JP7372215B2 - Composition for fired body and method for producing fired body using the same - Google Patents

Description

The present invention relates to a composition for a fired body and a method for producing a fired body using the composition. In particular, production of compositions for sintered bodies using materials containing iron oxide components such as industrial wastes such as coal ash, sewage sludge incineration ash, electric furnace oxidation slag, copper slag, zinc slag, etc., and production of sintered bodies using the same. Regarding the method.

Coal ash is emitted in large quantities from thermal power plants that use coal as fuel, and the use of coal ash as a resource is particularly important as it is used in large quantities in cement factories as an alternative to clay among the raw materials for cement production. . Breakdown by field of use in "Table 10 Breakdown of content by field of effective use of coal ash in 2017" of "National Survey Report on Coal Ash (FY2017 results), March 2019, Coal Energy Center, General Incorporated Foundation" According to the report, the amount of coal ash used as a cement raw material in the cement field is 67.8% of the total effective amount of coal ash used.

In addition, electric furnace oxidized slag and non-ferrous metal slag generated in the non-metal refining process of copper and zinc contain a large amount of iron oxide chemical components, and are used as road base material for road pavements, asphalt concrete pavement aggregates, It is used as a resource for earthworks, ground improvement, etc.

On the other hand, sewage sludge generated at a sewage treatment plant becomes dehydrated sludge during the treatment process at a sludge treatment facility, and finally, the dehydrated sludge is incinerated in an incinerator to reduce its volume to ash (hereinafter referred to as "sewage sludge incineration"). It is discharged as "ash"). Most of this sewage sludge incineration ash is disposed of in a landfill after undergoing certain treatments in order to meet the landfill conditions.

Furthermore, the demand for resource recovery of coal ash, steelmaking slag, and non-ferrous metal slag is highly influenced by the economic situation and the content of public investment budget implementation projects, so research and technology development for further effective use of industrial waste is required. is an urgent issue. Furthermore, creating a production environment that makes effective use of new coal ash and other resources can contribute to the creation of a recycling-oriented society by turning industrial waste into resources, which is one of the social issues. Furthermore, it is expected that this will lead to extending the lifespan of landfill sites.

Various methods for producing artificial aggregates using coal ash have been devised for some time. For example, in Patent Document 1, in order to obtain a high-strength artificial aggregate that can be used as an aggregate for ordinary concrete for civil engineering and construction, and to expand the uses of coal ash and aim for its effective use, After adjusting the particle size distribution of the ash within a certain range, the coal ash and limestone powder (calcium carbonate) are granulated by adding a caking agent and water, and the granules are fired to produce high-strength artificial aggregate. It is disclosed that it can be obtained.

Further, Patent Document 2 discloses blending coal ash from which magnetite contained in coal ash has been removed in advance in order to produce artificial aggregate with high strength and low water absorption. The physical properties of the artificial aggregate, which is the fired body, are as follows: absolute dry density is 1.50 g/cm3 or more and 2.00 g/cm3 or less, water absorption is 0.1 mass% or more and 6 mass% or less, and compaction load is It is said that a fired product with a grain size of 5 mm or more and less than 10 mm can yield a fired product of 0.5 kN or more, or a grain size of 10 mm or more and less than 15 mm can yield a fired product of 1.0 kN or more.

Furthermore, Patent Document 3 describes an artificial lightweight aggregate with a composition of 50 parts of coal ash, 33 parts of shale, and 17 parts of water, the specific gravity of which after firing is 1.63, and the crushing strength of 1600N, and coal ash. 47 parts of sewage sludge incineration ash, and 22 parts of water, a method for producing an artificial lightweight aggregate having a specific gravity of 1.35 and a crushing strength of 1450N after firing is disclosed. In this method, weight reduction is achieved by incorporating natural resource shale and sewage sludge incineration ash.

JP 7-206491 JP2001-151543 JP2007-269539

However, in the method of Prior Patent Document 1, it is necessary to adjust the particle size distribution range of coal ash, which is the main material of the granules, in advance as a prerequisite for producing high-strength aggregate, and the process is complicated. . Further, the method of Prior Patent Document 2 requires removal of magnetite from coal ash as a prerequisite for producing high-strength aggregate, which is quite complicated. The manufacturing methods disclosed in Patent Documents 1 and 2 have a problem in that there are many manufacturing steps and the costs involved are relatively high. Furthermore, in the method of Prior Patent Document 3, the use of natural resources does not fully contribute to the formation of a recycling-oriented society because the demand destination is limited, and the use of sewage sludge incineration ash makes the aggregate lightweight. Due to the recent slump in demand for lightweight aggregates in Japan, resource recovery through recycling has not been able to produce the material resources that will play a role in creating a new recycling-oriented society.

Therefore, an object of the present invention is to realize a method for producing a fired body with excellent physical properties, which allows industrial waste to be recycled by a simple production method without going through complicated steps. For example, under atmospheric firing conditions, an artificial aggregate with a specific gravity of 2.1 to 2.3, a water absorption rate of 3% or less, preferably 1% or less, and a crushing strength of 2000N or more, preferably 4000N or more. The goal is to realize a fired body with a specific gravity of 2.1 to 2.3 under atmospheric firing conditions, a water absorption rate of 10% or less, and a civil engineering and construction material with practical strength.

As the artificial aggregate, a firing composition made only from industrial waste can be used, and there is a problem in recycling and effectively utilizing industrial waste. When firing the firing composition to make artificial aggregate, for example, by firing at a firing temperature of about 1180°C, a fired body with an average particle size of about 12.1 mm is obtained, and the water absorption rate is 1.0% or less. It is desired that the crushing strength exceeds 4300N. Furthermore, we would like to use it widely in civil engineering and construction materials, such as rock-slope suppression materials (ferrous ion-generating materials) and environmental improvement materials such as wall tiles and electromagnetic wave suppression materials when made into flat plates.

