into the mine workings were identified. The investigation illustrates that water chemistry signatures and stable isotope signatures can successfully identify different sources of water that flows into the workings of an underground mine.

10:15am - 10:40am

Integration of Regional and Site Scale Models for an Open-Pit Mine

John Rupp1, Geoff Beale1, Kevin Howerton2, Phillip Maxwell Allen1

1Piteau Associates; 2Round Mountain Gold Corporation

Numerical groundwater modeling has progressively become the standard industry tool to evaluate and predict hydrogeologic responses to mine dewatering. Experience has shown that most mine sites require at least two numerical models, each at distinctly different scales, to answer key water management questions. This paper draws on over 30 years of dewatering data from an open pit mine in Nevada, USA to illustrate the importance of scale selection on model development. It uses the experience gained from a 3-D regional-scale model and a 2-D pit-scale model to highlight how both are needed to adequately assess the mine’s water management system.

10:40am - 11:05am

Looking Deeper: Key Considerations for Planning Mining Hydrogeology Investigations using Deep Boreholes

Ed Austin1, Grace Yungwirth1, Michal Dobr2, Sofia Nazaruk1

1Golder Associates (UK) Ltd; 2Golder Associates Ltd

Hydrogeological investigations of the deep subsurface are becoming an integral part of mine design and development alongside the geological, geophysical, and geotechnical investigation programmes. Data obtained from these site and depth specific investigations improve hydrogeological characterisation, resulting in reduced project risk and uncertainty.

Deep hydrogeological investigations using deep boreholes (>500 m depth) require specialised planning, services and equipment, and testing procedures. This paper aims to present key considerations when planning and executing deep borehole-based hydrogeology investigations, drawing on experience across three different continents, to aid practitioners planning for similar programmes on mining projects.

11:05am - 11:30am

Application of Anthropogenic Organic Contaminants and Environmental Isotopes as tracers to determine water ingress in the Witwatersrand Goldfields

Lufuno Ligavha-Mbelengwa1, Godfrey Madzivire1,2, Pamela Nolakana1, Tebogo Mello1, Henk Coetzee1

1Council for Geoscience, South Africa; 2University of South Africa, South Africa

Historical mining has led to environmental degradation in the Witwatersrand Goldfields ever since mining companies ceased pumping water from the mines. A study of using emerging organic contaminants as tracers to map the sources and pathways of water ingress into the mine voids is underway. Water samples from the surface, boreholes and shafts were collected and analysed. Atrazine and caffeine were the most persistent and displayed average concentrations of 0.176 ng/mL and 0.793 ng/mL in surface water respectively. Bisphenol A showed high concentrations in the subsurface with averages of 0.162 ng/mL and 1.082 ng/mL for wet and dry seasons respectively.

9:50am - 11:55amMining Operations
Location: Meeting Room 3
Session Chair: John George Annandale
Meeting Room 3 
9:50am - 10:15am

Comparative Life Cycle Assessment For Acid Mine Drainage Management Options In The Central Basin Of The Witwatersrand Goldfields

Godfrey Madzivire1,2, Thakane Ntholi1, Henk Coetzee1

1Council for Geoscience, South Africa; 2University of South Africa

Acid mine drainage (AMD) is a product of oxidation of disulfide minerals in the presence of water and oxygen. AMD management is site specific and has to be fine-tuned to meet the volumes and the quality of the water. Life cycle assessment was used to evaluate the environmental impacts associated with the prevention of AMD formation through the construction of a canals. Allowing ingress affects the water quality, affecting human health and ecosystem depletion. Ingress control has the effects on resource depletion. The role of LCA is not to give a directive, but rather to reveal trade-offs for proposed solutions.

10:15am - 10:40am

Monitoring of Water-Bearing Adits – Current Results and Perspectives

Tobias Rudolph, Christian Melchers, Peter Goerke-Mallet, Detlef Engel

Technische Hochschule Georg Agricola Bochum University, Germany

Adits represent underground drainage systems. Their functionality is of considerable importance in mining areas around the world, with regard to safety issues at the surface. A variety of monitoring methods have to be used to analyse and document their functioning. A large number of drainage adits were investigated. An essential step forward is the evaluation of available mine survey maps of the adits and the hydraulically connected mine workings. The investigations and analyses show that, in order to achieve a reliable process understanding of the drainage adits, it is necessary to conduct and evaluate comprehensive geomonitoring.

