Reductive smelting of spent lead–acid battery colloid sludge in a molten Na2CO3 salt

• Published in: International journal of minerals, metallurgy and materials Vol. 22; no. 8; pp. 798 - 803
• Main Authors: Hu, Yu-jie, Tang, Chao-bo, Tang, Mo-tang, Chen, Yong-ming
• Format: Journal Article
• Language: English
• Published: Beijing University of Science and Technology Beijing 01.08.2015; Springer Nature B.V; School of Metalurgy and Environment, Central South University, Changsha 410083, China
• Subjects: Ceramics; Characterization and Evaluation of Materials; Chemistry and Materials Science; Composites; Corrosion and Coatings; Dosage; Fixing agents; Glass; Lead acid batteries; Materials Science; Metallic Materials; Molten salts; Natural Materials; Recovery; Salts; Sludge; Smelting; Sodium carbonate; Sulfur; Surfaces and Interfaces; Thin Films; Tribology; Zinc oxide; Zinc sulfide; lead smelting; solid waste recycling; desulfurization; lead–acid batteries; molten salts; lead-acid batteries
• ISSN: 1674-4799; 1869-103X
• DOI: 10.1007/s12613-015-1136-5

Lead extraction from spent lead–acid battery paste in a molten Na 2 CO 3 salt containing ZnO as a sulfur-fixing agent was studied. Some influencing factors, including smelting temperature, reaction time, ZnO and salt dosages, were investigated in detail using single-factor experiments. The optimum conditions were determined as follows: T = 880°C; t = 60 min; Na 2 CO 3 /paste mass ratio = 2.8:1; and the ZnO dosage is equal to the stoichiometric requirement. Under the optimum conditions, the direct recovery rate of lead reached 98.14%. The results suggested that increases in temperature and salt dosage improved the direct recovery rate of lead. XRD results and thermodynamic calculations indicated that the reaction approaches of lead and sulfur were PbSO 4 →Pb and PbSO 4 →ZnS, respectively. Sulfur was fixed in the form of ZnS, whereas the molten salt did not react with other components, serving only as a reaction medium.