As a result of intensive study, the inventor provides the following invention.
[1] Coal ash (a) was used as the main material, sewage sludge incineration ash (b) was used as a medium to promote densification by calcination, and electric furnace oxidized slag and magnetite powder were used as iron oxide-containing components. To provide a baking composition characterized by containing one or more types (c) selected from disposable body warmers.
[2] It is characterized in that it is obtained by adding a binder to the firing composition described in [1], granulating it or press-molding it in a mold, and then firing it in the atmosphere. A method for producing a fired body is provided.
[3] The method for producing a fired body according to [2] is provided, wherein the medium further contains one or more of copper slag and zinc slag as an iron oxide component.
[4] The method for producing a fired body according to [2], wherein the iron oxide component (c) in the medium is 5% to 20% by weight in the firing composition. provide.
[5] The sewage sludge incineration ash (b) in the medium melt is 5% by weight or more and 20% by weight or less in the baking composition, and the iron oxide component (c) is 5% by weight or less in the baking composition. Provided is a method for producing a fired body according to item [2], characterized in that the amount is from 10% by weight to 10% by weight.
[6] The firing method according to any one of [2] to [5], wherein the coal ash (a) in the firing composition has a specific gravity of 1.5 or less when fired at 1100°C. A method for manufacturing a body is provided.
[7] Any one of [2] to [5], wherein the granulated product has a particle size of 6 mm to 24 mm, and is characterized by being fired in the atmosphere and used as an artificial aggregate. A method for manufacturing the fired body described above is provided.
[8] The method for producing a fired body according to [2] to [5], characterized in that the firing temperature in the atmosphere is 1080°C to 1220°C, and the specific gravity after firing is 1.4 to 2.4. ,I will provide a.
[9] A firing composition containing crushed steelmaking slag, coal ash, and the medium melts of [3] to [5] is granulated or press-formed in a mold, and then exposed to the atmosphere. Provided is a method for producing a fired body, characterized in that the fired body is obtained by firing in a sintered body.

The present invention uses sewage sludge incineration ash, iron oxide components, etc. from various industrial wastes to function as a medium that promotes densification during the firing of coal ash, which is the main material, and fills the voids in coal ash molded products. Therefore, it has been found that it is suitable as an infill material and can be applied to many industrial wastes.

Coal ash is particularly preferably, but not limited to, JIS fly ash (class 2), which is coal ash carried out from an ultra-supercritical (USC) coal-fired power plant. This is because the unburned carbon content is low. In ultra-supercritical (USC) coal-fired power plants, in order to prevent slagging and fouling that occur in equipment such as boilers and flues during the coal combustion process, the coal used as fuel is Fuel coal is selected based on the fact that the ash generated is in a high melting temperature range, the amount of ash emitted, and other influencing components. The coal ash of the present invention mainly used coal ash having a high melting temperature. However, the present invention does not preclude the use of coal ash having a low melting temperature of about 1,250° C. or lower. Table 1 shows representative values of the main components of coal ash. The amount of unburned carbon is preferably 4.5% by mass or less. This is because it is preferable that the firing atmosphere is unlikely to become a reducing atmosphere.

Sewage sludge incineration ash Dehydrated sludge is incinerated into ash in a high-temperature incinerator to reduce its volume, and the generated ash is collected with a dust collector. Constructed as a medium. The effect as a fluxing agent is largely influenced by the amount of K2O, which is a common component with coal ash as a main component. The content range is preferably 1.9 to 3.6% by weight. The particle size of the sewage sludge incineration ash is preferably in the range of 1 μm to 300 μm, and the cumulative weight of particles with a particle size of 100 μm or less is 90% or more. Moreover, it is preferable that the average particle size is smaller than the average particle size of coal ash. This is because iron oxide components also enter into the interparticle gaps of coal ash, which is the main material. Table 2 shows representative values of the main components of sewage sludge incineration ash.

Municipal waste incineration ash Furthermore, municipal waste is incinerated at an incineration plant to become incinerated ash and incinerated fly ash, and furthermore, molten slag, molten metal, and molten fly ash are discharged through melting processing. These industrial wastes (from "Study on the behavior of metal resources contained in municipal waste, etc. (1) to (4) Tokyo Metropolitan Institute of Environmental Science Annual Report 2012 to 2014") are similar to sewage sludge incineration ash. Since it includes a chemical composition and an elemental composition, it is included in the materials that perform the intended function in the present invention. In particular, it is preferable that K2O be contained in an amount of 1.9 to 3.6% by mass.

The sewage sludge incineration ash is preferably used in an amount of 5% by weight or more and 20% by weight or less together with the iron oxide component.

Iron oxide-containing component As the iron oxide-containing component, electric furnace oxidized slag, magnetite powder, and used disposable body warmers are preferred. Iron oxide-based crystalline minerals or glass compositions may be used, but iron oxides with a site indicated as FeO in the chemical composition display, composite oxides containing FeO, iron hydroxide or its dehydrates may be used. Certain iron oxide containing components are preferred. Including those represented by Fe ₂ O ₃ .FeO (magnetite: Fe ₃ O ₄ ). However, it does not include highly oxidized hematite. In this application, coal ash with a low carbon content can also be used, and even when firing under conditions that do not easily create a reducing atmosphere, gas generation that causes foaming can be relatively suppressed, and firing conditions such as firing temperature can be controlled. It is easy to produce a sintered body with relatively high strength and the desired specific gravity. The iron oxide-containing component is preferably used as a fluxing agent in an amount of 5% by weight or more and 20% by weight or less in both sewage sludge incineration ash.

