Valuable metal recycling from thin film CIGS solar cells by leaching under mild conditions.

The increase in the manufacturing of copper-indium-gallium-diselenide (CIGS) thin film photovoltaics is accompanied by a growing amount of production waste, which contains a mixture of valuable, critical and hazardous elements. However, industrial recovery and reuse processes of these elements for production of new photovoltaics are still absent. In this paper, the possibility of using benign leaching conditions for recovering mainly silver and indium from production waste flexible CIGS solar cells was investigated, along with the contamination levels from other industrial elements in the leachate. At the same time, the prospect of selective leaching of contaminants was assessed, aiming to purer streams of the valuable metals and thus their reuse in new products. The results show an increase in the leaching yields of Ag and In when acid concentration and surface to liquid ratio (A:L) increase, however, this is also true for contamination. A complete Ag recovery and 85% recovery of In was achieved with 2 M HNO 3 and A:L equal to 1:3 cm2/ml after 24 h of leaching at room temperature. Under the same conditions, leaching with 0.5 M HNO 3 extracts 85% Ag and 30% In, with correspondingly reduced contamination levels. Finally, leaching with 0.1 M HNO 3 proved to be promising for achievement of higher Ag purity through an initial step of Zn selective leaching for 1 h. • Recycling of Copper Indium Gallium diSelenide cells is achieved at mild conditions. • 100% of silver and 85% of indium are extracted at room temperature with 2 M HNO 3. • Selective leaching of contaminants can be achieved with no more than 0.5 M HNO 3. • Molybdenum recovery reached 60 mg/cell with 2 M HNO 3 , close to that of silver. [ABSTRACT FROM AUTHOR]