CN106044784B - A kind of method using flyash production high-purity silicon dioxide - Google Patents
A kind of method using flyash production high-purity silicon dioxide Download PDFInfo
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- CN106044784B CN106044784B CN201610599980.0A CN201610599980A CN106044784B CN 106044784 B CN106044784 B CN 106044784B CN 201610599980 A CN201610599980 A CN 201610599980A CN 106044784 B CN106044784 B CN 106044784B
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- flyash
- acid
- organic acid
- silicon dioxide
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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 kind of methods using flyash production high-purity silicon dioxide, this method first carries out flyash the molten activation of acid using organic acid, to remove the other impurities other than silicon, again with NaOH aqueous solution alkali solubles, silicon therein is dissolved out in the form of sodium metasilicate, organic acid to neutrality is finally added dropwise under ultrasound or stirring condition and generates silica gel, filters, be drying to obtain high-purity silicon dioxide.The present invention breaches traditional thinking for always using the molten flyash of inorganic acid acid, extracts silica with organic acid combination inorganic base and combining ultrasonic or the method for stirring, can effectively extract the silicon in flyash, reduces alumina silica ratio, realization sial separation.Operating process of the present invention is simple and easy to control, and investment is small, at low cost, and added value of product is high, and universality is high, is that the flyash of great prospect becomes more meticulous comprehensive utilization industrialization method.
Description
Technical field
Comprehensive resource the invention belongs to flyash utilizes technical field, and in particular to one kind is from flyash waste
The method of extraction of highly pure silica.
Background technology
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, it is not only a large amount of to take up an area, but also seriously pollute environment.Flyash is comprehensively utilized, a large amount of flyash can be both consumed, alleviate it
Pollution to environment is reduced and is taken up an area, and can be that construction industry produces lightweight, high-strength, heat preservation building material, replaces clay brick,
It can be used for producing concrete again simultaneously, build the road, backfill, achieve many things at one stroke.A large amount of flyash are collected, how to carry out effective profit
With becoming a critical problem.
The main component of flyash is Al2O3And SiO2, contain a small amount of Fe2O3, FeO, CaO, MgO and other inorganic oxides
Object, wherein SiO2It is main that vitreum amorphous phase is presented, account for about the 40%~80% of flyash total amount.Different regions and type
Flyash constituent difference it is big, thus different flyash has very big difference in using effect.But Al2O3Content
It is only second to SiO2, how directly to extract high-purity SiO2Effectively realize that sial separating difficulty is larger, process is complex, cost
It is higher, it is difficult to realize industrialization.
SiO is extracted from flyash2Method it is numerous：(1) acid system.Acid system is mainly using sulfuric acid or hydrochloric acid equal solvent, powder
Coal ash is molten through certain condition acid, obtains corresponding aluminum salt solution, is detached so as to fulfill sial, Al is obtained through subsequent processing2O3With
SiO2.Such as：Flyash is ground to certain particle size when Lee comes etc., then with acid soak, roasts at a certain temperature, make Al2O3's
Degree of extraction is increased to 93.2%.This method is that a kind of traditional flyash extracting method, technical maturity, but this method have cycle
Acid amount is big, equipment is perishable, acid vapor and generates the shortcomings of HF pollutes the environment, is harmful using auxiliary agent.Simple
Acid leaching is because of Al in flyash2O3And SiO2Mainly with Al2O3-SiO2Key-shaped formula exists, it is difficult to be either directly solubilised, recovery rate is low.