Electric Furnace Oxidized Slag Among the slags generated when iron scrap is melted and refined, this is oxidized slag discharged from the oxidation refining process. It includes both slowly cooled slag and rapidly cooled slag. The conditions are that it does not contain a large amount of free lime like reduced slag, has a relatively stable composition, and has an FeO component.

Magnetite powder has _the chemical component of natural magnetite _Fe3O4 . It is also possible to use pigments containing this, such as Kurohama soil. In the experimental example, Kurohama soil pigment (hereinafter referred to as Kurohama soil) was used.

This is a processed powder of metal iron powder after the disposable body warmer used generated heat. For example, the processed contents of a used disposable hand warmer may include ferrous hydroxide, ferric hydroxide, dehydrated products thereof, and residual iron.

It is preferable that the electric furnace oxidized slag, magnetite powder, and the used disposable warmer (hereinafter referred to as disposable warmer) have an average particle size smaller than the average particle size of coal ash. This is because it is easy to exhibit its effect as a medium. The particle size distribution is particularly preferably 200 mesh or less (passed through a 74 μm mesh sieve).

This is a method for producing a fired product characterized by granulation molding or pressure molding in a mold and then firing in the atmosphere. The shape of the formwork for pressure forming is a flat plate, a rectangular body, a rectangular parallelepiped, etc., and corresponds to the shape of a civil engineering and construction material.

Binder Binders are added to the compounded materials during the series of manufacturing processes from kneading and forming various compounded materials to drying and baking to prevent breakage during handling of the molded product. For example, in addition to organic materials such as starch paste, blackstrap molasses, methyl cellulose, carboxyl methyl cellulose, polyvinyl alcohol, vinyl acetate, dextrin, and pulp waste liquid, inorganic materials such as bentonite, sodium silicate, potassium silicate, and aluminum phosphate. Materials etc. can also be used.

Water or an organic solvent can be used for granulation molding and pressure molding within a mold. Pressure molding includes left molding using its own weight. Furthermore, the firing in the present invention is performed in the air and does not require a reducing atmosphere. In addition, this does not preclude the use of a furnace to create a partially reducing atmosphere.

Copper slag and zinc slag can be used in the present application as long as they have iron oxide containing ferrous ions represented by FeO.

One or more types (c) selected from electric furnace oxidized slag, magnetite powder, and used disposable warmers are present in the firing composition in an amount of 5% to 20% by weight, preferably 10% to 20% by weight.

It is preferable that the coal ash (a) has a specific gravity of 1.5 or less when fired at 1100°C. This is because the heating process of the firing temperature can be easily controlled and a good density of the fired body can be obtained.

If the granulated product has a particle size of 6 mm to 24 mm, has high crushing strength when fired in the atmosphere, and has an appropriate specific gravity and water absorption rate, it is suitable for artificial aggregate, etc. . If we specialize in artificial aggregates, if the particle size to be granulated is less than 6 mm or greater than 24 mm, then the fired granules will have a particle size in the range of 13 mm to 20 mm, which is the particle size range of coarse aggregate for concrete. This is because it deviates from the More preferably, it is 13 mm to 15 mm. This is because if it is larger than 24 mm, it takes time to fire, and if it is smaller than 6 mm, it is not practical.

It is preferable that the firing temperature in the atmosphere is 1080°C to 1220°C, and the specific gravity after sintering is 1.4 to 2.4, and the specific gravity is 2.1 to 2. .3 is preferred. This is because stable firing is possible within this range.

A firing composition containing crushed steelmaking slag, coal ash, and the medium melts [3] to [5] was granulated or press-molded in a mold and fired.

Water absorption rate as artificial aggregate When the present invention is used as an artificial aggregate, the water absorption rate is preferably 1.0% or less at a firing temperature of 1170°C to 1190°C. This is because granular artificial aggregate allows the water/cement ratio to be set low, making it easier to prepare and control the solidified material, and having a positive effect on the physical properties of the cement solidified material.

Water absorption rate for other uses The use and utilization of fired bodies for civil engineering and construction purposes other than artificial aggregate uses is to set the water absorption rate to a high value of over 20% with a specific gravity of about 1.55 to retain soil water during greening. It can be used as a material, but by keeping the water absorption rate below 3%, it can be used as crime prevention gravel in addition to artificial aggregate, making it difficult for people to walk on and emitting high-pitched noise. Therefore, a crime prevention effect can be expected.
At this time, the material is required to have high strength (3400N to 5200N).

If the crushing strength is 2000N or more, it can be put to practical use as various civil engineering and construction materials, but as an artificial aggregate, it is preferably 4000N or more, and particularly preferably 4300N or more.

The present invention uses only coal ash (a), sewage sludge incineration ash (b), and wastes such as electric furnace oxidized slag, magnetite powder, and disposable body warmers as raw materials using a simple manufacturing method without going through complicated processes. A composition for firing can be formed, for example, under atmospheric firing conditions, a fired body with a specific gravity of 2.1 to 2.3, a water absorption of 3% or less, preferably 1% or less, and a crushing strength of 2000N or more, Preferably, using artificial aggregate of 4,000N or more and a fired body with a specific gravity of about 1.85 under atmospheric firing conditions, a civil engineering and construction material with a water absorption rate of 10% or less and a practical strength can be obtained, and a backing material with a high water absorption rate can be obtained. We can also manufacture filling materials and water retention materials.

