CN1321721C - Method of dealing with gases containing boric acid - Google Patents

Abstract

The present invention relates to a treatment method for safely and effectively removing gas containing boric acid components from gas containing boric acid components by an existing bag filter or an electric dust remover. The treatment method is a gas treatment method which removes boric acid components from gas by adding solid alkali metallic carbonate in gas containing boric acid components with the concentration of more than 15 mg/m converted into B2O3 under a standard state.

Description

Treatment method of gas containing boric acid components

technical field

The present invention relates to a method for efficiently removing boric acid components from gases containing boric acid components.

Background technique

In the past, borax or boric acid was used as a raw material in the manufacture of borosilicate glass, glazes, and enamelled ironware. Therefore, the exhaust gas of industrial furnaces or heating furnaces contains boric acid components, which has become a cause of air pollution. In addition, in coal-fired power plants, etc., raw coal contains boric acid components, so the exhaust gas after combustion contains boric acid components, which is also a cause of air pollution. It is well known that the boric acid content discharged into the surrounding environment is another cause of water or soil pollution.

For example, in the high-temperature melting process using borax, boric acid is mixed into the exhaust gas, and this boric acid has a molecular structure represented by molecular formulas such as H ₃ BO ₃ , HBO ₂ , B ₂ O ₃ according to its temperature and water vapor partial pressure .

In the past, there was no effective method to remove these boric acid components, although the wet scrubbing method using alkaline substances such as sodium hydroxide was used; the potassium hydroxide powder was spread in the flue, and then the hydrogen was oxidized with a bag filter or an electric precipitator A method of removing potassium powder together with acidic components; and a method of finely filtering the gas containing boric acid particles through a filter, etc. However, the concentration of the boric acid component after the removal treatment cannot be sufficiently reduced, and therefore it is not a very effective removal method.

For example, when using wet scrubbing, etc., if the circulation of alkali solution is increased to improve the removal efficiency of boric acid components, the exhaust gas temperature will drop. When the exhaust gas temperature is lower than the acid dew point, the _SO3 gas in the gas or Sulfuric acid gas (hereinafter referred to as SO ₃ component) becomes sulfuric acid mist, which may cause corrosion. In addition, if the alkali concentration of the circulating liquid is increased, the concentration of sodium carbonate, sodium sulfate, and sodium borate in the reaction product will increase, resulting in crystallization and clogging of the circulation pipeline. On the other hand, in the method of injecting potassium hydroxide fine powder into the gas to be treated, since the reactivity of potassium hydroxide and boric acid components is poor, it is necessary to use a large amount of potassium hydroxide fine powder, and it is also necessary to use large-scale equipment and must be recycled. The disposal of reactants and unreacted solid waste, thus causing the problem of cost increase. In addition, in the method of finely filtering the gas, in order to fully remove the boric acid component, it is necessary to cool and precipitate the boric acid component after gasification. Since the temperature must be below the dew point of sulfuric acid and hydrochloric acid, special and very expensive bags must be installed. filter.

Contents of the invention

The present invention provides a gas treatment method for removing boric acid components contained in gas. In this method, a gas containing a boric acid component having a concentration of 15 mg/m3 or ^more in _terms of _B2O3 in a standard state is mixed with one or more solid alkali metals selected from alkali metal carbonates and alkali metal bicarbonates. The carbonates are contacted to remove the boric acid component in the aforementioned gas.

The present invention can effectively remove the boric acid component from the gas, which is difficult to achieve with the previous treatment methods. In addition, dry exhaust gas treatment equipment such as powder dispersing devices and bag filters used in conventional treatment methods are also applicable to the present invention.

The present invention also provides a method for further improving the operation of the denitrification device, and a method for effectively utilizing the boron component in the conventionally discarded exhaust gas.

Description of drawings

Fig. 1 is a flowchart of a method for treating gas containing boric acid components discharged from a glass melting furnace.

