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

A technology of silicon tetrafluoride and gas phase hydrolysis, applied in the directions of silicon oxide, silicon dioxide, fluorine/hydrogen fluoride, etc., can solve the problems of high investment in industrial production equipment, difficult industrialization of silicon tetrafluoride, and failure to realize industrialization, etc. To achieve the effect of reducing the requirements of equipment structure and material, the method is simple, and the hydrolysis temperature is reduced

Inactive Publication Date: 2014-02-26
班仁义
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  • Abstract
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Problems solved by technology

[0011] In summary, due to the one-step conversion method of silicon tetrafluoride high-temperature gas phase hydrolysis in the prior art, there are some problems in terms of process flow, process parameters, equipment structure and materials, etc. Many shortcomings or deficiencies have resulted in high investment, high energy consumption and high operating costs for industrial production equipment, so it has not been industrialized so far
Over 100 years ago, foreign research institutions began to conduct experimental research on the high-temperature gas-phase hydrolysis of silicon tetrafluoride. Many institutions and individuals have applied for many patents, but so far the world has not realized the one-step conversion technology of high-temperature gas-phase hydrolysis of silicon tetrafluoride. Industrial transformation means that the existing technology has technical defects that are difficult to industrialize

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

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Effect test

Embodiment 1

[0038] Use concentrated sulfuric acid to contain dust, liquid foam, H 2 Gas raw materials with impurities such as O and HF are washed and purified, and the concentration of concentrated sulfuric acid used for washing and purification is determined by H 2 SO 4 Calculated as 98%, the temperature of concentrated sulfuric acid in the washing treatment is controlled at 50°C; after purification and removal, SiF-containing 4 The gas raw material, the volume percentage composition of the gas raw material is: SiF 4 content of 45%, the balance is air and other inert gases; 3 / min flow rate and 0.6kg / min flow rate of water vapor are continuously fed into the reactor to mix for continuous gas-phase hydrolysis reaction and continuous fluorine-silicon separation operation. The molar ratio of silicon tetrafluoride gas and water vapor in the gas raw material is 1.2: 1. Control the temperature of the gas-phase hydrolysis reaction at 95-105°C, stay in the reactor for 5 seconds, and the...

Embodiment 2

[0040] In this embodiment, a closed-circuit circulation process is adopted to circulate the tail gas material D as a gas raw material containing silicon tetrafluoride for hydrolysis reaction and fluorine-silicon separation operation: the gas raw material is purified by the same purification method as in Example 1 to remove dust, liquid foam, H 2 O, HF and other impurities to obtain SiF 4 The gaseous raw material, its SiF 4 The content is 99.5%, and the balance is air and other inert gases; the above gas raw materials are mixed with 1M 3 / min flow rate, the tail gas material D that is recycled and returned is 11.4M 3 / min (SiF 4Content 99.5%) flow rate and 2kg / min flow rate of water vapor are continuously fed into the reactor to mix for continuous gas-phase hydrolysis reaction and continuous fluorine-silicon separation operation. The molar ratio of silicon tetrafluoride gas and water vapor in the gas raw material is 5:1; control the temperature of the gas phase hydrol...

Embodiment 3

[0042] This embodiment adopts an open-circuit process, that is, the tail gas material D enters seven "hydrolysis and fluorine-silicon separation" operation units connected in series in sequence, and the tail gas material D discharged from the previous operation unit is used as the silicon tetrafluoride-containing silicon tetrafluoride in the next operation unit. Gas feedstock up to SiF in silicon tetrafluoride-containing gas feedstock input from the first operating unit 4 After 7 operating units are exhausted, the operation of each unit is as follows:

[0043] (1) The operation in the first unit is: the gas raw material entering the first operation unit is purified SiF-containing 4 The gaseous raw material, its SiF 4 The volume percentage content is 6%, air and other inert gases are 94%, and the control gas raw material is 20M 3 / min flow rate and 1.0kg / min flow rate of water vapor are continuously fed into the reactor to mix for continuous gas phase hydrolysis rea...

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Abstract

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.

Description

technical field [0001] The invention relates to a gas-phase hydrolysis of silicon tetrafluoride and a method for separating fluorine and silicon, and belongs to the technical field of inorganic fluorine chemical industry. Background technique [0002] Due to the special physical and chemical properties of fluorine and silicon, in the phosphorus chemical and fluorine chemical industries, when fluorine and silicon exist in the raw materials, the two are always combined together to form fluorosilicon compounds. Fluorosilicon compounds mainly include tetrafluoroethylene Silica, fluosilicic acid and its salts. Although silicon tetrafluoride, fluorosilicate and its salts are also products with certain uses, their market demand is limited. Therefore, for phosphorus and fluorine chemicals, it is necessary to convert a large amount of by-product fluorosilicon compounds into products with a relatively large market capacity. Large fluorine compounds and silica. Especially for the pho...

Claims

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Application Information

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IPC IPC(8): C01B33/12C01B7/19
Inventor 班仁义何国勤
Owner 班仁义
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