Extraction and separation of zinc, lead, silver, and bismuth from bismuth slag
Peng Xing 1,   Baozhong Ma 1,   Chengyan Wang 1  
,   Yongqiang Chen 1  
 
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School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing
CORRESPONDING AUTHOR
Chengyan Wang   

School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, 30 Xueyuan Road, Haidian District, Beijing, 100083 Beijing, China
Yongqiang Chen   

School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, 30 Xueyuan Road, Haidian District, Beijing, 100083 Beijing, China
 
Physicochem. Probl. Miner. Process. 2019;55(1):173–183
 
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ABSTRACT
The present paper deals with the extraction and separation of zinc, lead, silver, and bismuth from a refractory bismuth refining slag via a hydrometallurgical route. The process consists of a preliminary leaching of zinc with water, followed by the selective leaching of lead and silver with a calcium chloride solution, leading to the crystallization of lead chloride and the cementation of silver. The diagrams of the total concentrations of [Pb]/[Ag] versus [Cl-] and temperature in the Pb/Ag-Cl-H2O system were drawn, respectively, to determine the optimum concentration of leaching agent and leaching temperature. The potential-pH diagram of the Pb/Ag/Bi-H2O system indicates that the preferential leaching of lead and silver could be achieved. Finally, 98.8% of lead and 90.4% of silver were selectively removed by further leaching the water leaching residue with 400 g/dm3 of CaCl2 solution at pH 4.5 and 80 °C, while only 3.7% of bismuth was leached in this stage. Fifty-nine percent of lead in the leach liquor was separated out as PbCl2 by natural cooling. Ninety-five percent of silver in mother liquor was recovered by cementation with a lead sheet. The depleted CaCl2 solution can be sent to the leaching step again to close the loop.
eISSN:2084-4735
ISSN:1643-1049