10:40am - 11:05am

A 3D Feflow hydrogeological Uranium underground mine Model, France

Fabrice Compère1, Guillaume Kern2, Gaël Bellenfant1

1BRGM, France; 2ORANO, France

A groundwater flow model was implemented to reproduce the complex hydrosystem behaviour of a remediated uranium mine, in order to better control its environmental footprint. The geology was represented using a layered approach. The open-pit, the underground galleries and the tailing storage area were integrated into the model through 3D unstructured finite elements. The model is based on unsaturated Richard’s equations and includes interaction between groundwater and rivers. After an inversion procedure, the calibrated model successfully reproduces the observed water level fluctuations (piezometers and open pit).

11:05am - 11:30am

🎓 Investigating The Radiological Safety Of Uranium Ore Deposits From A Uranium Mine In Namibia

Vaino Indongo1,2, Vera Uushona1,3, Manny Mathuthu1, Zivayi Chiguvare2

1North-West University (Mafikeng), South Africa; 2Namibia University of Science and Technology (NUST), 13 Jackson Kaujeua Street, P/Bag 13388, Windhoek, Namibia; 3National Radiation Protection Authority of Namibia, Ministry of Health and Social Services, Harvey Street, Namibia

The main aim of this study was to assess radiological hazards posed to employees by uranium ores deposits from a uranium mine in the Erongo Region. Gamma spectrometry was used to determine the radiological health indices of primordial radionuclides of 238U, 232Th and 40K in samples. The external hazard, gamma and alpha indices were ranging between 7.93 ± 0.10 and 18.59 ± 0.20, 576.03 and 1004.60 and 12.93 and 36.63, respectively.These are all above the WHO stipulated limits. The findings of this research indicates that uranium mining activities pose a high risk of radiation hazards to employees.

11:30am - 11:55am

The Use of Systematic Sampling and XRF-XRT Based Scanning to Determine Potential Recovery of Metals from Waste Rock

Stefan Sädbom1, Lotta Sartz1, Jan-Erik Björklund2, Mathias Svenlöv2, Mikael Bergqvist3, Mattias Bäckström1,4

1Bergskraft Bergslagen AB, Sweden; 2Lovisagruvan AB, Sweden; 3Orexplore, Sweden; 4Örebro University, Sweden

It is often complicated to sample and determine average concentrations of elements in historical waste rock. This makes it hard to evaluate the potential for reprocessing and extraction of minerals with valuable and/or harmful elements.

Early evaluation of the potential for reprocessing need to consider the concentrations of relevant elements, their host mineralogy and paragenesis, grainsizes and distribution between different size fractions in the mining rock waste.

In this paper, we present a new sampling strategy/protocol for waste rock, specifically developed for historic mining sites, in combination with XRF-XRT scanning.

Håkansboda historical mine site in Sweden was used as a case study to look at the potential for the combination of techniques. Håkansboda mine site has primarily been mined for copper, but also some cobalt. The mineralization is sulfide based and contains chalcopyrite, pyrite, pyrrothite, sphalerite, galena, arsenopyrite and some cobaltite. From a sample set of 67 average concentrations were 4.5% sulfur, 8 600 mg/kg copper, 340 mg/kg cobalt and 4 100 mg/kg arsenic.

It was found that by using a randomized sampling it is enough to sample 15-20 composite samples from a site in order to obtain an average within acceptable limits from the “true” average.

Scanning of the crushed waste rock with a XRF-XRT scanner (GX10) provided an indication on elemental concentration, elemental associations (including sulfide association) and the distribution of grades between particles. This information provide information about the association and clustering of elements within the waste rock and if the mineralization is enough liberated for mechanical sorting at the chosen particle size. The results will also provide an indication about how much of the potentially acid producing sulfides that will be removed from the site.

