2023-04-13 チャルマース工科大学
しかし、CIGSには希少金属であるインジウムと銀が必要であり、製造過程で排出される廃棄物には貴重な金属と有害物質が混ざっているため、環境上の問題がある。
研究者たちは、より環境に優しいリサイクル方法を開発し、実証している。新しい方法では、過去の方法に比べて使用する化学薬品量が大幅に減り、室温で行われるため、環境にも優しい。この方法で、銀100％、インジウム85％を回収することができ、再利用に適した高純度の金属に戻すことができる。研究者たちは、この方法が将来的には大規模に使用される可能性があるとしており、リサイクルプロセスの最適化に役立つことを期待しています。
＜関連情報＞
- https://news.cision.com/chalmers/r/gentle-method-allows-for-eco-friendly-recycling-of-solar-cells,c3749437
- https://www.sciencedirect.com/science/article/pii/S0927024822005955?via%3Dihub
温和な条件下での浸出による薄膜CIGS太陽電池からの貴重な金属リサイクル Valuable metal recycling from thin film CIGS solar cells by leaching under mild conditions
Ioanna Teknetzi, Stellan Holgersson, Burçak Ebin
Solar Energy Materials and Solar Cells Available online: 16 January 2023
DOI:https://doi.org/10.1016/j.solmat.2022.112178
Highlights
•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 HNO3.
•Selective leaching of contaminants can be achieved with no more than 0.5 M HNO3.
•Molybdenum recovery reached 60 mg/cell with 2 M HNO3, close to that of silver.
Abstract
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 HNO3 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 HNO3 extracts 85% Ag and 30% In, with correspondingly reduced contamination levels. Finally, leaching with 0.1 M HNO3 proved to be promising for achievement of higher Ag purity through an initial step of Zn selective leaching for 1 h.
