Extraction and separation of Fe and Ti from extracted vanadium residue by enhanced ammonium sulfate leaching and synthesis of LiFePO4/C for lithium-ion batteries

Recycling and utilization of metal resources in extracted vanadium residue can effectively alleviate resource shortage and environmental pollution problems. In this work, a closed-loop recovery process of Fe and Ti from extracted vanadium residue with ammonium sulfate as a roasting additive is proposed. The results show that the acidifier-ammonium bisulfate produced during the roasting process of ammonium sulfate can significantly reduce the roasting temperature. Under the optimal process conditions, 96.91% Fe and 27.33% Ti are leached, and 81.79% Fe is recovered in the form of ammonium jarosite. Ti-doped LiFePO4/C is prepared by solid-state synthesis with ammonium jarosite as Fe source, and the initial discharge specific capacity of the LiFePO4/C reached 141.6 mAh·g−1 at 0.1C. The waste residue after recovering Fe and Ti from extracted vanadium residue is a high-quality raw material for preparing petroleum proppant, and the ammonium sulfate generated during the roasting process can also be recycled. The closed-loop process proposed in this study not only avoids the use of a large number of strong acids but also realizes the full utilization of extracted vanadium residue, improves the utilization rate of mineral resources, reduces environmental pollution, which has important reference significance for the high-value utilization of similar metallurgical waste slag. © 2021 Elsevier B.V.