CN102633267A

CN102633267A - Preparation method of nano SiO2

Info

Publication number: CN102633267A
Application number: CN2012101218457A
Authority: CN
Inventors: 章浩龙
Original assignee: ZHEJIANG YUDA CHEMICAL INDUSTRY Co Ltd
Current assignee: ZHEJIANG YUDA CHEMICAL INDUSTRY Co Ltd
Priority date: 2012-04-19
Filing date: 2012-04-19
Publication date: 2012-08-15

Abstract

The invention discloses a preparation method of nano SiO2. The preparation method is characterized by taking soluble silicate M2O.nSiO2 and hydrocarbonate MHCO3 as raw materials to obtain hydrate SiO2 through precipitation, separating out filtrate through filtration, then washing the filter cake, displacing the filter cake with an organic solvent and drying and grinding the product to obtain the nano SiO2 product, wherein the filtrate mainly contains carbonate M2CO3 and little hydrocarbonate MHCO3; and M in the soluble silicate M2O.nSiO2, hydrocarbonate MHCO3 and carbonate M2CO3 is an alkali metal Na or K. The preparation method has the following beneficial effects: the filtrate mainly contains carbonate M2CO3 and little hydrocarbonate MHCO3 and the reaction raw materials can be obtained through different processing modes, so the materials can be recycled, thus the preparation cost is reduced, fewer resources are consumed, emission is reduced, and the problems of environmental pollution and the like because plenty of inorganic acids need to be consumed in the prior art are avoided.

Description

A kind of preparation method of nano silicon dioxide

Technical field

The present invention relates to a kind of method of producing nano silicon, belong to the new chemical materials technical field.

Background technology

Nano silicon (nm-SiO ₂) be the soft silica product of particle size at nano level (being generally 1-100nm); Outward appearance is a white powder; It is a kind of nontoxic, tasteless, free of contamination nonmetal oxide material; Microstructure is three-dimensional netted accurate particle globosity, because of its small size that has, bigger serface, high surface energy, the interface that contacts with polymkeric substance can high characteristics, and superior stability, reinforcement property, thickening property and thixotropy; Have in a lot of fields very and use widely, particularly all more and more manifest the effect that it is not replaced in Application Areass such as rubber, speciality coating, textile industry, polymer matrix composites modifications.

Produce nm-SiO at present ₂Method mainly contain two kinds of dry method and wet methods, dry method mainly refers to vapor phase process and arc process, wet method can be divided into the precipitator method and solution-gel method.Use dry method and with tetraethyl silicate as the solution-gel method of presoma owing to there are drawbacks such as the prices of raw and semifnished materials are expensive, preparation cycle is long, with cheap raw material preparing nm-SiO ₂The increasing attention that causes people of method.

The 25th the 2nd phase of volume of University Of Nanchang's journal (industry science version) of publishing in June, 2003 has been delivered the article of Zheng Dianmo, Su Xuejun, and " chemical precipitation method prepares nanometer SiO ₂Research ", water glass and the sulfuric acid introduced with cheapness are raw material, through the pH value of control solution, adopt the method for chemical precipitation to produce nanometer SiO ₂The method of micro mist, the precipitin reaction of this technology is:

Na ₂O·nSiO ₂+H ₂SO ₄+(nx-1)H ₂O→nSiO ₂·xH ₂O↓+Na ₂SO ₄

Remove and generate SiO ₂Outward, reaction has also generated Na ₂SO ₄, at washing SiO ₂Can produce a large amount of saliferous (Na during deposition ₂SO ₄) contain acid (remaining H ₂SO ₄) waste water, because the factor of aspects such as the concentration and the cost of technology, the cost recovery of these saliferous acid-bearing wastewaters is higher, recovery value is little again, therefore inevitably can discharge great amount of wastewater.

Therefore, though above-mentioned technology has solved the problem that substitutes expensive raw materials with cheap material, having brought needs to consume a large amount of mineral acids, and producing a large amount of saliferous acid-bearing wastewaters can't circulate or recycle, and causes problems such as environmental pollution simultaneously.

Summary of the invention

To the problems referred to above; The problem that quasi-solution of the present invention is determined provides outside a kind of silica removal source (soluble silicate or silica sand); The method of producing nano silicon that other chemical can recycle with the manufacturing cost of further reduction nano silicon, is lacked consumption of natural resource simultaneously; Reduce discharging, reduce infringement as far as possible environment.

