JPH0615033B2 - Exhaust gas purification agent - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a method for treating flue gas, and more specifically, to wastes such as coal, heavy oil, and municipal waste, and other combustion, drying, roasting, etc. Exhaust gas purification agent

[Conventional technology]

Sulfur oxides and nitrogen oxides, chlorides, fluorides, etc., contained in the exhaust gas generated by the combustion of coal, heavy oil, etc. are extremely harmful to buildings, structures, etc., and to animals, plants, and even the human body. It has been found that there are many effects, and a method for removing the above substances in exhaust gas, that is, desulfurization, dehydrochlorination
The equal method has been studied and a wide variety of methods have been developed.

Methods such as desulfurization and HCl removal are roughly classified into a dry method and a wet method. The exhaust gas purification method to which the present invention pertains is
The methods shown in the table are known. In the absorption method shown in Table 1, (1) expensive NH ₃ is required for the regeneration of the reactant (sulfur or recovery of sulfur compound) (active manganese oxide method) and a valuable reducing gas ( It is necessary to increase the reaction temperature (alkalized alumina method) or increase the reaction temperature (alkalized alumina method) (lime blowing method). In the adsorption method, the activated carbon used is expensive, and deterioration easily occurs. There is a drawback of. In the catalytic oxidation method, there are various problems in the conventional dry desulfurization method such that the vanadium-based catalyst used is expensive and easily deteriorates and the reaction temperature is relatively high.

Other harmful gas removal treatment methods are also roughly divided into a wet method and a dry method, and the wet method absorbs the harmful gas by contacting it with an alkaline aqueous solution or an alkaline slurry in a gas-liquid contact device such as a packed tower or a spray tower. The advantage is that it removes harmful substances and has a high effect of removing harmful components. However, wastewater containing harmful components such as sulfite ion, sulfate ion, and chlorine ion is generated, which requires advanced wastewater treatment. Further, the exhaust gas after treatment contains a large amount of water vapor, and when it is discharged into the atmosphere, white smoke is generated, and there is a drawback that a white smoke prevention device is required.

The dry method uses an alkaline powder such as calcium hydroxide, calcium carbonate or the like, or particles of these as an absorbent, reacts and absorbs a harmful gas through exhaust gas, and collects a reaction product or an absorbent powder in an exhaust gas passage. It is common to spray and react with harmful gas and collect with a dust collector.

Since the dry method is a direct contact reaction between a gas and a solid absorbent, there is almost no generation of waste water having a lowered temperature and white smoke is not generated, so that there is a great advantage over the wet method.

The method for treating the exhaust gas in the moving bed method of the particulate absorbent is a method in which massive calcium oxide, calcium carbonate, and calcium hydroxide formed into pellets are moved as an alkaline absorbent while contacting with gas. Is. The cross direction is generally used as the gas passage direction for the moving bed, but in addition to this, co-current flow and counter current flow are also possible. The discharged absorbent has the surface coated with the reaction product,
Since unreacted alkali remains inside the particles, the reaction product is usually peeled off and separated by a dry separation method using a sieve, etc., and then the alkali absorbent is used repeatedly to improve the alkali utilization rate. I am letting you.

Since the alkali absorbent has insufficient mechanical strength, it has a drawback in that it is easily pulverized when moving in the moving bed and when it is vibrated by the sieve, and the pressure loss of the moving bed increases.
As a countermeasure, as in JP-A-56-67524, a granular (or spherical) porous body is used as a carrier, and an alkaline aqueous solution of sodium hydroxide, potassium hydroxide or the like, or
There is also a method of using a slurry in which a slurry of calcium hydroxide, calcium carbonate, magnesium hydroxide, etc. is adhered and supported, but it is difficult to completely separate the reaction product due to a small amount of alkali adhered. There was a problem.

[Problems to be solved by the invention]

An object of the present invention is to solve various problems of the above-mentioned conventional dry desulfurization method and the like, and to provide a novel exhaust gas purifying agent which is a cured composition obtained from an inexpensive raw material by a relatively simple manufacturing method. is there.

[Means for solving problems]

INDUSTRIAL APPLICABILITY The present invention uses, as a first raw material, a fuel residue containing calcium oxide, which is obtained by allowing calcium carbonate to coexist at the time of combustion of a combustible material and which is active against an acidic substance produced by the combustible material. , A sulfuric acid compound, a halogenogen element compound, aluminum oxide, a sulfide, and a substance capable of supplying a hydroxide of an alkali metal are used as the second raw material, and the first raw material is used alone or selected from the first raw material and the second raw material. It is an exhaust gas purifying agent which is obtained by mixing one or more substances with water and curing them with wet air or steam.

