New technology breaks the "heel" of polysilicon

According to the "Polysilicon Industry Access Standards" issued by the Ministry of Industry and Information Technology, the recovery and utilization rates of silicon tetrachloride, hydrogen chloride and hydrogen in the reduction tail gas shall not be less than 98.5%, 99% and 99% respectively. At present, more than 80% of polysilicon enterprises in my country cannot meet this requirement. In this way, 80% of enterprises will face the fate of being "eliminated". A scientific research result that has just been appraised in our province may bring new vitality to them.

□Reporter Li Qiuyi

Recently, the "Chemical Treatment and Comprehensive Utilization of Polysilicon Byproduct Silicon Tetrachloride" developed by Sichuan Yinbang Silicon Industry Co., Ltd. passed the technical appraisal of the Provincial Science and Technology Department. This technology is a major key technology research project in our province. The appraisal team believes that the first domestic 1,000-ton continuous, closed tower polysilicon byproduct preparation high-purity alkoxysilane system device independently developed and built by Yinbang Silicon Industry has reached the international advanced level. It will solve the environmental pressure of the polysilicon industry and become a winning magic weapon to deal with the "reshuffle" of the polysilicon industry.

The Achilles' heel of polysilicon

"There are three main factors that hinder the healthy development of the polysilicon industry: environmental protection, processing of silicone intermediate products, and cost." Tian Yunhui from the High-tech Department of the Provincial Science and Technology Department said that if there is a technology that can change these three factors, polysilicon will get rid of the label of "high pollution and high energy consumption", and the entire industry will pay tribute to it.

According to the current domestic polysilicon production capacity that has been built and is under construction, by the end of 2012, the domestic polysilicon production capacity will reach more than 80,000 tons per year, and the by-product silicon tetrachloride will reach more than 1 million tons. Due to the high price, the output of polysilicon is expected to expand further. Sichuan has built a polysilicon production facility with an annual production capacity of 14,000 tons by the end of 2010, producing up to 250,000 tons of silicon tetrachloride. By the end of 2014, Sichuan's annual polysilicon production capacity will exceed 30,000 tons, and the annual production of silicon tetrachloride will be nearly 500,000 tons.

A quick search on Baidu will reveal that silicon tetrachloride "releases heat when heated or in contact with water, and emits toxic and corrosive fumes" and "is a strong irritant to the eyes and upper respiratory tract if inhaled, ingested, or absorbed through the skin". If such a large amount of toxic byproducts cannot be properly handled, the development of the polysilicon industry will be devastating. This can be called the "Achilles heel" of the polysilicon and photovoltaic industries.

Technological breakthrough turns byproducts into treasures

Leshan, a cluster of polysilicon industries, took the lead in making technological breakthroughs.

Sichuan Yinbang Silicon Industry Co., Ltd. took the lead in the research and independently developed a technology for processing silicon tetrachloride. Silicon tetrachloride and low-level fatty alcohols are reacted under certain process conditions to produce organosilicon intermediates. The annual processing capacity of silicon tetrachloride can reach 4,500 tons, and 4,200 tons of high-purity alkoxy silicon products can be prepared, and 10,000 tons of 31% hydrochloric acid as a by-product can be produced. Its organosilicon intermediate product process has broken through the technical difficulty of domestic continuous large-scale production of high-purity organosilicon intermediates above 99.9%.