Method and system for cyclic utilization of materials during production of polycrystalline silicon

Abstract

The invention discloses a method and system for cyclic utilization of materials during production of polycrystalline silicon. The method comprises the steps of (1) performing reduction reaction on trichlorosilane and hydrogen to obtain polycrystalline silicon and reduction tail gas; (2) performing dust removal treatment on the reduction tail gas to obtain reduction tail gas subjected to dust removal; (3) performing compression cooling treatment on the reduction tail gas subjected to dust removal so as to separate first chlorosilane and compressed gas from the reduction tail gas; (4) performing distillation and purification on first chlorosilane to obtain residual liquid, trichlorosilane, dichlorosilane and silicon tetrachloride; (5) returning trichlorosilane obtained in the step (4) to the step (1) to perform reduction reaction, and performing hydrogenation reaction between one part of silicon tetrachloride and silicon powder and hydrogen so as to obtain second chlorosilane; (6) performing reverse disproportionation reaction between one part of silicon tetrachloride and dichlorosilane so as to obtain third chlorosilane; (7) returning second chlorosilane and third chlorosilane to the step (4) to perform distillation and purification.

Description

technical field [0001] The invention relates to the field of polysilicon production, in particular, the invention relates to a method and a system for material recycling in the polysilicon production process. Background technique [0002] Due to increasingly stringent environmental protection requirements in recent years, fierce market competition, and relevant departments have strengthened the management of chlorosilane transportation, a large amount of high-boiling substances, low-boiling substances, and dichlorodihydrosilanes produced during the production of polysilicon by the improved Siemens method handling has become a thorny issue. [0003] The general treatment methods of high boiling matter and low boiling matter are roughly as follows: hydrolysis, hydrolysis to make acid and then decompose hydrogen chloride, re-distillation and rectification of these materials. These methods will lose a lot of chlorine without increasing waste water, or consume energy to recover ...

AI Technical Summary

Problems solved by technology

These methods will lose a lot of chlorine without increasing waste water, or consume energy to recover part of chlorine, and the rest will be hydrolyzed

For dichlorodihydrosilane, most of them are passed into the reduction furnace, but a large amount of dust will be generated and need to be thrown away

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