Solarworld Aktiengesellschaft

Torsten Sill

Hans-Dieter Block

Andreas Bulan

Rainer Weber

Leslaw Mleczko

Sigurd Buchholz

The invention relates to a method for producing silane (SiH) by a) reacting metallurgical silicon with silicon tetrachloride (SiCl) and hydrogen (H), to form a crude gas stream containing trichlorosilane (SiHCl) and silicon tetrachloride (SiCl), b) removing impurities from the resulting crude gas stream by washing with condensed chlorosilanes, c) condensing and subsequently, separating the purified crude gas stream by distillation, d) returning the partial stream consisting essentially of SiClto the reaction of metallurgical silicon with SiCland H, e) disproportionating the partial stream containing SiHCl, to form SiCland SiHand f) returning the SiHformed by disproportionation to the reaction of metallurgical silicon with SiCland H, the crude gas stream containing trichlorosilane and silicon tetrachloride being liberated from solids as far as possible by gas filtration before being washed with the condensed chlorosilanes. The washing process with the condensed chlorosilanes is carried out at a pressure of 25 to 40 bar and at a temperature of at least 150&#xb0; C. in a single-stage distillation column and is carried out in such a way that 0.1 to 3 wt. % of the crude gas stream containing trichlorosilane and silicon tetrachloride is recovered in the form of a condensed liquid phase consisting essentially of SiCl, this liquid phase then being removed from the SiClcircuit and expanded to a pressure of 1 bar outside said SiClcircuit and cooled to a temperature of 10 to 40&#xb0; C., whereby dissolved impurities separate out and are then removed by filtration.

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Schwelm, Germany

Torsten Sill