CN106698443A

CN106698443A - Preparation method for high-purity silicon dioxide

Info

Publication number: CN106698443A
Application number: CN201510789515.9A
Authority: CN
Inventors: 李春梅
Original assignee: Qingdao Senmeike Chemical Technology Co Ltd
Current assignee: Qingdao Senmeike Chemical Technology Co Ltd
Priority date: 2015-11-16
Filing date: 2015-11-16
Publication date: 2017-05-24

Abstract

The invention discloses a preparation method for high-purity silicon dioxide. The preparation method comprises the following steps: with diatomite as a raw material, carrying out a reaction with an ammonium fluoride aqueous solution at a certain temperature, and carrying out precipitation, filtration and centrifuging so as to obtain an ammonium fluorosilicate solution; subjecting the ammonium fluorosilicate solution to evaporative crystallization so as to obtain a high-purity ammonium fluorosilicate solid; subjecting the high-purity ammonium fluorosilicate solid to thermal decomposition so as to obtain high-purity silicon tetrafluoride; and subjecting silicon tetrafluoride gas to a reaction with high-purity ammonia water so as to generate a silicon dioxide precipitate, and carrying out solid-liquid separation, washing and vacuum drying so as to prepare high-purity silicon dioxide powder. The method provided by the invention has the advantages of low costs of raw materials, simple operation process and no generation of pollutants in the process of production; meanwhile, the silicon dioxide powder prepared by using the method provided by the invention has a purity larger than 6N.

Description

The preparation method of high-purity silicon dioxide

Technical field

The present invention relates to Inorganic Chemicals preparation field, more particularly to a kind of preparation method of high-purity silicon dioxide.

Background technology

(N represents after decimal point 9 digit to high-purity silicon dioxide (more than 5N), such as：5N represents that purity is 99.99999%) it is the indispensable important foundation material of the industries such as polysilicon, optoelectronics industry, is also using increasingly wide General new and high technology material.

The method of traditional production high-purity silicon dioxide mainly has：Silica method for refining, gas phase synthesis method (dry method) and Precipitation method (wet method) etc..Silica method for refining is by being refining to obtain height using natural purity quartz, silica very high Pure silicon dioxide.The method is limited by the limitation of raw material, is not only also difficult to meet green wood high on limited amount, and quality The requirement in material field.Vapor phase method is with the halide or silanol of silicon as raw material, and price is higher, and has flammable, severe corrosive, , investment high to process units requirement is big, and production cost is high, is not suitable for large-scale production.The precipitation method generally with sodium metasilicate or Ammonium fluosilicate is raw material, and price is relatively low, and operation is comparatively safe, but the difficulty of purification is larger, and product quality easily receives raw material The influence of purity, production process has pollutant emission.

The content of the invention

It is an object of the invention to provide a kind of low raw-material cost, operating procedure be simple and production process non-pollutant discharge High-purity silicon dioxide preparation method.

Therefore, technical scheme is as follows：

A kind of preparation method of high-purity silicon dioxide, comprises the following steps：

1) diatomite and ammonium fluoride aqueous solution react generation ammonium fluosilicate solution and ammonia, the fluorine silicon at 80~90 DEG C Acid ammonium solution removes impurity after filtering, centrifugation purification；The ammonia is made high-purity ammonia water through absorbing pure water；

2) ammonium fluosilicate solution after preliminary purification is realized into separation of solid and liquid by multiple evaporative crystallization, then by washing High-purity fluorine ammonium silicate solid is obtained, the high-purity fluorine ammonium silicate solid purity is preferably not below 4N；

3) the high-purity fluorine ammonium silicate solid is heated to 100~150 DEG C, make its decompose generation silicon tetrafluoride gas and Ammonium fluoride gas；

4) ocratation and ammonium fluoride gas are imported into consersion unit, it is carried out ammonolysis with high-purity ammonia water anti- Should, generate precipitation of silica；

5) precipitation of silica is dehydrated by high speed centrifugation, washed and is vacuum dried, obtain purity more than 6N High-purity silicon dioxide powder.

In above-mentioned step 2) in, the ammonium fluosilicate solution after the purification is put into triple effect evaporation crystallizer, pass through Cross three evaporative crystallizations and realize separation of solid and liquid；In above-mentioned step 3) in, the high-purity fluorine ammonium silicate solid is put Enter heat resolve in thermal decomposition reactor.The content of SiO 2 is 95% or so in the diatomite.

Method of the present invention cost of material is relatively low, operating procedure simple, and the ammonia that production process is produced is only absorbed by the water, institute Produced with contamination-free.The silicon-dioxide powdery purity prepared with the method is more than 6N, it is possible to meeting new and high technology material Expect the requirement to its purity.

Specific embodiment

The method of the present invention is described in detail with reference to specific embodiment.