When the main firing composition is fired to produce artificial aggregate, for example, if a fired body with an average particle size of about 12.1 mm is obtained by firing at a firing temperature of about 1180°C, the physical property is a water absorption rate of 1.0. % or less, the crushing strength exceeds 4300N. In addition, the present artificial aggregate can use a firing composition made only from industrial waste, and is suitable for recycling and effective utilization of industrial waste. In addition, it can be used as environmental improvement materials such as rock eroding suppression materials (iron ion generating materials), wall tiles and electromagnetic wave suppression materials when made into flat plates, and civil engineering and construction materials.

The present invention will be explained below based on more detailed experimental examples.

Coal ash (A), coal ash (B), and coal ash (C) that correspond to JIS fly ash (class 2) were used. This is coal ash discharged from ultra-supercritical (USC) coal-fired power plants. Coal ash (B) has a light beige color in its fired product, and compared to the other two types of coal ash (A) and (C), which are dark brown. B) contains less iron oxide as determined visually by color. Regarding the particle diameters, the 97% frequency cumulative total is 200 μm or less, and the 72% frequency cumulative total is 80 μm or less.

The sewage sludge incineration ash used was sewage sludge incineration ash (A) and sewage sludge incineration ash (B). Incidentally, sewage sludge incineration ash (A) is incineration ash obtained from an incinerator with an incineration temperature of 800°C in the freeboard part of the incinerator, and sewage sludge incineration ash (B) is incineration ash obtained in the freeboard part of the incinerator. This is incinerated ash obtained from an incinerator with an incineration temperature of 850°C. The reason for incinerating at an incineration temperature of 850°C is that emissions of N ₂ O (nitrous oxide), which is a greenhouse gas, can be reduced. The particle size distribution used was such that the maximum particle size was about 400 μm and the cumulative weight of particles with a particle size of 100 μm or less was 90% or more. The sewage sludge is incinerated in a fluidized bed incinerator, the fly ash contained in the exhaust gas is collected in a waste heat boiler, the fine fly ash is collected in a cyclone, and a dry electrostatic precipitator, and each ash is transferred and stored in an ash hopper using a conveyor. be. The chemical components of the main substances of the sewage sludge incineration ash (A) are shown in Table 3.

The electric furnace oxidation slag was product name: CK Hyper No. 7 (manufactured by Hoshino Sansho Co., Ltd.), and raw powder with a maximum particle size of 300 μm or less was prepared. This was processed and two types of powders with different degrees of powder were produced and used. In each recipe, electric furnace oxidized slag (A) and electric furnace oxidized slag (B) were indicated.

The electric furnace oxidized slag (A) is prepared by using a sieve with an opening of 150 µm to obtain a product with a particle size range of 300 µm or less, and the part where the slag passes through the sieve is used as a composition material for fired bodies. That is. Electric furnace oxidized slag (B) is a product whose particle size range is 300 μm or less, and is crushed for 10 minutes using a dedicated crushing device (disc-type vibrating mill) to produce a composition material for fired bodies with a particle size of 200 mesh or less (74 μm). This is a sieve with open mesh sieves. Table 4 shows the main chemical composition of the electric furnace oxidized slag. It is preferable to use an iron oxide component material having an average particle size smaller than the average particle size of coal ash and the average particle size of sewage sludge incineration ash.

Disposable Warmer: The powder was taken out from a commercially available disposable body warmer 3 days after use, washed, dried and heated, pulverized, and passed through a 150 μm sieve before use.

The firing temperature pattern is to raise the temperature from room temperature to 1000°C in 120 minutes, maintain that temperature increase rate up to 1020°C, and change the temperature at each temperature from 1020°C to 1220°C, which is the maximum temperature for each firing. Accordingly, the temperature was raised for 5 minutes to 100 minutes, and then the maximum temperature for each firing was held for 15 minutes, and a fired product was obtained by natural slow cooling. Hereinafter, the maximum firing temperature may be abbreviated as firing temperature. The electric furnace is SH-2035D manufactured by Motoyama.

In the present invention, specific gravity and water absorption were measured using Shimadzu analytical balance AUX120 and specific gravity measurement kit SMK-401 (manufactured by Shimadzu Corporation). Specific gravity is a value measured using SMK-401 according to the measurement method of this device, and is the same value as the value expressed in density (g/cm3). Furthermore, the crushing strength was measured in accordance with JSCE-C505 (compressive load test method for high-strength fly ash artificial aggregate).

In Experimental Example 32, the blending ratio (hereinafter referred to as blending ratio) of coal ash (A), iron oxide Kurohama (hereinafter referred to as Kurohama soil), and sewage sludge incineration ash (A) was 90:5:5. The blending ratio of Experimental Example 33 is 85:10:5, the blending ratio of Experimental Example 34 is 85:5:10, the blending ratio of Experimental Example 35 is 80:10:10, and the blending ratio of Experimental Example 36 is 80:5: It is 15. Experimental example 37 is 75:10:15.

To each of the above formulations, predetermined amounts (unit: g) of the binder and water shown in Table 5 were added to produce granules (nine samples for each).

Compositions for fired bodies having the formulations shown in Table 5 for coal ash (A) and coal ash (C) were fired according to the firing pattern described above. Table 6 shows the specific gravity of the fired body, and Table 7 shows the water absorption rate (wt%).