(2) alkaline process.1. sintering process：Make the cosolvents mixed calcining such as flyash and lime stone, soda lime or sodium carbonate in flyash
Mullite and quartz are separately converted to dicalcium silicate (2CaOSiO2) and C 12 A 7 (7Al2O312CaO), from dusting
Clinker afterwards is dissolved out using sodium carbonate, and the insoluble matters such as ten dicalcium of dicalcium silicate and aluminic acid are stayed in filter residue, and calcium aluminate filtrate passes through
Decompose sodium metaaluminate it is achieved thereby that sial detach.2. alkali solution technique：Flyash is directly mixed with lye, under certain condition
Dissolution filtering, obtained filtrate containing sodium metasilicate get SiO through carbon2, filter residue can be extracted further using alkali solution technique or sintering process
Al2O3, detached so as to fulfill sial.Example：Wu Guodong etc. is studied flyash dissolution sial using low temperature alkali solution technique, as a result
It was found that 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
Experiment effect is best when going out the time for 4~6h, at this time SiO2Dissolution rate is 29.33%, Al2O3Dissolution rate is 1.26%, dissolves out ratio
Up to 23.63, Al in flyash can be tentatively realized2O3And SiO2Step by step arithmetic.This method is easy to operate, and reagent is single, cost
Low, but can generate solid calcium-silicon slag using limestone sintering process, calcium-silicon slag processing is difficult, utility value is low, can produce cement but
Cement sale radius is limited, market can not digest completely, it will generates secondary accumulation pollution, can not further extract SiO2.This
Method greatly reduces the energy consumption of sintering process compared with limestone sintering process, but needs to be additionally provided carbon dioxide, and filter residue
It is low as portland cement raw material utility value, it is difficult to therefrom extract SiO2.(3) acid and alkali combination method.1. first alkali after acid：Through certain
Pretreated flyash, acid adding leaching filtering, filtrate containing aluminium obtain siliceous filter through handling to obtain aluminium oxide, the further alkali soluble of filter residue
Liquid, it is treated to obtain SiO2.For example, Wu Yan etc. has detached the Al in flyash using alkali technique after first acid2O3And SiO2, system
It is standby gone out high-purity Al2O3With ultra-fine SiO2.In this producing process, there is deep-etching using strong oxidizing property in the dissolution of first step acid
Property high-concentration sulfuric acid as the molten reagent of acid, and heat under 250~300 DEG C of hot conditions that acid is molten, and an obtained blob of slag is at 300 DEG C
Left and right high-temperature calcination；The leaching of second step concentrated base need to carry out, and then obtain sodium silicate solution at 100 DEG C of temperature higher above, so
Carrying out carbon point in sodium metasilicate extracting solution afterwards (need to introduce sodium carbonate or sodium bicarbonate and acid reaction generates carbon dioxide to displace
SiO2) obtain SiO2.Finally the sodium carbonate liquor obtained after carbon point need to be carried out with calcium oxide causticization processing generation NaOH solution with
CaCO3It precipitates, concentrated base extract technology, the CaCO of generation is returned after the NaOH solution evaporation and concentration of generation3Precipitation is by Roasting Decomposition
Afterwards, the CO of generation2Gas returns to carbonation decompsition process, and CaO returns to causticization process.This technique realizes feedstock circulation utilization, 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 very high, cumbersome, and condition is harsh.2. acid after first alkali：Through certain pretreated flyash, alkali leaching is added to filter
Filtrate containing aluminium and silicon, the filtrate and white residue that acid adding filters containing aluminium, filtrate is through handling to obtain Al2O3, filter residue through processing obtain
SiO2。
Invention content
The technical problems to be solved by the invention are to provide one kind and are combined by organic acid and inorganic base, in temperate condition
Under, high-purity SiO can be extracted from flyash without techniques such as high-temperature calcination, carbon point and causticization processing2Method.
Technical solution is made of following step used by solving above-mentioned technical problem：
1st, will grind the flyash after activating and organic acid is 1 in mass ratio:1~4 mixing, room temperature reaction 0.5~2 are small
When, filtering obtains acid leaching residue, wherein the organic acid is any one in oxalic acid, citric acid, glacial acetic acid.