The method of the present invention as raw material, is existed with diatomite (contents of SiO 2 are about 95wt%) with ammonium fluoride aqueous solution Dissolved under uniform temperature, reacted, ammonium fluosilicate solution is obtained by precipitation, filtering, centrifugation；Tied by evaporating Crystalline substance obtains high-purity fluorine ammonium silicate solid；High-purity fluorine ammonium silicate solid is by thermally decomposing to yield high-purity silicon tetrafluoride；Four Silicon fluoride gas reacts with high-purity ammoniacal liquor, generates precipitation of silica, is done by separation of solid and liquid, washing, vacuum It is dry, prepare high-purity silicon dioxide powder.In the process, high-purity ammonia water is obtained by first step reaction, last Step reaction generation silica and ammonium fluoride, ammonium fluoride can be continued cycling through and used.

Embodiment 1

1) diatomite (contents of SiO 2 about 95%) and ammonium fluoride (NH 4F) aqueous solution are in 80~90 DEG C of bars Stirring and dissolving under part, reaction generation ammonium fluosilicate solution and ammonia.Impurity elimination is removed by steps such as precipitation, filtering, centrifugations Matter, obtains the ammonium fluosilicate solution that purity is more than 99, and ammonia is made more than 99.99% through absorbing pure water High-purity ammoniacal liquor.Reaction equation is as follows：

SiO 2+6NH 4F→(NH 4)2 SiF 6+2H 2 O+4NH 3↑ (1)

2) obtained ammonium fluosilicate solution is imported in triple effect evaporation crystallizer, is realized admittedly by three evaporative crystallizations Liquid is separated, and then obtains the high-purity fluorine ammonium silicate solid that purity is not less than 4N by washing, is partly dissolved in solution Impurity be removed.

3) obtained high-purity fluorine ammonium silicate solid is heated to 100~150 DEG C in thermal decomposition reactor, makes its point Solution generation ocratation (SiF 4) gas and ammonium fluoride (NH 4F) gas, impurity quilt micro in solid Separate.Reaction equation is as follows：

(NH 4)2 SiF 6→SiF 4↑+NH 4 F↑ (2)

4) Gaseous silicon tetrafluoride and gaseous state ammonium fluoride are imported into consersion unit, with obtained high-purity in step 1 Ammoniacal liquor carries out ammonolysis reaction, generates precipitation of silica.Reaction equation is as follows：

SiF 4+2NH 4F+2H 2 O+4NH 3→SiO 2↓+6NH 4 F (3)

5) then obtained precipitation of silica is vacuum dried by more than twice of centrifugation, washing, obtains pure Degree>The high-purity silicon dioxide powder of 6N.

If in above-mentioned step 4) in, the purity≤4N of ammonium fluosilicate solid then should observe whether it influences subsequently Step 5) purity, if influence, the ammonium fluosilicate solid of purity≤4N needs return to step 2) again Crystallized；If do not influenceed, can not consider.

Step 5) washing be usually no more than 3 times, the influence of the washing of excessive pass to purity is limited.

Product obtained in the method, the 1/3 of its cost deficiency same purity product of import, compared with domestic prior art, Production technology of the invention is easy, and production process does not have pollutant emission, ammonium fluoride reusable edible.

Claims

1. a kind of preparation method of high-purity silicon dioxide, it is characterised in that comprise the following steps：

1) diatomite and ammonium fluoride aqueous solution react generation ammonium fluosilicate solution and ammonia, the ammonium fluosilicate solution at 80~90 DEG C Impurity is removed after filtering and high speed centrifugation, preliminary purification is realized；The ammonia is made high-purity ammonia water through absorbing pure water；

2) ammonium fluosilicate solution after preliminary purification is carried out into secondary purification, Ran Houtong by multiple evaporative crystallization by separation of solid and liquid Cross washing and obtain high-purity fluorine ammonium silicate solid；

3) the high-purity fluorine ammonium silicate solid is heated to 100~150 DEG C, it is decomposed generation silicon tetrafluoride gas and ammonium fluoride gas Body；

4) ocratation and ammonium fluoride gas are imported into consersion unit, it is carried out ammonolysis reaction with high-purity ammonia water, generated Precipitation of silica；

5) precipitation of silica is dehydrated by high speed centrifugation, washed and is vacuum dried, obtain high-purity of the purity more than 6N Silicon-dioxide powdery.

2. preparation method according to claim 1, it is characterised in that：In step 2) in, by the fluosilicic acid after the purification Ammonium salt solution is put into triple effect evaporation crystallizer, and separation of solid and liquid is realized by three evaporative crystallizations.

3. preparation method according to claim 1, it is characterised in that：In step 3) in, by the high-purity fluorine ammonium silicate Solid is put into heat resolve in thermal decomposition reactor.