Silicon purification in vacuum induction furnace


In this paper the removal of impurities from metallurgical grade silicon by vacuum melting in an induction furnace was studied, in order to produce solar grade silicon, which is raw material of the photovoltaic cells to convert solar energy into electricity. The work was focused ono the removal of phosphorus, which is one of the most difficult impurities to remove from silicon. Phosphorus concentration dropped from 119 ppm to 8 ppm of phosphorus in 3 hours at 1650°C under pressure of 0.2 Pa. It was concluded that this method is technically feasible for purification of metallurgical grade silicon. The kinectic rates constants were obtained for phosphorus (kP=5·10-6 m/s), aluminum (kAl=2·10-6 m/s) and calcium (kCa=1·10-5 m/s). Silicon losses by vaporization during the test averaged around 13%.

LOTTO, André Alexandrino; FERREIRA NETO, João Batista; MOURÃO, Marcelo Breda. Silicio purification in vacuum induction furmance. Revista Basileira de Aplicações a Vácuo, v.34, n.1, p.35-38, jan.-abr., 2015.

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