An integrated approach for waste repurposing and environmental remediation in the South African coal mining industry
|
Authors: Stander, H-M; Du, S; Mokomela, R; Broadhurst, JL Open access courtesy of:
|
DOI https://doi.org/10.36487/ACG_repo/2515_54
Cite As:
Stander, H-M, Du, S, Mokomela, R & Broadhurst, JL 2025, 'An integrated approach for waste repurposing and environmental remediation in the South African coal mining industry', in S Knutsson, AB Fourie & M Tibbett (eds), Mine Closure 2025: Proceedings of the 18th International Conference on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 1-15, https://doi.org/10.36487/ACG_repo/2515_54
Abstract:
Coal is an important energy source for the South African economy and is likely to remain so in the medium term, but several mines are nearing closure. Coal extraction, processing and combustion, however, produce industrial wastes, which can be toxic to the surrounding natural and agricultural environments, as well as the health of nearby communities. Discards and tailings from washing operations occupy large tracts of land, sterilising these for a variety of uses and require post-mining landform shaping. These also represent a longterm acid rock drainage risk. Coal combustion waste, especially fly ash, also occupy large tracts of land and is a potential source of water pollution due to high metal loads and high pH’s. Current waste management approaches, including co-disposal, lining tailings dams and covering waste facilities with soil and vegetation, require monitoring and maintenance over a long timeframe and carry a risk of environmental failure. To reduce the need for post-closure waste management and increase the number of post-closure land use options, an integrated circular-economy approach aimed at valorising whole waste bodies and simultaneously remediating the surrounding environment has been proposed. This approach makes use of and remediates the solid waste, fly ash, acid mine drainage, and mining affected soils. In this paper, the industrial ecology approach is specified, the relative volumes of each waste stream are estimated, and the materials streams are calculated. It is estimated that – in addition to avoiding waste disposal – this approach could annually return 135,000 Mℓpa of irrigation-quality water to Mpumalanga province, rehabilitate 12.6 km2 of mining impacted land with fabricated soil, ameliorate 20,000–63,000 ha of alkaline or sodic soils, and produce 40 Mm3 of backfill material on a regional scale. This approach can also produce nano-iron and sulphuric acid.
Keywords: regionally integrated waste repurposing, coal mine waste, acid mine drainage, fly ash, mining affected soils
References:
Agnello, VN 2003, Cement Industry in South Africa, Department of Minerals and Energy of the Gauteng Provincial Government, Pretoria.
Akinwekomi, V, Maree, JP, Masindi, V, Zvinowanda, C, Osman, MS, Foteinis, S, ... Chatzisymeon, E 2020, ‘A viable option for the synthesis of goethite, hematite, magnetite, and gypsum – gearing towards a circular economy concept’, Minerals Engineering, vol. 148,
Amaral Filho, JR, Firpo, BA, Broadhurst, JL & Harrison, STL 2020, ‘On the feasibility of South African coal waste for production of ‘FabSoil’, a Technosol’, Minerals Engineering, vol. 146,
Amaral Filho, JR, Gcayiya, M, Kotsiopoulos, A, Broadhurst, JL, Power, D & Harrison, STL 2022, ‘Valorization of South African Coal Wastes through Dense Medium Separation’, Minerals, vol. 12, pp. 1–11,
Ayers, B, Day, S, Gusek, J, Hulett, L, Kemp, D, Kleinmann, R, ... Zandvliet, L 2009, ‘The acid rock drainage process’, The Global Acid Rock Drainage Guide, International Network for Acid Prevention, viewed 6 August 2021,
index.php/Chapter_2
article/kusile-power-plant-project-south-africa-2013-11-08
Broadhurst, JL 2015, ‘A desulfurization flotation approach for the integrated management of sulfide wastes and acid rock drainage risks’, in STL Harrison (ed.), 10th International Conference on Acid Rock Drainage & IMWA Annual Conference, ICARD and IMWA, Santiago.
Broadhurst, JL 2022, LF Petrik, L Folifac, A Ameh, J Jason, A Jehoma & W Gitari (eds), Integrating Nano Iron Production into the Acid Mine Drainage Neutralisation Treatment Process, Water Research Commission, Pretoria.
Chamber of Mines of South Africa 2007, Chamber of Mines of South Africa Annual Report 2006 - 2007, Johannesburg.
Cole, MJ, Mthenjane, M & Van Zyl, AT 2023, ‘Assessing coal mine closures and mining community profiles for the ‘just transition’ in South Africa’, Journal of the South African Institute of Mining and Metallugy, vol. 123, pp. 329–341.
Cope, J & T Nadar (eds) 2021, Emalahleni Water Reclamation Consolidated Environmental Management Programme, WSP, Johannesburg.
Department of Minerals and Energy 2002, National Inventory Discard And Duff Coal – 2001, Pretoria.
Du Preez, K 2022, Treatment of Acid Mine Drainage for Re-use in Irrigation, Coaltech, Johannesburg.
