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

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.