阅读说明：本技术 一种高效溶解硅酸盐类物质并提取高纯氧化硅的方法 (Method for efficiently dissolving silicate substances and extracting high-purity silicon oxide ) 是由 史志铭 殷文迪 闫华 于 2021-03-01 设计创作，主要内容包括：本发明公开一种高效溶解硅酸盐类物质并提取高纯氧化硅的方法,将含硅无机固废或含硅天然沙土的粉体原料置于反应釜中,加入无机酸X、无机酸Y、无机酸Z、水溶性醇和水的混合酸作为浸取液,加热并在大于或等于0.1MPa的条件进行反应,反应结束后过滤得到酸性混合溶液和滤渣,将酸性混合溶液加热沸腾,用收集器收集含硅挥发组分,并使含硅挥发组分在收集器中分解、沉积；将收集器中分解、沉积出的无定型二氧化硅进行干燥,得到高纯氧化硅粉体；滤渣经过水洗、干燥后,得到二氧化硅。本发明不产生新的废渣,做到废渣不增量,从而使工业废弃物的减量化利用效果显著,减轻工业废渣对环境的污染,充分利用工业固废和闲置自然资源。(The invention discloses a method for efficiently dissolving silicate substances and extracting high-purity silicon oxide, which comprises the steps of placing a powder raw material containing silicon-containing inorganic solid wastes or silicon-containing natural sandy soil into a reaction kettle, adding a mixed acid of inorganic acid X, inorganic acid Y, inorganic acid Z, water-soluble alcohol and water as an extraction solution, heating and reacting under the condition of being more than or equal to 0.1MPa, filtering after the reaction is finished to obtain an acidic mixed solution and filter residues, heating and boiling the acidic mixed solution, collecting silicon-containing volatile components by a collector, and decomposing and depositing the silicon-containing volatile components in the collector; drying the amorphous silicon dioxide decomposed and deposited in the collector to obtain high-purity silicon oxide powder; and washing and drying filter residues to obtain silicon dioxide. The invention does not generate new waste residue and does not increase the waste residue, thereby having remarkable reduction and utilization effects of industrial waste, reducing the pollution of the industrial waste residue to the environment and fully utilizing industrial solid waste and idle natural resources.)

1. A method for efficiently dissolving silicate substances and extracting high-purity silicon oxide is characterized by comprising the following steps:

step A: placing a powder raw material containing silicon inorganic solid waste and/or silicon natural sandy soil into a reaction kettle, adding a mixed acid composed of inorganic acid X, inorganic acid Y, inorganic acid Z, water-soluble alcohol and water as an leaching solution, heating and reacting under the condition of more than or equal to 0.1MPa, and filtering after the reaction is finished to obtain an acidic mixed solution and filter residue;

and B: heating the acidic mixed solution obtained in the step A to boil, collecting silicon-containing volatile components by using a collector, and decomposing and depositing the silicon-containing volatile components in the collector;

and C: drying the amorphous silicon dioxide decomposed and deposited in the collector to obtain high-purity silicon oxide powder;

step D: and C, washing and drying the filter residue obtained in the step A to obtain silicon dioxide.

2. The method for efficiently dissolving silicate substances and extracting high-purity silicon oxide according to claim 1, wherein in step a: the silicon-containing inorganic solid waste is one or a combination of more of fly ash, coal gangue, red mud, metal tailings and non-metal tailings; the natural sand soil is one or a combination of several substances of desert sand, river sand and clay.

3. The method for efficiently dissolving silicate substances and extracting high-purity silicon oxide according to claim 1, wherein in step a: the inorganic acid X is hydrochloric acid, the inorganic acid Y is hydrofluoric acid, and the inorganic acid Z is sulfuric acid; the water-soluble alcohol is ethanol.

