以高溫氯化法從廢棄銅銦鎵硒太陽能板中回收金屬 鎵、銦

Abstract

有鑒於全球暖化與環保意識高漲，裝設再生能源儼然成為改善氣候變遷的重要目標，太陽能因此成為各國推動綠色能源的主力，使得全球太陽能板裝置容量快速增加。然而，隨之而來的廢棄太陽能板處置將是一大問題，根據國際能源總署預估，2030 年時全球太陽能板廢棄物可能達到 800 萬噸，到 2050 年時可能達 到 7800 萬噸，可見發展太陽能板廢棄回收再利用有其重要性。 在現今的太陽能市場當中，晶矽太陽能電池仍是主流，其餘市場則由薄膜太 陽能電池佔據;薄膜銅銦鎵硒 (CIGS) 太陽能板中的光吸收層由銅、銦、鎵、硒 四種元素所組成，其中金屬鎵與金屬銦已被歐盟訂定為關鍵原材料，主要用於半 導體與液晶顯示器的製造。由於兩者在地殼存量皆稀少，且資源集中在少數地 區，所以如果能從廢棄太陽能板當中回收鎵、銦再供給製造產業，將能減低廢棄 物所帶來的環境衝擊，也能確保太陽能板供應鏈的永續。 本研究使用微波熱裂解等方式進行銅銦鎵硒太陽能板的前處理，以有效去除 太陽能板中的有機質，以利後續回收流程進行。研究結果顯示，在微波功率 250 瓦、40 分鐘的操作條件下，CIGS 太陽能板的失重率及可達 48.1%，經過磨碎與 篩分後，可將金屬鎵的回收率從 2.70% 提升至 65.4%。 在鎵回收實驗中，高溫氯化反應在 400°C 下，即可達到 97.97% 的回收率；然而，考量到回收產物純度與反應參數最佳化後，最適合的反應條件是 300°C、氮氣流量 150 mL/min.、氯化氨加藥量重量比 1:3，反應時間 2 小時，其回收率為65.4%，回收產物中鎵的金屬佔比為 98.0% 。在銦回收實驗中，高溫氯化反應在560°C 下，則可從去鎵殘渣中回收 93.85% 的銦;然而，考量回收產物純度後，在氮氣流量 150 mL/min.、氯化氨加藥量重量比 1:3，反應時間 2 小時的條件下，最適合的反應溫度是 400°C，此時銦回收率為 72.40%，回收產物中銦的金屬佔比為58.0% 。

Increasing concern over global warming and depletion of fossil fuels have led to a concentrated effort to develop alternative energy sources, such as solar energy. However, proper management of end-of-life solar panels is imperative, highlighting the need for effective recycling and disposal methods. Gallium and indium are globally recognized as critical materials due to their scarcity within the Earth’s crust and the difficulty in refining. Major applications of gallium and indium are in the semiconductor industry, where they are used to produce the photovoltaic (PV) layer for copper indium gallium selenide (CIGS) solar cells and other electronic components. With the yearly installed PV capacity significantly increasing in recent years, the issue of solar panel waste has become urgent. Recycling critical materials from waste CIGS solar panels can not only reduce environmental harm, but also ensure a sustainable supply chain. In this study, a recycling process was developed for waste CIGS solar panels. The process includes two main steps: microwave-induced pyrolysis as pretreatment and a pyrometallurgical chlorination process to recycle gallium and indium. The study showed that a weight loss percentage of 48.1 wt% could be achieved at a power level of 250 W for 40 minutes during the microwave-induced pyrolysis process. The overall pretreatment process significantly enhanced the gallium recovery rate from 2.70 to 65.4% in the chlorination process. In the gallium recycling process, an significant gallium recovery rate of 97.97% could be achieved at 400°C during the pyrometallurgical chlorination process. Through optimization studies, an operating temperature of 300°C was identified as the optimal condition for gallium recovery, enabling the production of high-purity gallium products. In the indium recycling process, 93.85% of the indium could be recovered from the gallium separation residue at 560°C during the pyrometallurgical chlorination process. Through optimization, an operating temperature of 400°C was identified as the optimal condition for indium recovery, allowing the production of high-purity indium products. These serial processes demonstrate a direct recycling of valuable materials from waste CIGS solar panels, showing promise for efficient and sustainable resource recovery. Additionally, this is the first research using a pyrometallurgical recycling process to recycle critical raw materials from CIGS solar panels.