The issue of reducing gold losses in tailings during the enrichment of non-ferrous metal ores is currently receiving special attention. The presence in most non-ferrous metal ores of significant quantities of pyrite, which goes simultaneously with gold into the tailings, gave reason to explain the loss of gold in the tailings by its close association with pyrite. It is necessary to establish whether gold is really closely associated with pyrite and is in such a finely disseminated state that it is not released during the most intensive grinding and remains inaccessible to solvents in subsequent hydrometallurgical processing operations. Experiments in the synthesis of gold sulfide and gold-containing iron sulfides have shown that pyrite and pyrrhotite formed at temperatures of 400 ° C are capable of including measurable amounts of finely dispersed gold, undetectable under a microscope even at the highest magnifications. Submicroscopic gold in some cases can be represented by sulfide dissolved in iron sulfides. Such finely dispersed gold in some cases may be a product of the decomposition of primary gold sulfide dissolved in iron sulfide. The form of gold released from pyrite in our experiments corresponds to the forms of natural gold in pyrites of some deposits.