For achieving the above object, the present invention adopts following technical scheme: a kind of preparation method of nano silicon dioxide, it is with soluble silicate M ₂OnSiO ₂With supercarbonate MHCO ₃Be raw material, with M ₂OnSiO ₂And MHCO ₃Mol ratio be 1: 2.0-2.3 reacts, and is settled out hydration SiO ₂, warp filters branch and goes to filtrate, and filter cake is again through washing, obtaining the nano silicon product with organic solvent displacement, drying, pulverizing; Mainly contain carbonate M in the said filtrating ₂CO ₃With a spot of supercarbonate MHCO ₃Said soluble silicate M ₂OnSiO ₂, supercarbonate MHCO ₃, carbonate M ₂CO ₃In M be alkali metal Na or K, said soluble silicate M ₂OnSiO ₂In n be its modulus.

Said soluble silicate M ₂OnSiO ₂Modulus n, when M was alkali metal Na, the n value was at 1.0-3.7, when M was alkali metal element K, the n value was 2.2-3.7.

Also carried out roasting after the said drying.Said filtration is to adopt vacuum filtration or pressure filter to filter.Described washing is the water washing leaching cake, to remove electrolyte ion contained in the filter cake.The water of said washing usefulness is tap water, deionized water, contain little amount of N H ₄HCO ₃Water, contain small amount of H ²SO ₄Or wherein one or more of the water of HCl.Described organic solvent displacement is with the filter cake of organic solvent washing after water washing, or removes the contained water of filter cake with the organic solvent azeotropic distillation.

Feed CO in the said filtrating ₂, make the carbonate M in the filtrating ₂CO ₃Generate MHCO ₃, circulation is as the reaction raw materials of preparation nano silicon.

After the said concentrating filter liquor, feed CO ₂, generate supercarbonate MHCO ₃Saturated solution and the mixture of its crystallisate, described concentrating is to be controlled to make crystalline MHCO ₃Account for MHCO in the mixture ₃40-45%, filtered and recycled MHCO then ₃Solid, filtrating recycles as the raw material of preparation nano silicon.

Carbonate and supercarbonate partial crystallization in said concentrating filter liquor to the filtrating obtain the mixture of saturated solution and crystallisate, then said mixture and silica sand are reacted generation soluble silicate M ₂OnSiO ₂And CO ₂, the soluble silicate M of said generation ₂OnSiO ₂Be used to generate the reaction raw materials of nano silicon, described concentrating is controlled at the water cut accords with production M that makes mixture ₂OnSiO ₂Processing requirement.

Adopt technique scheme, preparation method of nano silicon dioxide of the present invention, it is with soluble silicate M ₂OnSiO ₂With supercarbonate MHCO ₃For raw material reacts, be settled out hydration SiO ₂, obtain the nano silicon product through washing, organic solvent displacement, drying again.Owing to mainly contain carbonate M in the filtrating ₂CO ₃With a spot of supercarbonate MHCO ₃, can obtain reaction raw materials through different processing modes, so outside silica removal source (soluble silicate or silica sand); Other chemical can recycle, and compared with prior art, have reduced the manufacturing cost of nano silicon; Lack consumption of natural resource simultaneously, reduce discharging, reduce infringement environment.Avoid prior art need consume a large amount of mineral acids, caused producing a large amount of saliferous acid-bearing wastewaters, caused problems such as environmental pollution.

Also enumerated some in the technical scheme processing mode of filtrating different obtained reaction raw materials:

The one, can feed CO in the filtrating ₂, make the carbonate M in the filtrating ₂CO ₃Generate MHCO ₃, circulation is as preparation nanometer SiO ₂Reaction raw materials.

The 2nd, filtrating also can feed CO after concentrating ₂, generate supercarbonate MHCO ₃Saturated solution and the mixture of its crystallisate, filtered and recycled MHCO then ₃Solid, filtrating is as preparation nanometer SiO ₂Raw material recycle.

The 3rd, filtrating can also be in being concentrated into filtrating carbonate and supercarbonate partial crystallization, obtain the mixture of saturated solution and crystallisate, then said mixture and silica sand are reacted generation soluble silicate M ₂OnSiO ₂And CO ₂, the soluble silicate M of said generation ₂OnSiO ₂Be used to generate nanometer SiO ₂Reaction raw materials.

