Reciclar silicon

RECYCLING OF SILICON POWDER RETRIEVED FROM DIAMOND WIRE SLICING KERF Marwan Dhamrin, Tadashi Saitoh and Koichi Kamisako Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588, Japan, Toshinori Mori and Naohisa Iwamoto, Japan Fine Steel, 1-19-1, Ishide, Sanyoonoda, Yamaguchi 756-0063, Japan

ABSTRACT: Recycling procedure to retrieve the Silicon from the diamond wire saw sludge is proposed and examined. In order to clarify the impact of common impurities in the silicon sludge. The resulting evolution curves from the TDPMS measurement indicate that most of the organic gases will have high evolution intensity at temperatures below 200 oC. However, CO and N2 have almost the same evolution all over the range of temperatures between 100 and 1000oC. Model experiment was performed to investigate the impact of nickel and carbon on multicrystalline ingot quality. The diffusion length distribution was normal in the nickel contaminated ingot and comparable non-contaminated ingots while the carbon contaminated ingot have poor quality if compared with non-contaminated ingots. The Total oxygen measurement was used to evaluate the oxygen contents in our swarf material and the total oxygen contents were found to be below 5 %. We succeeded to melt the silicon swarf in small scale experiment and the impurity concentration was compared to the initial impurity concentrations in the silicon swarf. Keyword: Silicon Feedstock, Recycle, Diamond Wire, Sludge, Swarf

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INTORODUCTUION

Photovoltaics became one of the most promising technologies to supply world-wide clean energy. The number of solar cell fabrication companies has increased massively in the recent few years leading to a strong demand of the poly silicon required for the solar cell production in which about 90 % is based on crystalline silicon ingots. These ingots are sliced using multi-wiresaw machines with steel wires of 120-150 m diameters which therefore loses at least 40 % of the