Change in Specific Gravity of Fired Body The physical property test results of the specific gravity and water absorption rate of the fired body are shown in which the granules having the composition shown in Table 5 were tested six times at 40°C intervals at a firing temperature of 1020°C to 1220°C. Specific gravity was used as the main measure of densification of the fired body. The specific gravity should be 1170°C or more than 2.0 quickly (before reaching 1180°C), preferably 2.1 or more and 2.3 or less, and should not easily melt and foam. was the standard. Regarding granules that are a mixture of coal ash and sewage sludge incineration ash, etc., due to the influence of fluctuations in the composition of the coal ash and sewage sludge incineration ash, etc., the calcination melting temperature of the granules becomes lower, resulting in densification. This is because firing is accelerated excessively and baking control becomes difficult.

The addition of Kurohama soil combined with the function of sewage sludge incineration ash as a medium to further enhance its function, resulting in a densified sintered body. In addition, regarding the change in the fired body due to the difference in the blending ratio of Kurohama soil between Experimental Example 32 and Experimental Example 33, the ratio of iron oxide was increased to increase the function of the iron oxide as a medium by the sewage sludge incineration ash. densification was further promoted. In addition, it can be assumed that the specific gravity of the compositions for fired bodies of Experimental Examples 34 and 35 reached the maximum value during the heating process in which the maximum firing temperature exceeded 1180°C.

Further, in a comparison between Experimental Example 34 and Experimental Example 35, the specific gravity of the fired body increased as a result of enhancing the function of the sewage sludge incineration ash as a medium for iron oxide.

The results of Comparative Example 9 and Experimental Examples 36 and 37 are also the same as above, but in the firing at the maximum firing temperature of 1180°C in Experimental Examples 36 and 37, the fired body foamed due to the decrease in specific gravity. It can be assumed that the specific gravity of the granulated fired body of the fired body composition of No. 37 reached its maximum value during the heating process exceeding the maximum firing temperature of 1140°C.

From the results of firing a composition for fired body made by blending coal ash (A), which is the main material, and granulating it, it was found that Kurohama soil was added to the coal ash (A), which is the main material, relative to the total amount of the composition for fired body. Therefore, it is effective to combine 5% by weight or more and 10% by weight or less and sewage sludge incineration ash in an amount of 5% by weight or more and 15% by weight or less based on the total amount of the composition for a fired body. I confirmed that there is.

Comparative Example 7 had a blending ratio of coal ash (C), iron oxide (Kurohama soil), and sewage sludge incineration ash (A) of 90:0:10, and Kurohama soil was excluded. In Experimental Example 44, the blending ratio of coal ash (C), iron oxide (Kurohama soil), and sewage sludge incineration ash (A) was 90:5:5, and in Experimental Example 45, the blending ratio was 85:10:5. In Experimental Example 46, the ratio is 85:5:10. In Experimental Example 47, the ratio is 80:10:10. Experimental example 48 has a ratio of 80:5:15, and experimental example 49 has a ratio of 75:10:15.

Even when coal ash (C) was used, effects with the same tendency as when coal ash (A) were used were obtained.

From this, in the production of granulated products, by adding Kurohama soil to the composition for the fired body even in coal ash (C), in combination with the function of the sewage sludge incineration ash as a medium, The sintered body became noticeably denser.

Effects were obtained with the same blending ratio as the result of firing a molded product made by blending coal ash (A) and granulating it. That is, iron oxide (Kurohama clay) is contained in an amount of 5% by weight or more and 10% by weight or less based on the total amount of the composition for fired bodies, and sewage sludge incineration ash is contained in the total amount of the composition for fired bodies. It is preferable that the content is from 5% by weight to 15% by weight.

Table 8 shows the blending composition of the granulated composition of the fired body composition containing iron oxide in addition to coal ash (B), and Table 9 shows the firing temperature range of 1140°C to 1190°C for each fired body composition. Table 10 shows the water absorption rate (wt%) measurement results for each composition (unit: g), and Table 11 shows the physical properties of crushing strength (N). Show the test results. The crushing strength is the average value of the measurement results of 5 pieces of each granulated fired product, and when the maximum crushing strength exceeds the limiter setting of 4500N, the number of pieces is recorded.

Experimental example 50 is a comparative example in which the blending ratio of coal ash (A) and sewage sludge incineration ash (B) was 90:10. In Experimental Example 51, the blending ratio of coal ash (A), iron oxide (Kurohamada), and sewage sludge incineration ash (B) was 82.5:7.5:10. In Experimental Example 52, the blending ratio of coal ash (A), electric furnace oxidized slag (A), and sewage sludge incineration ash (B) was 80:10:10. Experimental example 53 is a comparative example in which the blending ratio of coal ash (B) and sewage sludge incineration ash (B) was 80:20. In Experimental Example 54, the blending ratio of coal ash (B), Kurohama soil, and sewage sludge incineration ash (B) was 72.5:7.5:20. Experimental example 55 is a mixture in which the blending ratio of coal ash (B), electric furnace oxidized slag (A), and sewage sludge incineration ash (B) is 70:10:20. Experimental example 56 is a comparative example in which the blending ratio of coal ash (C) and sewage sludge incineration ash (B) was 90:10. Experimental example 57 has a blending ratio of coal ash (C), Kurohama soil, and sewage sludge incineration ash (B) of 82.5:7.5:10.

The granulated material was fired at a maximum firing temperature of 1140°C to 1190°C at intervals of 10°C, and the specific gravity, water absorption, and crushing load of the resulting fired body were measured.

Experimental Examples 54 and 55 contain iron oxide, but are slightly inferior to Experimental Examples 51, 52, and 57 in terms of specific gravity and water absorption.
From this, when using Kurohama soil and electric furnace oxidized slag (A) to produce granules, combined with the function of sewage sludge incineration ash as a medium, it is possible to enhance the function of iron oxide as a medium. Regarding Experimental Examples 54 and 55 using coal ash (B), it was found that there was still room for improvement even when iron oxide containing FeO was used.