4. The method for efficiently dissolving silicate substances and extracting high-purity silicon oxide according to claim 1, wherein in step a: the mass ratio of the powder raw material, the inorganic acid X, the inorganic acid Y, the inorganic acid Z, the water-soluble alcohol and the water is (10-15): (25-35): (6-12): (5-10): (5-10): (15-35).

5. The method for efficiently dissolving silicate substances and extracting high-purity silicon oxide according to claim 3, wherein in the step A: the concentration of the used raw material hydrochloric acid is more than or equal to 36 wt%, the concentration of the used raw material hydrofluoric acid is more than or equal to 40 wt%, the concentration of the used raw material sulfuric acid is more than or equal to 95 wt%, and the used raw material ethanol is absolute ethanol, and the content of ethanol is more than or equal to 99 wt%.

6. The method for efficiently dissolving silicate substances and extracting high purity silica according to claims 1 to 5, wherein in the step A: the pressure in the reaction kettle is 0.1-0.3 MPa.

7. The method for efficiently dissolving silicate substances and extracting high-purity silicon oxide according to claim 6, wherein in step A: the reaction temperature in the reaction kettle is 90-140 ℃.

8. The method for efficiently dissolving silicate substances and extracting high purity silica according to claim 7, wherein in the step A: the reaction time is 0.5 to 2 hours.

9. The method for dissolving silicate substances and extracting high purity silica with high efficiency as claimed in claim 8, wherein the drying temperature in step C is 150 ℃.

10. The method for dissolving silicate substances and extracting high purity silica with high efficiency as claimed in claim 9, wherein the drying temperature in step D is 150 ℃.

Technical Field

The invention relates to the technical fields of resource recycling, chemical industry, materials, minerals, metallurgy and the like. In particular to a method for efficiently dissolving silicate substances containing low-grade silicon, efficiently dissolving silicate substances and extracting high-purity silicon oxide.

Background

High purity silica is an important industrial raw material for the manufacture of optical glass, optical fibers, functional materials, additives and important components of the electronics industry.

At present, a plurality of methods for synthesizing high-purity silicon oxide exist, wherein a gas phase method takes high-purity silicon tetrachloride, silicon tetrafluoride, methyl silicon trichloride and the like as raw materials, and carries out high-temperature hydrolysis in oxyhydrogen flame to generate silicon dioxide particles, and then processes such as quenching, aggregation, separation, deacidification and the like are carried out to obtain the high-purity silicon oxide; the hydration-gelation method for producing high purity silica is a method in which a reactant is decomposed with an acid or an alkali to form a silica sol, the pH value is adjusted with an alkali or an acid, and a silica gel is formed by filtration and purification; adding an acid solution into the water glass solution to obtain a reaction solution, submitting the reaction solution to pH 9-13 by using alkali to prepare silica sol, and adding the silica sol into the aqueous solution to form silica gel. The reaction solution can also be evaporated or concentrated to prepare silica sol; adding silicon powder into a sodium hydroxide solution at 65 ℃, adding ammonia water to adjust the pH value to 9-10, and preparing silica sol; mixing diluted water glass and dilute sulfuric acid to prepare silica gel; and drying the silica sol to obtain the purified silicon dioxide. In addition, after the micron-sized silicon dioxide, water, hydrochloric acid, fluoride and mineralizer mixed solution is reacted for a long time, cooling and filtering are carried out, filtrate is treated by lime water, then deionized water is used for washing until the filtrate is neutral, and drying is carried out, so that purified silicon dioxide is obtained. The above methods all use high-purity secondary raw materials and have high cost.

On the other hand, industrial wastes discharged from enterprises such as mines, electric power, metallurgy and the like occupy a large amount of land and cause serious environmental pollution, and a resource regeneration method which is efficient, high in added value, low in cost and free of secondary waste is urgently needed to be developed. These inorganic solid wastes and natural sandy soils contain a large amount of silica components such as fly ash, desert sand, coal gangue, red mud, metal or nonmetal tailings, etc. The extraction of high-purity compounds including silicon oxide from these substances is the development direction of comprehensive utilization of resources, and meets the requirements of constructing an environment-friendly and resource-saving society and protecting ecological environment.