Explanation of symbols:

1: Glass melting furnace containing boric acid, 2: Stabilizer, 3: Bag filter, 4: Exhaust fan, 5: Exhaust denitrification device, 6: Chimney, 7: Alkaline water, 8: Bicarbonate in Example 1 Sodium powder, potassium hydroxide powder in example 2, 9: collected dust, 10: first flue, 11: second flue, 12: third flue, 13: fourth flue, 14: first flue 5 flue.

Detailed ways

The gas containing boric acid components (hereinafter referred to as gas to be processed) in the present invention includes gas discharged from the heating process or melting process of glass or other inorganic materials containing boric acid components. Specifically, borosilicate heat-resistant glass, glass curtain wall insulation material, glass fiber, glass for liquid crystal display, glass frit glaze, ferroboron alloy, porcelain, etc., which contain boric acid components gas. The boric acid component described in this specification refers to H ₃ BO ₃ or its dehydrated product, and is mainly represented by H ₃ BO ₃ , HBO ₂ , or B ₂ O ₃ . The concentration of the boric acid component is calculated in terms of B ₂ O ₃ . The method of the present invention has the effect of removing all acid gases, and when the treated gas containing boric acid components also includes acid gases such as boron trifluoride (BF ₃ ) or boron trichloride (BCl ₃ ), they can be removed simultaneously. remove. Other acid gases that may be removed include HCl, _SO2 , _SO3 , _H2SO4 , HF, HBr, _HI , and the like.

The amount of boric acid contained in the gas to be treated in the present invention is more than 15 mg/m ³ in terms of B ₂ O ₃ under standard conditions. However, the present invention is ^still effective even if the amount of boric acid contained in the gas to be processed is 15 mg/ _m3 or less in terms of _B2O3 .

In the present invention, solid alkali metal carbonates are dispersed and uniformly dispersed in the gas to be treated, contacted with the boric acid component in the gaseous state, and removed after neutralization. When other acids (such as sulfuric acid) other than boric acid are contained in the gas to be processed, it is advisable that the temperature of the gas to be processed is above its dew point. As another example, solid alkali metal carbonates may be formed into pellets, spheres or lumps, and the molded product may be used to form a filled layer. When dealing with a large amount of high-temperature exhaust gas, it is appropriate to scatter solid alkali metal carbonate powder in the exhaust flue.

In the present invention, the solid alkali metal carbonates are not particularly limited as long as the boric acid component can be removed after the neutralization reaction. When using solid alkali metal carbonates, it is preferable to use anhydrous salts from the viewpoint of a large gas treatment amount per unit mass, but of course, hydrous salts can also be used in the same way.

As an alkali metal bicarbonate, because it can be purchased in large quantities and cheaply, it is non-hygroscopic, easy to granulate, easy to store, and easy to obtain a fine particle size after further pulverization, so it can form porous ( ^1m2 /g) after sintering. Above) sodium carbonate, wherein particularly preferred is sodium bicarbonate. Potassium bicarbonate can be used if sodium is not suitable for gas refining etc.

In addition, sodium carbonate, potassium carbonate, etc. can be used as alkali metal carbonates, and sodium carbonate is preferably used because it can be purchased in large quantities and at low cost. Potassium carbonate is preferably used where sodium is not suitable. As sodium carbonate, porous sodium carbonate called light ash is particularly suitable because it has a large specific surface area and is easily micronized.

When porous sodium carbonate is used, light ash having a specific surface area of 1 m ² /g or more is preferable. In addition to porous, the specific surface area increases when the average particle size is small, and even the non-porous sodium carbonate called heavy ash can be micronized to make the specific surface area more than 1m ² /g, thereby improving its reactivity . From the perspective of easy crushing and porosity, light ash has the advantages of larger specific surface area and better performance. On the other hand, heavy ash has the advantages of being generally readily available, small in volume, and low in shipping costs. The specific surface area is a value obtained by the BET method.

