Green Extraction of Metallic Bismuth from Bismuth Sulfide Concentrate via Reductive Sulfur-Fixed Smelting

A novel technology for clean and efficient extraction of metallic bismuth from bismuth sulfide concentrates is proposed: reductive sulfur-fixed smelting. The reaction mechanisms of metallic bismuth extraction and elemental sulfur immobilization are revealed by thermodynamic calculations and phase characterization. Under the reducing atmosphere, Bi2S3 reacts with Fe2O3 and Na2CO3 to produce metallic Bi, and the element S is transferred and immobilized into the FeS and Na2S phases, thus effectively eliminating the generation of low-concentration sulfur-containing flue gas. Controlling the mass ratio of charge as WBismuthinite/WHematite/WNa2CO3/WC = 100:60:21.33:10, the crude bismuth alloy (Bi 91.11%, Pb 7.08%), matte (Fe 53.39%, Na 5.80%, Cu 2.79%, Mo 2.82%, S 29.14%), and slag are obtained after smelting at 1200 °C for 120 min. A total of 95.08% Bi, 71.55% Pb, and 84.35% Ag in the raw material can be enriched in crude bismuth by one step, and a total of 95.22% S is immobilized as sulfide in the solidified products. In general, the new technology of Bi2S3–Fe2O3–Na2CO3–C reductive sulfur-fixed smelting has the advantages of environmental friendliness and a high recovery rate of valuable metal elements. This provides a new solution for the comprehensive utilization of bismuth ore resources.