A novel approach for recycling spent ITO through electro-deoxidization in a low-Temperature molten salt electrolyte

The recycling and utilization of spent ITO (s-ITO) presents a critical solution to address the dual challenges of environmental burden and resource scarcity arising from the accumulation of high-value electronic waste and the surging global demand for strategic metal indium. Conventional pyrometallurgical and hydrometallurgical recovery approaches, involving thermal reduction and acid leaching processes respectively, face significant sustainability limitations due to their inherent generation of greenhouse gas emissions and excessive consumption of chemical reagents. While molten salt electro-deoxidation using CaCl2 electrolyte demonstrates technical feasibility, its elevated operating temperature (850 °C) results in substantial energy consumption, thereby compromising the economic viability of the recovery process. To overcome these limitations, we propose a novel low-Temperature molten salt electrolysis strategy for ITO recycling. In a NaOH-KOH melt system at 250 °C, s-ITO can undergo direct electro-deoxidation at the cathode. Simultaneously, s-ITO can dissolve in the electrolyte to form soluble indates and stannates, which are subsequently reduced at the cathode. Ultimately, s-ITO is reduced through these two mechanisms to yield In-Sn alloys. Compared to the CaCl2-based molten salt recovery methods, this strategy significantly lowers the recovery temperature, enhancing its operability and offering greater potential for scalability.