These solid alkali metal carbonates may be used alone or in combination without any difference. In addition, as described below, natural or synthetic products can be used as anti-caking agents added in order to improve the fluidity of solid alkali metal carbonates and their powders and to prevent caking. When sodium carbonate or potassium carbonate is used as solid alkali metal carbonates, they need to be stored in long-term packaging due to their strong hygroscopicity, so it is advisable to use packaging materials after moisture-proof treatment for packaging. As a specific packaging material, it is preferable to use a material whose moisture permeability at 40°C according to JIS-Z0208 is 5 g/m ² ·day or less. The moisture permeability refers to the packaging material as an interface, one side of the interface is air with a relative humidity of 90%, and the other side of the interface is calcium chloride kept in a dry state, and then the mass of water vapor passing through the interface after 24 hours is converted into The value of packaging material per unit area. It is particularly desirable that the moisture permeability at 40°C is 1 g/m ² ·day or less.

The volume average particle diameter of the solid alkali metal carbonates used is preferably 1 to 100 µm. In this way, the solid alkali metal carbonate particles have a large specific surface area, have high reactivity with boric acid components, and can effectively remove boric acid components. In addition, since the number of particles per unit mass is large, the number density in the gas to be processed increases, and the distance for the boric acid component to diffuse into the particles in the flue can be shortened, thereby improving reactivity. From the viewpoint of the removal effect of the boric acid component, the lower limit of the average particle size is not particularly specified, but if the average particle size is less than 1 μm, the pulverization operation will increase the cost of industrial production. If the average particle size exceeds 0.1 mm, it cannot react sufficiently when dispersed in the flue, and sinks directly to the bottom of the flue, which is not preferable. Therefore, the average particle diameter is preferably at most 50 μm, more preferably at most 30 μm, particularly preferably at most 20 μm.

In the present invention, the average particle size refers to measuring with a laser diffraction and scattering particle size distribution measuring device. The total volume is regarded as 100%, and the cumulative curve is obtained. When the cumulative volume reaches 50%, the particle size is called the average particle size. Diameter (μm).

The amount of solid alkali metal carbonates dispersed in the gas to be treated is 0.5 to 50 times the mole of the boric acid component in the gas converted to 1 _mole of _B2O3 (for example, sodium bicarbonate is expressed in terms of _NaHCO3 The number of moles of sodium carbonate expressed in terms of _Na2CO3 ) is appropriate _. If the dispersion amount is less than 0.5 times mole, the equivalent weight is not enough when reacting with the boric acid component, so that the reduction of the boric acid component is not sufficient, and the effect is not ideal; if the addition amount exceeds 50 times the mole, the cost is too high and is not ideal. In addition, in many cases, the exhaust gas contains acid gases such as sulfur oxides, hydrogen chloride, and hydrogen fluoride, and the solid alkali metal carbonates of the present invention have a high reaction rate with these acid gases, so they are consumed by the reaction. Therefore, in order to remove other various acid gases, it is advisable to use it in combination with the spraying of calcium hydroxide powder or the wet spraying of sodium hydroxide, so that the amount of spraying of the above-mentioned solid alkali metal carbonates can be reduced.

The method of distributing solid alkali metal carbonates into the gas to be treated includes the method of injecting into the flue by air delivery, the method of injecting the powder while sucking the compressed gas using a jet pump, and crushing immediately before use as described later, That is, the method of directly injecting from the discharge port of the pulverizer, etc.

In order to remove solid alkali metal carbonates dispersed in the treated gas, equipment such as electrostatic precipitators, bag filters, Venturi scrubbers, and packed towers can be used.

Utilize the method of _the present invention, make the concentration of the boric acid component in the processed gas converted into _B2O3 under the standard state can be reduced to below 60 mass % before processing, more preferably below 50 mass % before processing .

When large particles of solid alkali metal carbonates need to be pulverized before use, the method of adjusting the average particle size includes the method of pulverizing immediately before spreading to the flue (hereinafter referred to as the on-site pulverization method). A method in which the particles are finely pulverized and stored in a storage tank for later use (hereinafter referred to as the pre-pulverization method).

