USING THIOUREA AS AN EXTRACTING AGENT FOR GOLD EXTRACTION

Abstract

Currently, the amount of waste polluting the environment, as well as the atmosphere, hydrosphere, and lithosphere, is increasing from year to year. From this point of view, the integrated use of mineral raw materials, which involves the optimal and economically feasible extraction of useful and associated minerals with minimal losses in the subsoil at all stages of the technological process, the disposal of processing waste and the implementation of environmental measures aimed at restoring ecosystems, as well as the creation of waste-free technologies are very relevant.

For centuries, the best reagent for leaching gold was cyanide due to its high recovery, low cost and reliability. However, cyanide is highly toxic and causes environmental problems, which has prompted widespread research aimed at identifying and developing less toxic leaching reagents. Among the alternative leaching agents, chlorides, thiourea and thiosulfate have received the most attention. The use of thiourea as a lixiviant for gold recovery has proven more promising.

This article presents the results of identifying the optimal parameters for gold extraction by leaching with thiourea from sulfide polymetallic ores of the Megradzor deposit of the Republic of Armenia.

It was found that to optimize the process, it is advisable to carry out the first stage of leaching for 60 minutes, and the remaining stages for 30 minutes. In the first stage, ~ 45% of the gold is recovered, and a significant part of the thiourea is spent on dissolving other metals.

The optimal conditions for the process of leaching gold with thiourea sulfate solution have been established: preliminary acid treatment of the source material, which allows removing some of the interfering impurities before the first stage and repeated use of thiourea solutions until saturation with gold. Repeating the process in 3…7 cycles makes it possible to achieve a yield of gold in solution of up to ~ 97% in a short time.