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Method for preparing silicon tetrafluoride through pyrolysis of sodium fluosilicate in rotary reaction furnace

A technology of sodium fluorosilicate and silicon tetrafluoride, which is applied in the direction of silicon halide compounds, halosilanes, etc., can solve the problems that the products are not easy to handle, silicon tetrafluoride has many impurities, complex components, etc., and can solve the problem of waste gas treatment Difficult, low content of impurity ingredients, single ingredient effect

Active Publication Date: 2011-08-31
西安三瑞实业有限公司 +1
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The disadvantages of this process are: the reactant is a mixture of various substances, the composition is relatively complex, and the silicon tetrafluoride produced has more impurities. To remove the impurities, the cost of input is relatively high, and it is not continuous production. Therefore, the production capacity is low, and the solid product produced has relatively high acidity, and the product is not easy to handle
more serious environmental pollution

Method used

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  • Method for preparing silicon tetrafluoride through pyrolysis of sodium fluosilicate in rotary reaction furnace

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Experimental program
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Effect test

Embodiment 1

[0029] Sodium fluorosilicate is sent to the sodium fluorosilicate silo through the hopper elevator; according to the amount of feed, it will be automatically discharged into the powder hopper scale through the screw. Precisely measured by a weighing instrument, put 100kg of sodium fluorosilicate into a rotary calciner for drying, at 250°C and a slight negative pressure of 20mm H 2 Drying and internal dehydration are carried out between O, and after drying, it is cooled by the mixing screw and sent to the feeding screw of the rotary reaction furnace. of sodium fluoride mixed. At 500°C (material temperature), micro-negative pressure 15mm H 2 The reaction is carried out in the reaction furnace under the condition of O to generate sodium fluoride (NaF) and silicon tetrafluoride (SiF 4 )gas. The silicon tetrafluoride gas is generated at a temperature of 300°C, enters the gas duct of the furnace head of the reaction furnace, and passes through the dust collector to remove the dus...

Embodiment 2

[0034](1) Dry and heat-treat 100kg of sodium fluorosilicate in a rotary calciner at 260°C for 90 minutes, and control the negative pressure at 15mm H 2 O.

[0035] (2) Before the sodium fluorosilicate enters the rotary reaction furnace, it is mixed with 100kg of inert auxiliary agent silicon dioxide, and then enters the rotary reaction furnace for cracking.

[0036] (3) Send the dried sodium fluorosilicate into a rotary reaction furnace, react at 700°C (material temperature) for 1 hour, and thermally crack to obtain silicon tetrafluoride and sodium fluoride. The negative pressure value is controlled at 10mm H 2 O.

[0037] (4) The generated silicon tetrafluoride gas is dedusted, cooled, dried, compressed, and high-purity silicon tetrafluoride gas is collected.

Embodiment 3

[0039] (1) Dry and heat-treat 100kg of sodium fluorosilicate in a rotary calciner at 280°C for 65 minutes, and control the negative pressure at 10mm H 2 0.

[0040] (2) Before the sodium fluorosilicate enters the rotary reactor, it is mixed with 150kg of inert additive alumina, and then enters the rotary reactor for cracking.

[0041] (3) Send the dried sodium fluorosilicate into a rotary reaction furnace, react at 630°C (material temperature) for 85 minutes, and thermally crack to obtain silicon tetrafluoride and sodium fluoride. The negative pressure value is controlled at 15mm H 2 O.

[0042] (4) The generated silicon tetrafluoride gas is dedusted, cooled, dried, compressed, and high-purity silicon tetrafluoride gas is collected.

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Abstract

The invention provides a process for preparing silicon tetrafluoride through pyrolysis of sodium fluosilicate in a rotary reaction furnace, which comprises the steps of: performing drying and heat treatment on the sodium fluosilicate at a temperature of between 200 and 300 DEG C in a calciner to remove the moisture in the sodium fluosilicate, and maintaining a negative pressure in the calciner, wherein the negative pressure value is controlled to between 10 and 30mmH2O; and sending the dried sodium fluosilicate into the rotary reaction furnace for the pyrolysis at a temperature of between 500and 900 DEG C (material temperature) for 1 to 2 hours, and obtaining the silicon tetrafluoride and sodium fluoride after the pyrolysis. The generated silicon tetrafluoride gas is dedusted, cooled, dried, compressed and collected to form high-purity silicon tetrafluoride gas. The process has the advantages of single reactant and no discharge of waste gas, waste water and waste residue, and belongsto an environmentally-friendly comprehensive utilization project.

Description

technical field [0001] The invention relates to a new process for industrialized production of silicon tetrafluoride - a process for preparing silicon tetrafluoride by pyrolyzing sodium fluorosilicate in a rotary reactor, which belongs to the technical field of fluorine chemical industry. Background technique [0002] SiF 4 In the electronics and semiconductor industries, it is mainly used as etchant for silicon nitride, tantalum silicide, etc., P-type dopant, epitaxial deposition diffusion silicon source, etc. It can also be used to prepare electronic grade silane or polysilicon. SiF 4 It can also be used as a raw material for high-purity quartz glass for optical fibers. It can be hydrolyzed in a high-temperature flame to produce a heat sink SiO with a high specific surface area. 2 . In addition SiF 4 It is also widely used in the preparation of solar cells, fluorosilicic acid and aluminum fluoride, chemical analysis, fluorinating agents, oil well drilling, magnesium al...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01B33/107
Inventor 何建祥余福元魏超张卫鑫张纪中
Owner 西安三瑞实业有限公司
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