This project, led by researchers from the universities of Pretoria, Southampton and Cape Town, began in February 2019, with the aim to catalogue mine tailings suitable for potential CO2 sequestration schemes across South Africa.
Weathering of rocks at the Earth’s surface is a natural process that converts atmospheric CO2 into carbonate minerals or alkalinity, occurring over a geological timescale. Speeding up this process through geoengineered methods represents a meaningful approach to CO2 removal on human timescales.
Due to their favourable physical and chemical properties and worldwide abundance, mafic and ultramafic mine wastes are highly reactive with atmospheric CO2, and are therefore subject to much study and assessment. The high metal and precious stone mining activities and tailings production in South Africa make this an ideal country to spearhead geoengineered processes to capture CO2 at mine sites. The aim of this proposed research is to identify and catalogue the potential of mine tailings for CO2 sequestration in the South African mining sector.
Data compilation will include the mapped and calculated volumes of targeted tailing deposits for suitable (mafic and ultramafic-hosting) mine sites and production systems, and the calculated volume of CO2 that could be captured for sites, regions and the country as a whole.
The database, GIS resources and evaluations published from this study will be used by scientific researchers and industrial projects to identify favourable sites for maximum sequestration potential. This may also lead to pilot studies or implementation of large-scale CO2 sequestration projects at South African mine sites. The project will aid current and future decision making and policy development regarding tailing treatment and carbon footprint of the mining industry of South Africa.
The science behind the project
The 2018 global IPCC report stressed the need for solutions to limit impacts of global warming in the next two decades. Strategies focus on major reductions in CO2 concentrations and decreasing the impact on global ecosystems and human health. The increasing trend in CO2 emissions and links to global warming has led to the need for efficient methods of CO2 reductions and negative emissions technologies. The focus of this project is to explore the potential of enhanced weathering and mineral carbonation for removing CO2 through accelerated weathering of mine tailings, and conversion of CO2 to alkalinity and carbonate minerals. The principle is to accelerate natural chemical weathering, whereby minerals are dissolved in a reaction with atmospheric CO2 and water, with products transported to oceans, or stored as solid mineral materials. This natural uptake needs to be accelerated to be an efficient CO2 removal strategy. Geoengineered methods speed up weathering rates such that CO2 is removed from the atmosphere in meaningful quantities on human timescales. Global mine wastes offer a suitable material for CO2 sequestration owing to their favourable physical and chemical properties, and their high volumes could annually offset more CO2 than currently emitted. Countries, such as South Africa, which hosts millions of tonnes (Mts) of mine wastes, constitute ideal study areas. Further investigation of site-specific engineering requirements can lead to significant CO2 storage on a scale of Mts achievable this century by the mining industry.
Our project has a number of collaborators and support from the host researcher universities (Pretoria, Southampton and Cape Town), working in partnership with the UK’s Natural Environment Research Council funded “Greenhouse Gas Removal by Enhanced Weathering (GGREW)” project (led by the universities of Oxford, Southampton, Herriot-Watt and Cambridge).
The project has also established direct partnerships with Anglo American’s Mogalakwena PGM Mine, and De Beers’ Project Minera consortia. In addition, the project leads are partaking in on-going talks with the South African Centre for Carbon Capture and Storage (SACCCS) in order to officially have the SAT4CCS project be a part of the agency’s suite of CCS key projects.
About the lead researchers
Zakhele completed both his undergraduate and M.Sc. in geology at the University of Pretoria. His M.Sc. dissertation was on the mineral carbonation research, using platinum mining derived tailings. The dissertation earned the 2019 John Handley award from the Geological Society of South Africa. He is currently pursuing his PhD at the University of Johannesburg under the supervision of Profs W. Altermann and K.S Viljoen. The research continues to be on mineral carbonation; however, the focus is on kimberlite tailings. He is currently serving as a member of the academic staff at the University of Pretoria with a core teaching focus on applied mineralogy, paleontology, paleoclimatology and geo ethics. Most of his teaching time is devoted to first- and second-year student cohort, and the supervision of two honours and an M.Sc. student.
Liam is a Research Fellow at the University of Southampton in the UK. Liam’s area of research is geochemistry and petrology, and he has previously worked at the University of Aberdeen on the Natural Environment Research Council-funded TeaSe Project, part of the SOS Minerals programme, investigating critical “E-tech” trace element concentrations in the Earth's crust for use in low-CO2 technologies. His research has centred on mineral resource exploration and finding environmental solutions to reduce CO2 emissions through newly developed technologies or during mine waste production. Liam has established UK-based partnerships with Airbus, Kier Group, Banks Group and Parys Underground Group, and international partnerships with Ur-Energy and Anglo Platinum. He has held academic and private sector positions, including previous work as a geologist for Ethiopia-based gold exploration company GP Resource Mining. Liam has 23 scientific publications, including research in coal, graphite, sulphur, uranium and gold mining regions, and has presented at several international conferences. Liam’s work has attracted reproduction in online publishers such as USA Gold, Cambridge Africa and the Ethiopian Embassy UK Newsletter.
Maxwell is a PhD candidate at the University of the Western Cape (UWC), South Africa. He has a broad research background in Environmental and Applied Geology. He obtained a Bachelor of Science degree in Mining and Environmental Geology (MEG) from the University of Venda for Science and Technology, during which time he also took up a Teaching Assistant position at the MEG Department in his final year. Following his undergraduate degree, he worked as a Geologist (predominantly working on Witwatersrand gold mineralization projects) with the geological consulting firm, Shango Solutions, in Johannesburg between 2010 and 2013.
He also has a Master of Science Degree in Applied Geology from the University of Cape Town. His research work involved the mineralogical characterization of South African mine tailings for the purpose of mineral carbonation. The outcome of this research project has garnered much interest in the Mineral Carbonation enterprise. Currently, Maxwell is conducting an exciting research project as part of his PhD in Petroleum Geosciences at UWC, with the main focus on fault seal analysis for carbon dioxide storage within the offshore Pletmos Basin of South Africa. As part of this project, he has been working closely with research collaborators from Coventry University (United Kingdom) with sponsorship from the South Africa Centre for Carbon Capture and Storage (SACCCS).
How can we work together?
This consortium aims to produce a comprehensive catalogue, atlas and GIS database for available and suitable mine tailings for potential future CO2 sequestration projects. This includes both annual production volumes and historic stockpiles. The development of a South Africa mafic and ultramafic mine tailings database will provide the first large-scale and highly detailed catalogue for material abundances suitable for CO2 sequestration. The project will collaborate with project partners and relevant contacts to collect and summarise information on mine tailings and their amounts. This will allow for the documentation of sanctioned, up-to-date quantities for tailings, an evaluation of site opportunities and additional qualitative expertise of site potential.
In order to achieve our aims, we need access to mine production statistics. This may include (but is not limited to) annual and historic (up to previous 5 year) commodity production, utilised economic cut-off grades, annual tailings production (where recorded), historic stockpiles and anticipated life of mine. If a mine site or operator wishes for their site to remain anonymous, names can be hidden in any published outputs. However, this project aims to shed a positive light on the unlocked potential for CO2 sequestration and reduced carbon footprint for the mine and country. The selection criteria utilised in this study means that any mine that is contacted is done so due to the opportunities that the site presents. We hope that the establishment of contact and the transparency between the project and partners will lead to future collaboration and teamwork.
Email address: [email protected]
Phone number: +27 (0)12 420 5012