Method for preparing silicon tetrafluoride and anhydrous hydrogen fluoride from sodium fluosilicate acidified by sulfuric acid

The invention provides a method for preparing silicon tetrafluoride and anhydrous hydrogen fluoride from sodium fluosilicate acidified by sulfuric acid, which relates to the technical field of fluorine chemical industry, in particular to a method for preparing silicon tetrafluoride gas and anhydrous hydrogen fluoride gas by reaction of sodium fluosilicate and sulfuric acid. The method of the invention comprises the following steps: (a) stirring sodium fluosilicate and excessive sulfuric acid at the temperature lower than 150 DEG C for reacting to obtain silicon tetrafluoride gas, wherein hydrogen fluoride remains in solid residues; (b) dedusting, cooling, drying, refining and compressing the silicon tetrafluoride gas generated in the step (a) to obtain high-purity silicon tetrafluoride gas; (c) continuously heating to 200 DEG C to enable the hydrogen fluoride gas to escape; and (d) dedusting, cooling, drying, refining and compressing the hydrogen fluoride gas escaping in the step (c) to obtain the anhydrous hydrogen fluoride (AHF) gas. The invention enables the specific fluorine and silicon resources of phosphate fertilizer enterprises to be fully and efficiently utilized.