JP2005320188A - Inorganic foamed, fired body and its production method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inorganic foamed, fired body obtained by using, as a main component, ash produced by incinerating municipal wastes, which is made more porous. <P>SOLUTION: The inorganic foamed, fired body is formed from a raw material mixture blended so as to satisfy following composition condition (a) containing ash obtained by incinerating municipal wastes, and a foaming agent in which an iron oxide, silicon carbide and carbon are added so as to satisfy following composition condition (b) and then is produced by firing the formed body at a temperature between 1,000 to 1,250°C. The composition condition (a) is such that when SiO<SB>2</SB>, Al<SB>2</SB>O<SB>3</SB>, and K<SB>2</SB>O in the raw material are converted into Na<SB>2</SB>O in equivalent mol and when the total amount of SiO<SB>2</SB>, Al<SB>2</SB>O<SB>3</SB>, and Na<SB>2</SB>O expressed in terms of Na<SB>2</SB>O is set to be 100 wt.%, the amount of Na<SB>2</SB>O is 5-12 wt.%, the amount of Al<SB>2</SB>O<SB>3</SB>is 12-20 wt.%, and Na<SB>2</SB>O/(Na<SB>2</SB>O + Al<SB>2</SB>O<SB>3</SB>) is <38 wt.%. The composition condition (b) is constituted such that the blending amounts of iron oxide, the silicon carbide and the carbon are 3-12 wt.% expressed in terms of haematite, 0.02-5 wt.%, and 3-6 wt.%, respectively, based on the total amount of the raw material mixture. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention is a lightweight and porous foam aggregate (inorganic foam fired) used for microbial carriers, agricultural and horticultural soil improvement materials, construction or civil engineering, etc., mainly using ash generated during incineration of municipal waste Body) and its manufacturing method.

  When municipal waste is incinerated in an incinerator, the main ash remains in the incinerator, and the ash scattered in the exhaust gas (hereinafter referred to as fly ash) is collected by a bag filter or an electric dust collector. Conventionally, the collected main ash and fly ash have been disposed of by being buried in the ground as waste. However, since these ashes, especially fly ash, contain a large amount of harmful heavy metals such as lead, zinc, and cadmium, the heavy metals eluted into the ground after landfill may cause environmental pollution. It was.

  Therefore, conventionally, as a means for preventing the elution of these harmful heavy metals, a method of solidifying the collected ash with cement, a method of chemically fixing the harmful heavy metals with a chemical to insolubilize, and the collected ash A method of melting glass at a temperature of 1300 ° C. or more to form a glassy slag has been adopted.

However, even though these methods do not dissolve harmful substances, heavy metals often remain inside, and there is still concern about the long-term, stable detoxification of the treated ash, and the treated product is effectively used as a resource. There was a problem that it was difficult.
In order to solve these problems, the inventors of the present application have developed a technique for making incinerated ash an aggregate as well as volatile separation of harmful substances by high-temperature treatment (see Patent Document 1). These aggregates have an absolute dry density of 1.6 kg / l to 2.0 kg / l, which is a lightweight aggregate, but has a relatively high dry density, and is excellent as an aggregate for concrete and a roadbed for civil engineering. It has been confirmed that it has characteristics.
Japanese Patent No. 3204104

  However, even though these methods do not dissolve harmful substances, heavy metals often remain inside, and there is still concern about the long-term, stable detoxification of the treated ash, and the treated product is effectively used as a resource. There was a problem that it was difficult.

  The present invention has been made in view of such circumstances, and an object of the present invention is to incinerate municipal waste that can be effectively used as a highly functional resource by further promoting the porous formation. It is to provide an inorganic foam fired body using ash obtained as a main raw material and a method for producing the same.