One method for preparing silicon dioxide by using fly ash is to mix the fly ash with Na₂CO₃Uniformly mixing, finely grinding, reacting at 800-900 ℃, carrying out acid leaching on a reaction product by hydrochloric acid with the concentration of 3.14mol/L, filtering out impurities to convert the sol into gel, filtering again, and drying to obtain SiO with the purity of more than 98 percent₂. Calcining coal gangue powder at the temperature of 700-900 ℃, reacting with hydrochloric acid, and reacting filter residue with HF to generate SiF₄Hydrolyzing in ethanol solution to obtain precipitate, and washing to obtain silicon oxide powder (white carbon black). And adding sodium hydroxide solution into the filter residue for continuous reaction, and filtering, salting out, drying and the like to obtain the white carbon black. Calcining quartz ore at high temperature, water quenching, removing impurities, oven drying, grinding into fine powder, mixing with a certain amount of chlorinating agent (carbon tetrachloride, hydrogen chloride, chlorine, ammonium chloride, and trichloroethylene), and calcining at 900 deg.C for 60 min. The chloridized silicon oxide powder is reused by HCl and HNO₃And soaking the HF mixture for more than 40 hours, washing the chloridized silicon oxide powder to be neutral by using electrodialysis water or deionized water, and drying at the temperature of 900 ℃ by using 200-. Calcining the ferrosilicon-rich tailing powder dissolved and dealuminized by hydrochloric acid, reacting with excessive dilute hydrochloric acid, filtering, mixing filter residue with NaOH, calcining again, pouring into water, heating, stirring and filtering. Adding NaCl and hydrochloric acid into the filtrate, adjusting the pH value to 8-9, carrying out ultrasonic washing on the flocculent precipitate, and drying to obtain the white carbon black.

In addition, in order to obtain the highest leaching rate of alumina, the fly ash is leached by adopting a mixed solution of HCl with the concentration of 4.95mol/L and HF with the concentration of 4.93mol/L, the liquid-solid mass ratio is (4.5-5.0): 1, and the leaching is carried out for 3 hours at the temperature of 90-95 ℃, so that the effect is the best. It was found that HF promotes mullite leaching, and also causes leached Al³⁺Aluminum fluoride formation to reduce Al₂O₃Leaching while enlarging the SiO phase of the non-mullite phase₂Leaching to form SiF₆ ^2-The environment is burdened and the concentration of HF is therefore tightly controlled by the leaching process.

Therefore, the defects of great consumption of alkaline and acidic substances, difficult recovery, difficult water treatment, great amount of discharged secondary waste residues and new solid waste treatment problem are overcome in the process of extracting silicon oxide from fly ash, coal gangue and iron tailings leached by an acid method and an alkaline method.

Disclosure of Invention

Therefore, the technical problem to be solved by the invention is to provide a method for efficiently dissolving silicate substances and extracting high-purity silicon oxide, so as to solve the problems of huge consumption and difficult recovery of alkaline and acidic substances, difficult water treatment, high cost, huge amount of discharged secondary waste residues, new solid waste treatment and the like when extracting silicon oxide from substances with high silicon oxide content such as inorganic solid waste, natural sandy soil and the like, thereby fully utilizing industrial solid waste and natural idle resources, saving mineral resources and protecting ecological environment.

In order to solve the technical problems, the invention provides the following technical scheme:

a method for efficiently dissolving silicate substances and extracting high-purity silicon oxide comprises the following steps:

step A: placing a powder raw material containing silicon inorganic solid waste and/or silicon natural sandy soil into a reaction kettle, adding a mixed acid of inorganic acid X, inorganic acid Y, inorganic acid Z, water-soluble alcohol and water as an leaching solution, heating and reacting under the condition of more than or equal to 0.1MPa, and filtering after the reaction is finished to obtain an acidic mixed solution and filter residue;

and B: heating the acidic mixed solution obtained in the step A to boil, collecting silicon-containing volatile components by using a collector, and decomposing and depositing the silicon-containing volatile components in the collector;

and C: drying the amorphous silicon dioxide decomposed and deposited in the collector to obtain high-purity silicon oxide powder;

step D: and C, washing and drying the filter residue obtained in the step A to obtain silicon dioxide.

