Process for continuous closed-loop production of silane and polysilicon by magnesium silicide combined method

Abstract

The invention discloses a technology for continuously carrying out closed-loop production on silane and polycrystalline silicon through a magnesium silicide combination method. The technology comprises the following steps: synthesizing magnesium silicide through silicon and magnesium; enabling the magnesium silicide to react with ammonium chloride dissolved in liquid ammonia, thus obtaining a silane mixture and hexammoniate magnesium chloride; decomposing the hexammoniate magnesium chloride, thus obtaining magnesium chloride and ammonia, wherein the ammonia is liquefied and recycled; carrying out electrolysis on the magnesium chloride, thus obtaining magnesium and chlorine, wherein the magnesium is used for synthesizing the magnesium silicide; synthesizing hydrogen chloride from the chlorine and hydrogen, absorbing the hydrogen chloride by the liquid ammonia, thus obtaining ammonium chloride, wherein the ammonium chloride is used for generating the silane; cooling and separating the silane mixture, thus obtaining disilane and silicane, and respectively purifying the disilane and the silicane, thus obtaining high-purity disilane and high-purity silicane; decomposing the high-purity silicane, thus obtaining high-purity polycrystalline silicon. According to the technology disclosed by the invention, closed-loop production is realized, the production cost is reduced, and no environment pollution exists.

Description

technical field [0001] The invention relates to a closed-loop continuous production process of high-purity monosilane, high-purity disilane and high-purity polysilicon by magnesium silicide combined method. Background technique [0002] The magnesium silicide method has a long history of preparing high-purity silane and high-purity silicon. Our country had systematic research and industrial production as early as the 1960s, but it was considered that the production cost was too high and it has been limited to small-scale production. . The main reason is that closed-loop production and continuous production cannot be truly realized. [0003] The existing magnesium silicide method for preparing high-purity silane and high-purity silicon mainly discloses a silicon cycle (industrial silicon → magnesium silicide → silane → high-purity silicon); and an ammonia cycle (ammonia → hexaammoniated magnesium chloride → ammonia), mainly in order to reduce cost, reducing environmental po...

AI Technical Summary

Problems solved by technology

CN102030332A proposed for the first time the magnesium cycle (magnesium→magnesium silicide→hexaammoniated magnesium chloride→magnesium chloride→magnesium), chlorine cycle (ammonium chloride→hexaammoniated magnesium chloride→magnesium chloride→chlorine gas→hydrogen chloride→ammonium chloride) and hydrogen cycle (hydrogen gas→hydrogen chloride→ ammonium chloride → silane → hydrogen), but no specific operating conditions

[0004] The intermittent production of the traditional magnesium silicide method has exposed many shortcomings, such as high production cost, small production scale, high unit energy consumption, high labor intensity, poor safety, etc., and is on the verge of being eliminated

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