A fundamental study of the alkaline sulfide leaching of gold

Due to the increasing concerns over the emission of sulfur dioxide from roasting and smelting, there has been an increased interest in pressure oxidation as a means of treating gold bearing ores and concentrates. One of the problems with the partial oxidation of the sulfide host matrix to form elemental sulfur is that sulfur containing streams are difficult to treat using cyanidation. In the present paper, the alkaline sulfide system was studied as an alternative to cyanide for recovering gold from elemental sulfur. It was found that the dominant lixiviant for gold in this system is sulfide, and polysulfide was ascertained to be the oxidant. The leaching reaction was determined to be chemically controlled, thus highly dependent on temperature. Other variables investigated include the effect of pH, gold purity, and the ratio of sulfide to polysulfides. It was found that each of these variables had a large impact on the system. © 2003 SDU. All rights reserved.