Next, the first raw material of the present invention will be described.

The first raw material of the present invention is a combustion residue, and coal, municipal waste, sludge and other combustible substances are coexisted with sufficient calcium carbonate, burned in various combustion furnaces, and collected in a flue or a furnace bottom. It is a solid substance. Sufficient calcium carbonate here means that it reacts with acidic substances such as SO _x , NO _x , HCl, HF, and H ₂ S that are generated as a result of the combustion of vapor combustible substances (these reaction products are referred to as Ca * Abbreviated as "), and CaO produced by the thermal decomposition of calcium carbonate, which has a reaction activity with these acidic substances, is an amount of calcium carbonate. The amount of the acidic substance generated by the combustion of the combustible substance varies depending on the composition of the combustible substance, the combustion conditions, etc., and therefore it is not possible to unambiguously indicate the sufficient amount of calcium carbonate to be added. It is advisable to use calcium carbonate containing 6 times the stoichiometric amount of Ca that reacts with the source of acidic substances.

The flammable materials and / or calcium carbonate used here are
Since Al ₂ O ₃ and SiO ₂ are usually contained as impurities, the first raw material also contains Al ₂ O ₃ and SiO ₂ . Further, the added calcium carbonate is usually thermally decomposed into CaO, but residual CaCO ₃ is not preferable because it deteriorates the performance of the target exhaust gas purifying agent.

The above first raw material is at least 10% active CaO, at least 10% SiO ₂ at least ₃ % Al ₂ O ₃ , at least 3% Ca *, preferably at least 15% active CaO and 20% Al ₂ SiO _{2. If} 5% of ₂ O _{3 and} 5% of Ca * are contained, the first raw material alone can constitute the raw material of the present invention.

As mentioned above, Ca * is a reaction product of the acidic substance and Ca in the combustion gas as described above, and when the combustible is coal, it is usually CaSO.
_When the combustible material is municipal waste, it is usually CaCl ₂ .

The main reason for using combustion residues in which active calcium oxide is present in excess is that CaO, which is an absorber of acid gas in exhaust gas, can be obtained at low cost. CaO, etc. and SiO ₂ , Al ₂ O ₃
Is a highly reactive, active SiO that plays an important role in the production of a cured composition that is amorphous because the reaction proceeds at high temperatures, in other words, in the formation of an exhaust gas purifying agent and in the reaction thereof. _This is because it contains ₂ , Al ₂ O _3, etc.

Combustion furnace combustibles are raw material manufacturing apparatus for manufacturing the exhaust gas purifying agent, it should be emphasized that not only because to simply perform the furnace de SO _x, etc. to add the CaCO _3. That is, in order to obtain the exhaust gas purifying agent of the present invention, it is necessary to add calcium carbonate into the combustion furnace. Due to the presence of this step, SO _x , HCl, HF, Cl ₂ , H
A part of ₂ S etc. is removed by reacting with calcium carbonate, and at the same time, most of the remaining calcium carbonate is changed to CaO.
At this time, the substances produced are the combustion residues that have been described so far. In the combustion residues, if the reaction product of the "calcium carbonate + acid gas" peculiar to the furnace, such as coal combustion exhaust gas, is mainly CaSO. ₄ is present.

The Ca * is one of the following four most important components that are indispensable for producing the exhaust gas purifying agent of the present invention.

The reasons for using a combustion furnace as a raw material manufacturing apparatus emphasized by the present invention are summarized in the following three matters.

(1) Formation of CaCO ₃ → CaO (2) Formation of Ca * such as CaSO ₄ , CaCl ₂ , CaF (3) Generation of active SiO ₂ and Al ₂ O ₃ Basic curing composition of exhaust gas purifying agent according to the present invention Is 4 components
The substance that is composed of CaO ・ Al ₂ O ₃・ SiO ₂・ Ca * and absorbs and fixes the acidic substance is CaO, so the CaO content in the combustion residue is around 10% depending on the combustion conditions of the combustion furnace. In this case, it is necessary to add a second raw material in order to increase the formation and strength of the basic curing composition and the acid gas absorption capacity, as described below.

Examples of substances that can supply the calcium oxide of the present invention include quick lime, slaked lime, lime carbonate, cement, slag,
Examples include by-products such as dolomite plaster (containing lime) and acetylene slag.

