Method for preparing silicon tetrafluoride by rotary kiln

A silicon tetrafluoride and rotary kiln technology, applied in the direction of silicon halide compounds, halosilanes, etc., can solve the problems of poor purity, low product recovery rate, high energy consumption, etc., to reduce energy consumption, save equipment investment, and reaction full effect

Inactive Publication Date: 2013-03-20
SP CHEM TAIXING
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Problems solved by technology

[0009] When adopting said method to carry out industrialized production, used energy consumption is high, and the rate of recovery that obtains product is low, and purity is poor

Method used

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  • Method for preparing silicon tetrafluoride by rotary kiln

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Embodiment 1

[0033] 1) Under the condition of furnace temperature 100-130°C, dry the sodium fluorosilicate raw material, and the dried water-containing gas is absorbed by alkali and sent to the waste water treatment device for treatment, and the dried sodium fluorosilicate is sent to the fluorosilicone through a belt conveyor Sodium acid funnel; control the water content in the dried sodium fluorosilicate to ≤0.5%;

[0034] 2) 98% sulfuric acid, 105% sulfuric acid and recovered 95% sulfuric acid are measured by a flow meter, and after being made into sulfuric acid with a concentration of 99.5% to 100%, they enter the mixed acid storage tank;

[0035] 3) Sodium fluorosilicate is weighed by the funnel through the belt (accuracy requirement: 0.2% ~ 0.25%), and then sent to the kneader to pre-react with 99.5% ~ 100% sulfuric acid from the acid mixing tank. Sodium fluorosilicate and sulfuric acid The feed ratio is controlled at 1-1.1:1; in order to make the conversion rate of sodium fluorosilic...

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Abstract

The invention discloses a method for preparing silicon tetrafluoride by a rotary kiln. The method is characterized in that sodium fluosilicate and sulfuric acid undergo a pre-reaction; reaction products are fed into a rotary kiln and then undergo a further reaction, wherein the pressure in the rotary kiln is in a range of -2 to -5 Kpa and temperatures of front, middle and rear sections in the rotary kiln are respectively controlled to 160-190 DEG C, 191-220 DEG C and 221-250 DEG C; and after the reaction, silicon tetrafluoride and HF mixed gas are separated. According to the invention, sodium fluosilicate and sulfuric acid undergo a reaction in the rotary kiln as a reactor; a by-product sodium fluosilicate produced by phosphate fertilizer plants can be used as a raw material; and a main solid waste sodium sulfate produced by the rotary kiln still can be recovered by the phosphate fertilizer plants and be used for producing sodium fluosilicate. By a three-section heating method, the raw materials react completely. In addition, intractable three wastes are not produced; a waste acid concentration device is avoided; and a device investment is greatly saved.

Description

technical field [0001] The invention relates to the technical fields of fluorine chemical industry, silicon chemical industry and the like, in particular to a method for preparing silicon tetrafluoride by using a rotary kiln. Background technique [0002] Silicon tetrafluoride is an electronic special gas used in semiconductor and optical fiber processing applications, and is an important component in the ion implantation method used in the manufacture of silicon-based semiconductor devices. Silicon tetrafluoride is mainly used in the electronics and semiconductor industries for etching silicon nitride, tantalum silicide, etc., P-type dopants and epitaxial deposition diffusion silicon sources, etc.; it can also be used to prepare electronic grade silane or silicon. Silicon tetrafluoride can also be used as a raw material for high-purity quartz glass for guiding fibers. It can be hydrolyzed in a high-temperature flame to produce heat sink silicon dioxide with a high specific ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B33/107
Inventor 汪小华曾宪相吴震
Owner SP CHEM TAIXING
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