METHOD OF PURIFYING METALLURGICAL SILICON WITH WET ALTERNATING CURRENT PLASMA IN VACUUM Russian patent published in 2012 - IPC C01B33/37 C30B29/06 C30B28/06 

FIELD: chemistry.

SUBSTANCE: invention relates to the technology of purifying silicon using plasma technology during industrial production of silicon for photoelectronic industry, as well as for making solar panels. The method involves heating silicon in a crucible until a melt is obtained and treating the melt with a plasma jet directed at an acute angle to the surface, containing an inert gas and water vapour, wherein crude silicon is heated and melted in a cylindrical quartz crucible in a vacuum using a graphite heater; the molten silicon is then treated using a system consisting of three dual-mode plasmatrons with anodes insulated from the housing and a system for feeding water into the anode channel, first with dry argon plasma at direct current of 50-80 A, and then with wet argon plasma at alternating current of 100-200 A, after which a polycrystalline silicon ingot is formed by slowly cooling the melt in the quartz crucible.

EFFECT: obtaining from metallurgical silicon with purity of 98-99,9% a polycrystalline silicon ingot of purity 99,9999% with phosphorus content of not more than 0,1 ppmw, boron content of 0,1-1 ppmw, which is suitable for industrial production of photoconverters.

1 dwg