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.

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.

Abstract: A process for biooxidation of sulfides in a heap of mineral ores by freeing precious metals dispersed or occluded within said ores as pyritic or arsenopyritic sulfides and the like; the process comprises forming particulates from ore particles with an inoculate comprising bacteria capable of attacking, by biooxidation, sulfides and/or elemental sulfur in said ore particles; from these particulates a heap is constructed; and the biooxidation takes place in such heap by adding to or dispersing within the heap a leaching solution, circulating the leaching solution within the heap and recovering the precious metal values from the heap; recovery may be accomplished with a cyanide, thiourea, or a thiosulfate lixiviant.

Abstract: A method is provided for the recovery of precious metal values, such as gold and silver, from refractory carbonaceous, or carbonaceous-sulfidic ore material. The ore material is inoculated using a specific microbial consortium and then incubated to deactivate the carbonaceous component of the material to prevent binding of the precious metal values to the carbonaceous component. The precious metal is then recovered.

Abstract: The recovery of precious metals from refractory carbonaceous and sulfidic ores or concentrates is improved by subjecting an oxidized slurry of this type of ore to thiourea leaching in the presence of carbon instead of subjecting the slurry to cyanidation leaching.