Above-mentioned three kinds obtain reaction raw materials to the different processing of filtrating, in actual production, can adopt corresponding processing mode respectively to different production status, to obtain best effect.Calculate by existing cost of material, compared with prior art, adopt the inventive method can reduce nano silicon product direct production cost more than 20%.Main is the discharging that has reduced waste water and dioxide gas, has reduced the infringement to environment.

Do some concise and to the point analysis in the face of technique scheme down.

Make a point earlier, the M described in the technique scheme is sodium Na or potassium K, because Na and K are both alkali metal, the two many corresponding compounds performance is all very close.Na with modulus ₂OnSiO ₂And K ₂OnSiO ₂Its many performances are all very similar, other Na ₂CO ₃With K ₂CO ₃Its physical and chemical performance is also all very similar, thus mainly be to be that Na performs an analysis with M in following analysis, to M be K situation roughly and the like get final product.To the salient features and the preparation method of water glass, potassium silicate product, can understand with reference to corresponding document, like " production of silicon compound and application " (No. 015, (river) Xindeng word) of press of Chengdu Univ. of Science & Technology in May, 1994 distribution.

Briefly introduce down main raw material water glass below as the preparation nano silicon.

Water glass, popular name water glass, commodity are called sodium silicate, and molecular formula can be write: Na ₂OnSiO ₂, n is SiO ₂With Na ₂The mol ratio of O often is called modulus, and the modulus of general water glass product is at 1.0-4.0.

Water glass is generally by Na ₂CO ₃Make with reaction at high temperature, its reaction formula is:

Na ₂CO ₃+nSiO ₂＝＝Na ₂O·nSiO ₂+CO ₂

About producing the technological process of water glass, preceding " production of silicon compound and application " 21-42 page or leaf detail of having mentioned has been discussed the technology that solid phase method is produced water glass, and this also is that this patent is with the Na that reclaims ₂CO ₃With silica sand (SiO ₂) react and produce the method that water glass adopts, so no longer carefully state here.Unique difference is the Na that reclaims in the patent art scheme ₂CO ₃In, can be mixed with NaHCO in addition ₃, but NaHCO ₃Promptly be decomposed into Na in the production temperature rise period at initial stage ₂CO ₃:

So be mixed with NaHCO ₃Na ₂CO ₃With SiO ₂Reaction and popular response and indifference, the just NaHCO of 2mol when calculating batching that notes ₃Be equivalent to the Na of 1mol ₂CO ₃Usefulness also need be done some the phase considered simultaneously when making heat balance, the fuel ratio that promptly reacts used is all used Na ₂CO ₃Many slightly.

Water glass very easily reacts with acid and separates out silicon-dioxide, and the front has been write Na ₂OnSiO ₂With H ₂SO ₄The equation of reaction, but in fact, Na ₂OnSiO ₂Even ability and NH ₄ ⁺Such weak acid (Lewis acid) reaction:

Na ₂O·nSiO ₂+2NH ₄Cl+(nx-1)H ₂O→nSiO ₂·xH ₂O↓+2NaCl+2NH ₃

Here, NH ₄ ⁺Be as an acid:

PKa＝9.25

Similar, Na ₂OnSiO ₂Also can with HCO ₃ ^-Reaction:

Na ₂O·nSiO ₂+NH ₄HCO ₃+(nx-1)H ₂O→nSiO ₂·xH ₂O↓+Na ₂CO ₃+NH ₃

Na ₂O·nSiO ₂+2NaHCO ₃+(nx-1)H ₂O→nSiO ₂·xH ₂O↓+2Na ₂CO ₃

PKa＝10.3

This is a reaction principle of the present invention.

When using NaHCO ₃Make Na ₂OnSiO ₂Middle SiO ₂After separating out, through washing, can obtaining the nano silicon product with organic solvent displacement, drying, these subsequent treatment process are equal to the production technique that existing water glass acid system is produced nano silicon basically.Replenish some in addition:

1, straining installation: existing straining installation such as pressure filter, vacuum filter all can use in principle, but considers washing effect, and factors such as water saving in the washing process particularly are so use the membrane pressure filter effect can be better.