In order to achieve the above object, an inorganic foam fired body according to the present invention includes a raw material mixture containing ash obtained by incineration of municipal waste so as to satisfy the following composition condition (a), an iron oxide, Silicon carbide and carbon are molded from a foaming agent added so as to satisfy the following composition condition (b), and fired at a temperature between 1000 and 1250 ° C .;
(A) of SiO _2, Al ₂ O and K ₂ O in the raw material converted at equimolar to Na ₂ O, Na ₂ O-converted SiO _2, Al ₂ O ₃ and the total amount of Na ₂ O 100 wt% When Na ₂ O is 5 to 12% by weight, Al ₂ O ₃ is 12 to 20% by weight, and Na ₂ O / (Na ₂ O + Al ₂ O ₃ ) is less than 38% by weight,
(B) The amount of iron oxide, silicon carbide and carbon in the total raw material mixture, the amount of iron oxide is 3-12% by weight as a hematite conversion amount, the amount of silicon carbide is 0.02-5% by weight, Carbon should be 3 to 6% by weight.

In addition, the method for producing an inorganic foam fired body according to the present invention is the method for producing an inorganic foam fired body using ash obtained by incineration of municipal waste as a main raw material. Is blended to satisfy the following composition condition (b), pulverized and mixed, and water is added to this to form, The obtained molded body is fired at a temperature of 1000 to 1250 ° C .;
(A) of SiO _2, Al ₂ O and K ₂ O in the raw material converted at equimolar to Na ₂ O, Na ₂ O-converted SiO _2, Al ₂ O ₃ and the total amount of Na ₂ O 100 wt% When Na ₂ O is 5 to 12% by weight, Al ₂ O ₃ is 12 to 20% by weight, and Na ₂ O / (Na ₂ O + Al ₂ O ₃ ) is less than 38% by weight,
(B) The amount of iron oxide, silicon carbide and carbon in the total raw material mixture, the amount of iron oxide is 3-12% by weight as a hematite conversion amount, the amount of silicon carbide is 0.02-5% by weight, Carbon should be 3 to 6% by weight.

  According to the present invention, the CaO content in the raw material is 15% by weight or less.

According to the present invention, the SiO ₂ source is composed of at least one of the ash, silica sand, porcelain stone, feldspar, ocarinite, kibushi clay, coal ash, and sewer incineration sludge.

  According to the present invention, hematite is used as the iron oxide.

  According to the present invention, the silicon carbide is a powder having a specific area of 6000 brain or more.

  According to the present invention, coal or coke is used as the carbon source.

  According to the present invention, the average particle size of the raw material mixture is set to 40 μm or less.

  Moreover, according to this invention, the inorganic foam baking body is shape | molded by the pellet form.

  According to the invention, at least one of bentonite, molasses and pulp waste liquid is added to the raw material mixture.

ADVANTAGE OF THE INVENTION According to this invention, the incinerated ash of municipal waste can be used as a main raw material, and a very lightweight and porous foam with a large water absorption and a chemically stable can be obtained. As a result, the aggregate obtained from the incineration ash of municipal waste, which has been used as a substitute for natural aggregates, can only be obtained if it is not a baked product such as a microbial support or soil improvement for horticulture. Can be granted.
In addition, according to the present invention, it is possible to detoxify harmful substances in the incineration ash of municipal waste by firing, and to produce a material having high functions that can only be obtained by a firing method. It can greatly contribute to the resolution of environmental problems such as the maintenance of an environment free of environmental problems and the elimination of insufficient final disposal problems, and it can also contribute greatly to the recycling of resources by supplying useful materials.

Prior to the description of the examples, the progress of the study that led to the completion of the present invention will be described.
In order to achieve the object of the present invention, the inventors of the present application adjust the composition of the ash by adding a composition preparation material to the ash obtained by incineration of municipal waste, and baked it to obtain high strength. In addition, a method for obtaining a porous and lightweight solidified body was studied. As a result, with regard to SiO ₂ , Al ₂ O ₃ , K ₂ O, and Na ₂ O, which are the main chemical components of ash obtained by incineration of municipal waste, high-strength, porous, and lightweight sintered bodies are obtained by firing. The chemical composition range obtained was found.

