CN106044784A - Method for producing high-purity silicon dioxide by utilizing flyash - Google Patents
Method for producing high-purity silicon dioxide by utilizing flyash Download PDFInfo
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- CN106044784A CN106044784A CN201610599980.0A CN201610599980A CN106044784A CN 106044784 A CN106044784 A CN 106044784A CN 201610599980 A CN201610599980 A CN 201610599980A CN 106044784 A CN106044784 A CN 106044784A
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- flyash
- acid
- silicon dioxide
- organic acid
- silicon
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B33/00—Silicon; Compounds thereof
- C01B33/113—Silicon oxides; Hydrates thereof
- C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/80—Compositional purity
Abstract
The invention discloses a method for producing high-purity silicon dioxide by utilizing flyash. The method comprises the following steps: carrying out sour molten activation on the flyash by using organic acid at first to remove other impurities except silicon; then carrying out alkali dissolution with a NaOH aqueous solution; dissolving silicon in the flyash in the form of sodium silicate; and finally, under the ultrasonic or stirring condition, dropwise adding the organic acid until the mixture is neutral and silica gel is produced, filtering and drying to obtain the high-purity silicon dioxide. The traditional thinking of dissolving the flyash by using inorganic acid is broken through, silicon dioxide is extracted by combining the organic acid and inorganic base and using an ultrasonic or stirring method, the silicon in the flyash can be extracted effectively, the aluminum-silicon rate is reduced, and aluminum-silicon separation is realized. An operation process is simple and easy to control, low in investment, low in cost, high in added value of products and high in universality, and is a flyash refining, comprehensive utilizing and industrializing method with good prospect.
Description
Technical field
The comprehensive resource that the invention belongs to flyash utilizes technical field, is specifically related to a kind of from flyash garbage
The method of extraction of highly pure silica.
Background technology
Along with the development of power industry, the fine coal ash quantity that power plant emission goes out increases therewith, and flyash is stored up with ash shape, abandons
On one side, take up an area the most in a large number, and serious environment pollution.Comprehensive utilization flyash, both can consume substantial amounts of flyash, alleviate it
Pollution to environment, reduces and takes up an area, and can be again that building industry produces lightweight, high-strength, the building material of insulation, replace clay brick,
May be used for the most again producing simultaneously concrete, build the road, backfill etc., achieve many things at one stroke.Collect a large amount of flyash, how to carry out effective profit
With, become a critical problem.
The main component of flyash is Al2O3And SiO2, containing a small amount of Fe2O3, FeO, CaO, MgO and other inorganic oxide
Thing, wherein SiO2Mainly presenting vitreous body amorphous phase, it accounts for the 40%～80% of flyash total amount.Different regions and kind
Flyash constituent difference big, thus different flyash has the biggest difference in using effect.But Al2O3Content
It is only second to SiO2, how extracting directly high-purity SiO2Effectively realizing sial separating difficulty relatively big, process is complex, cost
Higher, it is difficult to realize industrialization.
SiO is extracted from flyash2Method numerous: (1) acid system.Acid system mainly uses sulphuric acid or hydrochloric acid equal solvent, powder
Coal ash is molten through certain condition acid, obtains corresponding aluminum salt solution, thus realizes sial and separate, obtains Al through subsequent treatment2O3With
SiO2.Such as: flyash is ground to certain particle size when Lee comes etc., then with acid soak, at a certain temperature roasting, makes Al2O3's
Extraction degree brings up to 93.2%.The method is a kind of traditional coal ash lifting access method, technical maturity, but the method exists circulation
Acid amount is big, equipment is perishable, acid vapor and use auxiliary agent produce HF pollute the environment, the shortcoming such as harmful.Simple
Acid leaching is because of Al in flyash2O3And SiO2Main with Al2O3-SiO2Key-like formula exists, and is difficult to be either directly solubilised, and extraction ratio is low.