2nd, it is 1 in mass ratio by the sodium hydrate aqueous solution that acid leaching residue and mass fraction are 10%~20%:2~6 mixing,
100 DEG C are reacted 1~2 hour, filtering, and with the distillation water washing of 6~8 times of sodium hydrate aqueous solution quality, are obtained sodium metasilicate and are carried
Take liquid.
3rd, sodium metasilicate extracting solution washing, is freezed under ultrasound or stirring condition with organic acid for adjusting pH to neutrality, suction filtration
It is dry, obtain silica.
In above-mentioned steps 1, will preferably grind the flyash after activating with organic acid is 1 in mass ratio:2~3 mixing, room temperature
Reaction 1 hour, the preferred glacial acetic acid of the organic acid.
It is 1 in mass ratio preferably by the sodium hydrate aqueous solution that acid leaching residue and mass fraction are 15% in above-mentioned steps 2:4
~5 mixing, 100 DEG C are reacted 2 hours.
The present invention has continued the thinking of previous traditional acid and alkali combination method extraction silica, but breaches and uses nothing always
Machine strong acid carrys out the thinking of acidleach flyash under the high temperature conditions, using common and cost is relatively low, organic acid of safe and non-toxic come
Substitution inorganic acid reaches same purpose, in conjunction with inorganic base NaOH and combines the conditions such as ultrasonic wave added and extracts high-purity
Silica product, started extraction silica new thought, compared with prior art, the present invention have it is following excellent
Point：
1st, the present invention uses the higher mild moderate strength organic acid of etch factor very lower security coefficient, and acidleach condition is simple
It is mild only to carry out at normal temperatures；The concentration of sodium hydroxide used in alkali soluble is relatively low, and only needs 100 DEG C of heating；It obtains
Sodium metasilicate extracting solution generation silica gel used in acid solution it is consistent with sour molten step, the material for making input is as few as possible, and sodium metasilicate
Extracting solution does not need to carry out carbon point except complex processes such as iron, it is not required that carries out the causticization processing after carbon point, breaches and carry in the past
Carbon grades complex process during taking, and does not need to introduce additional more material and equipment, whole process also simpler easy behaviour
Make.
2nd, the silica product purity that extracts of the present invention is very high, and yield is also higher, and product quality is very light, granularity compared with
Very thin for uniform and particle, entire technical process is simple, temperature-controllable, and investment is small, at low cost, does not discharge any poisonous and hazardous
Substance, and waste liquid discharging amount is small.
3rd, the present invention adequately achieves the comprehensive resources utilizationization of flyash, greatly reduces silica alumina ratio, realizes silicon
Aluminium efficiently separates, and improves value-added content of product, and the adsorption bleaching applied to dyestuff that gained silica can be fabulous remains
Remaining high residue of aluminum can also further carry out the purification of aluminium or applied to other field, such as in terms of ceramics building, being
The flyash of one great prospect, which becomes more meticulous, comprehensively utilizes industrialization method.
Specific embodiment
With reference to embodiment, the present invention is described in more detail, but protection scope of the present invention is not limited only to these realities
Apply example.
Embodiment 1
1st, the flyash (dioxide-containing silica 49.2%) after 10g grinding activation is added in 30g glacial acetic acid, mixing is equal
It is even, reaction 1 hour is stirred at room temperature, fully removes the other impurities ingredient in flyash in addition to silicon, filtering obtains acidleach
Slag.
2nd, the acid leaching residue for obtaining step 1 is added in the sodium hydrate aqueous solution that mass fraction is 15%, is uniformly mixed,
The mass ratio of sodium hydrate aqueous solution that middle acid leaching residue is 15% with mass fraction is 1:4.5, it is small at 100 DEG C to be stirred to react 2
When, silicon therein in the form of sodium metasilicate is dissolved out, is filtered, and with the distillation water washing of 6 times of sodium hydrate aqueous solution quality, is obtained
To sodium metasilicate extracting solution.
3rd, sodium metasilicate extracting solution is adjusted into pH to neutrality with glacial acetic acid under ultrasound condition, forms a large amount of silica gel, filter,
Silica gel obtains silica, purity 98.7%, yield 51.9% through distilling water washing, freeze-drying.
