Process for recovering precious metal from an aqueous solution

A process for recovering precious metal from a precious metal-bearing solid material comprising at least one precious metal selected from gold and silver, the process comprising:

• leaching the precious metal-bearing solid material with an aqueous lixiviant comprising thiosulfate to produce a leach solution comprising thiosulfate and precious metal;
• introducing a soluble reducing agent to the leach solution in excess of any oxidants present in the leach solution;
• contacting the leach solution with a cementation substrate comprising a metallic composition comprising a base metal, wherein the precious metal is reduced in the presence of the reducing agent and the cementation substrate so that reduced precious metal deposits on the cementation substrate to form a precious metal cementation product;
• and
• separating the precious metal cementation product from a precious metal-lean leach solution comprising the thiosulfate.

A process for recovering precious metal from a loaded absorbent comprising thiosulfate and at least one precious metal selected from gold and silver, the process comprising:

• eluting the loaded absorbent with an aqueous eluant to produce an eluate comprising thiosulfate and precious metal;
• introducing a soluble reducing agent to the eluate in excess of any oxidants present in the eluate;
• contacting the eluate with a cementation substrate comprising a metallic composition comprising a base metal, wherein the precious metal is reduced in the presence of the reducing agent and the cementation substrate so that reduced precious metal deposits on the cementation substrate to form a precious metal cementation product;
• and
• separating the precious metal cementation product from a precious metal-lean eluate comprising the thiosulfate.