South Africa’s mines are facing multiple challenges. Extraction is getting more technically complex, while environmental rules are being tightened, raising the costs of compliance.
Implementing more advanced and environmentally friendly technologies across various aspects of extraction and processing can help address several of these challenges at once. ‘The goal of green hydrometallurgy is to reduce environmental disasters – while boosting mines’ productivity at the same time,’ explains Daniel Verwey, business development manager at BME Metallurgy. BME provides advanced mining chemicals and metallurgical processing solutions with a focus on sustainable mineral recovery.
South Africa’s mining industry has an illustrious past. It supplied nearly half of all gold ever mined in human history. But as the most accessible minerals are depleted, miners are pursuing precious metal deposits at increasingly greater geological depths. For instance, the Mponeng gold mine near Johannesburg is over 2.5 miles deep, with rock temperatures reaching over 60°C, making extraction uneconomic without complex technology and high commodity prices.
The problems are compounded by the 14,000–30,000 illegal small-scale miners who work with little regard for the environment, extracting minerals from gold to coal and chromium to platinum. This is intensifying already difficult tasks such as suppressing sulfur dioxide emissions, or ensuring tailings pool dams don’t spill residues contaminated with arsenic, mercury, cyanide, or lead onto farmland, rivers, or settlements. Authorities, who are sensitive to mining’s pollution footprint, are working to strengthen the National Greenhouse Gas Emission Reporting law in 2026. Jail terms, hefty fines and taxes will be imposed on corporations that don’t comply with pollution limits.
The most prominent sustainable strategies that miners in South Africa are adopting include efficient wastewater treatment and re-use; replacing hazardous materials with greener alternatives; testing safer surfactants for capturing or suppressing acid aerosols released during processing; and nanofiltration to recover and recycle reagents such as sulfuric acid, hydrochloric acid and caustic soda, explains Verwey.
South Africa is among the 30 most water stressed nations on earth. Hence, most miners ‘are looking at ways to reduce and/or recycle water,’ says Kevin Harding from the school of chemical and metallurgical engineering at the University of the Witwatersrand, Johannesburg, who has consulted on waste minimisation projects for the oil and gas industries.
A prominent example is Ivanhoe’s Platreef mine in the drought-prone Limpopo province of northern South Africa, which is using treated wastewater from the local municipality to run its operations. Around three quarters of all the water used by mining giant Gold Fields is reused or recycled, and the company has reduced its freshwater withdrawal from 14.5 million m3 in 2018 to between 8.5 and 11.1 million m3 in 2022–2024. The company has targets of using over 80% recycled water and drawing less than 8 million m3 of freshwater per year by 2030.
The main advantage of nanofiltration technology is reducing acid and alkali reagent demand – both for processing and for chemical neutralisation of residues, explains Verwey. Some hazardous reagents can also be entirely substituted. ‘For instance, we introduced hydrogen peroxide-based emulsions to replace nitrate-based emulsions for blasting. This has [reduced] nitrogen oxide emissions by 90%,’ he adds.
Similar technologies are being applied in mines elsewhere around the world, such as Brazil and Australia, in response to similar pressures of increased regulation and increasing complexity of extracting minerals as the geology of sources changes.
‘Most changes are typically cost based (including to avoid fines),’ says Harding. Although there may be elements of ‘promoting better environmental practices, and/or because it is just the right thing to do – although we can’t really determine which,’ he adds.
But while larger companies can afford the cost of adopting alternative technologies, smaller miners in South Africa like Ndalamo Resources are publicly voicing frustration that the cost of compliance with the proposed greenhouse gas emission rules is escalating and could become an ‘existential crisis’ for them. ‘Green chemistry practices may impact financial decisions,’ says Harding, acknowledging that changes that could save companies money in the long run can require significant initial investments.