Examples of the substance capable of supplying the sulfuric acid compound and the halogen element compound include, for example, alkaline earth metals such as calcium and magnesium, and alkali metals such as sodium and potassium,
A substance produced by combining sulfuric acid and hydrogen halide, calcium sulfate, magnesium sulfate, calcium chloride, magnesium chloride, sodium sulfate, potassium sulfate, calcium sulfite, calcium hydrogen sulfate, sodium chloride, strontium chloride, calcium bromide. , Calcium iodide, potassium chloride, sodium thiosulfate,
Examples include sodium hydrocarbon, calcium hydrocarbon, and black liquor combustion ash.

Substances that can supply silicon dioxide are, for example, silicic acid, hydrous silicic acid, metasilicic acid, aluminum silicate, calcium silicate and cristobalite, tridymite, kaolin, bentonite, talc, perlite, shirasu, diatomaceous earth, glass, etc. Examples thereof include compounds containing silicon dioxide.

The substance capable of supplying aluminum oxide is, for example, alumina, calcium aluminate, aluminum hydroxide, aluminum silicate, alum sulfate, alum, aluminum sulfide, aluminum sulfate, aluminum chloride, bentonite, kaolin, diatomaceous earth, zeolite. , Perlite, bauxite, sodium aluminate, cryolite, and other compounds containing reactive aluminum.

Examples of substances that can supply sulfides include calcium sulfide, iron sulfide, zinc sulfide, and the like.

Examples of the substance capable of supplying the hydroxide of the alkali metal include sodium hydroxide and potassium hydroxide.

Furthermore, in the case where the required materials described so far, for example, by adding elemental sulfur, mutual reaction between the materials proceeds, and as a result, calcium sulfide, calcium sulfate, etc. are produced and supplied, It also includes water glass produced by the reaction of silicic acid and caustic alkali.

In addition, as examples of other substances that can simultaneously supply two or more of the above seven compounds, coal ash and volcanic ash, coal fluidized bed combustion ash (calcium oxide, silicon dioxide, aluminum oxide, calcium sulfate, sodium sulfate, Source of potassium sulfate, one example is shown in Table 2), cement and cement clinker (sources of calcium oxide, calcium sulfate, silicon dioxide, aluminum oxide), slag and shirasu,
Reactive silicon dioxide such as andesite, bauxite, cheat, quartz trachyte, opal, fluorspar, feldspar, clay mineral, ettringite (sodium oxide, silicon dioxide, aluminum oxide, calcium oxide), sodium, aluminum, calcium, etc. and chloride Materials, minerals containing sulfate, etc., and in-furnace desulfurization ash such as fluidized bed combustion ash, waste desulfurization ash after flue gas desulfurization, sludge incineration ash, municipal waste incineration ash, cement waste, acetylene slag, etc. I can give you something.

Table 2 shows an example of the chemical composition of these typical substances.
Although the in-furnace desulfurized ash ⁽¹⁾ and the in-furnace desulfurized bottom ash ⁽²⁾ in the table are produced by the same operation as the first raw material of the present invention,
It does not imply the present invention that it contains very little CaO, almost no self-hardening property, and contains at least 10% active CaO.

The exhaust gas purifying agent used in the exhaust gas treatment of the present invention includes combustion residues alone or in the combustion residues calcium oxide, alkaline earth metal, sulfuric acid compounds, halogen element compounds, silicon dioxide, aluminum oxide, sulfides, alkali metal hydroxides, etc. Can be obtained by adding a substance capable of supplying And, by using this agent, it is possible to maintain a remarkably excellent exhaust gas purification performance.

As 0 to 30% SiO ₂ as a blending ratio 0-60% alkaline earth as 10 to 100% CaO metal or alkali metal sulfate compounds and / or halo gen element compound as a combustion residue of the base material 0 to 60% Al ₂ O ₃ as 0 to 60% Sulfide as 0 to 20% Alkali metal hydroxide as 0 to 20% As combustion residue, 40 to 100% CaO as 0 to 50% Alkaline earth metal or alkali metal sulfuric acid As the compound and / or halogen element compound, one or more of CaSO ₄ , Na ₂ SO ₄ , CaCl ₂ and NaCl is preferably 0 to 20% as SiO ₂ 0 to 40% as Al ₂ O ₃ 0 to 40% As sulfide, preferably calcium sulfide is 0 to 10%, as an alkali metal hydroxide is preferable, and NaOH and / or KOH is 0 to 10%. The present inventor has proposed the above-mentioned eight substances (combustion residue, calcium oxide, Sulfur Compound, halogen element compound, silicon dioxide,
Aluminum oxide, sulfide, hydroxide of alkali metal)
(Includes substances produced by these mutual reactions.)
The present invention has been completed by discovering that various combinations of substances capable of supplying ## STR3 ## are mixed with water to accelerate the synthetic reaction, and unexpected performance is exhibited depending on the combination and the adjustment method.