The method for efficiently dissolving silicate substances and extracting high-purity silicon oxide comprises the following steps: the silicon-containing inorganic solid waste is one or a combination of more of fly ash, coal gangue, red mud, metal tailings and non-metal tailings; the natural sand soil is one or a combination of several substances of desert sand, river sand and clay.

The method for efficiently dissolving silicate substances and extracting high-purity silicon oxide comprises the following steps: the inorganic acid X is hydrochloric acid, the inorganic acid Y is hydrofluoric acid, and the inorganic acid Z is sulfuric acid; the water-soluble alcohol is ethanol. Nitric acid is less acidic than sulfuric acid and hydrochloric acid, is unstable, is subject to visible light and thermal decomposition, and emits nitrogen dioxide during the reaction (N0)₂) Gas, reduce acidity, not easy to liquefy and recover, and cause environmental pollution.

The method for efficiently dissolving silicate substances and extracting high-purity silicon oxide comprises the following steps: the mass ratio of the powder raw material, the inorganic acid X, the inorganic acid Y, the inorganic acid Z, the water-soluble alcohol and the water is (10-15): (25-35): (6-12): (5-10): (5-10): (15-35).

The method for efficiently dissolving silicate substances and extracting high-purity silicon oxide comprises the following steps: the concentration of the used raw material hydrochloric acid is more than or equal to 36 wt%, the concentration of the used raw material hydrofluoric acid is more than or equal to 40 wt%, the concentration of the used raw material sulfuric acid is more than or equal to 95 wt%, and the used raw material ethanol is absolute ethanol, and the content of ethanol is more than or equal to 99 wt%.

The method for efficiently dissolving silicate substances and extracting high-purity silicon oxide comprises the following steps: the pressure in the reaction kettle is 0.1-0.3 MPa.

The method for efficiently dissolving silicate substances and extracting high-purity silicon oxide comprises the following steps: the reaction temperature is 90-140 ℃.

The method for efficiently dissolving silicate substances and extracting high-purity silicon oxide comprises the following steps: the reaction time is 0.5 to 2 hours.

The method for efficiently dissolving silicate substances and extracting high-purity silicon oxide comprises the following steps: the drying temperature in the step C is 150 ℃.

The method for efficiently dissolving silicate substances and extracting high-purity silicon oxide comprises the following steps: the drying temperature in the step D is 150 ℃.

The process principle of the method is as follows:

the industrial solid waste and natural sandy soil are mainly made of quartzThe composite material consists of (crystalline and amorphous), mullite, iron-titanium oxide, carbonate, magnesium, calcium, potassium, sodium and other alkali metal and alkaline earth metal ions, silicon, aluminum and other feldspar, kaolinite silicate or aluminosilicate with complex composition structures, and the components are very complex and unstable. The naturally formed quartz also has a small amount of ions such as magnesium, calcium, potassium, sodium, aluminum, iron, etc. dissolved therein. Hydrochloric acid is highly aggressive to iron titanium oxides, carbonates, and partial silicates and aluminosilicates, and can dissolve out these substances well, but the dissolution rate of these substances is not increased after adding hydrochloric acid in a very excessive amount, because hydrochloric acid is less aggressive to quartz and partial silicates such as mullite (aluminum silicate). The addition of hydrofluoric acid has great influence on the dissolution of the powder raw material; the addition of HF can destroy Al-Si bonds in mullite and other compounds, and has certain effect on destroying Si-Si bonds in quartz, so that mullite, quartz and the like can be effectively dissolved. However, excess hydrofluoric acid forms a large number of fluoride, fluoroaluminate and fluorosilicate ions which react with free metal ions to form complex multi-element complexes such as CaAlF₅And CaSiF₅And fluorides of Al, Na, Fe, Mg, etc., and fluorinated complexes obtained by complexing these fluorides with crystal water. They tend to form precipitates which result in a reduction in the silicon and metal ion content of the solution and a reduction in the purity of the acid leach residue. Therefore, the amount of hydrofluoric acid added is appropriate. In addition, a proper amount of sulfuric acid is added into the mixed acid solution to play a role in the complex action of the polybasic acid, so that the dissolution assisting effect can be obviously played, and the subsequent evaporation and deposition of the amorphous silicon oxide can be well promoted. The concentration of the solution also has a large influence on the dissolution effect and the formation of fluoride, silicon-rich compound precipitates.