Eberhard, A 2011, The future of South African Coal: Market, Investment, and Policy Challenges, Institute for International Studies at Stanford University, Standford.
Eskom 2021, Ash Management In Eskom, fact sheet, Johannesburg.
Eskom 2024a, Generation Plant Mix, fact sheet, Johannesburg.
Eskom 2024b, Eskom Leads Sustainable Road Construction by Using Recycled Coal Ash as an Alternative to Concrete, Johannesburg.
Eskom 2025, Eskom Adds 800MW of New Capacity to the Grid, press release, Johannesburg.
Eze, CP, Nyale, SM, Akinyeye, RO, Gitari, WM, Akinyemi, SA, Fatoba, OO & Petrik, LF 2013, ‘Chemical, mineralogical and morphological changes in weathered coal fly ash: a case study of a brine impacted wet ash dump’, Journal of Environmental Management, vol. 129, pp. 479–492,
Galdames, A, Ruiz-Rubio, L, Orueta, M, Sánchez-Arzalluz, M & Vilas-Vilela, JL 2020, ‘Zero-valent iron nanoparticles for soil and groundwater remediation’, International Journal of Environmental Research and Public Health,
ijerph17165817
Gitari, WM, Petrik, LF, Etchebers, O, Key, DL, Iwuoha, E & Okujeni, C 2008, ‘Passive neutralisation of acid mine drainage by fly ash and its derivatives: A column leaching study’, Fuel, vol. 87, pp. 1637–1650,
Glencore 2019, Water Report, Baar.
Grobbelaar, R 2001, The Long-term Impact of Intermine Flow from Collieries in the Mpumalanga Coal Fields, PhD thesis, University of the Free State, Bloemfontein.
Gule, N 2020, Factors Contributing to Unsuccessful Rehabilitation: A Case Study Investigating the Rehabilitation Practices in Opencast Coal Mines in the Mpumalanga Province, South Africa, master’s thesis, University of Cape Town, Cape Town.
Hancox, PJ & Götz, AE 2014, ‘South Africa’s coalfields - a 2014 perspective’, International Journal of Coal Geology, vol. 132,
Harrington, A, Teitelman, J, Rummel, E, Morse, B, Chen, P, Eisentraut, D & McDonough, D 2017, ‘Validating Google Earth Pro as a scientific utility for use in accident reconstruction’, SAE International Journal of Transportation Safety, vol. 5, no. 1,
Harrison, STL, Broadhurst, JL, Opitz, AKB, Fundikwa, B, Stander, H & Kotsiopoulos, A (eds) 2020, An Industrial Ecology Approach to Sulphide- containing Mineral Wastes to Minimise ARD Formation, Water Research Commission, Pretoria.
Hattingh, R, Tanner, P & Aken, M (eds) 2019, Land Rehabilitation Guidelines for Surface Coal Mines, Coaltech Research Association, Minerals Council of South Africa, Land Rehabilitation Society of Southern Africa, Johannesburg.
Horak, I, Horn, S & Pieters, R 2021, ‘Agrochemicals in freshwater systems and their potential as endocrine disrupting chemicals: a South African context’, Environmental Pollution, vol. 268,
Hutton, B, Kahan, I, Naidu, T & Gunter, P 2009, ‘Operating and maintenance experience at the Emalahleni Water Reclamation Plant’, International Mine Water Conference, Pretoria.
Iroala, O 2014, Combining Froth Flotation with Reflux Classification to Mitigate ARD Generating Potential of the Waterberg and Witbank Coal Ultrafines via Sulfide Removal, master’s thesis, University of Cape Town, Cape Town.
Jeffrey, LS 2005, ‘Characterization of the coal resources of South Africa’, Journal of the South African Institute of Mining and Metallurgy, vol. 105, pp. 95–102.
Kalombe, RM, Ojumu, TV, Katambwe, VN, Nzadi, M, Bent, D, Nieuwouldt, G, ... Petrik, LF 2020, ‘Treatment of acid mine drainage with coal fly ash in a jet loop reactor pilot plant’, Minerals Engineering, vol. 159,
Karlsson, S, Allard, B & Bäckström, M 2020, ‘Weathering mechanisms and composition of effluents from a sulphide mine waste deposit after covering – twenty years of field data’, in Wolkerdorfer & Freund (eds), Mine Water and Innovative Thinking, International Mine Water Association, Sydney, pp. 359–362.
Limpitlaw, D, Aken, M, Lodewijks, H & Viljoen, J 2005, ‘Post-mining rehabilitation, land use and pollution at collieries in South Africa’, Sustainable Development in the Life of Coal Mining, The South African Institute for Mining and Metallurgy, Johannesburg.
Madikizela, LM 2023, ‘A journey of 10 years in analytical method development and environmental monitoring of pharmaceuticals in South African waters’, South African Journal of Chemistry, vol. 77, pp. 80–100.
McCarthy, TS & Pretorius, K 2009, ‘Coal mining on the Highveld and its implications for future water quality in the Vaal River system’, International Mine Water Conference, Water Institute of Southern Africa’s Mine Water Division & International Mine Water Association, Pretoria, pp. 56–65.
