Abstract: To address the low indium recovery rate obtained from secondary zinc oxide weak acid residues, this work focused on the process intensification of conventional acid leaching technology. Key operational parameters, including sulfuric acid concentration, liquid-to-solid ratio, reaction temperature, reaction time, and rotation speed, were systematically investigated to explore their effects on indium leaching efficiency, with the aim of identifying the optimal leaching conditions for practical application. Experimental results demonstrated that under the specific conditions, sulfuric acid concentration of 3 mol/L, liquid-to-solid ratio of 4∶1, reaction temperature of 80℃, reaction time of 120 min, and rotation speed of 500 r/min, the indium leaching efficiency reached 90.51%. To further enhance indium leaching performance and achieve higher leaching efficiency, subsequent intensive optimization was carried out. The results revealed that under the aforementioned optimal leaching conditions, adding sodium sulfite as a reductant significantly increased the indium leaching efficiency to 93.50%, showing obvious intensification advantages for industrial practice. To unravel the intrinsic leaching reaction mechanism, multiple characterization methods including XRD, SEM-EDS, and XPS were adopted to comparatively analyze solid samples before and after leaching. The characterization results indicated that part of indium was isomorphically embedded in the lattice structure of zinc ferrite. During reductive leaching, redox reactions effectively disrupted the crystal structure of zinc ferrite, facilitating the release of indium elements encapsulated within the lattice into the solution in a soluble form. This mechanism significantly enhanced the leaching effect and realized a substantial improvement in indium extraction efficiency. The outcomes of this study can offer a reliable theoretical basis and technical support for the development of new high-efficiency indium recovery processes from indium-containing zinc residues in the metallurgical industry.

Key words: indium, secondary zinc oxide weak acid residues, zinc ferrite, sulfuric acid leaching, reductive leaching

摘要： 针对次氧化锌弱酸渣中铟回收利用率低的问题，本研究对常规酸浸过程进行工艺强化，系统考察了硫酸浓度、液固比、温度、反应时间等因素对铟浸出率的影响。实验结果表明，在硫酸浓度3 mol/L、液固比4∶1、温度80℃、反应时间120 min、转速500 r/min的条件下，铟浸出率达90.51%。在此基础上，进一步开展还原浸出，在相同条件下加入亚硫酸钠为还原剂后铟浸出率提升至93.50%。对不同条件下反应前后的样品进行X射线衍射(XRD)、扫描电镜-能谱(SEM-EDS)、X射线光电子能谱(XPS)表征分析，以阐明浸出过程反应机理。结果表明，少量铟以类质同象的形式存在于铁酸锌(ZnFe2O4)晶格中，通过还原浸出能有效破坏ZnFe2O4晶格，释放出可溶性铟，从而强化浸出效果，进一步提高铟的浸出效率。

关键词: 铟, 次氧化锌弱酸渣, 铁酸锌, 硫酸浸出, 还原浸出