Embodiment 2
1st, the flyash (dioxide-containing silica 47.6%) after 10g grinding activation is added in 20g glacial acetic acid, mixing is equal
It is even, reaction 1 hour is stirred at room temperature, fully removes the other impurities ingredient in flyash in addition to silicon, filtering obtains acidleach
Slag.
2nd, the acid leaching residue for obtaining step 1 is added in the sodium hydrate aqueous solution that mass fraction is 15%, is uniformly mixed,
The mass ratio of sodium hydrate aqueous solution that middle acid leaching residue is 15% with mass fraction is 1:4, it is stirred to react at 100 DEG C 2 hours,
Silicon therein in the form of sodium metasilicate is dissolved out, is filtered, and with the distillation water washing of 8 times of sodium hydrate aqueous solution quality, is obtained
Sodium metasilicate extracting solution.
3rd, sodium metasilicate extracting solution is adjusted into pH to neutrality with glacial acetic acid under ultrasound condition, forms a large amount of silica gel, filter,
Silica gel obtains silica, purity 98.0%, yield 45.7% through distilling water washing, freeze-drying.
In order to determine the process conditions of the present invention, inventor has carried out a large amount of laboratory research experiment, various experiment feelings
Condition is as follows：
1st, the selection of acidleach reagent
Respectively using concentrated hydrochloric acid, oxalic acid, citric acid, glacial acetic acid as acidleach reagent, while to be compared without acidleach, other
Step is same as Example 1, and influence of the different acid in examination hall to the silica purity of extraction the results are shown in Table 1.
Influence of the different acidleach reagents of table 1 to the silica purity of extraction
By table 1 as it can be seen that using concentrated hydrochloric acid room temperature acidleach flyash, the silica purity finally obtained is only
40.035%, and oxalic acid, citric acid, glacial acetic acid room temperature acidleach flyash are used, the silica purity finally obtained can reach
More than 85%, therefore, the present invention selects oxalic acid, citric acid, glacial acetic acid as the molten leaching reagent of acid.
2nd, the mass ratio of flyash and organic acid is determined
It is 1 in mass ratio that the flyash after activating will be ground respectively with glacial acetic acid:1、1:2、1:3、1:4 mixing carry out acid
Leaching, other steps are same as Example 1, and the purity and yield of the silica product finally obtained are shown in Table 2.
Influence of the mass ratio of 2 flyash of table and organic acid to silica product purity and yield
As can be seen from Table 2, the mass ratio of flyash and glacial acetic acid is 1:When 1~4, the purity of gained silica product
Reach more than 96%, and the yield of silica is higher, wherein the mass ratio of flyash and glacial acetic acid is 1:When 2~3, gained two
Silica product yield can reach more than 48%.Therefore, it is 1 that the present invention, which selects the mass ratio of flyash and glacial acetic acid,:1~4, it is excellent
It is 1 to select the mass ratio of flyash and glacial acetic acid:2~3.
3rd, acidleach temperature is determined
It is 1 in mass ratio that the flyash after activating, which will be ground, with glacial acetic acid:3 carry out acidleach at different temperatures, other steps
Rapid same as Example 1, the purity and yield of the silica product finally obtained are shown in Table 3.
Influence of the 3 acidleach temperature of table to silica product purity and yield
By table 3 as it can be seen that when although acidleach temperature is 25~100 DEG C, the purity of the silica product finally obtained
Reach more than 95%, but temperature increases, the yield of silica product is relatively low.Therefore, consider the pure of silica product
Degree, yield and energy consumption, present invention selection carry out the acidleach of flyash under the conditions of 25 DEG C (room temperature).