Minerals Council of South Africa 2025, Facts and Figures Pocketbook 2024, Johannesburg, viewed 5 June 2025,
Morrill, J, Chambers, D, Emerman, S, Harkinson, R, Kneen, J, Lapointe, U, ... Turgeon, R 2022, Safety first: Guidelines for Responsible Mine Tailings Management, Earthworks, MiningWatch Canada and London Mining Network, Washington, DC.
Mothogoane, M 2025, Eskom Coal Combustion Products: Challenges Faced By Ash Off-takers, Eskom, viewed 5 June 2025,
Moyo, A 2018, Characterising the Potential Environmental Risks of South African Coal Processing Wastes, master’s thesis, University of Cape Town, Cape Town.
Nani, C 2025, Kusile Power Station Monthly Emissions Report, Eskom.
National Cleaner Production Center of South Africa 2023, IEE Guideline for the cement manufacturing industry in South Africa, CSIR, Pretoria.
Petrik, LF, Vadapalli, VRK, Gitari, W, Etchebers, O, Reynolds, K, Surender, D, ... Sery, G 2007, Large Scale Stability and Neutralisation Capacity of Potential Mine Backfill Material Formed by Neutralisation of Fly Ash and Acid Mine Drainage, Coaltech Research Association, Johannesburg.
Pierce, W & Le Roux, M 2023, Statistics of Utility-scale Power Generation in South Africa in 2021, CSIR Energy Centre, Pretoria,
Politis, A, Paspaliaris, I, Taxiarchou, M & Tsertou, E 2017, Innovative Waste Management and Mine Closure, Min Guide: Minerals Policy Guidance for Europe, Athens.
Qi, C & Fourie, A 2019, ‘Cemented paste backfill for mineral tailings management: review and future perspectives’, Minerals Engineering, vol. 144,
Reynolds-Clausen, K & SIngh, N 2019, ‘South Africa’s power producer’s revised coal ash strategy and implementation progress’, Coal Combustion and Gasification Products, vol. 11,
Roselt, M & Mpofu, AB 2021, Mpumalanga Water Market Intelligence Opportunity Brief 2021, GreenCape, Cape Town.
Runkel, M & Sturm, P 2009, ‘Pyrite roasting, an alternative to sulphur burning’, Sulphur and Sulphuric Acid Conference, South African Institute of Mining and Metallurgy, Sun City, pp. 101–110.
Sackett, S 2025, ‘Regional growth prospects for acid’, Proceedings of the 9th Sulphur and Sulfuric Acid Conference, South African Institute of Mining and Metallurgy, Stellenbosch.
South African Coal Roadmap Steering Committee 2011, Overview of the South African Coal Value Chain, Fossil Fuel Foundation and South African National Energy Development Institute, Johannesburg.
Schutte, C 2018, Value Added Utilisation Possibilities of Coal Combustion Products in South Africa, master’s thesis, North West University, Potchefstroom.
Shongwe, BN 2017, The Impact of Coal Mining on the Environment and Community Quality of Life: A Case Study Investigation of the Impacts and Conflicts Associated with Coal Mining in the Mpumalanga Province, South Africa, master’s thesis, University of Cape Town, Cape Town.
Simpson, GB, Badenhorst, J, Jewitt, GPW, Berchner, M & Davies, E 2019, ‘Competition for land: the water-energy-food nexus and coal mining in Mpumalanga province, South Africa’, Frontiers in Environmental Science, vol. 7, .
2019.00086
Stander, H & Broadhurst, JL 2025, ‘Conceptualising a regionally integrated approach for the valorisation of coal mining-related waste: A South African case study’, International Coal Processing Conference XXI, Sun City (in publication).
Stander, H, Harrison, STL & Broadhurst, JL 2022, ‘Using South African sulfide-enriched coal processing waste for amelioration of calcareous soil: a pre-feasibility study’, Minerals Engineering, vol. 180,
Statistics South Africa 2020, Census of Commercial Agriculture, 2017, Statistics South Africa, Pretoria, viewed 21 May 2018,
Verger, R 2018, Water Balance Update for the Exxaro Matla Coal Mine - Addendum, GCS Water and Environmental Consultants, Johannesburg.
Villain, L, Alakangas, L & Öhlander, B 2013, ‘The effects of backfilling and sealing the waste rock on water quality at the Kimheden open-pit mine, northern Sweden’, Journal of Geochemical Exploration, vol. 134, pp. 99–110,
j.gexplo.2013.08.003
Weaver, SM & Crangle, RD 2020, 2017 Minerals Yearbook: Gypsum, U.S. Geological Survey, Reston, viewed 6 May 2025,
© Copyright 2025, Australian Centre for Geomechanics (ACG), The University of Western Australia. All rights reserved.
View copyright/legal information
Please direct any queries or error reports to repository-acg@uwa.edu.au
View copyright/legal information
Please direct any queries or error reports to repository-acg@uwa.edu.au