Method for preparing inorganic chemical product using waste produced by polycrystalline silicon

Abstract

A method using polysilicon production waste for preparing inorganic chemical products is disclosed. The wastes which are generated in the process of producing polysilicon by an improved Siemens method mainly comprise silicon tetrachloride, trichlorosilane, dichloro-dihydro-silicon, and the like; the method using polysilicon production waste for preparing inorganic chemical products comprises two steps: firstly, polysilicon production waste is hydrolyzed; when the polysilicon production waste is put into the water, the hydrolysis reaction is carried out on the silicon tetrachloride, the trichlorosilane, and the dichloro-dihydro-silicon, thereby generating silicic acid and hydrochloric acid; secondly, the silicic acid and hydrochloric acid are used; the hydrochloric acid is used for being reacted with carbonate to prepare chloride, or the hydrochloric acid is used for being reacted with phosphate to prepare phosphoric acid or acid phosphate; the silicic acid is used for being reacted with alkali to prepare silicate or metasilicate, or the silicic acid is used for preparing silicon dioxide or silica gel by heating and dehydration. The invention has the advantages that by the hydrolysis, silicon tetrachloride becomes 'harmlessness'; by the reuse of the silicic acid and the hydrochloric acid, inorganic chemical products which are needed urgently by the market are prepared, thereby changing the silicon tetrachloride into 'resource' and changing the waster into valuables. The production process achieves 'zero emissions'; the obtained inorganic products have stable quality and high purity; large-scale production can be easily realized; the invention also has the advantages of low energy consumption, low production cost, can be conducive to solve the pollution problem in the polysilicon industry, and has great economic and social benefits.

Description

1. Technical field [0001] The invention relates to a method for preparing inorganic chemical products by utilizing polysilicon production waste. 2. Background technology [0002] High-purity polysilicon is the most important raw material for electronic information industry and photovoltaic solar energy industry. In recent years, the solar energy industry has developed rapidly in my country, and China is expected to become the largest photovoltaic power generation market in the world. At present, due to high photoelectric conversion efficiency, relatively low manufacturing threshold, and relatively mature technical equipment, crystalline silicon cells account for 95% of the global solar cell market share, and the high-purity polysilicon market presents a serious shortage of supply. Stimulated by the increasing gap in the market and rising prices, high-purity polysilicon, the upstream raw material for solar cells, has become a hot spot for domestic investment. As of May 2008,...

AI Technical Summary

Problems solved by technology

[0007] The purpose of the present invention is to solve the recycling problem of the waste produced in the process of improving the Siemens method to produce polysilicon, and to use the polysilicon production waste to prepare the method for inorganic chemical products