The ferroalloy phase is remelted and spray-dried into powder using standard equipment under an inert atmosphere, and then leached with dilute sulfuric acid at room temperature; the leaching reaction is very rapid. The leachate can be comprehensively utilized, with iron alum (FeSO4·7H2O) being one of the byproducts.
The concentrations of Pt, Pd, and Rh in the leachate are all <0.0005 g/L, with no chemical loss. The grade of the platinum group metals (PGM) concentrate produced depends on the grade of the raw material. Processing material A with a grade of approximately 170 g/t yields a PGM concentrate grade >1.6%, an enrichment of approximately 160 times. Processing materials B and C with a grade of 1000-1300 g/t yields PGM concentrates with a grade >7% (Pt 2.08-2.3%, Pd 3.24-3.62%, Rh 1.05-1.16%), an enrichment of approximately 72 times.
