Clean Extraction of Bismuth from Bismuth Sulfide Concentrate and Resources Utilization of Lead Dust

For the technical challenges in the smelting process of bismuth sulfide concentrate and hazardous characteristics of lead dust, a clean co-smelting process of bismuth sulfide concentrate and lead dust is introduced in this paper. The hazardous waste lead dust (ZnO) is used as a sulfur-fixing agent to recover metallic bismuth and lead from furnace charge by reductive sulfur-fixing smelting. This process fixes elemental sulfur into iron matte, avoiding the emission of sulfur-containing gases. The mechanism of bismuth extraction and sulfur fixation in co-smelting was revealed by thermodynamic calculations and phase transformation experiments. Under the reducing atmosphere, PbSO 4 in lead dust was firstly reduced to PbS, then Bi 2 S 3 and PbS interacted with ZnO to form Bi 2 O 3 , PbO, and ZnS, and finally intermediate products, Bi 2 O 3 and PbO, were reduced to metallic bismuth and lead. The feasibility and reliability of this technique were confirmed by process simulation experiments. Under the optimum conditions (W Bismuthine :W Lead dust :W Na2CO3 :W Coke  = 10:6:15:1, 900 °C, 60 min), the bismuth recovery rate and sulfur-fixing rate were 98.57% and 97.32%, respectively, and the grade of crude bismuth was 89.81%. This technique provided a new solution for bismuth extraction and lead-bearing solid waste environmentally-friendly disposal.