4th, acid leaching residue and NaOH aqueous solution mass ratioes are determined
It is respectively 1 in mass ratio by the sodium hydrate aqueous solution that acid leaching residue and mass fraction are 15%:2、1:3、1:4、1:
4.5、1:5、1:6 mixing carry out alkali solubles, other steps are same as Example 1, the purity of the silica product finally obtained and
Yield is shown in Table 4.
4 acid leaching residue of table and influence of the NaOH aqueous solutions mass ratio to silica product purity and yield
By table 4 as it can be seen that the mass ratio of sodium hydrate aqueous solution that acid leaching residue is 15% with mass fraction is 1:When 2~6, institute
The purity for obtaining silica product can reach more than 94%, and the yield of silica is higher, wherein acid leaching residue and quality point
Number is 1 for the mass ratio of 15% sodium hydrate aqueous solution:When 4~5, the purity of gained silica product up to 98% with
On, and yield is higher, up to 50% or so.Therefore, the present invention select acid leaching residue and mass fraction for 15% sodium hydroxide water
The mass ratio of solution is 1:2~6, the preferably mass ratio of flyash and glacial acetic acid is 1:4~5.
5th, alkali soluble temperature is determined
It is 1 in mass ratio by the sodium hydrate aqueous solution that acid leaching residue and mass fraction are 15%:After 4.5 mixing, in difference
At a temperature of carry out alkali soluble, other steps are same as Example 1, and the purity and yield of the silica product finally obtained are shown in Table 4.
Influence of the 5 alkali soluble temperature of table to silica product purity and yield
By table 5 as it can be seen that when alkali soluble temperature is 25~80 DEG C, not only purity is low for the silica product finally obtained, and
Yield is also very low, and alkali soluble temperature be 110~120 DEG C when, although the silica product purity finally obtained can reach 91%
More than, but yield is very low.Therefore, present invention selection carries out alkali soluble at 100 DEG C.
Claims (4)
- A kind of 1. method using flyash production high-purity silicon dioxide, it is characterised in that it is made of following step：(1) will grind the flyash after activating with organic acid is 1 in mass ratio:1~4 mixing, reacts at room temperature 0.5~2 hour, mistake Filter, obtains acid leaching residue, wherein the organic acid is any one in oxalic acid, citric acid, glacial acetic acid；(2) it is 1 in mass ratio by the sodium hydrate aqueous solution that acid leaching residue and mass fraction are 10%~20%:2~6 mixing, 100 DEG C reaction 1~2 hour, filtering, and with the distillation water washing of 6~8 times of sodium hydrate aqueous solution quality, obtain sodium metasilicate and extract Liquid；(3) sodium metasilicate extracting solution is done under ultrasound or stirring condition with organic acid for adjusting pH to neutrality, suction filtration, washing, freezing It is dry, obtain silica.
- 2. the method according to claim 1 using flyash production high-purity silicon dioxide, it is characterised in that：In step (1) in, will grind the flyash after activating with organic acid is 1 in mass ratio:2~3 mixing, react at room temperature 1 hour.
- 3. the method according to claim 2 using flyash production high-purity silicon dioxide, it is characterised in that：Described Organic acid is glacial acetic acid.
- 4. the method according to claim 1 using flyash production high-purity silicon dioxide, it is characterised in that：In step (2) it is 1 in mass ratio by the sodium hydrate aqueous solution that acid leaching residue and mass fraction are 15% in:4~5 mixing, 100 DEG C of reactions 2 Hour.
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| CN107311181B (en) * | 2017-06-28 | 2020-02-07 | 昆明理工大学 | Method for preparing high-purity nano silicon particles from industrial silicon ash |
| 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 |
| CN115072746A (en) * | 2022-05-24 | 2022-09-20 | 广东邦普循环科技有限公司 | Method for recycling lithium and silicon from slag sample of MVR system |
| 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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| KR100909997B1 (en) * | 2009-04-07 | 2009-07-29 | (주)삼원건설시스템 | Composition of acid-resistant repair mortar and acid-resistant surface coating, and repair method of section and surface of concrete using its |
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