(2) alkaline process.1. sintering process: by cosolvent mixed calcinings such as flyash and limestone, soda lime or sodium carbonate, make in flyash
Mullite and quartz are separately converted to dicalcium silicate (2CaO SiO2) and C 12 A 7 (7Al2O312CaO), from efflorescence
After grog use sodium carbonate dissolution, the insoluble matter such as dicalcium silicate and aluminic acid ten dicalcium is stayed in filtering residue, and calcium aluminate filtrate warp
Decompose sodium metaaluminate it is achieved thereby that sial separate.2. alkali solution technique: flyash is directly mixed with alkali liquor, under certain condition
Dissolution is filtered, and the filtrate containing sodium silicate obtained gets SiO through carbon2, filtering residue uses alkali solution technique or sintering process to extract further
Al2O3, thus realize sial and separate.Example: Wu Guodong etc. use low temperature alkali solution technique to be studied flyash dissolution sial, result
Finding, under an increased pressure, heat treatment temperature is 950 DEG C, alkali concn is 2～3mol/L, leaching temperature is 120～130 DEG C, molten
Go out the time when being 4～6h experiment effect optimal, now SiO2Dissolution rate is 29.33%, Al2O3Dissolution rate is 1.26%, dissolution ratio
Reach 23.63, can tentatively realize Al in flyash2O3And SiO2Step by step arithmetic.The method is simple to operate, and reagent is single, cost
Low, but use limestone sintering process can produce solid calcium white residue, calcium-silicon slag difficult treatment, value are low, cement can be produced but
Cement sells that radius is limited, market cannot catapepsis, it will produces secondary and piles up and pollute, it is impossible to extracts SiO further2.This
Method greatly reduces the energy consumption of sintering process compared with limestone sintering process, but needs to be additionally provided carbon dioxide, and filtering residue
Low as portland cement raw material value, it is difficult to therefrom extract SiO2.(3) acid and alkali combination method.1. alkali after first acid: through certain
Pretreated flyash, adds Acid leaching and filters, and the filtrate containing aluminum is treated obtains aluminium oxide, and the further alkali of filtering residue is molten obtains siliceous filter
Liquid, treated obtains SiO2.Such as, after Wu Yan etc. utilize first acid, alkali technique has separated the Al in flyash2O3And SiO2, system
For having gone out high-purity Al2O3With ultra-fine SiO2.In this producing process, first step acid dissolution use strong oxidizing property have deep-etching
The high-concentration sulfuric acid of property is as sour molten reagent, and it is molten to add hot acid under 250～300 DEG C of hot conditionss, and the blob of slag obtained is at 300 DEG C
Left and right high-temperature calcination；Second step concentrated base leaches and need to carry out at 100 DEG C of temperature higher above, and then obtains sodium silicate solution, so
After in sodium silicate extracting solution, carry out carbon divide and (sodium carbonate or sodium bicarbonate and acid reaction need to be introduced generate carbon dioxide and displace
SiO2) obtain SiO2.The sodium carbonate liquor obtained after finally carbon being divided need to calcium oxide carry out causticization process generate NaOH solution and
CaCO3Precipitation, returns concentrated base extract technology, the CaCO of generation after the NaOH solution evaporation and concentration of generation3Precipitation is through Roasting Decomposition
After, the CO of generation2Gas returns carbonation decompsition process, and CaO returns causticization process.This technique achieves feedstock circulation and utilizes, acid consumption, alkali
Consumption reduces, and waste sludge discharge amount is low, but aluminum sulfate Roasting Decomposition and sodium hydroxide inspissation energy consumption are big, and acid concentration is big, and corrosivity is strong, acid
Solubility temperature is the highest, complex operation, and condition is harsh.2. acid after first alkali: through certain pretreated flyash, adds alkali leaching and filters
Containing aluminum and the filtrate of silicon, filtrate that acid adding filters containing aluminum and white residue, filtrate treated Al2O3, filtering residue is treated to be obtained
SiO2。
Summary of the invention
The technical problem to be solved is to provide one and is combined, at temperate condition by organic acid and inorganic base
Under, it is not necessary to high-temperature calcination, carbon divide and the technique such as causticization process can extract high-purity SiO from flyash2Method.