CaO, Al ₂ O ₃ and Si which are basic substances in the case of desulfurization of the present invention
The exhaust gas purifying agent composed of O ₂ and CaSO ₄ is not simply composed of a mixture of basic substances, but sulfuric acid composed of unexplained XCaO ・ Al ₂ O ₃・ ZSiO ₂・ YSO ₃・ nH ₂ O. -It is suggested that it may be a substance very similar to the calcium aluminate complex compound.

In this formula, X = 4 to 7 and Y = 2 to 4
Is larger than Y and Z = 0.1 to 3, preferably 0.3 to 1,
Also, a composition in which n is 5 to 22 is reported as a synthetic pigment, but there is no description of gas purifying properties.

Also, ettringite, which is used in the form of a paper-coating aqueous paste, has this approximate formula composed of a substance without SiO ₂ .

3CaO ・ Al ₂ O ₃・ 3CaSO ₄・ 31-32H ₂ O This ettringite has a low ability to purify exhaust gas, and its synthetic strength is low, so its value as an exhaust gas treatment agent is small. However, Ca incorporating the SiO _{2 of the} present invention
O, Al ₂ O ₃ , SiO ₂ and CaSO ₄ based compounds are hard and their performances such as desulfurization are dramatically increased. At this time, the exhaust gas purifying agent contains Ca
Crystals of (OH) ₂ cannot be detected by X-ray diffractometry.

Absorbing and fixing acidic substances such as SO ₂ is CaO in the oxide display.
However, the effect of each basic substance on the performance of the desulfurization agent built up is that SiO ₂ contributes to the sustainability of performance and Al ₂ O ₃ does not
Help the reaction rate of O ₂ or the like to raise, SiO _2, Ca
Hard materials are obtained by O, Al ₂ O ₃ and CaSO ₄ . At this time, CaSO ₄ seems to have a role of promoting the synthetic reaction of the mixture.

Next, a method for preparing the cured composition will be described.

If necessary, the above raw materials are ground and mixed, and then water is added and mixed. The water-soluble salt in the raw material is used by dissolving it in water to be added. The water content of the raw material mixture after addition of water is dry matter.
20 to 80 parts by weight, preferably about 30 to 70 parts, per 100 parts by weight. Since this water naturally contains water derived from the raw materials, the use of dilute sulfuric acid, dilute hydrochloric acid or the like may occur even when water is not required to be added.

Next, the mixture is cured at room temperature by wet air or steam. The curing step is indispensable for molding after a sufficient amount of water necessary for the production of the active substance during treatment is provided.

By going through this process, the slurry-like or mud-like mixture ends the important initial stage of active compound formation necessary for gas purification, during which the majority of the water is consumed in the compound formation reaction.

Wet air curing is at a temperature of 10 ℃ to 40 ℃ and relative humidity of 50% to 100%.
A few days or tens of days are preferable, and steam curing is
The temperature is preferably 40 ° C to 180 ° C and the relative humidity is 100%, and 10 minutes to several days is preferable.

The cured product after curing is crushed, crushed or granulated by a conventional method,
The exhaust gas purifying agent of the present invention can be obtained by sizing and pulverizing.

Curing can also be performed in the following two stages.

The conditions of the first stage wet air curing are preferably a temperature of 10 ° C. to 40 ° C. and a relative humidity of 50% to 100% for several tens of hours to several days. Also, steam curing is performed at a temperature of 40 to 180 ° C and a relative humidity of 100% at approximately 10
Minutes to several days are preferred.

The first stage curing is performed under conditions such that a proper moisture state and a cured state are obtained for molding, granulating and pulverizing the mixture after the curing.

Next, the material that has undergone the first-stage curing is molded (granulated) by a pre-ketching machine, pelletizer or the like, or molded (plate-shaped, honeycomb, lattice-shaped, Raschig ring) by an extrusion molding machine or the like. The molding is performed easily and with a high yield because it undergoes the above steps.

The molded product can be subjected to a second stage curing and sized to obtain the exhaust gas purifying agent of the present invention.

