On his frequent drives back home to Rustenburg, Alseno Kagiso Mosai would pass through Krugersdorp on the West Rand of Gauteng.
There, Mosai, a water remediation expert at the University of Pretoria’s Department of Chemistry, saw the hazardous dust that billowed from the mine dumps looming over the town.
“We tried to collect some samples from these mine dumps and we saw that the concentrations of toxic metals are still very high,” he said. “You can still find uranium and mercury there because most of them are due to gold mining.”
Mosai and his colleagues located sites contaminated with acid mine drainage (AMD), a toxic legacy of gold mining. It is harmful to humans, plants and animals because it is acidic and carries heavy metals, atoms that emit radiation, and salts in hazardous concentrations.
“What we found is that, because they are not enclosed, some kids go out there and they play in those mine dumps and, if we find these high concentrations of metals, then it’s a serious problem.
“What’s sad is some of the mine dumps are … a street away from the residential area. It’s also a dusty place and this means that these elements can also travel through the air, so people are being negatively affected [by the pollution], without knowing, of course.”
Children, warned Mosai, are breathing in the uranium, arsenic and mercury fumes wafting from the abandoned legacy mines. The pollutants are also seeping into the groundwater and nearby dams and lakes.
“If this is not treated now, the effects of legacy mines will continue and the impact will be much more severe. This means that the government will need large amounts of money to clean the water to bring it up to the standard needed for households.”
Krugersdorp is full of legacy mines, and most people who live in the vicinity of the dumps have had serious health issues, such as asthma, Mosai said, noting that this has been backed up by several research studies.
“It is not only kids. There are dams in this area that are used by older people for recreational activities like swimming, as well as religious activities like baptisms. We talk to them about the dangers, but they’re just doing these things innocently; it’s really sad for me and my colleagues to see.”
As the toxins can spread in both the air and in water, even people who live some distance away from mine dumps could be affected, he added.
Clean-up technologies
While the mining companies responsible for the pollution are “often nowhere to be seen”, ultimately, it’s up to the government to fund acid mine drainage clean-ups to protect the right of citizens to a healthy environment and clean water.
Many AMD clean-up technologies exist, Mosai said. “Some are more or less expensive, while others are more or less effective, depending on the local context.”
To help authorities take urgent action in Krugersdorp and other parts of the country, Mosai and fellow experts Gebhu Ndlovu, of the national mineral research organisation Mintek, and Hlanganani Tutu, of the School of Chemistry at the University of the Witwatersrand, wrote an article, published in Science of the Total Environment in April, in which they reviewed existing technologies.
They recommended a combined approach that is both affordable and effective.
“There are different technologies that have been developed for the treatment of wastewater or AMD,” they wrote. “However, there is no ‘one-size-fits-all’ solution, hence a combination of available technologies should be considered to achieve effective treatment.”
They are calling on authorities to make use of two technologies developed by local researchers at Mintek. One precipitates unwanted toxins and the other uses micro-organisms sourced from plant waste to “eat” heavy metal pollutants. The technologies are trademarked as SAVMINTM and CloSURETM, respectively.
In the case of using microorganisms, there is the double benefit of recycling plant waste while saving costs on water-treatment chemicals, according to the researchers. Both technologies would also enable precious metals such as cobalt, copper and nickel to be recovered for commercial use.
“It is therefore in the interest of municipal decision-makers, industry and other researchers to take note of the review article, so that South Africa doesn’t keep reinventing the wheel when it comes to researching new AMD clean-up technologies and so that the benefits of mine remediation for governance, business and the safety of our children become clear,” said Mosai.
He added that experts from the University of Pretoria, including himself, have been supporting remediation efforts by the national department of water and sanitation, which has detected toxic mine elements in several areas. “If we don’t act now, though, this issue is not going to go away.”
The researchers noted in their review article how residents living near mining activities are prone to the negative side effects of acid mine drainage. “Prolonged exposure can lead to serious health effects including cancer, diarrhoea, dermatitis, impaired morphology in infants and asthma, among others.”
Toxic legacy
Referring to Krugersdorp’s abandoned mine dumps, Mariette Liefferink, the chief executive of the Federation for a Sustainable Environment (FSE), said that Mintails South Africa was part of the Mintails group of companies, a gold mining and tailings processing company listed on the Australian Stock Exchange, which touted itself as a mining rehabilitation venture.
Instead, it had wrought a trail of ecological destruction across Krugersdorp and Randfontein over the years. In 2018, its local operations were liquidated.
Mintails left in its wake an unfunded environmental liability of R460 million. The ecological damage included unrehabilitated reclaimed tailings storage facilities; polluted and toxic dams; clusters of open pits 30m to 40m deep; partially reclaimed tailings storage facilities with no mitigation and management measures and acid-producing stockpiles of waste.
“The FSE notified the regulators … for years of Mintails’ environmental non-compliances and had extensively whistle-blown the environmental risks to the national and international news media, the relevant parliamentary portfolio committees, the office of the public protector and the South African Human Rights Commission,” she said.
The FSE has conducted hundreds of site visits to the polluted and ecologically degraded areas with mining-affected communities, the regulators, NGOs, academics including the UN Special Rapporteur on Toxics and Human Rights and other special interest groups.
Pan African Resources, a mid-tier gold mining company, has since acquired the mining right of Mintails for the reclamation of the tailings storage facilities and Mintails’ environmental liability of R460 million was transferred to it. The mining right for the open pits was transferred by the former department of minerals and energy to Amatshe Mining.
“The FSE, however, continues to conduct regular site visits of these areas and continues to extensively engage with mining affected communities on the risks and hazards of tailings storage facilities and AMD.”
‘Track record’
Hethen Hira, the head of investor relations at Pan African Resources, said it is the first mining company with a track record of successfully re-mining and rehabilitating tailings dumps.
“We have raised all the required capital (about R2.5 billion) to construct the up to one million tonnes per month retreatment plant at Mintails with a life-of-mine of 20 years and to commence with initial rehabilitation work. This is to ensure that activities are not likely to be abandoned, should economic conditions deteriorate.”
He said that Pan African has obtained the necessary environmental authorisations to commence with activities over the mining rights areas and dumps it has acquired. It has undertaken to implement global standards regarding the reprocessing and redeposition of tailings and “rehabilitation will be concurrent with our re-mining activities”.
“As construction is completed and re-mining commences, the company has already conducted community awareness programmes on the dangers of historic tailings dams and has started with remediation work on the ground while, at the same time, restricting access and encroachment on the tailings dams to deter access by community members and livestock.
“This has also deterred illegal mining activity and improved safety for locals,” Hira said.
He added that Pan African would use best practices in its retreatment of historic tailings to reduce environmental effects and improve conditions for rehabilitation “so that the re-mined footprints of these tailings are made suitable for economic use”. The company also has a water treatment plant on site. It will clean the polluted water for use in its processing plant and improve water quality before it is decanted safely into the environment.
