Abstract: A hydrometallurgical process for the recovery of precious metal values from refractory precious metal ore materials containing preg-robbing carbon by leaching with a thiosulfate lixiviant, the process comprisinga. providing a body of particles and/or particulates of an ore material having precious metal values and preg-robbing carbonaceous components;b. contacting the body of particles and/or particulates with a thiosulfate lixiviant solution at conditions conducive to the formation of stable precious metal thiosulfate complexes;c. recovering the thiosulfate lixiviant from the body of particles and/or particulates after a period of contact which is sufficient for the lixiviant solution to become pregnant with precious metal values extracted from the ore material; andd. recovering the precious metal values from the lixiviant solution.In a preferred embodiment, the refractory ore materials are low grade precious metal ore materials.

Abstract: A hydrometallurgical process for the recovery of one or more metal values from a metal ore material in the presence of clays and/or fines material, said ore material being comprised of one or more metal values and a matrix material having a sulfur content wherein the sulfur is present in an oxidation-reduction state of zero or less. The process comprises forming particulates from particles of said ore material, particles comprising said clays and/or fines material, an acid-resistant polymeric agglomeration aid and an inoculate comprising bacteria capable of at least partially oxidizing the sulfur content; forming a heap of said particulates; biooxidizing the sulfur content and recovering those one or more metal values.