Electrodeposition of Indium and Tin from Molten Chloride Electrolytes

Wednesday, 31 May 2017: 15:00
Marlborough A (Hilton New Orleans Riverside)
G. M. Haarberg (Norwegian University of Science and Technology), B. Qin (Kunming University of Science and Technology), and A. M. Martinez (SINTEF)
Recycling of electronic waste to recover the metal value is of prime importance, especially for metals with limited resources. An electrochemical approach should be an interesting option to develop sustainable recycling processes.

The electrochemical deposition of tin was studied by using cyclic voltammetry at glassy carbon electrodes in molten LiCl-KCl at 450 ℃. Tin deposition on the glassy carbon electrode was found to be diffusion controlled in molten LiCl-KCl containing 0.1mol% SnCl2. At higher anodic voltage, Sn2+ was oxidised to Sn4+. Metallic tin of high purity was obtained in potentiostatic electrolysis experiments. The current efficiency for deposition of Sn was as high as 95%.

The electrochemical reduction processes in molten LiCl-KCl eutectic containing InCl3, InCl2 and InCl were studied on glassy carbon electrode at 450 °C. The cathodic discharge of indium ions to form metallic indium was shown to take place by a consecutive two-step electrochemical process involving In3+, In+ and metallic In.

Metallic indium was deposited by constant voltage electrolysis in molten LiCl-KCl containing InCl3.

The electrochemical behaviour of ITO (indium oxide combined with 10 percent tin oxide) was studied in molten LiCl-KCl at 450 °C. The direct deoxidation of solid ITO was investigated by using different electrodes such as Mo wire and liquid zinc. An ITO covered glass electrode was investigated by electrochemical means in molten LiCl-KCl at 450 °C using Mo wire current collector. The findings, together with SEM and EDX analyses, confirmed that some ITO had been reduced.