The liquid in the reaction kettle can be adjusted by increasing the vapor pressure in order to obtain higher temperature. Stirring, heating and pressurizing also significantly improved the dissolution effect, but too high a temperature also easily caused more silicate precipitate to be generated. Compared with the prior art, the concentration of the hydrochloric acid is relatively high, the concentration of the hydrofluoric acid is relatively low, and particularly, the consumption of the hydrofluoric acid is related to the content of quartz. The good dissolving effect can be generated only under the conditions of reasonable proportion and concentration of the dosage of the hydrochloric acid, the hydrofluoric acid and the sulfuric acid and proper liquid temperature.

Those with lower boiling point, such as H, as the temperature of the acidic mixture increases and even after boiling₂O、HF、HCl、SiF₄、SiCl₄、H₂SiF₆And H₂SiO₃The components are volatilized or evaporated into a gas. The silicon-containing gas decomposes in the trap to deposit amorphous or crystalline silicon oxide. The amorphous silica is in gel or flocculent precipitate according to the difference of the pressure of the reaction kettle. The larger the air pressure of the reaction kettle is, the higher the speed of airflow entering the collector is, the easier dehydration and decomposition are carried out, and flocculent precipitates tend to be formed; conversely, a colloidal material is formed. The proper amount of ethanol is added, so that the volatilization and evaporation effects of the silicon-containing gas can be improved, and the dehydration and decomposition of the silicon-containing gas can be well promoted. Drying the gel or flocculent precipitate for further dehydration to obtain the silicon oxide powder with the purity higher than 99.8 percent. The hydrogen chloride and the hydrogen fluoride in the airflow are condensed into hydrochloric acid and hydrofluoric acid in the collector and return to the reaction kettle to continuously participate in the reaction.

The powder raw materials impregnated by the mixed solution still have undissolved residue, the silicon oxide purity of the powder raw materials after washing and drying is higher than 90.0%, and the specific components and the residue of the powder raw materials are related to the types of dissolved matters and the content of silicon oxide crystals in each powder raw material besides the mixed acid solution.

As the acid liquor has strong corrosivity, all surfaces of reaction kettles, pipelines, detection instruments and the like which are in contact with the acid liquor need to be subjected to corrosion prevention treatment.

The technical scheme of the invention achieves the following beneficial technical effects:

firstly, inorganic solid wastes such as fly ash, coal gangue, metal or nonmetal tailings, red mud and the like, and natural sandy soil such as desert sand, river sand, clay and the like are used as raw materials, and besides high-purity silicon oxide is prepared, silicon oxide with higher purity is further extracted from silicate substances containing low-grade silicon. The method obviously reduces the quantity of residual slag, has obvious reduction utilization effect on industrial wastes, and reduces the pollution of the industrial waste slag to the environment.

Secondly, industrial solid wastes and idle natural resources are fully utilized, mineral resources are saved, national soil resources are protected, and the ecological environment is protected.

And thirdly, no strong alkaline substance is added, so that no other new waste residue is generated, and the waste residue is not increased.