Solve the technical scheme that above-mentioned technical problem used to be made up of following step:
1, the flyash after grinding activation mixes for 1:1～4 in mass ratio with organic acid, and room temperature reaction 0.5～2 is little
Time, filtering, obtain acid leaching residue, wherein said organic acid is any one in oxalic acid, citric acid, glacial acetic acid.
2, acid leaching residue is mixed for 1:2～6 in mass ratio with the sodium hydrate aqueous solution that mass fraction is 10%～20%,
100 DEG C are reacted 1～2 hour, filter, and with sodium hydrate aqueous solution quality 6～the distilled water wash of 8 times, obtain sodium silicate and carry
Take liquid.
3, by sodium silicate extracting solution under ultrasonic or stirring condition with organic acid for adjusting pH to neutral, sucking filtration, washing, freezing
It is dried, obtains silicon dioxide.
In above-mentioned steps 1, the flyash after preferably grinding activation mixes for 1:2～3 in mass ratio with organic acid, room temperature
React 1 hour, the preferred glacial acetic acid of described organic acid.
In above-mentioned steps 2, preferably by sodium hydrate aqueous solution that acid leaching residue and mass fraction are 15% in mass ratio for 1:4
～5 mixing, 100 DEG C react 2 hours.
The present invention has continued conventional traditional acid and alkali combination method and has extracted the thinking of silicon dioxide, but breaches and uses nothing always
Machine strong acid carrys out the thinking of acidleach flyash under the high temperature conditions, uses common and cost is relatively low, the organic acid of safety non-toxic evil comes
Replace inorganic acid and reach same purpose, in conjunction with inorganic base NaOH and combine the conditions such as ultrasonic wave added and extract high-purity
Silica product, started extract silicon dioxide new thought, compared with prior art, the present invention has following excellent
Point:
1, the present invention uses the higher gentle moderate strength organic acid of etch factor very lower security coefficient, and acidleach condition is simple
Gentle need to be carried out at normal temperatures；The concentration of the molten sodium hydroxide used of alkali is relatively low, and only needs 100 DEG C to heat；Obtain
Sodium silicate extracting solution to generate acid solution step molten with acid used by silica gel consistent, the material making input is the fewest, and sodium silicate
Extracting solution is made without carbon and divides except complex processes such as ferrum, it is not required that carries out the causticization after carbon divides and processes, breaches and carried in the past
During taking, carbon grades complex process, it is not necessary to introduce the most more material and equipment, the most simpler easy behaviour of whole process
Make.
2, the silica product purity that the present invention extracts is the highest, and productivity is the highest, and product quality is very light, and granularity is relatively
Very thin for uniform and granule, whole technical process is simple, and temperature-controllable is invested little, low cost, does not discharge any poisonous and hazardous
Material, and discharging of waste liquid amount is little.
3, the present invention adequately achieves the comprehensive resources utilizationization of flyash, greatly reduces silica alumina ratio, it is achieved that silicon
Efficiently separating of aluminum, improves value-added content of product, the adsorption bleaching being applied to dyestuff that gained silicon dioxide can be fabulous, surplus
Remaining high residue of aluminum can also carry out the purification of aluminum further or be applied to other field, as, in terms of the buildings such as pottery, being
The flyash of one great prospect becomes more meticulous comprehensive utilization industrialization method.
Detailed description of the invention
Below in conjunction with embodiment, the present invention is described in more detail, but protection scope of the present invention is not limited only to these in fact
Execute example.
Embodiment 1
1, the flyash (dioxide-containing silica is 49.2%) after 10g being ground activation adds in 30g glacial acetic acid, and mixing is all
Even, reaction 1 hour is stirred at room temperature, fully other impurity components except silicon in addition in flyash is removed, filtration, obtain acidleach
Slag.
2, acid leaching residue step 1 obtained adds in the sodium hydrate aqueous solution that mass fraction is 15%, mix homogeneously, its
Middle acid leaching residue and mass fraction be the mass ratio of the sodium hydrate aqueous solution of 15% be 1:4.5, at 100 DEG C, stirring reaction 2 is little
Time, by silicon therein with the form dissolution of sodium silicate, filter, and with the distilled water wash of sodium hydrate aqueous solution quality 6 times, obtain
To sodium silicate extracting solution.
