Method for preparing silicon tetrafluoride by quartz sand

Abstract

The invention discloses a method for preparing silicon tetrafluoride by quartz sand, which comprises the following steps: taking 1000-1100 parts by weight of sulfuric acid with the concentration of 96-98% by mass percent and 560-575 parts by weight of hydrofluoric acid with the concentration of 50-52% by mass percent to be premixed together and absorbed, after the premixing and the absorption, obtaining the hydrofluoric acid with the concentration of 11-24% and the sulfuric acid with the concentration of 80-85%, and then obtaining a mixture A; taking 200-220 parts by weight and 150-200 meshes of silica powder and 500-550 parts by weight of the sulfuric acid with the concentration of 80-85% in mass percent to be premixed together, and obtaining a mixture B; adding the mixture A and the mixture B orderly into a reactor, stirring to react, and after 10-120 min of reaction with the reaction temperature of 60-80 DEG C, obtaining silicon tetrafluoride gas; and guiding the silicon tetrafluoride gas into a cooler by a honeycomb duct to be cooled and then enter a gasholder through a pipeline. The invention not only overcomes the high cost problem, but also achieves the reuse of reaction exhaust liquor and sizing agent, has no influence on environmental protection, and greatly reduces the energy consumption.

Description

technical field [0001] The invention relates to a compound preparation method, in particular to a method for preparing silicon tetrafluoride from quartz sand. Background technique [0002] Silicon tetrafluoride, also known as tetrafluorosilane, its molecular formula is SiF4, silicon tetrafluoride (SiF4) is a colorless, poisonous, pungent odorous gas. Density 4.69g / L, melting point -90.2°C (1.73×105Pa). Silicon tetrafluoride produces smog due to hydrolysis in humid air, producing silicic acid and hydrofluoric acid. It can condense into a liquid when pressurized under refrigeration. Soluble in nitric acid and ethanol. Silicon tetrafluoride is relatively stable. It can react with hydrofluoric acid to generate fluorosilicate H2SiF6. Silicon tetrafluoride is also easily decomposed by lye. [0003] Silicon tetrafluoride has many uses, for example: 1) It is used in the preparation of fluorosilicic acid and lead fluoride, 2) It is used as a hardening agent for cement and artif...

AI Technical Summary

Problems solved by technology

[0010] 1) A large amount of fluorite powder is used as raw material, and the purchase cost of fluorite is relatively high, which greatly increases the production cost;

[0011] 2) This method is accompanied by a large amount of HF generation, and the cost of removing HF is also very high, and simultaneously wastes fluorine resources, which is also unfavorable for the industrial scale production of silicon tetrafluoride

It is generally difficult to achieve this condition

[0020] 2) The cost of environmental protection treatment is relatively high

[0024] 1) The pyrolysis temperature is high and the energy consumption is large;

[0025] 2) The adequacy of pyrolysis is insufficient, the conversion rate is 50-60%, and the yield of SiF4 is low, so the production cost is relatively high

[0026] 3) The output of the device is low, which is not conducive to large-scale production

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