J. Japan Inst. Metals, Vol. 61, No. 10 (1997),
pp. 1086-1093

Removal of Phosphorus, Aluminum and Calcium by Evaporation in Molten Silicon

Noriyoshi Yuge, Kazuhiro Hanazawa,Kohji Nishikawa and Hisaei Terashima

Abstract:

Vacuum refining under the atmospheres of 8.0{×}10^-3{~}3.6{×}10^-2 Pa was applied for removing phosphorus, aluminium and calcium in metallurgical grade silicon (MG-Si) at 1722{~}1915 K, and the low-pressure refining under the atmospheres of 4.0{~}190 Pa was applied for removing phosphorus at 1733{~}1823 K.
The phosphorus and calcium contents decreased under 0.1 mass ppm by vacuum refining at 1915 K. The removal rates of these elements from molten silicon were roughly expressed by the equations of the first order. The apparent rate constants were expressed as follows;

(Received November 13, 1996)

Keywords:

refining, metallic silicon, removal, vaporization, phosphorus, aluminium, calcium, activation energy, mass transfer controlled, chemical reaction controlled

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