Indium Recovery by Selective Removal of Copper and Tin from ITO Etching Waste Solution by Cementation with Cobalt and Subsequent Electro-Winning: A Validation Experiment

Abstract

AbstractA three-step batch-type indium recovery method was developed to prove feasibility of recovering indium powders from highly acidic dilute indium chloride solution prepared by dissolving indium tin oxide (ITO) electrodes of waste liquid crystal display (LCD) panels in concentrated hydrochloric acid (HCl) solutions. More specifically, a batch-type three-step indium recovery by cementation and subsequent electro co-deposition process was designed and performed and its individual experimental parameters were varied to get insights in the engineering feasibility of validation experiments. Significant proportion of copper and tin was removed by cementation with cobalt powder. Residual copper and tin ions were further removed by primary electro co-deposition directly from the highly acidic etching waste solution recovered from cementation process. Synergistic effect of cobalt electro co-position on indium electro-reduction was observed during secondary electro co-deposition, which warrants additional electro-refining process for selective removal of indium from cobalt-indium metal mixture and its purification. Ionic and metallic species thus obtained from the validation experiments were further characterized using various analytical tools such as inductively coupled plasma/atomic emission spectroscopy (ICP/AES), X-ray diffraction (XRD), scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDS), and X-ray fluorescence (XRF).