JP2023142727A - Composition for calcination body and production method of calcination body using the same - Google Patents

Abstract

To provide a production method of a calcination body which does not require a complicated step, can make industrial solid waste into resources by a simple production method, and can produce a calcination body which is excellent in physical properties, for example, it is possible to achieve, a calcination body whose relative density is 2.5 or greater in a calcination condition of a relatively low temperature under atmosphere, the calcination body being grain bodies whose water absorption is 3% or lower, preferably 1% or lower, and whose diameter is 12 mm, and artificial aggregate whose collapse intensity is 2500 N or greater and preferably 3000 N or greater.SOLUTION: There is provided a calcination composition including, to (a) 100 pts.wt. of blast furnace slug fine powder, as a main material, as a medium fusion object for promoting a densified state by calcination, (b) 5 to 20 pts.wt. of sewage sludge incineration ash.SELECTED DRAWING: None

Description

The present invention relates to a composition for a fired body and a method for producing a fired body using the same. In particular, the present invention relates to a composition for a sintered body using industrial wastes such as blast furnace slag, sewage sludge incineration ash, and electric furnace oxidized slag, and a method for producing a sintered body using the same.

Blast furnace slag has latent hydraulic properties and solidifies when it reacts with water, increasing its strength over time, so it can be expected to have supporting capacity, has no risk of alkaline aggregate reaction, and does not contain clay or organic impurities. Therefore, like natural aggregate, it is also used as a coarse aggregate for concrete, and its use as a fine concrete aggregate is progressing. It is also used for roadbed materials, 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.

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.

Furthermore, demand for resource recovery of blast furnace slag, steelmaking slag, and non-ferrous metal slag is highly influenced by economic conditions and the content of public investment budget implementation projects, so research into further effective use of industrial waste and Technology development is an urgent issue. Achieving a production environment that makes effective use of these materials can contribute to the formation 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.

According to Non-Patent Document 1, the physical properties of currently produced blast furnace slag coarse aggregate are a specific gravity of 2.4 or more and a water absorption rate of 4.0% or less. Furthermore, since it is not a sintered body, the compressive strength of concrete using current blast furnace slag coarse aggregate is about 40 N/mm2 (91-day compressive strength) (Steel Slag Association). Since the sintered artificial aggregate of the present invention is mainly intended for use as a high-strength concrete coarse aggregate, it does not compete with currently produced blast furnace slag coarse aggregate. Then, there will be no hindrance to the utilization of recyclable resources.

Methods for producing sintered bodies and artificial aggregates using blast furnace slag have been devised for some time. For example, Patent Document 1 describes an invention of a construction material in which a blast furnace slag sintered body is made lighter by using reinforcing fibers. In addition, Patent Document 2 describes an artificial lightweight aggregate made by granulating and molding a mixed raw material made of blast furnace slag and fly ash as main raw materials, to which clay such as bentonite and optionally silicon carbide is added, and then fired. is described. However, the strength and low water absorption characteristics were insufficient.

When firing a firing composition made mainly of industrial waste to produce artificial aggregate, for example, a fired body with an average particle size of about 12 mm is obtained by firing at a low temperature of about 1200°C, and the water absorption rate is It is desired that the content is 3.0% or less and the crushing strength exceeds 3000N. However, there has been no use of blast furnace slag under these conditions as the main material. Furthermore, we would like to use it widely in civil engineering and construction materials as an improvement material that contributes to reducing environmental impact with the aim of creating a recycling-oriented society.

Katsuro Kokufu Technical Forum Effective use of resources and concrete Concrete using slag aggregate Concrete engineering vol.34 No.3 1996/3 88-93

Japanese Patent Application Publication No. 04-042872 Japanese Patent Application Publication No. 09-077543

An object of the present invention is to realize a method for producing a fired body with excellent physical properties, which enables recycling of industrial waste by a simple production method without going through complicated steps. For example, under relatively low temperature firing conditions in the atmosphere, a fired body with a specific gravity of 2.5 or more, a water absorption rate of 3% or less, preferably 1% or less, a 12mm diameter granule, and a crushing strength of 2500N or more. , preferably an artificial aggregate of 3000N or more, and a civil engineering/construction material, and a fired body with a specific gravity of 2.1 to 2.5 under atmospheric firing conditions, a water absorption rate of 10% or less, and a practical strength for civil engineering/construction. The challenge is to realize the materials.

The artificial aggregate has a rounded shape, moderate unevenness, high strength, low water absorption rate, and dense aggregate, and fine aggregate and coarse aggregate for high-strength concrete are desired.

