METHOD OF RECOVERING PRECIOUS METALS FROM EXHAUSTED CATALYSTS Russian patent published in 1998 - IPC

FIELD: precious metal recovery. SUBSTANCE: catalyst is treated by freshly prepared mixture of concentrated hydrochloric acid and hydrogen peroxide under static, dynamic, or circulation conditions at 0 to 100 C and atmospheric pressure. Filtered solution is combined with that obtained after washing precipitate with water on filter. Combined solution is treated by sorbent 10-hydroxy- (perhydro-1,3,5-dithiazine)-5 yl-ethane in quantity 5-10 g per 1 g of metal to be recovered, treatment being carried out at 0 to 100 C and atmospheric pressure for 2 to 10 h until traces of precious metals are no longer found in solution. Sorbent exhibits high sorption capacity toward precious metals so its intake is 10-12- fold lower, whereas recovery reaches 95-98%. EFFECT: enhanced precious metal recovery efficiency. 1 tbl