2, bath water can be directly with tap water or deionized water, the also available little amount of N H that contains ₄HCO ₃Dilute solution, this is because hydration SiO ₂There is adsorptivity on the surface, adsorbs a large amount of Na easily ⁺And K ⁺Ion, simple water is difficult for cleaning.Utilize NH ₄ ⁺The ionic exchange interaction can improve the effect of washing.Also available a small amount of rare H ₂SO ₄Or rare HCl soaks, washing, afterwards again with tap water or deionized water wash, generally is washed till the wash water pH value and gets final product at 6-7.Certainly, these processes all can be accomplished in filter.

Remove to contain SiO when filtering to divide ₂Post precipitation, filtrating mainly contains Na ₂CO ₃NaHCO with non-reacted parts ₃, at this moment can have kinds of schemes to reclaim these Na ₂CO ₃And NaHCO ₃The confession recirculation is used, as can in filtrating, leading to CO ₂Reaction generates NaHCO ₃, the NaHCO of generation ₃Solution can be used as and Na ₂OnSiO ₂The raw material of reaction recycles.Also can directly concentrate and reclaim Na ₂CO ₃Product is sent in the time of extremely meeting the requirement (mainly being water cut) of reacting with silica sand and is produced Na ₂OnSiO ₂Only compare this liquid concentrator and SiO with common process ₂Reaction can relate to NaHCO ₃Decomposition:

Here the Na that generates ₂CO ₃Promptly be the raw material of preparation water glass, the CO of generation ₂Can be used for by Na ₂CO ₃Generate NaHCO ₃Reaction raw materials.What need to replenish is, by Na ₂CO ₃When producing water glass, by the CO of fuel combustion generation ₂Also can reclaim synchronously, to replenish CO in the process ₂Loss or deficiency.

The another kind of processing scheme of filtrating is: earlier tentatively concentrated, or, feed CO without concentrated (according to concentration) ₂, make the NaHCO of generation ₃Saturated part analyzes from the solution middle part, and filtered and recycled is separated out part NaHCO ₃, surplus NaHCO ₃Solution circulated is back to and Na ₂OnSiO ₂Precipitin reaction.NaHCO ₃To separate out be the poor solubility of having utilized the two.Na ₂CO ₃With NaHCO ₃Solubleness (g/100g water) relatively as follows:

Temperature	0℃	10℃	20℃	30℃	40℃
						Na ₂CO ₃	7.1	12.5	21.5	39.7	49.0
NaHCO ₃	6.9	8.1	9.6	11.1	12.7

Can utilize Na at normal temperature (about 20 ℃-30 ℃) ₂CO ₃With NaHCO ₃Solubleness official post NaHCO ₃From solution, separate out, can simplify like this and reclaim NaHCO ₃Technological process.

The NaHCO that obtains ₃Can be used as product and reclaim, but also thermolysis obtains Na ₂CO ₃And CO ₂, CO ₂Circulation is used to generate NaHCO ₃NaHCO ₃Thermal decomposition process can be with reference to " inorganic chemical technology (descending) " (standard book number 15063.3244 (K-246)) 351-361 page or leaf associated viscera of Chemical Industry Press's in December, 1981 publication.NaHCO ₃Also can be directly as producing Na ₂OnSiO ₂Raw material.

3, restock a bit, also recyclable Na in the washing filter cakes liquid ₂CO ₃And NaHCO ₃, particularly the washing lotion in early stage can further reduce the loss of recycle feed and the discharging of waste liquid like this.Washings can mix use with filtrating, also can concentrate and can preferentially use reverse osmosis process, the washing lotion circulation reusing technology after concentrating and the basically identical of filtrating earlier through concentrating.

4, the used organic solvent of replacement solvent can be by producing the recycling use of nano silicon current technology.

Can know that according to above explanation the present invention only is raw material with silica sand, Na ₂OnSiO ₂, Na ₂CO ₃, NaHCO ₃And CO ₂All can be recycled Deng starting material, promptly as long as replenish part Na in good time ₂CO ₃Or CO ₂Loss the technology continous-stable is carried out, not only significantly reduced the manufacturing cost of nano silicon, also significantly reduced waste water and CO ₂Discharging, and its concise production process, equipment and fixed capital less input, process advantage is fairly obvious.

With K ₂OnSiO ₂During for raw material, K ₂OnSiO ₂, K ₂CO ₃, KHCO ₃Circulation also basic identical.

Embodiment

Can know that from the explanation of front the present invention produces the nanometer titanium dioxide silicon technology roughly can cooperate composition by following three reactions (process) series connection:

(1) main reaction: by Na ₂OnSiO ₂/ K ₂OnSiO ₂Obtain hydration SiO with corresponding supercarbonate reaction ₂Gel (or deposition) can obtain the nano silicon product through washing, organic solvent displacement, drying then.