  In a method for producing an inorganic sintered body using ash obtained by incinerating municipal waste as a main raw material, the raw material mixture containing the ash is blended so as to satisfy the composition condition (a), and iron is used as a foaming material. Oxide, silicon carbide, and carbon are added so as to satisfy the above condition (b) and pulverized and mixed. Water is added to the raw material mixture to form a molded body, and the molded body is fired at a temperature of 1000 to 1250 ° C. .

In the present invention, a composition preparation of SiO ₂ source, Al ₂ O ₃ source, and Na ₂ O was added to the ash obtained by incineration of municipal waste to adjust the composition of the raw material mixture. As the composition preparation as the SiO ₂ source, at least one selected from quartz sand, porcelain stone, feldspar, karionite, kibushi clay, coal ash, and sewer incineration sludge was used.

  Further, trivalent iron oxide and silicon carbide were added as foaming agents. Carbon was added to promote the foaming effect of iron oxide. As iron oxide, wustite or hematite can be used. As silicon carbide, fine powder having a specific surface area of 6000 Blaine or more is preferably used, and as a carbon source, coal or coke is preferably used.

  The raw material to which the foaming agent was added after adjusting the composition was pulverized and mixed so that the average particle size was 40 μm or less, and then added to a particle size of 5 to 20 mm, which was fired using a rotary kiln. . Moreover, at least 1 sort (s) of bentonite, molasses, and pulp waste liquid was further added to the said raw material mixture as a binder.

  The inorganic foam fired body thus obtained is not only used as a substitute for natural aggregates such as river gravel and crushed stone, but also as an aggregate such as concrete aggregate and roadbed material, and the porous material of the fired aggregate. As a result, it was possible to construct an aggregate with a light weight, a high water absorption rate and a very high water retention rate.

  And this fired body can exert its characteristics greatly as a roadbed material and a porous concrete aggregate to prevent soil improvement and heat island phenomenon for cultivation of microorganisms and plants, and is discarded. It was confirmed that the incineration ash from municipal waste can be used effectively and can greatly contribute to recycling and elimination of environmental pollution. Moreover, since it can manufacture using the rotary kiln currently used for manufacture of cement etc. without requiring special manufacturing facilities, the processing efficiency of incineration ash can be raised remarkably and processing cost and equipment investment can be reduced greatly.

Next, an embodiment of the present invention will be described.
In order to heat and expand the raw material, 1) the matrix is densified so that the gas can be trapped, and 2) a liquid phase having an appropriate viscosity capable of trapping the generated gas and expanding and foaming is generated. It is necessary to generate sufficient gas necessary for foam expansion when gas can be captured.

The ash obtained from incineration of municipal waste, ie the main ash remaining in the incinerator and the fly ash scattered in the exhaust gas, is generally about 20-30% by weight of NaCl and KCl volatilization when reheated. oxidation, C, or de-CO ₂ from carbonate, the withdrawal or the like adsorbed water, a large amount to volatility. Therefore, before the matrix is densified so that the gas can be trapped, it is necessary to sufficiently fill the voids in the matrix generated by the volatilization so that the gas can be trapped.

In general, a large amount of gas is generated as the liquid phase is generated in the matrix.However, if time is required for densification due to the clogging of the voids, the gas is trapped when the gas can be trapped. The generation capacity is reduced, and sufficient foam expansion cannot be performed.
Further, when the viscosity of the generated liquid phase rapidly decreases as the temperature rises, the raw material pellets are fused together to form a lump or adhere to the kiln furnace wall, making stable firing impossible. Further, the generated gas cannot be retained, and the gas is blown out, so that the foam expansion cannot be performed.