In addition, the surface of the artificial aggregate has fine irregularities that enhance the adhesion between the aggregate interface and the cement paste, making it possible to manufacture coarse aggregate with a maximum dimension of 20 mm or 25 mm, reducing the water-cement ratio. What is possible is desired.

As a result of intensive study, the inventor provides the following invention.
[1] The main material is 100 parts by weight of pulverized blast furnace slag powder (a), and 5 to 20 parts by weight of sewage sludge incineration ash (b) is included as a medium to promote densification by firing. A firing composition characterized by:
[2] Contains 100 parts by weight of blast furnace slag powder (a) as the main material, 5 to 20 parts by weight of sewage sludge incineration ash (b) as a medium to promote densification by firing, and iron oxide. Provided is a firing composition characterized by containing, as a component, one or more selected from among electric furnace oxidized slag, Kurohama (magnetite), and red red iron (c).
[3] Obtained by adding a binder to the firing composition described in [1] or [2], granulation molding or pressure molding in a mold, and then firing in the air. Provided is a method for producing a fired body characterized by:
[4] Provides the method for producing a fired body according to [3], wherein the iron oxide component (c) in the medium is 3 to 20 parts by weight in the firing composition. do.
[5] The sewage sludge incineration ash (b) in the medium melt is 5 to 10 parts by weight in the firing composition, and the iron oxide component (c) is 5 parts by weight in the firing composition. Provided is a method for producing a fired body according to [2], characterized in that the amount is 10 parts by weight.
[6] According to any one of [3] to [5], the granulated product has a particle size of 6 mm to 24 mm, and is characterized in that it is used as an artificial aggregate by being fired in the atmosphere. Provided is a method for producing a fired body.
[7] The firing temperature in the atmosphere is 1180°C to 1220°C, the specific gravity after firing is 2.5 or more, the water absorption is 3.0% or less, and the crushing strength is 3000N or more [3 ] to [6] provide a method for producing a fired body.

The present invention provides that among various industrial wastes, sewage sludge incineration ash, iron oxide components, etc. function as a medium that promotes densification during the firing of blast furnace slag, which is the main material, and in particular, sewage sludge incineration ash is It has been discovered that even if the slag has an average particle diameter exceeding that of slag, it can be densified by firing, which is suitable, and further promotes the use of industrial waste.

Table 1 shows general values for the chemical composition of blast furnace slag. It is preferable that the particle size range is 1 μm to 100 μm, and the cumulative weight of particles with a particle size of 100 μm or less is 90% or more. The average particle size is preferably 9 to 12 μm.

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. The amount of K2O has a large influence. 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. Table 1 shows representative values of the main components of sewage sludge incineration ash.

Sewage sludge incineration ash is preferably added in an amount of 5% by weight or more and 20 parts by weight or less with respect to 100 parts by weight of blast furnace slag, either alone or when used with an iron oxide component.

Iron oxide-containing component As the iron oxide-containing component, electric furnace oxidized slag and magnetite powder 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, even when firing under conditions that are difficult to create a reducing atmosphere, gas generation that causes foaming can be relatively suppressed, firing conditions such as firing temperature can be easily controlled, and relatively high strength with a target specific gravity can be achieved. A fired body is obtained. The iron oxide-containing component is preferably used as a fluxing agent in an amount of 5 parts by weight or more and 20 parts by weight or less based on 100 parts by weight of blast furnace slag for both sewage sludge and 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) and red iron oxide were used.

It is preferable that the electric furnace oxidized slag and magnetite powder have an average particle size smaller than that of blast furnace slag. 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 a 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.

One or more types (c) selected from electric furnace oxidized slag, magnetite powder, red iron oxide is present in an amount of 3 to 20 parts by weight, based on 100 parts by weight of blast furnace slag in the firing composition, and 3 parts by weight. ~10 parts by weight is more preferred.

If the granulated product has a particle size of about 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. There is. 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 This is because if it is larger than 24 mm, it takes time to bake, and if it is smaller than 6 mm, it is impractical. In addition, since the material used for manufacturing this artificial aggregate is mainly granulated powder of blast furnace slag, alkali-silica reaction (ASR) is unlikely to occur even when used as concrete aggregate.

A firing composition containing blast furnace slag and a medium such as sewage sludge incineration ash was granulated or press-molded in a mold and fired. The firing temperature in the atmosphere is 1180° C. to 1220° C., and the specific gravity after firing is preferably 2.1 to 2.4, more preferably 2.5 or more. This is because stable firing is possible within this range.

