Indian Journal of Science and Technology

Abstract

Background: In pyroprocessing sulphide complex copper ores, considerable amount of selenium along with radio genic osmium and rhenium concentrated in the solid-phase products of acid wash is disappearing with waste chromiumcontaining solutions. Methods: Studying the peculiarities of selenium recovery in sulfuric acid chromium-containing medium is an important task, which will prevent channel losses of selenium with intermediates of sulphate production at complex processing of sulfide polymetallic raw materials and thereby increase up the production. On the basis of analysis of the literature and patent data as the most promising methods for the extraction of selenium and selenium from sulfuric acid solutions, recovery methods were chosen. Results: The thermodynamic evaluation of the possibility of extracting selenium from sulfuric acid solutions at the temperatures of 298-348 K, with the use of sulfur dioxide and sodium sulfite proved a high probability of recovering selenite-ions SeO3 2- and to a lesser extent, selenate-ions SeO4 2- . The experiment on precipitation of selenium were carried out on the basis of synthetic sulfuric solutions, containing, (g/l): 5-15 Se (IV), 5 Se (VI), 60 Cr (III), 5 Cr (VI), 100-250 H2 SO4 . It has been found that the temperature increase adversely affects the process of recovering selenium with sulfur dioxide, which is caused by reduction of the solubility of sulfur dioxide. The selenium selection process using sodium sulfate is characterized by significantly higher recovery rate due to removal of the diffusion constraints associated with the dissolution of sulfur dioxide. By using all studied reducing agents in the optimum conditions, almost complete recovery of selenium is ensured, selenium is at that recovered with not more than 60%. Conclusion: Taking into account high rates of extraction of selenium from sulphate chrome-bearing solutions, sulfur dioxide and sodium sulfite, choice of selenium recovery, largely determined by specific features of an enterprise.

Keywords: Chromium, Recovery, Selenium, Sulphide Copper Ores, Washing Acid