(2) processing of main reaction after-filtration filtrating;

(3) silica sand and Na ₂CO ₃/ K ₂CO ₃Reaction generates Na ₂OnSiO ₂/ K ₂OnSiO ₂Reaction.

Technology of the present invention can be formed a complete technological by above-mentioned three reactions (process); Also can be except that main reaction (process) (1), to assisted reaction (process) select with or need not, for example; Select only to carry out (1), (2), promptly at regeneration, recovery part NaHCO ₃/ KHCO ₃Or Na ₂CO ₃/ K ₂CO ₃After, no longer carry out the generative process of water glass/potassium silicate.In addition, in same reaction process, have numerous embodiments, and in actual production; Can be according to wherein a kind of production technique of production actual selection; Then with another process in some combinations, can form a complete technological, so; Its technological process will illustrate with above-mentioned three reactions (process) respectively for better explaining.Other explains that same or analogous with traditional (or existing) technology to corresponding technology, only work is simple explains, and lists corresponding reference as far as possible here.

(1) main reaction

Embodiment 1

Getting a kind of degree Beaume is the water glass of 37 ° of Be ' (20 ℃, down together), and the water that adds 4 times of amounts (weight, down together) dilutes, filters, and records diluent and contains SiO ₂%=5.0%, Na ₂O%=1.4%, its modulus n=3.7 takes by weighing this dilute solution 600g, under agitation with the NaHCO of 600g 3.8% ₃Solution mixes (the reaction mol ratio is 1: 2.0), does not have SiO in the liquid phase basically to checking ₂, continued stir about 15 minutes, filter, use the clear water washing precipitation, closely neutral to wash water, drain, with the washing with alcohol deposition, drain, dry in baking oven, pulverize again, can obtain the about 27.5g of nano silicon finished product.

Said clear water is tap water or deionized water.

Embodiment 2

Get the water glass that a kind of degree Beaume is 40 ° of Be ', add water dilution, the filtration of 3 times of amounts, record diluent and contain SiO ₂%=7.3%, Na ₂O%=2.3%, its modulus n=3.3 takes by weighing this rare sodium silicate solution 400g, under agitation contains 6.1% NaHCO with 450g ₃Solution mixes (the reaction mol ratio is 1: 2.2), does not have SiO in the liquid phase basically to checking ₂, continued stir about 15 minutes, filter, with clear water washing precipitation 2-3 time, again with containing little amount of N H ₄HCO ₃Water washing deposition 2-3 time, use clear water washing precipitation to wash water closely neutral again, drain, with washed with isopropyl alcohol deposition several times, drain again, dry in baking oven, pulverize again, can obtain the about 27.5g of nano silicon finished product.

Embodiment 3

Get the water glass that a kind of degree Beaume is 50 ° of Be ', add water dilution, the filtration of 4 times of amounts, record diluent and contain SiO ₂%=5.8%, Na ₂O%=2.6%, its modulus n=2.3 takes by weighing the rare sodium silicate solution 500g of this kind, under agitation contains 7.4% NaHCO with 500g ₃Solution mixes (the reaction mol ratio is 1: 2.1), does not have SiO in the liquid phase basically to checking ₂, continued stir about 15 minutes, filter, with clear water washing precipitation 2-3 time, again with containing small amount of H ₂SO ₄Water washing deposition 2-3 time, use clear water washing precipitation to wash water closely neutral again, drain; Join in the propyl carbinol, remove the contained water of filter cake, stop heating after distillation is accomplished with component distillation; Use the B suction filtration after being cooled to normal temperature; It is dry that filter cake is put into baking oven, obtains the powder that loosens after the drying, grinds slightly and can obtain the about 26g of nano silicon finished product.

Embodiment 4

Get a kind of Starso Na ₂SiO ₃9H ₂The O product is dissolved in water, filters, and records its SiO ₂%=3.1%, Na ₂O%=3.2%, its modulus n=1.0 takes by weighing this kind solution 600g, under agitation contains 6.6% NaHCO with 900g ₃Solution mixes (the reaction mol ratio is 1: 2.3), does not have SiO in the liquid phase basically to checking ₂, continued stir about 15 minutes, filter, with containing little amount of N H ₄HCO ₃Water washing deposition 2-3 time, again with clear water washing 2-3 time, again with the water washing deposition that contains small amount of H Cl 2-3 time; Use clear water washing precipitation to wash water closely neutral again, drain, join in the propionic acid; Remove the contained water of filter cake with component distillation, stop heating after distillation is accomplished, use the B suction filtration after being cooled to normal temperature; It is dry that filter cake is put into baking oven, obtains the powder that loosens after the drying, grinds slightly and can obtain the about 16g of nano silicon finished product.