In summary, the combination of the suggested sampling strategy/protocol and the dataset from the GX10 enables prediction of amenability for pre-processing with the use of mechanical sorting or if the extraction of valuable minerals only can be achieved through fine grinding, flotation or leaching. Recovery of valuable minerals or metals will increase the possibility for performing reclamation projects at historical sites at a lower cost.

11:55am - 12:40pmLunch
12:40pm - 2:20pmLegacy Mine Impacts
Location: Meeting Room 1
Session Chair: Tom Williams
Meeting Room 1 
12:40pm - 1:05pm

Using Geological Analogues And Proxies To Better Determine AMD Risk

Timothy Wright1, Steven Pearce1, Janjan Hertrijana2, Latipa Henin2, Muhammad Hidyat2

1Mine Environment Management Ltd, United Kingdom; 2PT Agincourt Resources, Indonesia

We present initial results from a combined structural and geochemical assessment designed to improve AMD classification at the Martabe gold mine, Indonesia. Martabe conforms to a classic epithermal acid sulfate model displaying local variations in structure and geochemistry that are difficult to constrain using existing resource models. Fracture-controlled mineralisation and oxidation explains the observed irregular and incomplete “oxidation zones” in which Jarosite, a non-sulfide cause of AMD is found. Supported by outcrop analogues such as the Rodalquilar gold mine in SE Spain, these observations imply detailed grade control drilling is justified to improve model resolution and improve waste rock management efficiency.

1:05pm - 1:30pm

Laboratory Testing To Determine The Effectiveness Of Capping And Risk Of Long-term Metal Release From Mine Waste At The Abandoned Abbey Consols Lead-Zinc Mine, Wales, UK

Julia Dent1, Andrew Barnes2, Ben Gersten2, Mark Roberts2, Tom Williams3, Thomas Eckhardt4

1Mine Environment Management, Vale Street, Denbigh, Denbighshire, UK, LL16 3AD; 2Geochemic Ltd, Lower Race, Pontypool, Wales UK, NP4 5UH; 3Natural Resources Wales, Swansea University Singleton Campus; 4WSP UK Ltd, Kings Orchard, 1 Queen Street, Bristol, BS2 0HQ, UK

The effectiveness of a proposed low permeability cover system for historical mining waste at the abandoned Abbey Consols lead-zinc mine, Wales, UK, was tested using laboratory columns. A reduced infiltration rate could still result in release of metals reducing the benefits of the cover system. Two column scenarios simulated average infiltration conditions and a reduced infiltration rate (the low permeability cover). Results showed the reduced infiltration column produced higher concentrations of key solutes (cadmium, lead and zinc) but a lower load. Zinc and cadmium loads narrowed between the two columns over time suggesting the low permeability cover benefit diminishes.

1:30pm - 1:55pm

Tracing The Water – Rock Interaction In The Ibbenbüren Mine - Towards A Reactive Transport Model For Coal Mine Drainage

Thomas Rinder1, Diego Bedoya Gonzalez1,2, Sylke Hilberg1

1University of Salzburg, Department of Geography and Geology, Hellbrunner Str. 34, 5020 Salzburg, Austria; 2University of Greifswald, Institute for Geography and Geology, Friedrich-Ludwig-Jahn Str. 17a, 17487 Greifswald, Germany

Traces of water-rock interaction in two drill cores from the West field of the former Ibbenbüren anthracite coal were related to both diagenesis and relatively recent weathering processes along open fractures. The coupled appearance of kaolinite-dickite-illite minerals in weathered and unweathered rock sections was clearly connected to the burial history of the Carboniferous sequence. In contrast, the formation of iron (oxide-) hydroxides together with the presence of oxidized pyrite in weathering profiles along both sides of the fractures was positively related to the geochemical footprint of the coal mine drainage.