Fourthly, under the condition of reasonably regulating and controlling the proportion and the temperature of the mixed acid liquid, the dissolution rate of the raw materials is high, and the decrement effect is obvious.

Fifthly, the hydrochloric acid, the hydrofluoric acid and the sulfuric acid condensed in the collector return to the reaction kettle to continue to react without discharging, and the environment-friendly effect is good.

Sixthly, the purity of the amorphous silicon oxide powder deposited by evaporation and decomposition is high and reaches more than 99.8 percent; the content of silica in the undissolved residue is also higher than 90.0%, and the specific content and residual amount thereof are related to the species to be dissolved.

The reaction is carried out at 90-140 ℃, high-temperature calcination is not needed, and the energy-saving effect is good.

The tail liquid after extracting the silicon oxide can further separate aluminum, iron, magnesium, calcium, titanium and other ions by an electrochemical method to form hydroxides or oxides thereof, and the waste liquid is precipitated and purified to be a fluorine-containing solution, and can also be reused. Finally, the high-efficiency and high-added-value utilization of inorganic solid wastes and natural resources is realized.

Drawings

FIG. 1 amorphous silica deposited by evaporation according to example 1 of the present invention has morphology (a), composition (b) and phase composition (c);

FIG. 2 morphology (a), composition (b) and phase composition (c) of the undissolved residue of example 1 of the present invention;

note: since the chemical and phase compositions of the evaporated deposits and the undissolved residue are relatively close in each example, they are not shown in the following example so as not to be too repeated. It is only given when a particular phenomenon of chemical composition or phase composition occurs.

FIG. 3 is a graph (b) showing the morphology of silicon oxide (a) vapor-deposited and undissolved residue in example 2 of the present invention;

FIG. 4 morphology (a) and phase composition (b) of the vapor deposited silicon oxide and morphology (c) of the undissolved residue of the slag of example 3 of the present invention;

FIG. 5 shows the morphology of the silicon oxide (a) and the undissolved residue (b) which were vapor-deposited in example 5 of the present invention.

Detailed Description

Example 1

In this example, 200g of fly ash, hydrochloric acid, hydrofluoric acid and sulfuric acid: ethanol: the mass ratio of water is 10: 30: 12: 5: 10: 35, the concentration of the used raw material hydrochloric acid is more than or equal to 36 wt%, the concentration of the used raw material hydrofluoric acid is more than or equal to 40 wt%, the concentration of the used raw material sulfuric acid is more than or equal to 95 wt%, and the used raw material ethanol is absolute ethanol, and the content of ethanol is more than or equal to 99 wt%. Adding the above raw materials into a reaction kettle, maintaining the temperature at 100 deg.C, stirring under vapor pressure of 0.1MPa (equivalent to 1 atmosphere) for 1.5 hr, evaporating to obtain silica gel, drying at 150 deg.C to obtain 99.85% purity silica gel; the undissolved residue was washed with water and dried at 150 ℃ to give a residue of 46.3g, having a silica content of 91.16%.

FIG. 1 shows the morphology (a), composition (b) and phase composition (c) of the amorphous silica vapor-deposited in this example, and FIG. 2 shows the morphology (a), composition (b) and phase composition (c) of the undissolved residue. As can be seen from the figure, the evaporation deposit is of a colloidal structure, the main component is silicon oxide, but contains trace impurities, and the deposit is amorphous silicon oxide; the residue soaked in the acid solution is granular, mainly contains silicon oxide, but contains more impurity elements, and the granular residue is silicon oxide crystal.