In addition, by adding iron oxide to the composition for fired bodies, a plateau phenomenon in firing (firing temperature range of 1170°C to 1190°C) that ensures high specific gravity (about 2.1) and low water absorption (less than 3.0%) is achieved. °C) was expressed. The appearance of a lull in calcination is due to the fact that sewage sludge incineration ash acts as an activator that enhances the function of iron oxide as a flux, combined with its own function as a flux. This is the effect. This has the effect that, in the firing of molded bodies such as granules, there is a margin for temperature control during firing, and the quality of the product can be easily controlled.

Average crushing strength The average crushing strength of the granulated sintered body of Experimental Example 53 increased from 1993N to 3527N. The average crushing strength of the granulated fired body of Experimental Example 54 was 3946N at the maximum firing temperature of 2312N to 1180°C, and exceeded the crushing load limit of 4500N at 1190°C.

Table 12 shows a blending table (unit: g) of coal ash (A), iron oxide passed through a 200-mesh sieve, and sewage sludge incineration ash (B). Electric furnace oxidation slag (B) was used as iron oxide. Examples containing no iron oxide are Experimental Examples 58, 63, and 67. The test results of specific gravity, water absorption, and crushing strength obtained by firing the granules at a firing temperature of 1140°C to 1190°C at 10°C intervals are shown in Table 13, Table 14 (unit: wt%), and Table 14. 15 (unit: N). Table 16 also shows the measured values (mm) of the granulation diameter after firing. Table 17 shows the reference value of the particle size ratio before and after firing, Table 18 shows the change in granulation size at 1180°C (shrinkage measurement results), and Table 19 shows the composition table of the experimental example (unit: g) I have summarized.

Experimental example 58 is a comparative example in which the blending ratio of coal ash (A), electric furnace oxidized slag (B), and sewage sludge incineration ash (B) is 90:0:10, and experimental example 59 is 82.5. :7.5:10, and Experimental Example 60 is a composition for a fired body having a ratio of 80:10:10. As a result of comparing specific gravity, water absorption rate, and crushing strength, Experimental Examples 59 and 60 generally exceeded the various physical property test values of Experimental Example 58 in the process of increasing the temperature from 1150°C.

Therefore, by adding electric furnace oxidation slag (B) (200 mesh all through) to the composition for the fired body in the production of granules, it is possible to improve the function of the sewage sludge incineration ash as a medium. Coupled with this, the result was that the densification of the fired body was even more remarkable than when electric furnace oxidized slag (A) was blended. In addition, by adding iron oxide to the composition for fired bodies, a plateau phenomenon in firing (firing temperature range of 1170°C to 1190°C) that ensures high specific gravity (about 2.2) and low water absorption (less than 3.0%) is achieved. °C), and in the firing of molded bodies such as granules, there is a margin for temperature control during firing, which has the effect of making it easier to control the quality of the product.

Experimental example 63 is a comparative example in which the blending ratio of coal ash (B), electric furnace oxidized slag (B), and sewage sludge incineration ash (B) was 80:0:20. In Experimental Example 64, the blending ratio of coal ash (B), electric furnace oxidized slag (B), and sewage sludge incineration ash (B) was 72.5:7.5:20, and in Experimental Example 65, it was 70:10: The composition was set at 20.

When coal ash (B), iron oxide, and sewage sludge incineration ash (A) are used, the specific gravity and water absorption rate are slightly higher than in the experimental examples using coal ash (A) and coal ash (C). However, by using 200 mesh electric furnace oxidized slag (B) and sewage sludge incineration ash (B), it was shifted to a lower value. This improvement effect is thought to be due to the atomization effect of FeO-containing iron oxide.

Regarding the change in particle size due to firing of the granulated product, the change in particle size of the fired product obtained at each maximum firing temperature of 1140°C to 1190°C for the granulated fired product of Experimental Example 63 is as follows: The previous particle size range was from 14.89 mm to 15.13 mm, but in the process of increasing the firing temperature, it became denser and decreased from 14.44 mm to 13.10 mm due to firing. The average crushing strength increased from 1531N at the maximum firing temperature of 1140°C to 2355N at the maximum firing temperature of 1180°C, and was 2223N at the maximum firing temperature of 1190°C.

The change in grain size of the granulated fired body of Experimental Example 64 obtained at each maximum firing temperature of 1140°C to 1190°C was that the particle size range before firing was 14.87 mm to 15.03 mm. However, as the maximum firing temperature increased from 1140°C to 1190°C, the grain size became densified and decreased from 13.57 mm to 12.29 mm. Moreover, the average crushing strength increased from 1970 N at the maximum firing temperature of 1140°C to 4808 N at the maximum firing temperature of 1180°C, and was 4717 N at the maximum firing temperature of 1190°C.

The change in grain size of the granulated fired body of Experimental Example 65 obtained at each maximum firing temperature of 1140°C to 1190°C shows that the particle size range before firing was 14.65 mm to 14.91 mm. However, as the maximum firing temperature increased from 1140° C. to 1190° C., the grain size became denser and decreased from 13.47 mm to 12.32 mm. Further, the average crushing strength increased from 2062N at the maximum firing temperature of 1140°C to 4620N at the maximum firing temperature of 1170°C, and increased to 4800N at 1180°C. In addition, at the maximum firing temperature of 1190°C, it was 4378N.

Experimental example 67 is a comparative example in which the blending ratio of coal ash (C), electric furnace oxidized slag (B), and sewage sludge incineration ash (B) was 90:0:10. In Experimental Example 68, the blending ratio of coal ash (C), electric furnace oxidized slag (B), and sewage sludge incineration ash (B) was 82.5:7.5:10, and in Experimental Example 69, it was 80:10: This is a composition for a fired body with a rating of 10.