1:55pm - 2:20pm

The Importance of Adequate Waste Rock Characterization: A Case Study of Unsuccessful Drainage Quality Prediction

Teemu Eemeli Karlsson1,2, Muhammad Muniruzzaman3,4, Päivi M. Kauppila1, Lena Alakangas2, Marja Lehtonen5

1Circular Economy Solutions, Geological Survey of Finland, Neulaniementie 5, 70211 Kuopio, Finland; 2Department of Civil, Environmental and Natural Resources Engineering, Division of Geosciences and Environmental Engineering, Luleå University of Technology, 97187 Luleå, Sweden; 3Water Management Solutions, Geological Survey of Finland, Vuorimiehentie 5, 02151 Espoo, Finland; 4Department of Environmental Engineering, Technical University of Denmark, Miljøvej, Building 115, 2800 Kgs. Lyngby, Denmark; 5Circular Economy Solutions, Geological Survey of Finland, 02151 Espoo, Finland

Current Finnish practices in waste rock characterization may result in improper drainage quality prediction. In this paper, we present a case study involving such inadequate predictions. Our results demonstrated that the waste rock materials with relatively low contents of harmful elements and S can still produce poor-quality drainage, and the waste rock characterization approach developed by the government should be re-evaluated. Special attention should be paid to low carbon content, low neutralization potential, and geochemical properties of single rock types rather than average concentrations of the whole rock mass.

12:40pm - 2:20pmMine Closure
Location: Meeting Room 2
Session Chair: Aaron Martin Lawrence Brown
Meeting Room 2 
12:40pm - 1:05pm

Using Coal Combustion Residues for Abandoned Coal Mine Reclamation

Chin-Min Cheng1, Tarunjit Butalia1, Robert Baker1, Justin Jent2, William Wolfe1

1The Ohio State University, United States of America; 2American Electric Power

Two full-scale demonstration projects using coal combustion residues (CCRs) to reclaim abandoned mines were carried out near the Conesville and Cardinal coal-fired power plants located in eastern Ohio. Water quality data collected over ten year period from 2010 to 2020 were analysed to assess the environmental impacts associated with this mine reclamation approach. Statistically significant water quality changes were observed at both sites after reclamation began. By using linear discriminant analysis on the hydrogeochemcial characteristics of the water samples, we identified if the backfilled CCRs have observable influences on the water qualities of the underlying shallow aquifers.

1:05pm - 1:30pm

Forecasting Evolution of Sulfide Mineral Oxidation Rates Over Decadal Time Scales

John Bradley Swenson1,2, Tamara Diedrich1

1MineraLogic LLC, United States of America; 2Dept. Earth & Environmental Sciences, Univ. Minnesota Duluth, USA

Leachate from 26 decadal-duration laboratory tests on tailings isolated the time-dependence of sulfide mineral oxidation from field scale sources of variability. Time series from all tests show a three-phase evolution, with an order-of-magnitude decrease in sulfate release rate during the second phase. The first phase is relatively short (0.7-yr avg.), with large, quasi-steady release rates. In the second phase—of two- to six-years duration—release rates show a power-law dependence on time. Third-phase release rates are near detection limits and quasi-steady or slowly decaying. We attribute the second evolutionary phase to an accumulation of weathering products that hinders sulfide oxidation.

1:30pm - 1:55pm

Planning And Implementation Of Environment-friendly Phasing Out Of German Hard Coal Mining Under Consideration Of Water-hazardous Organic Substances

Christoph Alexander Schabronath1, Christoph Klinger2, Joachim Loechte1

1RAG, Germany; 2DMT GmbH & Co. KG, Germany

Two hundred years of hard coal mining in Germany ended in 2018. During the phasing out process one of many challenges will be the reduction of the environmental impact of organic substances. Operating fluids which had to be used in the past for safety reasons (e.g. non-inflammable hydraulic liquids containing polychlorinated biphenyls (PCB)) which are now known as toxic.

With regard to the Water Framework Directive and the resulting German surface water regulation, the quality of surface water needs to be improved. RAG addresses this task by deriving a multi-lane concept in cooperation with DMT and the water authorities.

1:55pm - 2:20pm

The Influence Of Mine Water Rebound On Methane Degassing In Abandoned Coal Mines

Stefan Moellerherm, Christian Melchers

Technische Hochschule Georg Agricola, Germany

Hard coal mining is one of the major source for anthropogenic methane emissions. Even after mine closure, methane is still released over a longer period. Experts assume that methane degassing will gradually drop due to the water rising because hydrostatical pressure will reduce the desorption from the seams. However, some scientists have already proved that mine water can contain methane-producing bacteria. This secondary methane geneses potential has not been analysed since then. The authors postulate that bacteria can generate recent methane even in mine water rebound processes. In this paper, they describe their approach to support this thesis.

