CN107867696A

CN107867696A - The preparation method of high-purity silicon dioxide

Info

Publication number: CN107867696A
Application number: CN201610852512.XA
Authority: CN
Inventors: 李辉
Original assignee: Qingdao Jiuzhou Thousand Machinery Co Ltd
Current assignee: Qingdao Jiuzhou Thousand Machinery Co Ltd
Priority date: 2016-09-26
Filing date: 2016-09-26
Publication date: 2018-04-03

Abstract

The invention discloses a kind of method of high-purity silicon dioxide, and it reacts at a certain temperature using diatomite as raw material, with ammonium fluoride aqueous solution, by precipitating, filtering, centrifuging and obtain ammonium fluosilicate solution；High-purity fluorine ammonium silicate solid is obtained by evaporative crystallization；High-purity fluorine ammonium silicate solid is by thermally decomposing to yield high-purity silicon tetrafluoride；Silicon tetrafluoride gas is reacted with high-purity ammoniacal liquor, is generated precipitation of silica, by separation of solid and liquid, washing, vacuum drying, is prepared high-purity silicon dioxide powder.The silicon-dioxide powdery purity that this method cost of material is relatively low, operating procedure is simple, contamination-free is produced and prepared in production process is more 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 side of high-purity silicon dioxide Method.

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, and application is increasingly extensive 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 heavy Shallow lake method (wet method) etc..Silica method for refining is by being refining to obtain high-purity titanium dioxide using the very high quartz of natural purity, silica Silicon.The method is limited by the limitation of raw material, not only limited amount, and is also difficult to meet wanting for new high-tech material field in quality Ask.For vapor phase method using the halide of silicon or silanol as raw material, price is higher, and has flammable, severe corrosive, to process units requirement Greatly, production cost is high, is not suitable for mass producing for high, investment.The precipitation method are generally using sodium metasilicate or ammonium fluosilicate as raw material, price Relatively low, operation is comparatively safe, but the difficulty purified is larger, and product quality is easily influenceed by material purity, and production process has dirt Contaminate thing discharge.

The content of the invention

It is an object of the invention to provide a kind of low raw-material cost, operating procedure is 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 is filtered, removes impurity after centrifugation purification；High-purity ammonia water is made through absorbing pure water in the ammonia；

2) ammonium fluosilicate solution after preliminary purification is realized into separation of solid and liquid by multiple evaporative crystallization, then passes through 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, makes it anti-with high-purity ammonia water progress ammonolysis Should, generate precipitation of silica；

5) precipitation of silica is dehydrated by high speed centrifugation, washed and is dried in vacuo, it is high more than 6N to obtain purity Purity silica powder.

In above-mentioned step 2), the ammonium fluosilicate solution after the purification is put into triple effect evaporation crystallizer, passed through Evaporative crystallization realizes separation of solid and liquid three times；In above-mentioned step 3), the high-purity fluorine ammonium silicate solid is put into thermal decomposition Heat resolve in reactor.SiO 2 content is 95% or so in the diatomite.

Method cost of material of the invention is relatively low, operating procedure is simple, and ammonia is only absorbed by the water caused by production process, so Contamination-free produces.The silicon-dioxide powdery purity prepared with this method is more than 6N, so disclosure satisfy that new and high technology material pair The requirement of its purity.

Embodiment

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

The present invention method with diatomite (contents of SiO 2 are about 95wt%) for raw material, with ammonium fluoride aqueous solution certain At a temperature of dissolving, reaction, by precipitating, filtering, centrifuging and obtain ammonium fluosilicate solution；High-purity fluorine silicon is obtained by evaporative crystallization Sour ammonium solid；High-purity fluorine ammonium silicate solid is by thermally decomposing to yield high-purity silicon tetrafluoride；Silicon tetrafluoride gas and high purity ammonia Water reacts, and generates precipitation of silica, by separation of solid and liquid, washing, vacuum drying, prepares high-purity silicon dioxide powder. In the process, high-purity ammonia water is reacted to obtain by the first step, and final step reaction generation silica and ammonium fluoride, ammonium fluoride can Continue cycling through use.

Embodiment 1

1) diatomite (contents of SiO 2 about 95%) and ammonium fluoride (NH 4F) aqueous solution stir molten under the conditions of 80~90 DEG C Solution, reaction generation ammonium fluosilicate solution and ammonia.By precipitating, filtering, the step such as centrifuging and remove impurity, obtain purity for 99 with On ammonium fluosilicate solution, more than 99.99% high-purity ammoniacal liquor is made through absorbing pure water in ammonia.Reaction equation is as follows：

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

2) obtained ammonium fluosilicate solution is imported in triple effect evaporation crystallizer, solid-liquid is realized by evaporative crystallization three times Separation, high-purity fluorine ammonium silicate solid of the purity not less than 4N then is obtained by washing, part dissolved impurity quilt in solution Remove.

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

(NH 4)2SiF 6→SiF 4↑+NH 4F↑ (2)

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

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

5) by obtained precipitation of silica by centrifuging, washing more than twice, then it is dried in vacuo, obtains purity>6N High-purity silicon dioxide powder.

If in above-mentioned step 4), purity≤4N of ammonium fluosilicate solid should then observe whether it influences subsequently to walk Rapid purity 5), if influenceed, purity≤4N ammonium fluosilicate solid needs return to step 2) re-start crystallization；If no Influence, can not consider.

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

Product made from this method, the 1/3 of its same purity product of cost deficiency import, compared with domestic prior art, The production technology of the present 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 at 80~90 DEG C Solution is filtered and high speed centrifugation after remove impurity, realize preliminary purification；High-purity ammonia water is made through absorbing pure water in the ammonia；

2) ammonium fluosilicate solution after preliminary purification is passed through into multiple evaporative crystallization, secondary purification is carried out by separation of solid and liquid, so High-purity fluorine ammonium silicate solid is obtained by washing afterwards；

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

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

5) precipitation of silica is dehydrated by high speed centrifugation, washed and is dried in vacuo, it is high-purity more than 6N to obtain purity Spend silicon-dioxide powdery.

2. preparation method according to claim 1, it is characterised in that：In step 2), 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 evaporative crystallization three times.

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