Compared to Experimental Example 67, the specific gravity, water absorption rate, and average crushing strength of Experimental Examples 68 and 69 showed favorable values in all of the test results of specific gravity, water absorption rate, and crushing strength in the process of increasing the temperature from 1140 ° C. Compared to the case of iron oxide, which did not have 200 mesh, improvements in specific gravity and water absorption were observed.

From this, in the production of granules of electric furnace oxidized slag (B) (200 mesh), by adding it to the composition for the fired body, it is possible to improve the function of the sewage sludge incineration ash as a medium. Coupled with this, as a result of acting as an activator that enhances the function of iron oxide as a fluxing agent, the densification of the fired body was more pronounced than when electric furnace oxidized slag (A) was blended.
In addition, by adding iron oxide to the composition for fired bodies, a plateau phenomenon in firing (firing temperature range of 1170 °C to 1190 °C). In the firing of molded products such as granules, there is a margin for temperature control during firing, which has the effect of making it easier to control the quality of the product.

Particle size of granules Experimental example 61 has a blending ratio of coal ash (A), iron oxide (disposable warmer), and sewage sludge incineration ash (B) of 82.5:7.5:10, and experimental example 62 has This is a composition for a fired body in which the blending ratio of coal ash (A), iron oxide (disposable warmer), and sewage sludge incineration ash (B) is 80:10:10. A binder and water were added to each to produce granules (nine samples for each).

In Experimental Example 70, the blending ratio of coal ash (C), disposable warmer, and sewage sludge incineration ash (B) was 82.5:7.5:10, and in Experimental Example 71, the blending ratio was 80:10:10. did. The change in particle size of the fired body obtained at each maximum firing temperature of 1140°C to 1190°C in Experimental Example 70 was that the grain size range before firing was 14.35 mm to 14.57 mm, but the maximum firing temperature was 14.35 mm to 14.57 mm. Due to the rise in temperature, the size decreased from 13.38 mm to 12.08 mm due to densification due to firing. The particle size change of the fired body obtained at each maximum firing temperature of 1140°C to 1180°C in Experimental Example 71 was that the grain size range before firing was 14.21 mm to 14.31 mm, but at the highest firing temperature Due to the increase in the temperature, the size decreased from 13.18 mm to 11.95 mm due to densification due to firing. Note that since the particle size at the maximum firing temperature of 1190° C. was 12.12 mm, there was some over-firing. Then, taking into account the tendency for the strength to increase with densification, it is preferable that the granules are granulated and molded to have a particle size of 13 mm to 15 mm, and that they are fired in the atmosphere and used as an artificial aggregate.

Regarding the particle size reduction due to densification due to firing in Experimental Example 67 and Experimental Examples 70 and 71, the measurement results of the particle size at the maximum firing temperature of 1140°C to 1180°C in the temperature raising process show that at all maximum firing temperatures, Experimental Examples 70 and 71 resulted in densification exceeding the measured value of Experimental Example 67. By adding electric furnace oxidized slag (B) to the composition for the fired body in the production of granules, it can be used as a medium for iron oxide, in combination with the function of sewage sludge incineration ash as a medium. As a result of acting as an activator to enhance the functions of In addition, when producing granules of disposable body warmers using iron oxide, adding it to the composition for the fired body promotes the densification of the fired body, which can be confirmed from the particle size reduction phenomenon caused by firing. Ta.

Compared to Experimental Examples 58, 63, and 67, which did not contain iron oxide, by adding iron oxide to the composition for fired bodies, a high specific gravity (about 2.2) and a low water absorption rate (less than 3.0%) were achieved. A plateau phenomenon (firing temperature range: 1170° C. to 1190° C.) was observed in stable firing. In the firing of molded bodies such as granules, there is a margin for temperature control during firing, which has the effect of making it easier to control the quality of the product.

The above Table 17 shows the values obtained by dividing the average value of the particle size after calcination by the median value of the particle size before calcination in Experimental Examples 58 to 71 (excluding 66), and is a reference value of the particle size ratio before and after calcination. When fired at 1180°C, in experimental examples using coal ash, electric furnace oxidized slag (B), disposable body warmers, and sewage sludge incineration ash (B), excluding Experimental Examples 58, 63, and 67, 0.82 to 0.85 and is approximately 0.84 to 0.85.

Table 18 shows the results of similar shrinkage measurements at 1180° C. using an 80:20 ratio of coal ash (B) and sewage sludge incineration ash (A). This shows that if the composition is constant, the shrinkage rate is constant even if the particle size changes due to firing at a constant temperature, and the particle size ratio before and after firing is maintained.

If the shrinkage rate at 1180° C. is 84%, and the particle size of the granulated material after firing is 5 mm to 20 mm, the granulated particle size before firing is 6 mm to 24 mm. Table 19 summarizes the compositions (unit: g) of Experimental Examples 58 to 71.

Method for selecting coal ash as the main material It is preferable that the firing temperature in the atmosphere is 1080°C to 1220°C, and the specific gravity after sintering is 1.4 to 2.4. The main coal was selected to satisfy the temperature requirement of 2.1 to 2.3. Granules obtained by firing the granules prepared according to the composition table for fired bodies (unit: g) in Table 20 six times at a temperature increase of 40°C in the maximum firing temperature range of 1020°C to 1220°C. A fired body was prepared.