From the above viewpoint, as a result of studying a raw material composition suitable for foaming and expanding using a raw material containing a large amount of volatiles, Mullite's first ternary equilibrium diagram of SiO ₂ , Al ₂ O ₃ , and Na ₂ O was used. It has been found that the vicinity of the lowest eutectic point of the crystal region and the inside of the primary crystal region of mullite or tridymite are optimal. In terms of chemical composition range, the total amount of SiO ₂ , Al ₂ O ₃ , and Na ₂ O in which SiO ₂ , Al ₂ O ₃ and K ₂ O in the raw material are converted to Na ₂ O in equimolar amounts is defined as 100% by weight. In this case, Na ₂ O is 5 to 12% by weight, Al ₂ O ₃ is 12 to 20% by weight, and Na ₂ O / Al ₂ O ₃ is 38% by weight or less. In this chemical composition range, it is possible to efficiently capture the generated gas by filling the voids in a short time by capturing the generated gas rapidly and capturing the generated gas. Conceivable.

Such compositions adjusting material, and SiO ₂ or SiO ₂ as main a SiO ₂ source, minerals containing Al ₂ O _3, for example, silica sand, pottery stone, feldspar, Karionaito, kibushi clay, coal ash And sewer incineration sludge. Examples of the composition adjusting material that becomes the Al ₂ O ₃ source include alumina, bauxite, mullite, and kaolinite. Alkaline metals such as Na ₂ O and K ₂ O are contained in municipal waste incineration fly ash in an amount of about 15 to 20% by weight. Reduce to 12% by weight.

Next, CaO, which is abundant in municipal waste incineration fly ash, is generally a hydroxide at the time of supply to the rotary kiln, and is bulky in the raw material, and dehydrated with heating. In order to increase the voids, it is not preferable in promoting foam expansion. In addition, when the liquid phase starts to be generated along with the firing, the viscosity of the liquid phase is drastically lowered. Therefore, the pellets are easily fused, and the firing temperature is difficult to increase. Therefore, for pellet expansion, CaO is not a preferred component, but expansion is possible if the content in the raw material is 15% by weight or less, preferably 10% by weight or less.
As for CaO, municipal waste incineration fly ash contains about 10 to 40% by weight. Usually, silica and alumina-containing raw materials are mixed to make the content 15% or less, preferably 10% or less. To be adjusted.

As a foaming agent, hematite, which is iron oxide, and silicon carbide or carbon coexist. Since trivalent hematite is more stable in the glass phase in the divalent state, when a liquid phase begins to form in the matrix, oxygen is rapidly released to become wustite and diffuse into the glass phase. It is considered a thing. At this point, the coexisting carbon or silicon carbide is oxidized to CO or CO ₂ gas, which consumes oxygen, so the reaction is further promoted. The CO or CO ₂ gas generated here can be effectively used as a foaming gas. In addition, it is considered that hematite has the effect of maintaining the viscosity of the liquid phase moderately when it becomes wustite and diffuses into the liquid phase.

Silicon carbide is stable up to 2700 ° C. or higher when the oxygen partial pressure is low, but when the oxygen partial pressure is high, oxidation proceeds rapidly even near 1000 ° C. Accordingly, when the liquid phase starts to be generated and the hematite becomes wustite, it rapidly oxidizes to generate CO or CO ₂ gas, which is considered to work extremely efficiently as a foaming agent.

If the content of hematite in the raw material is less than 3% by weight, the effect as an oxygen supply source is small and the foaming expansion effect is insufficient. When it is diffused, the flux effect becomes excessive and the viscosity is remarkably lowered. If the amount of silicon carbide added is less than 0.02% by weight, the effect of generating CO or CO ₂ gas is small, and even if it is increased from 5%, the effect does not increase. Carbon depends on the porosity of the raw material pellets and the oxygen concentration in the combustion gas during firing, but if the content in the raw material is less than 3% by weight, oxidation proceeds to the inside of the pet, so the liquid phase formation temperature in the matrix And cannot contribute to gas generation. In addition, if the content is 6% or more, the reduced state proceeds to the pellet surface and wustite increases, so a hematite layer is formed on the pellet surface, improving the fire resistance and contributing to an increase in the firing temperature of the pellet. Can not be.
Further, since the voids in the pellets increase due to the advent of carbon itself, foam expansion is inhibited, which is not preferable.

