Method for purification of dichlorosilane from dry method recovered material

Abstract

The invention discloses a method for purification of dichlorosilane from dry method recovered materials, and comprises the following steps of: a) obtaining a dry-method recovered material by recovering from reduction tail gas of the polysilicon production process by a dry method, feeding the recovered material into a first dry method rectifying tower for rectification, recovering a first low-boiling-point substance from the tower top of the first dry method rectifying tower, and recovering intermediate chlorosilane from the tower bottom of the first dry method rectifying tower; b) feeding the first low-boiling-point substance into a separation column for separation, recovering boron impurity from the top of the separation column, and recovering dichlorosilane from the bottom of the separation column; c) feeding the intermediate chlorosilane into a second dry method rectifying tower for rectification, recovering a second low-boiling-point substance from the tower top of the second dry method rectifying tower, and recovering silicon tetrachloride from the tower bottom of the second dry method rectifying tower. According to the method of the invention, the second low-boiling-point substance is a mixture of dichlorosilane and trichlorosilane which can be directly fed into a reducing furnace for reduction reaction, thereby saving the process of mixing the dichlorosilane and the trichlorosilane.

Description

technical field [0001] The invention relates to the technical field of polysilicon, more specifically, the invention relates to a method for purifying dichlorodihydrogen silicon from dry recycled materials. Background technique [0002] Dichlorodihydrosilane, a by-product of polysilicon, has a unique low boiling point, flammable and explosive characteristics, which have become a technical bottleneck for polysilicon enterprises to expand production. The traditional treatment method has brought many problems not only in terms of safety, but also in terms of environmental protection; The purification process of chlorodihydrosilane is the key to determine whether it can be recycled in the future. [0003] In the process of producing polysilicon by the improved closed Siemens method, 1.6 tons of dichlorodihydrogen silicon will be produced for every ton of polysilicon produced. With the continuous expansion of scale, the current polysilicon factory is to pass the purified dichlor...

AI Technical Summary

Problems solved by technology

From the perspective of the difficulty of separation, the boiling points of dichlorodihydrosilane and low boilers are very close, and it is very difficult to remove impurities with a separation tower, which requires a considerable number of theoretical plates and reflux ratios, which requires a large amount of heat load

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