Spent Lead-Acid Battery Recycling via Reductive Sulfur-Fixing Smelting and Its Reaction Mechanism in the PbSO4-Fe3O4-Na2CO3-C System

摘要

An innovative and environmentally friendly lead-acid battery paste recycling method is proposed. The reductive sulfur-fixing recycling technique was used to simultaneously extract lead and immobilize sulfur. SO2 emissions and pollution were significantly eliminated. In this work, the detailed lead extraction and sulfur-fixing mechanisms in the PbSO4-Fe3O4-Na2CO3-C system were investigated thermodynamically and experimentally, and the phase transformation and microstructural evolution processes characterized. In addition, a series of bench-scale pilot experiments were carried out to confirm the feasibility of the technique. The results show that the lead extraction and sulfur-fixing reactions followed the shrinking unreacted-core model. The recycling products were separated into three distinct layers: slag, matte, and crude lead bullion. Primary recoveries of 96.2% for lead and 98.9% for sulfur were obtained. The purity of the crude lead bullion was 98.6wt.%. Sulfur was fixed in the solidified matte as FeS and NaFeS2.