At around 6 am on 11 September 2022, the wall of a mine tailings dam outside Jagersfontein in South Africa’s Free State province cracked, crumbled and burst. A wave of sludge poured over the town and its surrounding farmlands, destroying nine houses and damaging 20 more. At least three people died and hundreds were injured. Two weeks later, a further collapse occurred. More than 1 000 people were displaced.

The disaster shone a muddy spotlight on South Africa’s mining industry – specifically, on its environmental impact and on how it manages its waste. At a seminar last year, Mariette Liefferink, CEO of the Federation for Sustainable Environment, noted that ‘it is widely recognised that problems related to mining waste – tailings – may be rated as second only to global warming and stratospheric ozone depletion in terms of ecological risk. The release to the environment of mining waste can result in profound, generally irreversible destruction of ecosystems. Waste from gold mines constitutes the largest single source of waste and pollution in South Africa. Gold mining waste was estimated to account for 221 million tons or 47 % of all mineral waste produced in South Africa’.

However, the industry in general has been working to change that. ‘The mining industry at large is embracing change and finding new ways to integrate innovative waste-management strategies into its operations,’ says Kate Stubbs, marketing director at waste-management company Interwaste. ‘We are seeing many more mines mitigating risks by conducting comprehensive environment impact assessments and implementing sustainable solutions for the full life cycle of the mine, and adopting circular economy and zero waste to landfill strategies.’

Preventing disasters is the baseline of the industry’s ambition. Several mining companies are now looking beyond mere waste management, and into turning their waste into valuable, usable materials.

African Rainbow Minerals is one example. In July 2023 André Joubert, chief executive of ARM’s Ferrous division, told the London Indaba that the company intends to turn manganese waste placed on tailings dams into a ferromanganese product. Joubert said that while there is a good export market for high-grade quality manganese lumpy ore, the waste materials that are washed out of that ore (and which make up about 15% of the total tonnage produced) are currently being dumped in the tailings facility. ‘The philosophy is to advance from being normal miners to exploiting the entire value chain with even the final product not being waste but gypsum,’ he said.

ARM also plans to reprocess the stockpiles left over from phosphate mining at Phalaborwa, Limpopo, into rare earth oxides. By 2026 it aims to produce about 1 850 tons per year of NdPr (neodymium and praseodymium) oxides, which are essential to the electronics, technology and automotive industries – particularly when it comes to realising energy efficiency targets and reducing greenhouse gases.

Another key focus area is finding alternative energy sources, such as waste-derived fuel, through the beneficiation of mining waste. ‘Several technologies are available to convert waste to energy,’ says Stubbs. ‘Currently, as an example, Interwaste has pioneered two types of refuse derived fuels [RDF] locally, one solid and one liquid. We try to convert as much industrial waste into this product as our current capacity allows.’

RDF is a solid fuel source recovered through the shredding and bailing of certain pre-sorted dry industrial non-recyclable waste. ‘The RDF we produce requires no heat for drying, produces a cleaner RDF and a much higher heating value similar to that of A-grade coal, thus forming a very suitable and robust alternative to fossil fuel use. Such fuels can be used within sole/co-feeding plants and replace conventional fuels – like coal – in production plants for power, steam and heat generation, cement kilns and other suitable combustion installations,’ she says.

Rubber is another of the mining industry’s major waste streams, through disused tyres, conveyor belts and so on. ‘These can be put through an RDF process by using technology to strip out the wire, remove beading of off-road tyres, cut it in half, quarter it and shred it down into particular sizes for RDF use in other industries,’ says Stubbs. ‘While this is in its infancy, there is a growing need for it. Cost-wise, it can provide a good offtake for the mining sector if you consider the reuse of existing waste and the savings in carbon emissions and responsible waste management.’

Stubbs is seeing more and more mining companies looking to turn trash into treasure, or at least waste into something of worth. ‘There is a trend among the major players in the mining sector to seek to mitigate environmental impact and resource loss through beneficial waste-management practices.’

Jason Judkins, regional manager: inland north at EnviroServ Waste Management, agrees. ‘EnviroServ applies the waste hierarchy,’ he says. ‘Our service offering to our clients includes reuse, recovery and recycling. We find that the larger mining-waste streams, such as overburden and tailings, are not recycled but placed on tailing dams. We have seen that some of these waste streams are being exempted from the definition of waste, which is paving the way for the material to be used beneficially – such as land remediation and infilling. There are instances where tailings are used to backfill and overburden used for aggregates, but these waste streams are not recycled without massive investment. Many of the gold mine tailings dams on the East Rand have been reclaimed and re-processed, but this still generates large volumes of tailings after re-processing.’

Judkins says there is a drive to recycle as much of the industrial and general waste generated from mines as possible. ‘The biggest trend today is diverting waste from landfill by means of recycling, reuse, destruction or reprocessing,’ he says.

As Judkins hinted at – and as the Jagersfontein disaster demonstrated – reuse, recovery, recycling and beneficiation of solid matter may be the goals, but water remains central to the mining industry’s waste-management challenge.

‘Mining relies on water,’ says Chetan Mistry, strategy and marketing manager at Xylem Africa. ‘Water is ever-present in mines.

‘Mines are either removing water, or using water to manage the site, such as reduce dust, combat fires or move slurry or tailings. Wells and pumps are commonplace on mining sites. So mines know how to work with water.’

Mistry sees this as an opportunity for mining companies – particularly those in water-stressed regions such as Africa – to embrace new water stewardship and ‘wet’ waste-management systems. ‘They can apply new water-management principles and technologies more readily than most other sectors and see the benefits more quickly,’ he says.

He points to tech-enabled enhancements such as data-driven planning, remote control of water infrastructure, smart pumps and modular treatment systems such as ozone. ‘These provide mines with a wider range of options on how to manage their water consumption and reuse,’ he says.

‘These technologies are already making a difference for mines in the most rural and driest parts of the planet, such as the remote areas of Australia and Chile. They help those mines operate efficiently and reduce their impact on surrounding communities and environments. Above all, they help mines become more sustainable and self-sufficient while also reducing operating expenditure.’

Ultimately, waste management and water management are part of a larger picture of how mines effectively manage their resources, and how they extract the greatest value from their resources … be they solid or liquid.

By Mark van Dijk
Images: Gallo/Getty Images