Gas phase hydrolysis and fluoride-silicon separation method of silicon tetrafluoride

A two-step method is adopted to carry out low temperature gas phase hydrolysis and fluoride-silicon separation operations of silicon tetrafluoride. In a first step, a silicon tetrafluoride gas is hydrolyzed into a fluosilicic acid gas and silicon dioxide particles at a low temperature; in a second step, a hydrogen fluoride gas is dissolved by a washing operation of high concentrated sulfuric acid so as to promote complete decomposition of the fluosilicic acid into the hydrogen fluoride gas and a silicon tetrafluoride gas; decomposed and separated hydrogen fluoride gas is completely dissolved in high concentrated sulfuric acid; decomposed and separated silicon tetrafluoride can be continuously carried out hydrolysis and fluoride-silicon separation operations; and finally complete separation of the fluoride and silicon elements are realized. The method has the beneficial effects that a gas raw material containing relatively low silicon tetrafluoride content can be used; a method for purifying the raw material is simple; total conversion rate of silicon tetrafluoride introduced into a production apparatus system can reach over 98%; and hydrolysis temperature is relatively low, so that the method can realize industrial production relatively easily. The method is suitable for recovery and utilization of fluoride- and silicon-containing materials from industries such as phosphorus chemical industry, fluorine chemical industry, electron industry, glass processing industry and aluminium alloy processing industry.