An investigation on reusing process water in gold cyanidation

Water is used extensively in gold processing. The reuse of water is encouraged both to conserve water and to minimize the discharge of contaminated wastewater into surface streams. However, the use of recycled process water can negatively affect gold and silver recovery. In the present laboratory study, we compared Au, Ag, and Hg recoveries when leaching with fresh water, original process water, and process water that had been either neutralized or treated with activated carbon to remove the dissolved metals. Recovery of Au and Ag were 93 and 71.7% in leaching with fresh water, and 91 and 66.2% in leaching with process water that been treated with activated carbon for 1 h. Cyanide consumption was substantially reduced when process water was used, indicating that using process water is feasible.