OXIDATIVE PRESSURE LEACH RECOVERY OF PRECIOUS METALS USING HALIDE IONS

摘要

A method for recovering a precious metal from a host material, comprises the steps of subjecting the host material to an oxidative pressure leach process, in the presence of a halide ion constituent, preferably a chloride ion, which is reactive with the precious metal, and at an elevated temperature of at least 170 DEG C to cause at least a portion of the precious metal to be extracted by a leach solution in the form of a precious metal-bearing chloride complex, and recovering the precious metal from the leach solution. When the host material is a smelt malte material including a base metal and a precious metal, said malte is subjected to a first oxidative pressure leach process to recover substantially all of said base metal in the form of at least one sulphate complex into a first leach solution, and then said malte material is subjected to a second oxidative pressure leach process in the presence of a halide ion constituent and at a temperature sufficient to cause at least a portion of said precious metal to be recovered into a second leach solution, from which the precious metal is extracted.