Embodiment 5

Press embodiment 1-3,, use KHCO with the potassium silicate replacement water glass of close modulus ₃Replacement NaHCO ₃, by close amount and volumetric molar concentration, do not change other conditions and technological process, can obtain the nano silicon product of similar weight equally, the volumetric molar concentration of filtrating is basically identical also.

(2) assisted reaction (process): the reuse of filtrating

Embodiment 6

Leach SiO at embodiment 1 ₂Post precipitation obtains containing Na ₂CO ₃The about 900g of filtrating, logical CO ₂Reaction detects NaHCO ₃Content is 3.8%, basically with this embodiment before the NaHCO for preparing ₃Strength of solution is consistent, and the weight also 600g than former adding is many, is enough to recycle.

Embodiment 7

Filter elimination SiO at embodiment 2 ₂Post precipitation obtains containing Na ₂CO ₃With part NaHCO ₃The about 550g of filtrating, note is made A, the moist precipitate that weighing contains liquid is about 300g, divides with clear water and soaks moist precipitate, filtration for 2-3 time, drains as far as possible, the about 270g of filtrating that gets back leads to CO in this is filtrated ₂Reaction, reaction detects wherein NaHCO after accomplishing ₃Content is 4.3%, remembers that this solution is B, and is subsequent use.

A concentrates to filtrating, to the heavily about 170g of liquid, NaHCO is arranged ₃Crystal is separated out, and filters the NaHCO that weighing is separated out ₃Crystal is about 21g, the about 150g of saturated solution.This saturated solution mixes with solution B, obtains about 450g NaHCO ₃Solution detects its NaHCO ₃Concentration is 6.1%, capable of circulationly is used for main reaction and makes raw material and use.

Embodiment 8

Filter elimination SiO at embodiment 3 ₂Post precipitation obtains containing Na ₂CO ₃With part NaHCO ₃The about 770g of filtrating, note is made A, the moist precipitate that weighing contains liquid is about 230g, divides with clear water and soaks moist precipitate, filtration for 2-3 time, drains as far as possible, the about 230g of filtrating that gets back leads to CO in this is filtrated ₂Reaction, reaction detects wherein NaHCO after accomplishing ₃Content is 5.1%, remembers that this solution is B, and is subsequent use.

A concentrates to filtrating, to the heavily about 300g of liquid, NaHCO is arranged ₃Crystal is separated out, and filters the NaHCO that weighing is separated out ₃Crystal is about 32g, the about 270g of saturated solution.This saturated solution mixes with solution B, obtains about 500g NaHCO ₃Solution detects its NaHCO ₃Concentration is 7.4%, capable of circulationly is used for main reaction and makes raw material and use.

Embodiment 9

Filter elimination SiO at embodiment 4 ₂Post precipitation obtains containing Na ₂CO ₃With little amount of N aHCO ₃The about 1300g of filtrating, analyze and wherein to contain Na ₂CO ₃About 3.8%, NaHCO ₃About 0.4%, concentrate the mixture that obtains containing about 63g solid and less water, can generate Na ₂OnSiO ₂Raw material.

To embodiment 5 elimination SiO ₂The filtrating that contains potassium silicate, saleratus that post precipitation obtains is by reclaiming Na with embodiment 6-9 ₂CO ₃/ NaHCO ₃Same process, the process condition basically identical, only when concentrated need according to KHCO under the differing temps ₃Solubleness corresponding adjustment is done in the control that concentrates amount.