The second stage of curing is 10 ℃ to 40 ℃, relative humidity in wet air curing.
50% to 100%, preferably several days to several tens of days,
In steam curing, at a temperature of 40 ° C to 180 ° C and a relative humidity of 100%.
10 minutes to several days is preferable.

When the exhaust gas purifying agent is produced by only one-step curing, it is performed in the same manner as in the second step.

Furthermore, the molded product after curing is 30 ° C or higher, preferably 30 ° C to 50 ° C.
By performing heat treatment in the range of 0 ° C. for 0.3 to 10 hours, the performance of the treating agent can be further improved.

When steam curing and heat treatment are performed by dielectric heating, the treatment can be performed from the inside, so that the heat treatment time can be completed several times earlier than the hot air treatment, for example.

The preferable amount of water in the exhaust gas purifying agent depends on the object to be purified. For example, desulfurization is preferable to be 10% or less.
F is 27% or less and H ₂ S removal is 20% or less.

The treatment temperature of the exhaust gas of the exhaust gas purifying agent obtained by the method of the present invention can be performed in a wider temperature range than the conventional method, that is, 10 ° C to 1200 ° C, preferably 30 ° C to 1000 ° C for desulfurization and 50 ° C for denitration. ~ 400 ° C, dehydrochloric acid 30 ° C to 1000 ° C, deHF and dehydrogenation
H ₂ S is, for example, 30 ° C to 1000 ° C. The pressure may be normal pressure.

When used as a powder for flue desulfurization, etc., the agent should be crushed after the first stage curing and then pulverized again after the second stage curing, or after one curing or the same after drying. Can be obtained.

〔Example〕

Combustion residue obtained by adding commercially available charcoal 11% to domestic coal having ash content of 28%, comminuted and combusted at a maximum temperature of 1200 ° C. was used as a first raw material in each example. The chemical composition is shown in Table 3-1.

Example 1 Water was added to and mixed with the above combustion residue according to the mixing ratio shown in Table 3-2.

Next, as the first stage of curing, steam curing at atmospheric pressure of 100 ° C is performed 6 times.
Perform for 0 minutes, pass the obtained soft cured product through a 5 mm sieve to make seeds for granulation, granulate with a tube-type pelletizer, and perform 100 ° C. normal pressure and steam curing for 2nd stage curing. Do on time. 1.7 mm ~
The particles were sized to 2.5 mm and used as they were (undried product Example 1-1), 1
Heat treatment in a hot air dryer at 30 ° C. for 2 hours (Example 1-2),
And a heat treatment (Example 1-3) for 8 minutes using a 500 W dielectric dryer to obtain an exhaust gas purifying agent of the present invention.

The performance test is a flue gas treatment performance test (SO ₂ , NO _x , S under the conditions shown in Table 4 (space velocity 6000 h ^-1 and gas temperature 130 ° C).
A removal test for O ₃ , HCl, HF, etc.) was performed. The removal rate was calculated as an integrated value for 2 hours after passing gas. (The same applies hereinafter) The specific surface area was also measured. The specific surface area of the sample is 200
After degassing at ℃, it was performed by the BET method. The results are shown in Table 5.

Example 2 The same mixture as in Example 1 was steam-cured at normal pressure of 100 ° C. for 8 hours, the obtained cured product was crushed, sized to 1.7 to 2.5 mm, and treated with a dielectric dryer for 8 minutes, An exhaust gas purifying agent of the present invention was obtained.

The performance test was performed in the same manner as in Example 1, and the results are shown in Table 5.

Example 3 The water content of the unused exhaust gas purifying agent obtained in Example 1-1 was adjusted to 10%.
% (Example 3-1), 20% (Example 3-2),
An exhaust gas purifying agent of the present invention was obtained.

The performance test was conducted in the same manner as in Example 1, and the results are shown in Table 5.

Example 4 The exhaust gas purifying agent (moisture content of 0.4% or less) obtained in Example 1-1 was pulverized to obtain an exhaust gas purifying agent of the present invention in which 0.02-2.5 mm powder and small particles are mixed.

The performance test was conducted in the same manner as in Example 1, and the results are shown in Table 5.

Example 5 In the same manner as in Example 1, the first stage curing is performed, and the second stage curing is performed at 100 ° C. for 4 hours. The obtained granulated product was sized to 1.7 to 2.5 mm and dried for 8 minutes by a dielectric dryer to obtain an exhaust gas purifying agent of the present invention.

The performance test was performed in the same manner as in Example 1, and the results are shown in Table 5.

