Selective leaching and recovery of bismuth as Bi2O3 from copper smelter converter dust

• A hydro process has been developed to recover Bi as Bi2O3 from converter dust.
• Using an acidic-chloride medium 92% Bi leaching efficiency achieved.
• Saleable Bi2O3 product having a purity of 97.8% was produced.
• Antimony is difficult to remove from the Bi2O3 product.

Secondary materials such as converter dusts from the copper smelters are rich in bismuth and other valuable metals. This paper describes an economically viable Bi recovery process from the converter dust by a hydrometallurgical method. The results showed that, Bi could be effectively leached out from the converter dust using a combination of H2SO4 and NaCl as leaching reagent with a leaching efficiency of 92% under the optimum conditions. Small amount of impurities such as Ag, Pb, Te and Se were removed from the leach solution by SO2 reduction. Bismuth was separated from the leach solution as crude BiOCl cake by hydrolysis method. The final bismuth product, Bi2O3 was synthesized by NaOH treatment of the crude BiOCl cake at elevated temperature. The purity of the Bi2O3 product was about 97.8%, As, Pb and Sb being the major impurities. Based on the feasibility study, the process was deemed technically feasible and its product commercially saleable.