(3) assisted reaction (process): the regeneration of water glass, potassium silicate

The present invention is by Na ₂CO ₃/ K ₂CO ₃Make Na with quartz reaction ₂OnSiO ₂/ K ₂OnSiO ₂Process and existing dry method system Na ₂OnSiO ₂/ K ₂OnSiO ₂Technology is in full accord, specifically can be referring to " production of silicon compound and application " P21-P42 and P106-P111.Just by the NaHCO that reclaims ₃/ KHCO ₃Need analyse calculation when reacting, analyse the calculation value and be respectively with silica sand: 0.63 and 0.69, promptly every 1kgNaHCO ₃Can analyse to calculate and be 0.63kg Na ₂CO ₃, every 1kg KHCO ₃Can analyse to calculate and be 0.69kg K ₂CO ₃

With the NaHCO that reclaims ₃/ KHCO ₃Substitute Na ₂CO ₃/ K ₂CO ₃, insufficient section need replenish new Na ₂CO ₃And K ₂CO ₃Another problem here is the CO that at this moment generates ₂Amount can increase:

2NaHCO ₃＝Na ₂CO ₃+H ₂O+CO ₂

2KHCO ₃＝K ₂CO ₃+H ₂O+CO ₂

So, the CO that at this moment produces ₂Mainly having three parts forms: (1) Na ₂CO ₃/ K ₂CO ₃With SiO ₂Reaction generates CO ₂(2) NaHCO ₃/ KHCO ₃Decompose and generate CO ₂(3) CO of fuel combustion generation ₂These CO ₂Be mingled in the furnace gas, furnace gas can directly obtain CO after heat recuperation, dedusting ₂Supply to generate NaHCO ₃/ KHCO ₃Reaction usefulness, or with existing complete absorption unit recovery CO ₂, supply subsequent reactions to recycle.

Claims

1. a preparation method of nano silicon dioxide is characterized in that it is with soluble silicate M ₂OnSiO ₂With supercarbonate MHCO ₃Be raw material, with M ₂OnSiO ₂And MHCO ₃Mol ratio be 1: 2.0-2.3 reacts, and is settled out hydration SiO ₂, warp filters branch and goes to filtrate, and filter cake is again through washing, obtaining the nano silicon product with organic solvent displacement, drying, pulverizing; Mainly contain carbonate M in the said filtrating ₂CO ₃With a spot of supercarbonate MHCO ₃Said soluble silicate M ₂OnSiO ₂, supercarbonate MHCO ₃, carbonate M ₂CO ₃In M be alkali metal Na or K, said soluble silicate M ₂OnSiO ₂In n be its modulus.

2. preparation method of nano silicon dioxide according to claim 1 is characterized in that said soluble silicate M ₂OnSiO ₂Modulus n, when M was alkali metal Na, the n value was at 1.0-3.7, when M was alkali metal element K, the n value was 2.2-3.7.

3. preparation method of nano silicon dioxide according to claim 1 and 2 is characterized in that also having carried out roasting after the said drying.

4. preparation method of nano silicon dioxide according to claim 1 and 2 is characterized in that said filtration is to adopt vacuum filtration or pressure filter to filter.

5. preparation method of nano silicon dioxide according to claim 1 and 2 is characterized in that described washing is the water washing leaching cake, to remove electrolyte ion contained in the filter cake.

6. preparation method of nano silicon dioxide according to claim 1 and 2, it is characterized in that described is with the filter cake of organic solvent washing after water washing with the organic solvent displacement, or removes the contained water of filter cake with the organic solvent azeotropic distillation.

7. preparation method of nano silicon dioxide according to claim 1 and 2 is characterized in that feeding CO in the said filtrating ₂, make the carbonate M in the filtrating ₂CO ₃Generate MHCO ₃, circulation is as the reaction raw materials of preparation nano silicon.

8. preparation method of nano silicon dioxide according to claim 1 and 2, it is characterized in that said concentrating filter liquor after, feed CO ₂, generate supercarbonate MHCO ₃Saturated solution and the mixture of its crystallisate, described concentrating is to be controlled to make crystalline MHCO ₃Account for MHCO in the mixture ₃40-45%, filtered and recycled MHCO then ₃Solid, filtrating recycles as the raw material of preparation nano silicon.

9. preparation method of nano silicon dioxide according to claim 1 and 2; It is characterized in that carbonate and supercarbonate partial crystallization in said concentrating filter liquor to the filtrating; Obtain the mixture of saturated solution and crystallisate, with said mixture and silica sand reaction, generate soluble silicate M then ₂OnSiO ₂And CO ₂, the soluble silicate M of said generation ₂OnSiO ₂Be used to generate the reaction raw materials of nano silicon, described concentrating is controlled at the water cut accords with production M that makes mixture ₂OnSiO ₂Processing requirement.