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:: Extracting PGMs from Chromite Tailings at Kroondal - A World First
The new chromite-tailings retreatment plant for the recovery of platinum-group metals (PGMs) at Aquarius Platinum's Kroondal mine near Rustenburg, South Africa, designed, manufactured and erected by Bateman, is thought to be the first PGM-flotation plant in the world to process chrome-mine tailings.
According to Gert Ackerman, Managing Director of Aquarius Platinum (South Africa), the concept is simple, the engineering straightforward and the economics compelling. For a capital expenditure of about US$5M, Aquarius will initially be adding 20 000 ounces to its PGM production, while simultaneously cleaning the environment by putting discard material to good use.
The feed to the plant comprises a mixture of about 60% of newly generated tailings (a grade of 4 g/t of PGMs) piped through a 2 km pipeline from the neighbouring Kroondal Chrome mine, owned by Xstrata. The remaining 40% is dump material (a grade of 3 g/t of PGMs) trucked in from various dumps in the Rustenburg area, most of them belonging to Bayer"s Rustenburg chrome operation.
The plant design is simple and straightforward and its footprint has been concentrated within an area of only 20 m by 50 m. The front-end of the plant screens and scalps the dump material. Initially no crushing or milling is required, but plans are in hand to add a mill later this year.
The wet and dry feeds are mixed in a tank and the combined stream is passed through conventional tank-type flotation cells, supplied by Bateman, which also supplied the flotation-air blower. There are four stages of roughing and six of cleaning and the layout makes use of the slope of the land at the site so that the tank cell pairs are terraced, reducing the height that would normally be required by a conventional plant.
The retreated tailings are pumped to Kroondal's tailings facility. The concentrate containing 150 g/t of PGMs is sold in accordance with off-take agreements.
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