Comparison of Methods of Processing the Gold - Containing Refractory Concentrates

Abstract

Persistent ores, which are characterized by insufficient gold recovery under traditional conditions of cyanide leaching, occupy a prominent place in resource base of the modern gold mining industry. Gold in such ores is in a state of fine dispersion in sulfide minerals, most often in pyrite and arsenopyrite. Refining refractory gold ores to enhance extraction at cyanidation involves pretreatment. Traditional technologies for extraction of gold from sulfide refractory ores include flotation concentration, roasting and subsequent calcification of the calcine. However, the use of roasting is characterized by inevitable environmental pollution through gaseous emissions of arsenic and sulfur, the need for disposal of highly toxic arsenic trioxide and insufficiently high through-flow gold extraction in the technology. To date, the most environmentally friendly, highly profitable and fairly widely used ways in production practice technologies for processing refractory gold-bearing raw materials are: bacterial and autoclave oxidation. Experimental studies of the process of direct cyanidation of gold-containing flotation concentrate, as well as products of its preliminary oxidation using various methods (calcination of oxidative roasting, autoclave kecks (POX) and bacterial leaching (BIOX)) gave the following results: Cyanidation of the initial flotation concentrate provides for the extraction of Au 46.6%; the use of oxidative roasting leads to an increase in extraction of gold from 46.6% to 85%; the use of BIOX technology allows to increase the extraction of gold to 91.74%; preliminary autoclave oxidative leaching of flotation concentrate provides a stably high recovery of Au with subsequent cyanidation-at the level of 94.9-96.5%. The introduction of autoclave and biological oxidation is an important element in the intensification of technological processes, improving the industrial safety of gold processing enterprises and improving working conditions of production personnel.