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SA’s platinum ends up on the waste dump due to difficulties in extracting the metal from the ore. That might change.

South Africa is the world’s biggest producer of platinum – one of the key components of motorcar manufacturing, catalysts in the industrial chemistry and jewellery making worldwide.  But some of South Africa’s platinum ends up on the waste dump, due to difficulties in extracting the metal from the ore.

That might change.

Prof Marian Tredoux from the Department of Geology at the University of the Free State (UFS), and colleagues in Germany, have managed to prove a controversial theory regarding how minerals of platinum (and other elements in the platinum group) are formed.

This research was reported in an article of which Prof Tredoux is a co-author – Noble metal nanoclusters and nanoparticles precede mineral formation in magmatic sulphide melts – that was published earlier this month in the journal, Nature Communications (an online journal for research of the highest quality in the fields of biological, physical and chemical sciences). The study found that atoms of platinum and arsenic create nanoclusters at high temperatures long before conditions become suitable for minerals of platinum to crystallise.  It also showed that the platinum does not occur as a primary sulphur compound, as had previously been supposed.

Chemistry researchers have been talking about platinum clusters in watery environments for quite a while, but it was thought that these would not appear in magmas (molten rock) due to the high temperatures (>1 000 degrees celsius),” explains Prof Tredoux.

In layman’s terms, the study comes up with a better explanation of how the ores of platinum are formed.

“This has been a theory of mine for around twenty years,” says Prof Tredoux, “but the evidence had to wait for the development of technology to prove it.”

“Every bit of understanding takes us further along the road to knowledge,” Prof Tredoux adds.

“Now that we better understand the geochemistry of platinum, this new information could possibly be used by chemical engineers and metallurgists to devise more effective ways to extract the platinum, and that would decrease the amount of non-recovery during the processing of platinum ores.”

Estimates suggest that for every tonne of rock mined in the South African platinum industry, around $50 worth of platinum (at current prices) ends up on waste dumps.  For a shaft which mines a million tonnes of ore per year (typical for the larger mines in the Rustenburg area), this non-recovery amounts to a loss of hundreds of millions of rand annually. New ways of extracting this rare metal might decrease this wastage, and that would be economically beneficial for South Africa’s beleaguered platinum industry.

The South African side of the study received part of its funding from the Inkaba yeAfrica programme – a GermanSouth African collaboration administered by the National Research Foundation.

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