Abstract:

With the increase of renewable energy use in recent years, it has become feasible to reduce the use of fossil fuels and the associated CO2(g) emissions. However, the appropriate treatment of the waste from used batteries and solar panels is a serious concern due to their large waste amount. Although solar panels have a long-life span of approximately 25 years, recycling will become more and more important because the emission of waste solar panels is getting increase. On the other hand, the high demand of tin will continue in the future as a soldering and plating material, and it will be expected to be depleted after 2030. In conventional recycling processes of PV panels, glass and valuable metals such as copper, and silver are recovered mainly through high environmental load processes such as chemical and thermal processes. In this study, we aim to recover tin as well as cover glass, copper, and silver by a low environmental load process based on physical processes. Target grades were set at 20 wt%-copper, 1 wt%-silver, and 10 wt%-tin, respectively. First, characterization of the ground cell sheet material after hot knife separation with cover glass was conducted. The results showed that copper was concentrated in the coarse size particles group, silver was mainly in the medium size one, and that tin tends to be in the coarse and fine size one. The grade of these valuable metals can be improved via flowing-film concentration (wet shaking table separation) for the coarse group. In addition, silver and tin can be sorted by elbow-jet classifier (simultaneous multiple dry powder classifier) for the fine group. Finally, the grade of copper and silver exceeded the values required for their refining process while maintaining their recovery above 80%. However, tin showed relatively low recovery ratio (about 40%) and low quality (1 wt%) because it concentrated in the coarse group as a plating on copper busbar, making it difficult to separate the tin from the copper. For the higher recovery ratio and grade of tin, a novel method to remove the tin plating from the copper busbar will be necessary.

Keywords: photovoltaic panel, recycle, tin, smelting, renewable energy

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Mr. Kento Izumi