FEATURES OF BEHAVIOUR OF COPPER SELENIDE IN POLYSULFIDE SOLUTIONS
Selenium cementate generated during selenium cementation by metal copper from sulfate solutions of water scrubbing at copper and copper-nickel productions. It contains to 50 % of selenium, mainly in the form of copper selenides. Leaching of selenium cementate in alkaline sulfur-bearing solutions, where sulfur in different oxidation states acts as an oxidizer for selenium, is considered in article. This is done in order to create a universal method for the extraction of selenium from elementary and selenide forms with a closed loop solutions. The thermodynamic assessment of possibility of interaction of copper selenides with sulfur and polysulfides is carried out. It indicates about formation sulfoselenide- sulfodiselenide- ions, sustainable in an alkaline environment. It is established that regularities of leaching of copper selenide by polysulfides in the alkaline sulphurous environment are defined by degree of its polysulfidity. Use of tetrasulfide solution provides the maximum transition of selenium to alkaline solution (to 86 %). Release of selenium from the sulfodiselenide solutions at 20 °C with introduction of sulfur is followed by extraction of 60 % of selenium into the insoluble residue.