Leaching process intensification of gold-bearing raw materials

Abstract

Purpose. Research on the process intensification of gold-bearing product hydrometallurgical processing based on mechanochemical milling of the initial sulphide material. Methods. Mechanochemical activating (oxidation) of sulphide gold-bearing concentrate under conditions of superfine milling, sulphite-thiosulphate leaching of the milled product after liquid phase separation. The float concentrate sample with a particle size of -0.074 mm, the Au content is 15.5 g/t is tested. When loading into the mill of an initial concentrate sample weighing 300 g, 600 ml of a calcium hydroxide solution with a concentration of 143 g/l are added. The weight of balls loaded into the mill in relation to the concentrate weight is 10:1. The remainder of the solid product after milling is subjected to lea-ching with a sulphite-thiosulphate reagent. Findings. A sharp increase in the milled product of 10 µm fractions (from 14.05 to 34.63%) has been determined, and the mass fraction of gold in the final milling product decreases from 15.5 to 13.0 g/t. This corresponds to the recovery of gold into solution at this stage at the level of 16%. It has been found that with an additional supply of 1 g/l of copper sulphate for copper in the process of milling, it is possible to reduce the gold content in the milled product to 8.3 g/t. Thus, the recovery of gold into solution at the stage of milling increases from 16 to 48%. During the milling process, partial leaching of gold by reagents formed from its own sulphur has been revealed. It has been found that the transition of gold into solution is caused by the formation of a water-soluble hydrosulphide complex of gold during milling (AuS). As a result of leaching with the reagent, an additional 27% of gold has been recovered. Originality. Phase transformations of the sulphide gold-bearing beneficiary product as a result of mechanochemical activation have been determined. For the first time this process has been implemented to intensify the leaching process of gold-bearing mineral raw materials. Practical implications. The research results can be used in technological processes for the processing of refractory gold-bearing ores and technogenic raw materials.