Method for simultaneously treating chlorsilane residual liquor and waste gas

Abstract

The invention discloses a method for simultaneously treating chlorsilane residual liquor and waste gas, belonging to the technical field of polycrystalline silicon production industry. Chlorsilane waste gas is pressed into a Venturi atomizer, and chlorsilane residual liquor enters a Venturi pipe; the chlorsilane waste gas and chlorsilane residual liquor are mixed and atomized through a high-speed choke tube, enter an absorption tower, and are hydrolyzed and absorbed by an absorbent (water or hydrochloric acid), thereby achieving the goal of simultaneously treating the chlorsilane waste gas and residual liquor; and the waste gas / residual liquor ratio is regulated to control the slag / water ratio of the absorbent, thereby effectively preventing the hydrolysate silicon dioxide from gelation, and ensuring the quality of the silicon dioxide. The method can be used for simultaneously treating the chlorsilane residual liquor and waste gas, and ensures the properties of the silicon dioxide produced subsequently. The treatment on the chlorsilane residual liquor and waste gas only needs one tower set, thereby lowering the construction cost and operating cost of the separate treatment devices for chlorsilane residual liquor and waste gas.

Description

technical field [0001] The invention relates to a method for simultaneously treating chlorosilane raffinate and waste gas, and belongs to the field of chlorosilane raffinate and waste gas treatment and resource utilization in the polysilicon industry. Background technique [0002] The domestic mainstream polysilicon production process is the improved Siemens method. In the process of polysilicon production by the improved Siemens method, the synthesis of trichlorosilane, rectification and purification of trichlorosilane, reduction of trichlorosilane and cold (hot) hydrogenation processes are inevitable. Chlorosilane raffinate and waste gas are produced. [0003] The main components of chlorosilane raffinate: polychlorosilane, SiCl 4 , SiHCl 3 、SiH 2 Cl 2 , HCl, a small amount of silicon powder and metal chlorides. [0004] The main component of chlorosilane waste gas: SiCl 4 , SiHCl 3 、SiH 2 Cl 2 , HCl, H 2 , N 2 . [0005] At present, most domestic polysilicon...

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Problems solved by technology

[0006] The traditional chlorosilane raffinate treatment method has poor dispersion or atomization effect, resulting in high local chlorosilane concentration, incomplete hydrolysis in the hydrolysis tower, and continuous hydrolysis in the liquid phase slag pool. The generated hydrogen and HCl gas permeate the pool surface , Explosion accidents often occur, polluting the environment; the hydrolyzate wraps the chlorosilane residual liquid, which affects the quality of the product silica; at the same time, the local concentration of chlorosilane is too high, which will lead to a high local concentration of silicic acid in the absorption liquid, resulting in serious gelation of silicic acid , and even lead to the loss of fluidity of the absorption liquid, so that the physical properties of the produced silica cannot meet the industrial standards and cannot be reused

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