12:40pm - 2:20pmDecarbonisation
Location: Meeting Room 3
Session Chair: Gareth Farr
Meeting Room 3 
12:40pm - 1:05pm

🎓 Carbonation Of Magnesium Silicate Minerals In Mine Waste: Practical Laboratory Testing Methods To Assess The Dual Opportunity For Carbon Capture And AMD Mitigation

Rhys John Savage1,2, Malvina Chmielarski1,2, Andrew Barnes1, Steven Pearce3, Mark Roberts1, Phil Renforth4, Seth Mueller5, Devin Sapsford2

1Geochemic Ltd, United Kingdom; 2Cardiff University, United kingdom; 3Mine Environmental Management Ltd, United Kingdom; 4Heriot-Watt University, United Kingdom; 5Boliden AB, Sweden

Mineral carbonation has been widely recognised as an important mechanism in the sequestering of CO2into mining wastes and by-products. The generation of fast-reacting carbonates in the carbonation process may also have important implications for the mitigation and prevention of acid mine drainage (AMD). Laboratory-scale methods have been developed to assess carbonation potential in mine by-products from an active nickel mine site in Finland. Utilized methods allow assessment of key parameters controlling the carbonation process. It has been demonstrated that the methods can influence waste pore water chemistry and geochemistry as a result of the carbonation process.

1:05pm - 1:30pm

Beneficiation of Salts Crystallized from Lake Katwe Brine

Joseph Ddumba Lwanyaga1,2, Hillary Kasedde2, John Baptist Kirabira2, Alan Shemi3, Sehliselo Ndlovu3

1Busitema University, Uganda; 2Makerere University, Uganda; 3University of Witwatersrand, South Africa

A salt extraction process to enhance the quality and quantity of salt produced at Lake Katwe in Uganda is presented. To validate the designed process, laboratory experiments were conducted. The techno-economic analysis of the process flow sheet was modeled and simulated by SuperPro Designer. Halite of purity >98% was obtained by floating burkeite and trona which co-precipitate with it during evaporation. The other feasible products of the process are soda ash and sodium sulfate. With a net present value of US$25,077,817, the proposed process is economically viable.

1:30pm - 1:55pm

Potash Dump Leachates – Challenges from Environmental Regulatory Requirements and Climate Change

Anne Weber1, Antje Ulbricht2, Alexander Müller3, Astrid Gessert3, Felix Bilek2, Thomas Sommer1

1Dresden Groundwater Research Centre e.V; 2GFI Groundwater Consulting Institute GmbH Dresden; 3Lausitzer und Mitteldeutsche Bergbauverwaltungsgesellschaft mbH, Division Pottash-Spar-Ore

In a German former potash mining district, highly saline leachates (120 g/L chloride) from three potash dumps are collected in a basin and discharged into the receiving river in a controlled manner. This work illustrates the increasing constraints but also obstacles towards management of saline dump leachate that does not rely on dilution. Besides dump covering, evaporation of leachate is considered the most promising approach to reduce salt load into surface water in the long term and is currently put forward. Here, linking energy and material fluxes on a local basis is pivotal during development of a feasible process.

1:55pm - 2:20pm

Recovery Of Cobalt And Copper From Tailings Through Enhanced Oxidation And Selective Precipitation

Mark Roberts, Nina Swain, Andrew Barnes

Geochemic Ltd, United Kingdom

The oxidation of high sulfide tailings by ozone coupled with selective precipitation was investigated as a technique for the recovery of cobalt and copper. Iron was selectively removed from solution as precipitated oxides, with only minor loss of cobalt and copper. The remnant cobalt and copper were then precipitated out of solution forming a concentrate with 8.15% Co and 8.73 % Cu with recovery rates of approximately 0.175 kg/tonne achieved. This technique, though in its early stages of development, demonstrates considerable promise as a waste valorisation system which is also capable of reducing latent acidity potential in the waste stream.

2:20pm - 3:00pmClosing Ceremony

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