Recovery of Lead from Spent Lead Paste by Pre-desulfurization and Low-Temperature Reduction Smelting
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https://doi.org/10.1007/s11837-020-04186-5 2020 The Minerals, Metals & Materials Society
THERMODYNAMIC MODELING OF SUSTAINABLE NON-FERROUS METALS PRODUCTION
Recovery of Lead from Spent Lead Paste by Pre-desulfurization and Low-Temperature Reduction Smelting BOYI XIE,1,2 TIANZU YANG,1,2 WEIFENG LIU,1,2,3 DUCHAO ZHANG,1,2 and LIN CHEN1,2 1.—School of Metallurgy and Environment, Central South University, Changsha 410083, China. 2.—National Engineering Laboratory for High Efficiency Recovery of Refractory Nonferrous Metals, Changsha 410083, China. 3.—e-mail: [email protected]
The treatment of spent lead paste is essential for the recycling of spent leadacid batteries. In this study, we propose a facile route for the recovery of lead from spent lead paste by pre-desulfurization followed by low-temperature reduction smelting. The effects of two desulfurization methods, i.e., highpressure and normal-pressure processes, on the desulfurization efficiency of spent lead paste were compared. The high-pressure process was found to be more effective than the normal-pressure process; 99.1% of sulfur was removed under the high pressure conditions with NaOH excess of 1.1 at 150C for 30 min. Moreover, a part of PbO2 reacted with PbO to form Pb3O4. Afterwards, the desulfurized residue, mainly consisting of Pb3O4 and PbO2, was directly used in low-temperature reduction smelting, and the optimum smelting conditions were determined to be: starch/Pb-residue mass ratio = 1/6.3; Na2O/Pbresidue mass ratio = 1/15; B2O3/Pb-residue mass ratio = 1/7.5; smelting temperature 700C; and smelting duration 90 min. The lead recovery under the optimum conditions was as high as 93%. Scanning electron microscope images of the smelting slag showed that the smelting slag mainly consisted of PbOx and Na2O.
INTRODUCTION Lead-acid batteries are widely used in numerous fields due to their low price, excellent performance, safety, and reliability. Almost 86% of lead is used in the manufacturing of lead-acid batteries.1 Large amounts of spent batteries are discarded every year, thereby causing a series of environmental pollution and human health problems. Therefore, spent leadacid battery recycling is urgently required for the sustainable development of the lead industry.2–4 Spent lead-acid batteries comprise spent lead paste, spent electrolyte, a grid, a polymer container, and some other parts. Among these, spent lead paste with a complex composition, mainly including PbSO4, PbO2, PbO, and a small amount of metallic lead, is difficult to treat.5,6 In recent years, two main types of processes have been used for the treatment of spent lead paste, i.e., the pyrometallurgical process and the hydrometallurgical process.7,8 In the pyrometallurgical process, spent lead paste for smelting is mixed with lead
concentrate. This process has a high recovery rate and is widely used in industry.9,10 However, a high temperature is commonly required for the smelting stage, which constrains the development of this process. Moreover, the SOx gas released in this proc
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