  As trivalent iron oxide, hematite or pyrite cinder can be used. Since silicon carbide needs to increase the reaction rate, fine powder having a specific area of 6,000 blaine or more is used. When the particle size becomes coarser than this, the reaction rate is remarkably lowered, so that the gas releasing effect is remarkably lowered and the foaming effect cannot be obtained. Coal and coke can be used as carbon.

  As described above, the raw material mixture prepared by adding a composition adjusting material or the like to the main raw material ash, ie, fly ash and / or main ash, is preferably mixed and ground so that the average particle size is 40 μm or less. The average particle size of fly ash is about several μm, but the main ash and minerals that are composition modifiers have a large average particle size. Is preferred. When the average particle size of the raw material mixture is larger than 40 μm, the strength of the obtained solidified body tends to be lowered.

  Next, water is added to the pulverized and mixed raw material mixture to form a desired aggregate shape. Generally, it is shaped into pellets having a diameter of 5 to 20 mm by rolling granulation or extrusion granulation. As a molding method, any method may be used as long as it can be molded into a predetermined aggregate shape. However, in order to increase the bulk density of molded pellets as much as possible in order to promote foam expansion, extrusion molding is preferable.

  By firing the obtained molded body at 1000 to 1250 ° C., a solidified body having the strength required as an aggregate can be obtained. As the firing furnace, it is preferable to use a rotary kiln in consideration of the accelerated insertion of harmful heavy metals, continuous operability, quality uniformity, and the like. The rotary kiln is simple in equipment, and it is easy for the combustion gas stream for heating and the raw material to come into contact with each other, and the residence time is several tens of minutes at a high temperature. Therefore, volatilization of heavy metals into the gas is easy to promote. Therefore, it is preferable as an equipment for firing the aggregate in that the quality of the obtained aggregate is small and the reliability when the detoxification is reduced by reducing the elution of heavy metals.

  Furthermore, when baking with a rotary kiln, when a pellet transfers to a kiln and moves, it rubs down and pulverizes. When the amount of pulverization increases, the pulverized material adheres to the pellets at the firing section, and further, the pellets adhere to each other and to the inner wall of the kiln, making the firing operation difficult, reducing the actual yield and reducing dust collection equipment. This is not preferable because it increases the load. In order to reduce pulverization in the kiln, it is preferable to add a binder such as clay minerals such as bentonite, pulp waste liquid, and molasses to the raw material mixture.

  The inorganic fired foam obtained by the method of the present invention has a light dry density of 1.2 to 0.6 kg / 1 and a very high water absorption rate of 30 to 100% by weight (dry basis) for 24 hours. Excellent water retention capacity. Thereby, while being able to exhibit the light weight characteristic as an aggregate, the characteristic excellent as a soil improvement material excellent in the filter medium as a microorganisms support body, the growth bed of seaweed, water permeability, and water retention property can be exhibited.

  By using fly ash obtained by incineration of municipal waste as a main raw material and adjusting the composition with a composition adjusting material as described above and firing, an inorganic fired foam was produced as follows. Table 1 shows the chemical composition of fly ash used in the experiment, silica sand as a composition modifier, coal ash, alumina, slaked lime, hematite, silicon carbide, coke, and bentonite as a foaming agent. . These raw materials were weighed so as to have a blending ratio shown in Table 2. Their chemical compositions are shown in Table 3.

  The weighed raw materials were pulverized and mixed with a pickling machine. When the particle size distribution of the raw material mixture after pulverization was measured with a laser diffraction particle size distribution meter, the average particle size of the raw material mixture used in the experiment was 30 μm or less. Water is added to each raw material mixture obtained and kneaded.The resulting mixture is filled into a cylindrical mold having an inner diameter of 10 mm and a length of 10 mm, and is pressurized in the length direction of the cylinder at 800 N for 30 seconds to form a cylinder. Grained.

The granulated sample is dried to a constant weight at 105 ° C, then inserted into an electric furnace adjusted to an atmosphere with an oxygen concentration of 1% in CO ₂ , and heated at a rate of 10 ° C / min. After maintaining at the temperature for 30 minutes, the sample was taken out from the furnace and allowed to cool to obtain a sample for evaluating physical properties.

