Patent ID: 6551378
Filing Date: 2003-04-22
Classification: C22B,Y02P

Abstract:
A precious metal recovery method which comprises:a. grinding precious-metal and base metals containing solids to obtain a solids fraction passing a less than 100 mesh screen; b. contacting said precious-metal-containing and base metals solids in an extraction tank with a leach solution comprising hydrochloric acid and an oxidizing agent for a time period ranging from 10 minutes to 24 hours; c. decanting said leach solution from said extraction tank and filtering said leach solution; d. sending residual solids from filtration step in (c) to an extraction vessel where residual leach solution from said filtration step is removed from said solids and combining said residual leach solution with filtered leach solution from step (c); e. neutralizing filtered solution from step (d) by addition of a alkali or alkaline concentrated base and precipitating any base metals present in said filtered solution as base metal hydroxides; f. filtering or centrifuging base metal hydroxides and treating filtrate or centrifugate containing the precious metals in solution with a resin to remove remaining base metals; g. precipitating precious metals from base metal free solution of step (f) with a reducing agent and recovering said precious metals.