A study of the factors affecting copper cementation of gold from ammoniacal thiosulphate solution

Thiosulphate leaching of gold is a proposed alternative to cyanide leaching for certain types of refractory gold ores. The most promising method for r ecovering gold from thiosulphate leach solutions is by copper cementation. This study focused on determining how the factors of pH/ammonia concentrati on, copper concentration, thiosulphate concentration, sulphite concentratio n, and temperature, commonly manipulated in thiosulphate leaching studies, affect gold cementation performance using copper. These factors were varied in artificial leach solutions according to the ranges typically found in t he literature. Both powder cementation and rotating disk electrode cementat ion were used to study the kinetics of gold cementation. Overall, the cemen tation of gold by copper from ammoniacal thiosulphate solution was conclude d to be under mass transfer control. Higher temperatures and pH/ammonia con centration were determined to positively affect the rate of gold cementatio n. Conversely, sulphite and copper in solution were established to negative ly affect cementation performance. (C) 1999 Published by Elsevier Science B .V. All rights reserved.