Methods of Recovering Platinum-group Metals from Stillwater Complex Ore.
Ch in Sulphide Deposits-their Origin & Processing Inst Min and Metall PP 155-163 :155-163
As part of its strategic and critical minerals program, the U.S. Bureau of Mines investigated methods for beneficiating and recovering platinum-group metals (PGM) from ores found in the Ctillwater Complex, the only primary resource of platinum-group metals in the United States. Because the ore is sulfidic in nature, it was concentrated by froth flotation. A 45-kg/h process development unit (pdu) was constructed and 85 to 95 pct of the platinum and palladium were recovered from the ore by using mercaptobenzothiazole or sodium isobutyl xanthate as collectors. Bench-scale research showed that conventional matte smelting and leaching methods could be used to recover the precious metals from the flotation concentrate. More than 95 pct of the precious metals reported to the matte phase during smelting. Several leaching schemes were evaluated that selectively extracted the base metals from the matte and allowed recovery of high-grade PGM residues that were suitable as feed material for a precious metals refinery. Oxidative leaching of roasted flotation concentrate to selectively extract precious metal values was also investigated as an alternative to conventional matte smelting-leaching strategies. Ongoing research is evaluating the effect of bioleaching using thiobacillus ferrooxidans on sulfide oxidation and liberation of precious metals present in Stillwater Complex flotation concentrate.
Ch. in Sulphide Deposits-their Origin & Processing. Inst. Min. and Metall., PP. 155-163