Example 2

In the present example, 200g of desert sand fine powder is used, and the desert sand powder comprises hydrochloric acid, hydrofluoric acid and sulfuric acid: ethanol: the mass ratio of water is 15: 25: 9: 10: 5: 15, the concentration of the used raw material hydrochloric acid is more than or equal to 36 wt%, the concentration of the used raw material hydrofluoric acid is more than or equal to 40 wt%, the concentration of the used raw material sulfuric acid is more than or equal to 95 wt%, and the used raw material ethanol is absolute ethanol, and the content of ethanol is more than or equal to 99 wt%. Adding the above raw materials into a reaction kettle, maintaining the temperature at 90 deg.C, stirring under vapor pressure of 0.1MPa, reacting for 2 hr to obtain colloidal silica, drying at 150 deg.C to obtain 99.82% pure silica; the undissolved residue was washed with water and dried at 150 ℃ to give a residual amount of 128.5g, with a silica content of 92.63%. As shown in fig. 3, the undissolved portion is granular and substantially in the phase of the silicon oxide crystal.

Example 3

In the embodiment, 200g of iron tailing grinding powder is used, and the iron tailing powder comprises hydrochloric acid, hydrofluoric acid and sulfuric acid: ethanol: the mass ratio of water is 15: 35: 11: 7: 8: 20, the concentration of the used raw material hydrochloric acid is more than or equal to 36 wt%, the concentration of the used raw material hydrofluoric acid is more than or equal to 40 wt%, the concentration of the used raw material sulfuric acid is more than or equal to 95 wt%, and the used raw material ethanol is absolute ethanol, and the content of ethanol is more than or equal to 99 wt%. Adding the above raw materials into a reaction kettle, maintaining the temperature at 140 deg.C, stirring under vapor pressure of 0.3MPa, reacting for 0.5 hr to obtain silicon oxide flocculent, drying at 150 deg.C to obtain 99.86% pure silicon; the undissolved residue was washed with water and dried at 150 ℃ to give a residue of 86.5g, having a silica content of 92.87%. As shown in fig. 4, the deposit has a floc structure with crystalline phases therein, both of which are silicon oxide components.

Example 4

In the present example, 200g of red mud fine powder was used, and the weight ratio of red mud fine powder to hydrochloric acid to hydrofluoric acid to sulfuric acid: ethanol: the mass ratio of water is 10: 33: 6: 8: 6: 25, the concentration of the used raw material hydrochloric acid is more than or equal to 36 wt%, the concentration of the used raw material hydrofluoric acid is more than or equal to 40 wt%, the concentration of the used raw material sulfuric acid is more than or equal to 95 wt%, and the used raw material ethanol is absolute ethanol, and the content of ethanol is more than or equal to 99 wt%. Adding the above raw materials into a reaction kettle, maintaining the temperature at 100 deg.C, stirring under vapor pressure of 0.1MPa, reacting for 1.5 hr to obtain silicon oxide flocculent and colloidal, and drying at 150 deg.C to obtain silicon oxide with purity of 99.85%; the undissolved residue was washed with water and dried at 150 ℃ to give a residual amount of 75.2g, and the silica content was 91.9%.

Example 5

200g of coal gangue fine powder, hydrochloric acid, hydrofluoric acid, sulfuric acid and ethanol: the mass ratio of water is 12: 32: 10: 5: 5: 30, the concentration of the used raw material hydrochloric acid is more than or equal to 36 wt%, the concentration of the used raw material hydrofluoric acid is more than or equal to 40 wt%, the concentration of the used raw material sulfuric acid is more than or equal to 95 wt%, and the used raw material ethanol is absolute ethanol, and the content of ethanol is more than or equal to 99 wt%. Adding the above raw materials into a reaction kettle, maintaining the temperature at 120 deg.C, stirring under vapor pressure of 0.2MPa, reacting for 1 hr to obtain silicon oxide flocculent, drying at 150 deg.C to obtain a purity of 99.80%; the undissolved residue was washed with water and dried at 150 ℃ to give a residual amount of 103.6g, and the silica content was 92.3%. As shown in fig. 5, the deposit was mainly of a floc structure with a small amount of crystalline phase, which was determined to be the silicon oxide component.

It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications are possible which remain within the scope of the appended claims.