oa Treatment of Platinum Flotation Products

A flowsheet has been developed for the production of rich concentrates of precious and non-ferrous metals by a complex treatment of the flotation products from South African platinum-containing chrome ores. The procedure involves: autoclave leaching, roasting, hydrochlorination and precious metal recovery by sorption. Autoclave oxidative leaching of the initial material allows the non-ferrous metals to pass into solution from where they are recovered as a rich sulfide concentrate (> 30% nickel and copper). Recovering the precious metals into solution combines two operations: sinter roasting and hydrochlorination. Roasting destroys the precious metal acid-proof mineral forms. The precious metals are recovered from solution by ion exchange using anionites that are finally burned. The ash from the burning is a concentrate of precious metals (> 75% in total) which are recovered in three forms: ammonium chloroplatinate with purity > 98%, palladium dichlorodiamine with purity > 96%, and a mixture of rhodium, ruthenium and iridium hydrates. The flowsheet uses full water rotation and minimum consumption of reagents, and gives a good recovery of metals to commodity concentrates (nickel > 98%, copper > 80% and precious metals (in total) > 95%).