Conference Agenda

Legacy Mine Impacts
Tuesday, 13/July/2021:
1:00pm - 3:05pm

Session Chair: Diana Brookshaw
Location: 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.