For the on-site pulverization method, the large particles are usually stored in the storage tank, and immediately before use, the pulverizer is supplied to the pulverizer for pulverization, and then directly dispersed in the flue, etc. The pulverizer used includes an impact pulverizer such as a pinhole grinder and pulverizer, or an airflow pulverizer such as a jet attritor. In order to achieve high-efficiency pulverization with an average particle size below 20 μm, it is advisable to use a pulverizer with a classification device. In addition, in order to improve the reactivity with the boric acid component, it is advisable to inject the solid alkali metal carbonate particles into the gas after crushing and classifying, and the cumulative particle size distribution under the sieve reaches 90% of the particle size below 60 μm. It is better if 90% of the particles have a particle size below 30 μm. Described classifier can use wind type classifier. Described pulverizer can use the dry-type impact-type fine pulverizer (trade name: ACM pulverizer) manufactured by Hosoka Homicron Co., Ltd., etc., which are equipped with dry-type air classification device inside.

For the pre-crushing method, the large particles are crushed into the required average particle size in advance and stored in a storage tank, and then dispersed in the flue or the like when used. As the pulverizer to be used, in addition to the above, a media type pulverizer such as a ball mill, a vibrating mill, a media agitation mill, or the like can also be used. In addition, it is also possible to use a method of finely pulverizing with a wet pulverizer and then drying.

In general, the on-site crushing method is suitable for occasions where special crushing equipment can be installed with a large amount of use; the pre-grinding method is suitable for the removal of boric acid components with a small amount of use or micro-grinding of about 10 μm after crushing in other places after concentration occasion.

The average particle size of the raw material to be pulverized is preferably 50-500 μm. If the average particle size is less than 50 μm, it will be difficult to stably supply it to the pulverizer, so it is not ideal; The machine equipment is huge, so it is not ideal.

In the pre-crushing method, the pulverized product aggregates during storage, so that it is difficult to quantitatively supply the pulverized product to a flue or the like at the time of use. Therefore, the material to be pulverized can be pulverized together with the anti-caking agent, or the anti-caking agent can be added after pulverization.

The anti-caking agent is interposed between the solid alkali metal carbonate particles to prevent the solid alkali metal carbonate particles from contacting each other, thereby preventing the solid alkali metal carbonate particles from agglomerating. Since the addition of the anti-caking agent can prevent the agglomeration of solid alkali metal carbonates during pulverization or the solid alkali metal carbonate fine powders during dispersion, it is also suitable for on-site pulverization.

The average particle size of the anti-caking agent is preferably 0.005-5 μm. If the average particle diameter of the anti-blocking agent is 0.005 μm or less, the anti-blocking effect will be poor, and it will not be commercially available as an inexpensive industrial product, which is not preferable. If the average particle diameter exceeds 5 μm, then when the raw material is fine particles, even if the anti-caking agent is added in the same mass ratio, since the number of the anti-caking agent is small, the effect of preventing caking is poor, so it is not ideal. The average particle size of the anti-caking agent is more preferably 0.005-2 μm, and most preferably 0.005-0.1 μm.

The anti-caking agent can use well-known additives for the purpose of preventing powder caking or improving rolling properties, including magnesium carbonate, silicon dioxide, aluminum oxide, aluminosilicate, zeolite, talc, stearic acid Salt, etc., can also be used in combination with the above-mentioned several substances. Among them, silicon dioxide is preferred, and among silicon dioxide, wet silicon dioxide, which has a small average particle size, excellent effects of preventing caking and improving fluidity, and is easily available, is particularly preferred.

When wet silica is used, it is preferable to use hydrophilic wet silica that is well dispersible in water depending on where the solid alkali metal carbonates are dispersed in the device. The reason is that if hydrophobic wet silica is used, the effect of improving the fluidity of solid alkali metal carbonates is good, but the solid alkali metal carbonates and their The case of anti-caking agent is taken as an example. Hydrophobic wet silica is condensed in the absorption tower of the exhaust gas desulfurization device, and a film is formed at the gas-liquid interface. This may cause air to enter the film due to stirring and mixing, and appear Foaming phenomenon in which bubbles cannot disappear. In addition, when dissolving the reacted solid alkali metal carbonates in water and disposing of them, it is also preferable to use hydrophilic wet silica.