This is a blending table of coal ash A, B, and C, which are the main materials, and is shown in Table 22 (unit: g). The granulated product prepared from this composition for a fired product was fired six times at a temperature increase of 10°C in the maximum firing temperature range of 1140°C to 1190°C to produce a granulated fired product. Table 23 shows the test results of specific gravity and water absorption rate (wt%) of each fired body.

The highest value of specific gravity at 1140°C is 1.541 for coal ash (A). A granulated product made of the above-mentioned various coal ash as the main material and mixed with sewage sludge incineration ash (A), in the case of the combination of Experimental Example 2, the specific gravity reaches the maximum after exceeding 1.5, which is about 2.2. The firing temperature range up to 60° C. is about 60° C., and the changes in specific gravity in other experimental examples have a similar tendency.

In the case of the calcined bodies of Experimental Examples 59, 64, and 68, which contained iron oxide and sewage sludge incineration ash (A), the firing temperature range from the specific gravity exceeding 1.6 to the maximum specific gravity of about 2.2 was The temperature was about 40° C., and the changes in specific gravity in other experimental examples had a similar tendency. Based on the above-mentioned firing results, the main material, coal ash, is a single blend of coal ash, which is obtained by artificially blending coal ash with a high melting temperature and coal ash with a low melting temperature, for example. It was possible to adjust the specific gravity by firing the granulated material produced in this way.

Using such coal ash to lower the firing temperature range to produce resource-recycling materials has the effect of leading to energy savings. Therefore, in the present invention, specifying the properties of the coal ash used as the main material (particularly the specific gravity value based on the result of firing the granules of the main material) is important for the recycling of industrial waste according to the present invention. It is an important technical element in the method.

If the specific gravity of the fired granules made of coal ash alone is 1.5 or more at a firing temperature of 1100°C, the melting temperature will be low and densification will be too rapid, making it difficult to control firing, so it is not used in the present invention. The coal ash used as the main material was coal ash whose specific gravity at the maximum firing temperature of 1100° C. of the fired body obtained by blending the coal ash alone and granulating it was less than 1.5.

In Experimental Example 75, electric furnace oxidized slag and the like were completely crushed or pulverized using a 500 μm sieve. In this experimental example, the blending ratio of coal ash (B) and sewage sludge incineration ash (A) used as a gap filler was 87:13. The mixing ratio of the crushed material and the filler material for the electric furnace oxidized slag in Experimental Example 75 was 90:10. The blending ratio of Experimental Example 76 was 80:20. The blending ratio of Experimental Example 77 was 75:25. Table 24 shows the composition, specific gravity, water absorption, and strength of Experimental Examples 75 to 77.

Regarding the physical properties of the granulated fired bodies obtained as a result of three firings at maximum firing temperatures of 1170°C, 1180°C, and 1190°C, the granulated bodies of compositions for fired bodies Experimental Example 75 and Experimental Example 76 had As the maximum temperature increased, the specific gravity increased and the water absorption rate decreased. In addition, although the crushing strength tended to increase, densification due to firing was small until the mixing ratio of the crushed material and filler material of the electric furnace oxidized slag in Experimental Example 76 for fired body composition was about 80:20. .

However, as a result of firing the granulated material with the composition of experimental example 77 for fired body composition at the maximum firing temperature of 1170°C, 1180°C, and 1190°C three times, the granulated fired body obtained at the maximum firing temperature of 1190°C was found. The specific gravity increased, the water absorption rate decreased, and the crushing strength increased. From this, the blending ratio of the crushed material and filler material of the electric furnace oxidized slag, which is the blend of Experimental Example 77 of the composition for fired bodies, is 75:25, and with this blending ratio as the reference value, the By increasing the amount of filler material, sintering and densification of the void portions by firing the granules and sintering and fixation between the pulverized materials are realized.

As a result, by using materials obtained by crushing or pulverizing industrial waste such as electric furnace oxidized slag and forming it into granules or flat plates to produce fired bodies, we will be able to further utilize industrial waste as a resource. has increased.

Claims (9)

Coal ash (a) is the main material with a content of 70% by weight or more , sewage sludge incineration ash (b) is used as a medium to promote densification by firing, and electric furnace oxidized slag is used as an iron oxide-containing component. , magnetite powder, and one or more types (c) selected from used disposable body warmers. A fired body obtained by adding a binder to the firing composition according to claim 1, granulating it or press-molding it in a mold, and then firing it in the atmosphere. Manufacturing method. 3. The method for producing a fired body according to claim 2, wherein the medium further contains one or more of copper slag and zinc slag as an iron oxide component. The method for producing a fired body according to claim 2, wherein the iron oxide component (c) in the medium is 5% to 20% by weight of the firing composition. The sewage sludge incineration ash (b) in the medium is 5% by weight or more and 20% by weight or less in the firing composition, and the iron oxide component (c) is 5% by weight or less in the firing composition. The method for producing a fired body according to claim 2, wherein the content is 10% by weight. The fired body according to any one of claims 2 to 5, wherein the coal ash (a) in the firing composition has a specific gravity of 1.5 or less when fired at 1100°C. Production method. The fired product according to any one of claims 2 to 5, which is a granulated product having a particle size of 6 mm to 24 mm, and is used as an artificial aggregate by being fired in the atmosphere. manufacturing method. Production of the fired body according to any one of claims 2 to 5, characterized in that the firing temperature in the atmosphere is 1080°C to 1220°C, and the specific gravity after firing is 1.4 to 2.4. Method. A composition for firing comprising crushed steelmaking slag, coal ash, and the medium according to any one of claims 2 to 5 is granulated or pressure-formed in a mold, and then exposed to air. 1. A method for producing a fired body, characterized in that it is obtained by firing inside a fired body.