PRODUCING METALLIC ANTIMONY WITH THE LOW ARSENIC CONTENT FROM ANTIMONY CONCENTRATE

Abstract

The paper provides the method developed by the authors to produce low-arsenic crude antimony from the antimony concentrate containing 47,77 of Sb and 0,17 % of As. The basis of the concentrate is sodium hexahydroxoantimonate or mopungite mineral. Concentrate reduction with coke according to the traditional technology produced crude antimony with a high arsenic content – 0,34 %. To reduce arsenic content in crude metal to 0,1 % and eliminate a separate stage of antimony refining from arsenic, reduction melting is proposed in the presence of sodium plumbite or lead oxide. This allows obtaining crude antimony with an arsenic content of 0,07–0,1 %. The process of antimony concentrate reduction melting on crude antimony was carried out in an oven with silicon carbide heaters in alundum crucibles with charge batches 100–150 g each. The content of base metal and impurities in crude antimony was determined by chemical and atomic absorption methods. The form of arsenic in the concentrate was determined by X-ray phase analysis using the DRON-3 automated diffractometer (CuKα radiation, β filter). Arsenic concentration in the slag phase in the form of Pb2As2O7 lead diarsenate is shown. Thermal gravimetric analysis was performed for reduction melting of charge consisting of antimony concentrate, lead oxide and coke and it was found that metal antimony formation occurs in a temperatures range of 445–950 °C.