Wet silica, if not treated with hydrophobicity, is hydrophilic and suitable for use as an anti-caking agent. Hydrophilic wet silica does not float on the water surface but is dispersed in water, and therefore, failure due to the above-mentioned foaming does not occur. On the other hand, in the method of installing an electrostatic precipitator between the place where the solid alkali metal carbonates and their anti-caking agents are spread and the exhaust gas desulfurization device, since the aforementioned problems such as foaming do not occur, as an anti-caking agent, Either hydrophobic or hydrophilic can be used.

Zeolites can also be used as anti-caking agents. Zeolites are less effective than wet silica as anti-caking agents, but can be used due to their ability to neutralize acidic components in the gas being treated. Especially preferred is a synthetic zeolite called 4A type zeolite, which has a small average particle size of about 1 to 5 μm and contains sodium, so it also has a neutralizing effect on acidic components. Moreover, the dried powder of the zeolite can also be used as a desiccant, which can inhibit the agglomeration or agglomeration of the pulverized solid alkali metal carbonate micropowder due to water absorption. Therefore, if zeolite and wet silica are used in combination, the effect will be better, which is especially suitable for the occasion where sodium carbonate is selected as the solid alkali metal carbonate, which can prevent sodium carbonate from absorbing moisture and form monohydrate salt, and prevent condensation. piece.

The dosage of the anti-caking agent of the present invention is 0.1-5% by weight of the solid alkali metal carbonates. If the added amount is less than 0.1% by weight, the effect of improving the fluidity of solid alkali metal carbonates is poor, which is not preferable. On the other hand, if the added amount exceeds 5% by weight, the fluidity-improving effect of the solid alkali metal carbonates does not increase as the added amount increases, which increases the cost, which is not preferable. A particularly preferable addition amount is 0.3 to 2% by weight.

As a method of preventing caking and fluidity improvement of solid alkali metal carbonates, it is possible to add a solid with an average particle size of more than 20 μm, especially a particle size of 50 μm or more, to solid alkali metal carbonate fine powder with an average particle size of 20 μm or less Coarse particles of alkali metal carbonates. In this way, when the solid alkali metal carbonate fine powder is stored in the storage tank for a certain period of time by the pre-pulverization method and then used for gas treatment, the discharge performance of the fine powder from the storage tank described later can be improved. Under the action of the weight and volume of the larger coarse particles, the loose agglomerates formed by the fine particles are dispersed.

It is also possible to add the anti-caking agent and the above-mentioned coarse particles into the solid alkali metal carbonate micropowder with an average particle size of 20 μm or less before gas treatment. The mixing amount of coarse particles is generally 10 to 30% by weight of the total amount of solid alkali metal carbonates having an average particle diameter of 20 μm or less and the coarse particles. For example, when sodium bicarbonate or sodium carbonate is used as solid alkali metal carbonates, coarse granular sodium bicarbonate or sodium carbonate can be used accordingly.

Mixing coarse particles according to the above-mentioned dosage ratio can prevent the phenomenon of "concave hole" in which the powder is only discharged in the central part of the storage tank, while the powder near the tank wall remains. This effect can be achieved by using physical methods. particles are obtained. In view of the removal effect of the boric acid component, when coarse particles of the same type as solid alkali metal carbonates are used, the coarse particles themselves also have a function of removing the boric acid component to a certain extent.

In the gas treatment method of the present invention, it is preferable to use a flue gas desulfurization device after removing the boric acid component. Through the use of exhaust gas desulfurization equipment, SO ₂ , SO ₃ and sulfuric acid components in the gas can be effectively removed.

The present invention is a dry method, which disperses solid alkali metal carbonate powder in the treated gas. Therefore, the device used is different from the wet method, and its device and operation management are convenient and stable. In addition, unlike the case where calcium hydroxide, calcium carbonate, or magnesium hydroxide is used, the residue and unreacted matter after neutralization are water-soluble. Therefore, solid waste can be reduced if boric acid is removed by dissolving in water and using known wastewater treatment methods.

In the present invention, the gas to be treated can be treated with a flue gas desulfurization device or a flue gas denitrification device after being treated with solid alkali metal carbonates.