3, by sodium silicate extracting solution under ultrasound condition with glacial acetic acid regulation pH to neutral, form substantial amounts of silica gel, sucking filtration,
Silica gel, through distilled water wash, lyophilization, obtains silicon dioxide, and its purity is 98.7%, and productivity is 51.9%.
Embodiment 2
1, the flyash (dioxide-containing silica is 47.6%) after 10g being ground activation adds in 20g glacial acetic acid, and mixing is all
Even, reaction 1 hour is stirred at room temperature, fully other impurity components except silicon in addition in flyash is removed, filtration, obtain acidleach
Slag.
2, acid leaching residue step 1 obtained adds in the sodium hydrate aqueous solution that mass fraction is 15%, mix homogeneously, its
Middle acid leaching residue and mass fraction be the mass ratio of the sodium hydrate aqueous solution of 15% be 1:4, stirring reaction 2 hours at 100 DEG C,
By silicon therein with the form dissolution of sodium silicate, filter, and with the distilled water wash of sodium hydrate aqueous solution quality 8 times, obtain
Sodium silicate extracting solution.
3, by sodium silicate extracting solution under ultrasound condition with glacial acetic acid regulation pH to neutral, form substantial amounts of silica gel, sucking filtration,
Silica gel, through distilled water wash, lyophilization, obtains silicon dioxide, and its purity is 98.0%, and productivity is 45.7%.
In order to determine the process conditions of the present invention, inventor has carried out substantial amounts of laboratory research test, various test feelings
Condition is as follows:
1, the selection of acidleach reagent
Respectively with concentrated hydrochloric acid, oxalic acid, citric acid, glacial acetic acid for acidleach reagent, contrast not carrying out acidleach simultaneously, other
Step is same as in Example 1, the impact of the examination hall difference acid silica purity on extracting, and the results are shown in Table 1.
The impact of the table 1 different acidleach reagent silica purity on extracting
From table 1, using concentrated hydrochloric acid room temperature acidleach flyash, the silica purity finally given is only
40.035%, and use oxalic acid, citric acid, glacial acetic acid room temperature acidleach flyash, the silica purity finally given can reach
More than 85%, therefore, the present invention selects oxalic acid, citric acid, glacial acetic acid as sour molten leaching reagent.
2, the mass ratio of flyash and organic acid is determined
Flyash and glacial acetic acid after grinding activation respectively is that 1:1,1:2,1:3,1:4 mix and carry out acid in mass ratio
Leaching, other steps are same as in Example 1, and purity and the productivity of the silica product finally given are shown in Table 2.
The mass ratio of table 2 flyash and organic acid is on silica product purity and the impact of productivity
When being 1:1～4 from the mass ratio of table 2, flyash and glacial acetic acid, the purity of gained silica product
Reach more than 96%, and the productivity of silicon dioxide is higher, when wherein the mass ratio of flyash and glacial acetic acid is 1:2～3, gained two
Silica product productivity can reach more than 48%.Therefore, the present invention selects flyash to be 1:1～4 with the mass ratio of glacial acetic acid, excellent
Selecting flyash is 1:2～3 with the mass ratio of glacial acetic acid.
3, acidleach temperature is determined
Flyash after grinding activation carries out acidleach for 1:3 in mass ratio at different temperatures with glacial acetic acid, other steps
The most same as in Example 1, purity and the productivity of the silica product finally given are shown in Table 3.
Table 3 acidleach temperature is on silica product purity and the impact of productivity
From table 3, although when acidleach temperature is 25～100 DEG C, the purity of the silica product finally given
Reaching more than 95%, but temperature raises, the productivity of silica product is relatively low.Therefore, the pure of silica product is considered
Degree, productivity and energy consumption, the present invention selects to carry out the acidleach of flyash under the conditions of 25 DEG C (room temperature).
4, acid leaching residue and NaOH aqueous solution mass ratio are determined
Respectively by sodium hydrate aqueous solution that acid leaching residue and mass fraction are 15% in mass ratio for 1:2,1:3,1:4,1:
4.5, to carry out alkali molten in 1:5,1:6 mixing, and other steps are same as in Example 1, the purity of the silica product finally given and
Productivity is shown in Table 4.