Example 6 To the combustion residue, slaked lime, a used exhaust gas purifying agent having a chemical composition shown in Table 2 and water are added according to the formulation shown in Table 3-2 and mixed.

Thereafter, in the same manner as in Example 1, the first stage curing was carried out to granulate, and the second stage curing was carried out to obtain the obtained granulated product in an amount of 1.7 to 2.5.
The particle size was adjusted to mm and heat-treated in a dielectric dryer for 2 hours to obtain an exhaust gas purifying agent of the present invention.

The performance test was conducted in the same manner as in Example 1, and these results are shown in Table 5.

Example 7 Slaked lime, calcium chloride and water are added to and mixed with the combustion residue according to the formulation shown in Table 3-2.

Hereinafter, a granulated product was obtained and a performance test was conducted in the same manner as in Example 6. The results are shown in Table 5.

Example 8 Slaked lime, caustic soda and water were added to the combustion residue 3-2.
Mix according to the formulation in the table. Next, this mixture was molded with a compression molding machine (320 kg / cm ² ), and the resulting molded body was compressed to 1.7 to 2.5 m.
After crushing and sizing to m, steam curing was performed at 100 ° C. for 12 hours, and the obtained particles were dried to obtain an exhaust gas purifying agent of the present invention, and a performance test was conducted.

The results are shown in Table 5.

[Effects of the Invention] The exhaust gas purifying agent of the present invention is different from the conventional absorbing / adsorbing agent,
The raw material uses a specific combustion residue,
CaO, CaSO ₄ , CaCl ₂ etc. or Na ₂ S ₂ O ₃ , NaCl etc. and Si
It is produced by adding O ₂ , Al ₂ O ₃ and a substance capable of supplying a sulfur compound.

The combustion residue is not a mere supplement of CaO, calcium sulfate, etc. as described in detail, but by using this, very inexpensive and highly reactive Ca can be supplied, and the purifying agent of the present invention can be used. As the synthesis reaction of the complex consisting of the basic substances CaO, SiO ₂ , Al ₂ O ₃ , and Ca * proceeds, the ability to promote exhaust gas purification can be improved and the curing time can be shortened. It has a great effect on the progress of the purifying reaction and the improvement of the manufacturing process.

As auxiliary materials, cement, slag, glass, sulfur, shirasu, coal ash, volcanic ash, silicates such as clay, calcium, aluminum compounds, substances containing sulfur, etc. can be used, usable raw materials are It is inexpensive and widespread.

In addition, the manufacturing process is relatively simple, and the manufacturing equipment does not sometimes require elaborate equipment, so that the production cost is low.

Although the exhaust gas purifying agent according to the method of the present invention is a dry type, it can be effectively used for removing SO ₂ , SO ₃ , NO _x , HCl, HF, and H ₂ S, and greatly contributes to pollution prevention. be able to.

Further, as described above, in the method of the present invention, as a raw material,
Volcanic ash, coal ash, slag, glass waste, fluidized bed combustion ash, furnace desulfurization ash, sludge incineration ash, municipal waste incineration ash, cement waste,
Acetylene slag, black liquor combustion ash, cement red when manufacturing cement products and the like, including SiO ₂ , CaO, Al ₂ O ₃ , Ca
SO ₄ , CaCl ₂ , NaCl, Na ₂ O, K ₂ O, sulfates, sulfides, halides, and substances can be used, which is also useful as a waste resource recycling technology.

Claims (5)

[Claims] Claim: What is claimed is: 1. A fuel residue containing calcium oxide, which is obtained by allowing calcium carbonate to coexist during combustion of a combustible material and is active against an acidic substance produced by the combustible material.
As the second raw material, which is capable of supplying calcium oxide, silicon dioxide, a sulfuric acid compound, a halogen compound, aluminum oxide, a sulfide, and a hydroxide of an alkali metal, as the second raw material, the first raw material alone or the first raw material And an exhaust gas purifying agent obtained by mixing one or more substances selected from the second raw material with water, and subjecting the mixture to wet air curing or steam curing. 2. The exhaust gas purifying agent according to claim 1, wherein the amount of active calcium oxide in the fuel residue is larger than the calcium oxide equivalent amount of calcium reacted with the acidic substance produced during combustion. . 3. After curing, it is further molded and then it is kept at 30 ° C.
The exhaust gas purifying agent according to claim 1 or 2, which is heat-treated at the above temperature. 4. The exhaust gas purifying agent according to claim 3, which is recured after molding. 5. The exhaust gas purifying agent according to claim 1 or 2, wherein the water content is 4% to 27%.