Conference Agenda

Mining Operations
Thursday, 15/July/2021:
9:50am - 11:55am

Session Chair: John George Annandale
Location: 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.