Method for separating and isolating gold from copper in a gold processing system

A method for separating and recovering gold from an excavated gold-bearing ore, comprising:

• providing a supply of an ore comprising both gold and copper therein;
• placing said ore in contact with a leaching solution comprising cyanide therein, said leaching solution extracting said gold and said copper from said ore when said leaching solution comes in contact with said ore to generate a liquid product comprising a monovalent gold-cyanide complex and a multivalent copper-cyanide complex therein, wherein at least most of said copper in said liquid product is in the form of the multivalent copper-cyanide complex and said liquid product has a pH ranging from about pH 9 to about pH 11;
• providing at least one nanofiltration membrane, said nanofiltration membrane preventing passage of said copper-cyanide complex therethrough while allowing passage of said gold-cyanide complex;
• and
• delivering at least a portion of said liquid product to said nanofiltration membrane so that said liquid product flows onto said nanofiltration membrane to produce a retentate which does not pass through said nanofiltration membrane and a permeate which passes through said nanofiltration membrane, said retentate comprising at least most of said copper-cyanide complex and said permeate comprising at least most of said gold-cyanide complex, said gold-cyanide complex being separated from said copper-cyanide complex by said nanofiltration membrane.