The chemical composition of each aggregate raw material is shown in Table 4 according to the chemical composition of SiO ₂ , A 1 ₂ O ₃ and Na ₂ O. In addition, K ₂ O in the raw material is converted to Na ₂ O in an equimolar amount, and the chemical composition is calculated with the total amount of SiO ₂ , A1 ₂ O ₃ , K ₂ O and Na ₂ O converted to Na ₂ O being 100 wt%. Was calculated.
Further, the density and 24-hour water absorption of each obtained aggregate were measured and shown in Table 4 together with the firing temperature. The aggregate density and 24-hour water absorption were measured based on JIS AlllO.

  As can be seen from the above results, in Example 1-4 obtained by the production method of the present invention, the absolute dry density is 0.6 to 1.2 kg / 1 for 24 hours at a firing temperature of 1000 to 1250 ° C. A lightweight aggregate having a high water absorption rate with a water absorption rate of 60 to 100% by weight (dry basis) was obtained.

On the other hand, Comparative Examples 1 to 3 have more than 12% by weight of Na ₂ O in the ternary system and more than 20% by weight of Al ₂ O ₃ in the ternary system. The density was as high as 1.6 to 1.9 kg / l, and the 24-hour water absorption was also as low as 10 to 20%.

In Comparative Example 4, A1 ₂ O _{3 in} the ternary system is less than 12% by weight, and the Na ₂ O / (Al ₂ O ₃ + Na ₂ O) weight ratio in the ternary system is greater than 0.38, which is absolutely dry. The density was as high as 1.35kg / 1, and the 24-hour water absorption was 57% by weight (dry basis), which was less than 60% by weight (dry basis).

  In Comparative Example 5, the CaO content in the raw material was as high as 17.4%, the absolute dry density was 1.45 kg / 1, and the 24-hour water absorption was 31% by weight (on the basis of dry weight).

Comparative Example 6 is similar to the formulation of Example 1, but the content of Fe ₂ O _{3 in} the raw material is less than 3% by weight, the absolute dry density is 1.88 kg / 1, and the 24-hour water absorption is Also shows a low value of 13% by weight (on a dry basis), indicating that the expansion of the foam is not sufficient due to the low content of Fe ₂ O ₃ .

Comparative Example 7 is similar to the formulation of Example 1, but the content of Fe ₂ O _{3 in} the raw material is more than 12% by weight, the absolute dry density is 1.39 kg / 1, and the 24-hour water absorption is also It shows a low value of 39% by weight (on the basis of dry weight), indicating that foaming expansion is difficult when Fe ₂ O ₃ is excessive.

  Comparative Example 8 is similar to the formulation of Example 1, but the addition rate of SiC to the raw material is less than 0.02% by weight, the absolute dry density is 1.64 kg / 1, and the 24-hour water absorption is also 32. The value was as low as wt% (based on dry weight).

  Comparative Example 9 is similar to the formulation of Example 1, but the addition rate of SiC to the raw material is more than 5% by weight, the absolute dry density is 0.66 kg / 1, and the 24-hour water absorption is 77% by weight. Although it was a high value (on a dry basis), there was almost no difference from Example 1, indicating that the effect of increasing the amount of SiC added did not increase.

  The ratio 10 is similar to the formulation of Example 1, but the content of C in the raw material is less than 3% by weight, the absolute dry density is 1.53 kg / 1, and the 24-hour water absorption is also 28% by weight. (Dry basis) and a low value.

Comparative Example 11 is similar to the formulation of Example 1, but the content of C in the raw material is more than 6% by weight, the absolute dry density is 1.40 kg / 1, and the 24-hour water absorption is also 37% by weight. (Dry basis) and a low value.