In the present invention, when the gas to be treated is treated with a flue gas denitrification device, especially in the case of using sodium bicarbonate, potassium bicarbonate, light ash or potassium carbonate, the denitrification catalyst with V ₂ O ₅ etc. as active components can be used The _SOx concentration at the inlet of the layer falls below 10 ppm, more preferably below 5 ppm. This prolongs the useful life of the catalyst. The reaction of NH ₃ and SO ₃ used in combination for denitrification prevents the formation of NH ₄ HSO ₄ .

In the present invention, solid alkali metal carbonates are used to process the exhaust gas from the glass melting process with boric acid components as raw materials, and the potassium borate metal salt produced after the treatment is collected with a bag filter, and the potassium borate metal salt of capture can be It is recycled as a part of the raw material and used in the melting process. When the reaction products of solid alkali metal carbonates collected by bag filters, etc. also include reaction products formed with acid gases other than boric acid, the composition should be considered and the ratio of other raw materials should be adjusted. , used as a glass ingredient in the melting process.

In order to confirm the effect of adding sodium bicarbonate on the removal of boric acid components in the gas, a test was conducted in which sodium bicarbonate powder was sprinkled in the exhaust gas of a glass melting furnace that actually contained boric acid.

An embodiment of the present invention will be described below with reference to FIG. 1 .

The exhaust gas at about 500°C generated in the furnace 1 is sent to the stabilizer 2 through the first flue 10 . Add alkaline water 7 to the stabilizer 2 to remove SO2 _etc. , and lower the gas temperature to about 200°C. Then, inject sodium bicarbonate powder 8 into the exhaust gas entering the second flue 11 between the stabilizer 2 and the bag filter 3, neutralize and remove the boric acid component, then send to the bag filter 3, and then the dust is mixed with the stabilizer 2 Residual SO ₂ that has not been removed reacts with boric acid components to remove generated dust, etc. The dust 9 collected by the bag filter 3 is discharged out of the system. On the other hand, the exhaust gas passing through the bag filter passes through the third flue 12 and is sent into the fourth flue 13 by the action of the exhaust fan 4, then is sent into the chimney 6 through the fifth flue 14, and finally discharged from the chimney 6 .

The glass melting furnace containing boric acid is a heat exchange type open hearth furnace, its heavy oil consumption is 450L/h, the exhaust flow rate is 8000m ³ /h, and the boric acid component in the exhaust gas from the furnace is 600mg/m converted into B ₂ O ₃ ³ . L represents the unit "liter" of capacity, and the volume of gas refers to the volume under the standard state.

As shown in Figure 1, the exhaust gas is sampled at the 3rd flue 12 at the outlet of the bag filter, absorbing and fixing the boric acid components containing the exhaust gas with cylindrical filter paper and water, and using the ICP emission analysis method (inductively coupled plasma atom Spectroscopic analysis) to analyze boric acid components, and then convert to B ₂ O ₃ .

In this example, the average particle diameter was measured using _Microtrac FRA 9220 manufactured by Nikkiso Co., Ltd. In addition, SPS4000 manufactured by Seiko Electronics Co., Ltd. was used as the ICP emission analyzer.

[Example 1 (Example)]

Sodium bicarbonate (manufactured by Asahi Glass Co., Ltd.) with an average particle diameter of 102 μm was pulverized with a pulverizer (dry pulverizer manufactured by Hosoka Hemicron Co., Ltd., trade name: ACM pulverizer) into an average particle diameter of 9 μm and a cumulative under-sieve particle size distribution. 90% of the particles have a particle size of 19 μm sodium bicarbonate powder. During fine pulverization, hydrophilic wet silica (manufactured by Japan Aerosil Co., Ltd., trade name: AEROSIL-R90G) with an average particle diameter of 0.01 μm was added and mixed in an amount of 1.0% by weight (based on sodium bicarbonate powder). sodium bicarbonate powder.

Table 1 shows the results when sodium bicarbonate powder was injected. The amount of sodium bicarbonate dispersed is expressed in multiples corresponding to 1 mole of B ₂ O ₃ .

