SOLAR GRADE SILICON REFINING BY THE METALLURGICAL ROUTE
DOI:
https://doi.org/10.59627/cbens.2014.2217Keywords:
Solar grade silicon, photovoltaic, siliconAbstract
The solar energy has become an important alternative of clean energy. The installed capacity of photovoltaic energy reached the historical mark of 101 GW in 2012, representing a market of about US$ 75 billons. Yearly growth rates over the last ten years were more than 30%. Approximately 90% of solar cells are produced with crystalline silicon. This silicon must be pure enough to produce solar cells with high efficiency. In 2010, The Institute for Technological Research - IPT has started a research program funded by National Bank of Social and Economic Development - BNDES and by Cia Ferro Ligas Minas Gerais (MinasLigas) aiming the development of a metallurgical route for Solar Grade Silicon production. Impurities from silicon have been removed by pyrometallurgical steps, such as controlled solidification to allow the removal of metallic impurities and carbon, slag treatment or plasma remelting under H2/H2O atmosphere to remove boron and vacuum treatment of molten silicon to remove phosphorus. Results of such treatments are presented and discussed, showing an increasing of purity level from 99,5% to 99,999%.
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