Table 4 acid leaching residue and NaOH aqueous solution mass ratio are on silica product purity and the impact of productivity
When being 1:2～6 from the mass ratio of the sodium hydrate aqueous solution that table 4, acid leaching residue and mass fraction are 15%, institute
The purity obtaining silica product all can reach more than 94%, and the productivity of silicon dioxide is higher, and wherein acid leaching residue divides with quality
Number is the mass ratio of the sodium hydrate aqueous solution of 15% when being 1:4～5, the purity of gained silica product all up to 98% with
On, and productivity is higher, up to about 50%.Therefore, the sodium hydroxide water that the present invention selects acid leaching residue and mass fraction to be 15%
The mass ratio of solution is 1:2～6, and preferred powder coal ash is 1:4～5 with the mass ratio of glacial acetic acid.
5, alkali solubility temperature is determined
After acid leaching residue is mixed for 1:4.5 in mass ratio with the sodium hydrate aqueous solution that mass fraction is 15%, in difference
At a temperature of to carry out alkali molten, other steps are same as in Example 1, and purity and the productivity of the silica product finally given are shown in Table 4.
Table 5 alkali solubility temperature is on silica product purity and the impact of productivity
From table 5, when alkali solubility temperature is 25～80 DEG C, the silica product finally given not only purity is low, and
Productivity is the lowest, and when alkali solubility temperature is 110～120 DEG C, although the silica product purity finally given can reach 91%
Above, but productivity is the lowest.Therefore, the present invention selects that to carry out alkali at 100 DEG C molten.
Claims (4)
1. one kind utilizes the method that flyash produces high-purity silicon dioxide, it is characterised in that it is made up of following step:
(1) flyash after grinding activation mixes for 1:1～4 in mass ratio with organic acid, room temperature reaction 0.5～2 hours, mistake
Filter, obtains acid leaching residue, and wherein said organic acid is any one in oxalic acid, citric acid, glacial acetic acid；
(2) acid leaching residue is mixed for 1:2～6 in mass ratio with the sodium hydrate aqueous solution that mass fraction is 10%～20%, 100
DEG C reaction 1～2 hour, filters, and with sodium hydrate aqueous solution quality 6～the distilled water wash of 8 times, obtains sodium silicate extraction
Liquid；
(3) by sodium silicate extracting solution under ultrasonic or stirring condition with organic acid for adjusting pH to neutral, sucking filtration, washing, freezing dry
Dry, obtain silicon dioxide.
The method utilizing flyash to produce high-purity silicon dioxide the most according to claim 1, it is characterised in that: in step
(1), in, the flyash after grinding activation mixes for 1:2～3 in mass ratio with organic acid, room temperature reaction 1 hour.
The method utilizing flyash to produce high-purity silicon dioxide the most according to claim 2, it is characterised in that: described
Organic acid is glacial acetic acid.
The method utilizing flyash to produce high-purity silicon dioxide the most according to claim 1, it is characterised in that: in step
(2) in, acid leaching residue is mixed for 1:4～5 in mass ratio with the sodium hydrate aqueous solution that mass fraction is 15%, 100 DEG C of reactions 2
Hour.
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Cited By (4)
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| CN107311181A (en) * | 2017-06-28 | 2017-11-03 | 昆明理工大学 | A kind of method that industrial silicon silicon ash prepares high-purity nm silicon grain |
| CN114988418A (en) * | 2021-03-02 | 2022-09-02 | 香港理工大学 | Method for preparing nano silicon dioxide by using waste concrete sand powder |
| CN115176813A (en) * | 2022-07-16 | 2022-10-14 | 杭州声能科技有限公司 | Preparation method of preparation for preventing and treating anthracnose of tea trees |
| WO2023226551A1 (en) * | 2022-05-24 | 2023-11-30 | 广东邦普循环科技有限公司 | Method for recoverying lithium and silicon from mvr system slag sample |
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| CN115176813A (en) * | 2022-07-16 | 2022-10-14 | 杭州声能科技有限公司 | Preparation method of preparation for preventing and treating anthracnose of tea trees |
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