Process for the recovery of precious metal values from aqueous ammoniacal thiosulfate leach solutions

Abstract

The process of recovering precious metals from ores containing precious metals, such as gold and silver, from an aqueous ammoniacal thiosulfate leach solution to provide a significant practical and economical process for the recovery of gold or silver is disclosed. After leaching of the ore with an aqueous ammoniacal thiosulfate solution, the leach solution is contacted with a precious metal extraction reagent to extract the precious metal values from the leach solution, after which the precious metal values are stripped from the extraction reagent to form a concentrated solution of the precious metal values from which the precious metals may be recovered by conventional methods such as electrolysis. The extraction reagents are those having guanidyl functionality or a quaternary amine functionality mixed with a weak organic acid such as a phenol. In the process, novel thiosulfate complexes of the precious metals are formed with the quanidyl or the quaternary amine extractants.

Dependencies are inferred from the claim text.