{"title":"Lead removal from tin chloride solution by barium sulfate and coprecipitation of (BaxPby)(SO4)2 for the processing of PbSn smelter slag","authors":"Lining Yu, Huazhen Cao, Huibin Zhang, Junfeng Kong, Weilun Qian, Anyang Tang, Wenyu Feng, Guoqu Zheng","doi":"10.1016/j.hydromet.2024.106298","DOIUrl":null,"url":null,"abstract":"<div><p>Owing to the characteristics of mineral paragenesis (equilibrium sequence of mineral phases), the hydrochloric acid leach liquors of Sn ores and Sn-containing waste materials typically contain large amounts of Pb. In this study, barium sulfate coprecipitation was employed to efficiently remove Pb from a tin chloride solution. The lead removal efficiency, reaction mechanism, and limitations were investigated by varying the Cl<sup>−</sup> and SO<sub>4</sub><sup>2−</sup> concentrations. The results showed that the structural formula of the precipitates was (Ba<sub>x</sub>Pb<sub>y</sub>)(SO<sub>4</sub>)<sub>2</sub> (x + y = 2), and its solubility product was in the range of 1 × 10<sup>−12</sup>–1 × 10<sup>−13</sup>, indicating that Pb<sup>2+</sup> and Ba<sup>2+</sup> were more easily precipitated in the form of complex salts. In addition, thermodynamic analysis revealed that when the Cl<sup>−</sup> concentration was <1 mol/L in the Pb<sup>2+</sup>–Sn<sup>2+</sup>–Cl<sup>−</sup>–H<sub>2</sub>O system, [Pb<sup>2+</sup>] and [PbCl<sup>+</sup>] were the primary species. These positively charged species were readily adsorbed onto the surface of BaSO<sub>4</sub> via electrostatic forces, resulting in a significant increase in the Pb content of (Ba<sub>x</sub>Pb<sub>y</sub>)(SO<sub>4</sub>)<sub>2</sub>. Therefore, the Pb removal efficiency significantly improved as Cl<sup>−</sup> concentration decreased. The lead removal mechanism involves a combination of adsorption and replacement processes. Based on the aforementioned fundamental study, a method involving dechlorination and coprecipitation was proposed to remove lead from an acid leaching solution of Kaldo slag. With the dechlorination via distillation, the Pb removal efficiency could reach 99.9% at 1 mol/L Cl<sup>−</sup> and 0.5 mol/L SO<sub>4</sub><sup>2−</sup>.</p></div>","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":null,"pages":null},"PeriodicalIF":4.8000,"publicationDate":"2024-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Hydrometallurgy","FirstCategoryId":"88","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0304386X24000380","RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"METALLURGY & METALLURGICAL ENGINEERING","Score":null,"Total":0}
引用次数: 0
Abstract
Owing to the characteristics of mineral paragenesis (equilibrium sequence of mineral phases), the hydrochloric acid leach liquors of Sn ores and Sn-containing waste materials typically contain large amounts of Pb. In this study, barium sulfate coprecipitation was employed to efficiently remove Pb from a tin chloride solution. The lead removal efficiency, reaction mechanism, and limitations were investigated by varying the Cl− and SO42− concentrations. The results showed that the structural formula of the precipitates was (BaxPby)(SO4)2 (x + y = 2), and its solubility product was in the range of 1 × 10−12–1 × 10−13, indicating that Pb2+ and Ba2+ were more easily precipitated in the form of complex salts. In addition, thermodynamic analysis revealed that when the Cl− concentration was <1 mol/L in the Pb2+–Sn2+–Cl−–H2O system, [Pb2+] and [PbCl+] were the primary species. These positively charged species were readily adsorbed onto the surface of BaSO4 via electrostatic forces, resulting in a significant increase in the Pb content of (BaxPby)(SO4)2. Therefore, the Pb removal efficiency significantly improved as Cl− concentration decreased. The lead removal mechanism involves a combination of adsorption and replacement processes. Based on the aforementioned fundamental study, a method involving dechlorination and coprecipitation was proposed to remove lead from an acid leaching solution of Kaldo slag. With the dechlorination via distillation, the Pb removal efficiency could reach 99.9% at 1 mol/L Cl− and 0.5 mol/L SO42−.
期刊介绍:
Hydrometallurgy aims to compile studies on novel processes, process design, chemistry, modelling, control, economics and interfaces between unit operations, and to provide a forum for discussions on case histories and operational difficulties.
Topics covered include: leaching of metal values by chemical reagents or bacterial action at ambient or elevated pressures and temperatures; separation of solids from leach liquors; removal of impurities and recovery of metal values by precipitation, ion exchange, solvent extraction, gaseous reduction, cementation, electro-winning and electro-refining; pre-treatment of ores by roasting or chemical treatments such as halogenation or reduction; recycling of reagents and treatment of effluents.