Effective Separation and Recovery of Valuable Components from CIGS Chamber Waste via Controlled Phase Transformation and Selective Leaching

Abstract

Copper indium gallium diselenide (CIGS) chamber waste formed during CIGS solar-cell production was subjected to two-stage sulfation roasting for controlled phase transformation and selective leaching to separate valuable components. Selenium was initially separated in the first stage of sulfation roasting. Under the optimal conditions, 99.96% of selenium was volatilized into gas in the form of selenium dioxide, and the remaining components were converted to sulfates. The second stage of roasting followed by water leaching was investigated for the separation and recovery of the remaining components in slag. Controlled phase transformation of sulfates was completed in the second stage roasting. Indium and gallium sulfates are converted to oxides, whereas CuSO4 remained nearly unchanged. Afterward, 95.90% of copper was selectively leached into liquor, and the leaching rates of indium and gallium were only 5.67% and 2.89%, respectively. Consequently, the content of mixed indium and gallium oxides in the leach residue was 91.09%. Exploratory experiments show that indium and gallium can be effectively separated via alkali leaching and precipitation. Therefore, effective separation of valuable metals from CIGS chamber waste was achieved based on the different physical and chemical properties of the components.