Method and system for treating crude trichlorosilane

Abstract

The invention discloses a method and a system for treating crude trichlorosilane. The method comprises the following steps: (1) carrying out air stripping treatment on crude trichlorosilane to obtain a mixture; (2) purifying the mixture for the first time to obtain a first top gas and a first bottom liquid; (3) purifying the first top gas for the second time to obtain a second top gas and a second bottom liquid; (4) mixing the first bottom liquid with the second bottom liquid to obtain a mixed material; (5) disproportionating the mixed material in the presence of supported ion exchange resin to obtain a disproportionated product; (6) purifying the disproportionated product for the third time to obtain a third bottom liquid; and (7) purifying the second bottom liquid and the third bottom liquid for the fourth time to obtain trichlorosilane and a fourth bottom liquid and returning the fourth bottom liquid for purification for the first time. By adopting the method, the problem of the enrichment of dichlorosilane and silicon tetrachloride in crude trichlorosilane can be effectively solved and the quality of trichlorosilane can be significantly improved.

Description

technical field [0001] The invention belongs to the technical field of polysilicon production, in particular, the invention relates to a method and system for processing crude trichlorosilane. Background technique [0002] In the process of polysilicon production, synthesis, reduction and cold hydrogenation units will produce a certain amount of by-product dichlorodihydrogen silicon, especially reduction. Compared with trichlorosilane, dichlorodihydrogensilane is easier to precipitate on the wall of the reduction furnace to produce amorphous silicon powder, so it is necessary to strictly control the concentration of dichlorodihydrogensilane below a certain level. In the actual production process, the content of dichlorodihydrosilane in the reduction and recovery of trichlorosilane reaches 9 to 11%, which makes the reduction furnace prone to atomization and produces more amorphous silicon during the production process, which seriously affects the reduction. normal operation ...

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Problems solved by technology

In the actual production process, the content of dichlorodihydrosilane in the reduction and recovery of trichlorosilane reaches 9 to 11%, which makes the reduction furnace prone to atomization and produces more amorphous silicon during the production process, which seriously affects the reduction. Normal operation of the furnace

At the same time, because the boiling point of dichlorodihydrosilane is similar to that of boron impurities, in order to ensure the quality of trichlorosilane products, it is necessary to discharge the non-condensable gas from the trichlorosilane purification tower to the three wastes process for leaching treatment, but the non-condensable gas still remains Contains a large amount of chlorosilanes with low boiling points, direct leaching causes problems such as high material consumption, high environmental protection pressure, etc., and increases production and operation costs

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