Tecnologia em Metalurgia, Materiais e Mineração (Dec 2014)

SILICON REFINING BY VACUUM TREATMENT

  • André Alexandrino Lotto,
  • João Batista Ferreira Neto,
  • Marcelo Breda Mourão

DOI
https://doi.org/10.4322/tmm.2014.041
Journal volume & issue
Vol. 11, no. 4
pp. 304 – 310

Abstract

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This work aims to investigate the phosphorus removal by vacuum from metallurgical grade silicon (MGSi) (98.5% to 99% Si). Melting experiments were carried out in a vacuum induction furnace, varying parameters such as temperature, time and relation area exposed to the vacuum / volume of molten silicon. The results of chemical analysis were obtained by inductively coupled plasma (ICP), and evaluated based on thermodynamic and kinetic aspects of the reaction of vaporization of the phosphorus in the silicon. The phosphorus was decreased from 33 to approximately 1.5 ppm after three hours of vacuum treatment, concluding that the evaporation step is the controlling step of the process for parameters of temperature, pressure and agitation used and refining by this process is technically feasible.

Keywords