Lupi Carla, Ciro Erwin, Dell'Era Alessandro
Department ICMA, Sapienza University of Rome, Via Eudossiana 18, 00184 Roma, Italy.
Department SBAI, Sapienza University of Rome, Via del Castro Laurenziano 7, 00161 Roma, Italy.
Materials (Basel). 2025 May 2;18(9):2089. doi: 10.3390/ma18092089.
Indium, widely used as indium-tin oxide (ITO), has been recognized as a strategical metal for audiovisual, optoelectronic systems, semiconductors and photovoltaic fields. An increasing shortage and unflexible mineral supply have led indium to be recovered from secondary sources, such as waste electrical and electronic equipment (WEEE). The main step for indium hydrometallurgical recovery from WEEE is the electrowinning process using sulfate baths, giving lower environmental impact and improved workplace safety conditions. In this investigation, a titanium cathode has been employed for the study of the indium electrowinning process in a sulfate-based bath. This study was focused on analyzing current efficiency (CE), specific energy consumption (SEC) and deposit morphology and structure as the temperature, current density, pH and electrolyte composition were varied. Prior to conducting electrowinning tests, a conventional three-electrode cell was used to perform cyclic voltametric assessments of the electrodeposition reactions on the Ti electrode at room temperature. The indium electrowinning tests on Ti cathodes presented CE values higher than 90%, with low energy consumption at low current densities, showing a negligible influence of additive agents in the bath, different from results obtained with other cathodes in other works. Moreover, the increase of the current density beyond 75 A/m produced significant effects by etching the electrode surface with 1M HF. In particular, at the conclusion of this investigation, good results are obtained without additives, by etching the titanium cathode and operating at higher current density between 100 and 200 A/m at pH 2.3 and different temperatures (40 °C and 60 °C). Finally, indium deposits were analyzed by XRD and SEM in order to determine the influence of operative conditions on the structure and surface morphology.
铟作为铟锡氧化物（ITO）被广泛应用，已被公认为视听、光电系统、半导体和光伏领域的战略金属。日益短缺且缺乏灵活性的矿产供应促使人们从二次资源中回收铟，如废弃电子电气设备（WEEE）。从WEEE中湿法冶金回收铟的主要步骤是使用硫酸盐电解液的电解沉积过程，这对环境的影响较小，且改善了工作场所的安全条件。在本研究中，采用钛阴极来研究基于硫酸盐电解液的铟电解沉积过程。该研究聚焦于分析电流效率（CE）、比能耗（SEC）以及随着温度、电流密度、pH值和电解液成分变化时沉积物的形态和结构。在进行电解沉积测试之前，使用传统的三电极电池在室温下对钛电极上的电沉积反应进行循环伏安评估。在钛阴极上进行的铟电解沉积测试的CE值高于90%，在低电流密度下能耗较低，表明电解液中添加剂的影响可忽略不计，这与其他研究中使用其他阴极获得的结果不同。此外，当电流密度超过75 A/m²时，会用1M HF蚀刻电极表面，从而产生显著影响。特别是在本研究结束时，在不添加添加剂的情况下，通过蚀刻钛阴极并在pH值为2.3且不同温度（40℃和60℃）下以100至200 A/m²的较高电流密度运行，获得了良好的结果。最后，通过XRD和SEM对铟沉积物进行分析，以确定操作条件对结构和表面形态的影响。