Claims (18)

Raw material mixture containing ash obtained by incineration of municipal waste so as to satisfy the following composition condition (a), and iron oxide, silicon carbide and carbon so as to satisfy the following composition condition (b) An inorganic foam fired body formed from a foaming agent added to the base material and fired at a temperature of 1000 to 1250 ° C .;
(A) of SiO _2, Al ₂ O and K ₂ O in the raw material converted at equimolar to Na ₂ O, Na ₂ O-converted SiO _2, Al ₂ O ₃ and the total amount of Na ₂ O 100 wt% When Na ₂ O is 5 to 12% by weight, Al ₂ O ₃ is 12 to 20% by weight, and Na ₂ O / (Na ₂ O + Al ₂ O ₃ ) is less than 38% by weight,
(B) The amount of iron oxide, silicon carbide and carbon in the total raw material mixture, the amount of iron oxide is 3-12% by weight as a hematite conversion amount, the amount of silicon carbide is 0.02-5% by weight, Carbon should be 3 to 6% by weight.   The inorganic foam fired body according to claim 1, wherein the content of CaO in the raw material is 15% by weight or less. The inorganic foam fired body according to claim 1 or 2, wherein the SiO ₂ source is composed of at least one of the ash, silica sand, porcelain stone, feldspar, ocarnite, kibushi clay, coal ash, and sewer incineration sludge.   The inorganic foam fired body according to any one of claims 1 to 3, wherein hematite is used as the iron oxide.   The inorganic foam fired body according to any one of claims 1 to 4, wherein the silicon carbide is a powder having a specific area of 6000 brain or more.   The inorganic foam fired body according to any one of claims 1 to 5, wherein coal or coke is used as the carbon source.   The inorganic foam fired body according to any one of claims 1 to 6, wherein an average particle diameter of the raw material mixture is 40 µm or less.   The inorganic foam fired body according to any one of claims 1 to 7, which is formed into a pellet.   The inorganic foam fired body according to any one of claims 1 to 8, wherein at least one of bentonite, molasses and pulp waste liquid is added to the raw material mixture. In the method for producing an inorganic foam fired body using ash obtained by incineration of municipal waste as a main raw material, the raw material mixture containing the ash is blended so as to satisfy the following composition condition (a), and this is used as a foaming agent. Iron oxide, silicon carbide, and carbon are added so as to satisfy the following composition condition (b), pulverized and mixed, and water is added to this, and the resulting molded body is fired at a temperature of 1000 to 1250 ° C. A method for producing an inorganic foam fired body, characterized by:
(A) of SiO _2, Al ₂ O and K ₂ O in the raw material converted at equimolar to Na ₂ O, Na ₂ O-converted SiO _2, Al ₂ O ₃ and the total amount of Na ₂ O 100 wt% When Na ₂ O is 5 to 12% by weight, Al ₂ O ₃ is 12 to 20% by weight, and Na ₂ O / (Na ₂ O + Al ₂ O ₃ ) is less than 38% by weight,
(B) The amount of iron oxide, silicon carbide and carbon in the total raw material mixture, the amount of iron oxide is 3-12% by weight as a hematite conversion amount, the amount of silicon carbide is 0.02-5% by weight, Carbon should be 3 to 6% by weight.   The method for producing an inorganic foam fired body according to claim 10, wherein the content of CaO in the raw material is 15% by weight or less. The said foamed SiO ₂ source is made of at least one of the ash, quartz sand, porcelain stone, feldspar, ocarite, kibushi clay, coal ash, and sewer incineration sludge. Method.   The method for producing an inorganic foamed fired body according to any one of claims 10 to 12, wherein hematite is used as the iron oxide.   The inorganic foam fired body according to any one of claims 10 to 13, wherein the silicon carbide is a powder having a specific area of 6000 brain or more.   The method for producing an inorganic foam fired body according to any one of claims 10 to 14, wherein coal or coke is used as the carbon source.   The method for producing an inorganic foam fired body according to any one of claims 10 to 15, wherein an average particle size of the raw material mixture is 40 µm or less.   The method for producing an inorganic foam fired body according to any one of claims 10 to 16, which is formed into a pellet. The method for producing an inorganic foam fired body according to any one of claims 10 to 17, wherein at least one of bentonite, molasses and pulp waste liquid is added to the raw material mixture.