In addition, the exhaust gas composition from the chimney contained 10 volume % of O ₂ and 15 volume ppm of SO ₂ without spraying fine sodium bicarbonate powder which is a solid alkali metal carbonate.

Table 1

serial number Sodium bicarbonate dispersion [times mol] Converted to B ₂ O ₃ concentration (mg/m ³ ) B ₂ O ₃ residual rate (mass%) blank Injecting 1-1 15 82 39 48 1-2 25 75 14 18

At the fourth flue 13 at the outlet of the exhaust fan 4, use a continuous automatic analyzer to record the concentration change of SO ₂ , and record the SO ₂ concentration from 15 volume ppm to 3 volume ppm, showing the removal effect of SO ₂ . In this way, the service life of the denitration catalyst layer containing V ₂ O ₅ etc. as active components of the denitration device can be extended. In addition, the injection of sodium bicarbonate powder has no effect on existing equipment such as bag filter 3.

[Example 2]

In the test, except that calcium hydroxide of 33 μm in average particle diameter 4 μm and 90% of particle diameter is used to replace sodium bicarbonate in example 1, other conditions are all the same as example 1, and the results are shown in table 2.

When calcium hydroxide was not dispersed, the composition of the exhaust gas from the chimney during the test contained 10 volume % of O ₂ and 15 volume ppm of SO ₂ .

Table 2

serial number Dispersion amount of calcium hydroxide [times mol] Converted to B ₂ O ₃ concentration (mg/m ³ ) B ₂ O ₃ residual rate (mass%) blank Injecting 2-1 20 71 58 82 2-2 25 75 46 61

Same as Example 1, the concentration change of SO ₂ was recorded, and the SO ₂ concentration changed from 15 volume ppm to 12 volume ppm, and it can be seen that there was no significant decrease. In addition, the dispersion of calcium hydroxide has no effect on existing equipment such as bag filters.

Claims (10)

1. the processing method of the gas of boronic acid containing composition is characterized in that, makes to contain under the standard state to be converted into B ₂O ₃Concentration at 15mg/m ³The gas of above boric acid component contacts with the solid alkali metal carbonate class more than a kind that is selected from alkali carbonate and alkali metal hydrogencarbonate, remove the boric acid component in the aforementioned gas, wherein, the volume average particle size of aforementioned solid alkali metal carbonate class is 1～20 μ m, and aforementioned solid alkali metal carbonate class contains anticaking agent.

2. gas processing method as claimed in claim 1, its feature also are, contact with aforementioned solid alkali metal carbonate class by the aforementioned gas that contains boric acid component, make under the standard state in the gas and are converted into B ₂O ₃The concentration of boric acid component reduce to below the 60 quality % before handling.

3. gas processing method as claimed in claim 1 or 2, its feature are that also aforementioned anticaking agent comprises wet silica.

4. gas processing method as claimed in claim 1, its feature are that also aforementioned solid alkali metal carbonate class is a sodium carbonate.

5. gas processing method as claimed in claim 4, its feature are that also aforementioned sodium carbonate is that specific area is at 1m ²The light ash that/g is above.

6. gas processing method as claimed in claim 1, its feature are that also aforementioned solid alkali metal carbonate class is a sodium acid carbonate.

7. gas processing method as claimed in claim 1, its feature are that also the aforementioned gas that contains boric acid component is the gas from the heating process of glass or the discharge of fusion operation.

8. gas processing method as claimed in claim 1, its feature are that also the aforementioned gas that contains boric acid component is handled with flue gas desulfurization equipment again after aforementioned solid alkali metal carbonate class is handled.

9. gas processing method as claimed in claim 1, its feature are that also the aforementioned gas that contains boric acid component is handled with the smoke evacuation denitrification apparatus again after aforementioned solid alkali metal carbonate class is handled.

10. gas processing method as claimed in claim 1, its feature also is, the aforementioned gas that contains boric acid component is after aforementioned solid alkali metal carbonate class is handled, and the boric acid base slaine of treated generation enters the glass melting operation as the feedstock recycle of boronic acid containing composition.