Method for preparing silicon dioxide and hydrogen chloride by means of hydrolysis of polysilicon by-product silicon tetrachloride

Abstract

The invention relates to a method for preparing silicon dioxide and hydrogen chloride by means of hydrolysis of polysilicon by-product silicon tetrachloride. The method comprises the following steps of: adding additives and surfactants into an airtight reaction kettle with 5 to 30 mass percent of hydrochloric acid aqueous solution, adding the silicon tetrachloride into the airtight reaction kettle, wherein the input amount of the silicon tetrachloride is controlled to be between 0.4 and 0.9 m<3> / h; performing a hydrolysis reaction by controlling the temperature to be between 20 and 50 DEG C, and generating silica sol and hydrogen chloride gas; drying and recycling the hydrogen chloride gas; standing and aging the silica sol to form silicon dioxide precipitates; filtering and washing the silicon dioxide precipitates to remove the residual additives; and drying the washed silicon dioxide colloid, and thus obtaining precipitated white carbon black (silicon dioxide). The process has the characteristics of simple process flow, readily available raw materials, low production cost and the like.

Description

technical field [0001] The invention belongs to the field of inorganic chemical industry, and relates to a method for preparing silicon dioxide and hydrogen chloride by hydrolyzing silicon tetrachloride, a by-product of polycrystalline silicon. Background technique [0002] Silicon tetrachloride is the largest by-product in the production of polysilicon. Silicon tetrachloride recovered without treatment is a highly corrosive, toxic and harmful liquid, which is very harmful to safety and the environment. In 2010, my country's polysilicon output reached about 40,000 tons, and the by-product silicon tetrachloride was about 600,000 tons. The post-processing of a large amount of silicon tetrachloride has become a bottleneck restricting the development of the polysilicon industry. [0003] In recent years, there are mainly three methods for the post-treatment of polysilicon by-product silicon tetrachloride: one is hydrogenation reduction to produce trichlorosilane. Although this ...

AI Technical Summary

Problems solved by technology

This process requires a large amount of water or dilute hydrochloric acid to treat a certain amount of silicon tetrachloride, and the hydrogen chloride gas generated needs to be concentrated in hydrochloric acid before being analyzed, so the process is relatively complicated.