Method for producing nanosilicon dioxide and by-product hydrochloric acid through chlorosilane waste gas

Abstract

The invention discloses a method for producing nanosilicon dioxide and by-product hydrochloric acid through chlorosilane waste gas, and belongs to the field of chlorosilane waste gas recycling in the polycrystalline silicon industry. The method includes the steps that chlorosilane waste gas and water vapor react, gas-liquid separation is conducted on the reaction product to obtain the nanosilicon dioxide, gas obtained through gas-solid separation is cooled, most of the water vapor is condensed, part of hydrogen chloride is absorbed, the rest of the gas where gas-liquid separation is conducted is washed through hydrochloric acid and industrial water, and high-concentration hydrochloric acid is obtained. According to the method, the water vapor and the chlorosilane waste gas perform a gas-vapor hydrolysis reaction so that the nanosilicon dioxide can be obtained, and gas-solid separation is conducted on tail gas through the industrial water and the hydrochloric acid so that the concentrated hydrochloric acid can be obtained. The water vapor is mainly used as the hydrolysis reagent of the mixed chlorosilane waste gas, the high-concentration hydrochloric acid is used as absorbent, less impurity elements are brought in, and the quality of silicon dioxide and the concentrated hydrochloric acid is ensured. Harmless processing of the chlorosilane waste gas is achieved, and silicon elements and chlorine elements in the waste gas are recycled.

Description

technical field [0001] The invention relates to a method for producing nano silicon dioxide with chlorosilane waste gas and by-product hydrochloric acid, belonging to the field of resource utilization of chlorosilane waste gas in the polysilicon industry. Background technique [0002] The rapid development of the photovoltaic industry has driven the development of the polysilicon industry. The domestic polysilicon production process mainly uses the trichlorosilane reduction method. Due to the immature technology, chlorosilane waste gas is inevitably produced. [0003] The main sources of chlorosilane waste gas: the synthesis process of trichlorosilane, the rectification and purification process of trichlorosilane, the reduction process of trichlorosilane, and the CDI process. [0004] The main component of chlorosilane waste gas: SiCl 4 , SiHCl 3 、SiH 2 Cl 2 , HCl, H 2 , N 2 . [0005] At present, the main method of chlorosilane waste gas treatment is lye washing (NaO...

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Problems solved by technology

The main component of waste residue is NaCl or CaCl 2 、Na 2 SiO 3 or CaSiO 3 , SiO 2 , the waste residue is a mixture, the components are not easy to separate, easy to form secondary pollution, and also cause a waste of resources

[0006] CN101700466A improves the residual liquid and tail gas treatment process in Siemens polysilicon production. The invention uses milk of lime as the eluent. When the pH>8, the eluent is absorbed in a cycle. When the pH is less than or equal to 8, 10-30% milk of lime is added. The reaction product is mainly CaCl 2 , CaSiO 3 , SiO 2 , the reaction product is difficult to separate and cannot be utilized as a resource

[0007] CN102989300A improves Siemens' waste gas leaching treatment process and equipment for polysilicon production. The invention uses 10-15% sodium hydroxide solution as an absorbent, and the reaction products are mainly NaCl, Na 2 SiO 3 , SiO 2 , the composition of the filter residue obtained after filtration is relatively complex, and it is not easy to separate, so the residue can only be piled up

[0008] CN102500213B A method for treating waste gas and liquid in polysilicon production, the invention uses Ca(OH) 2 The solution acts as an absorbent, and the reaction product is mainly CaCl 2 , CaSiO 3 , SiO 2 , CaCl was obtained after evaporation and crystallization after filtration 2 Resource utilization, while the filtered filter residue CaSiO 3 , SiO 2 , also contains a large amount of CaCl 2 Left in the filter residue, it is not easy to remove cleanly, and the value of resource utilization is not great

[0009] CN103505996A A method and device for washing waste gas in the polysilicon industry. The invention uses 10-30% NaOH solution as an absorbent, and the reaction products are mainly NaCl and NaCl 2 SiO 3 , the solid obtained after evaporation and crystallization is a mixture, which is difficult to purify and has little value for resource utilization

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