Water absorption rate as artificial aggregate When the present invention is used as an artificial aggregate, the water absorption rate is preferably 3.0% or less at a firing temperature of 1190°C to 1210°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 12% with a specific gravity of about 2.1 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. In addition, it can be used in place of natural stone as a filter material in filtration facilities to further purify the treated water in the second sedimentation tank in sewage treatment facilities. At this time, the material is required to have high strength (3000N or more).

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 3000N or more, and particularly preferably 3400N or more.

The present invention provides a composition for sintering using waste materials such as blast furnace slag (a), sewage sludge incineration ash (b), electric furnace oxidation slag, and magnetite powder by a simple manufacturing method without going through complicated steps. For example, under atmospheric firing conditions, a fired body with a specific gravity of 2.5 or more, a water absorption rate of 3% or less, preferably 1% or less, a sphere with a diameter of about 12 mm, and a crushing strength of 2500N or more, Preferably, by using artificial aggregate of 3000 N or more and firing conditions in the atmosphere, a fired body with a specific gravity of about 2.5 can provide a civil engineering and construction material with a water absorption rate of 10% or less and a practical strength.

The present invention uses pulverized blast furnace slag powder as the main material, adjusts and blends sewage sludge incineration ash and/or iron oxide, blended water, and a caking agent, and then mixes, shapes, and dries the mixture, followed by firing. This material can be used as an artificial aggregate for concrete and other construction and civil engineering materials.

This artificial aggregate is characterized by its rounded shape, moderate unevenness, high strength, low water absorption, and dense aggregate. Artificial aggregates with such characteristics can be used as fine aggregates and coarse aggregates for high-strength concrete.

Furthermore, since the surface of the artificial aggregate according to the present invention has minute irregularities, it has the effect of increasing the adhesion between the aggregate interface and the cement paste. Furthermore, river gravel has a round shape and good filling properties, so it is possible to use aggregate with a maximum aggregate size of 20 or 25 mm, but in recent years, it has become difficult to collect such natural gravel. Have difficulty. However, since the artificial aggregate of the present invention is manufactured in a spherical shape, it has good filling properties similar to gravel aggregate, and can also be used to manufacture aggregates with a maximum dimension of 20 or 25 mm. Increasing the maximum aggregate size also has the effect of reducing the water-cement ratio.

Compared to ordinary cement concrete, blast furnace cement concrete has a lower initial strength and a slower hydration rate, making it more susceptible to the effects of low temperatures, and its carbonation rate is faster, so it is necessary to increase the cover of the structure. . Additionally, architectural structures are characterized by columns, beams, floor slabs, and walls having small dimensions and thinness. In response to these issues, when using blast furnace cement concrete, quality can be ensured by making the parts that make up the building frame larger and thicker, and by taking a longer curing period after pouring the concrete. It becomes inevitable. However, from the beginning, construction work was carried out on the assumption that blast furnace cement concrete would not be used in the framework of such buildings. Therefore, even in ordinary cement concrete, the use of the artificial aggregate of the present invention becomes a new use of recyclable resources.

When the main firing composition is fired to produce artificial aggregate, for example, if a fired body with an average particle size of about 13.6 mm is obtained by firing at a firing temperature of about 1200°C, the physical property is a water absorption rate of 1.0. % or less, the crushing strength is 3900N. 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. First, we produced a fired product that requires two components: granulated blast furnace slag and sewage sludge. Next, a fired body was produced in which an iron oxide-containing component was added.

Blast Furnace Slag As the blast furnace slag (a), Esment manufactured by Esment Kanto Co., Ltd. was used. Table 2 shows the chemical composition calculated by fluorescent X-ray analysis. The particle diameters are 37 μm at 95% frequency, 19 μm at 76% frequency, and 9.2 μm at 50% frequency.

The sewage sludge incineration ash used was incineration ash obtained from an incinerator with an incineration temperature of 850° C. in the freeboard part of the incinerator. 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 266 μm and the cumulative weight of particles with a particle size of 89 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 component analysis values (fluorescent X-ray analysis) of the main substances of the sewage sludge incineration ash are shown in Table 3.

As the electric furnace oxidation slag, product name: CK Hyper No. 7 (manufactured by Hoshino Sansho Co., Ltd.) was used.

The electric furnace oxidized slag has a particle size range of 300 μm or less and is crushed for 10 minutes using a dedicated crushing device (disk-type vibrating mill) to form a composition material for fired bodies with a particle size of 200 mesh or less (74 μm). The opening sieve was completely passed through. 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 the sewage sludge incineration ash.

Using each of the above materials, predetermined amounts (unit: g) of the binder and water shown in Table 5 were added to produce granules (granulation diameter 13 mm, 10 samples for each experimental example).

This was fired according to the firing pattern described above, with the upper limit of firing temperature set between 1170°C and 1220°C. Table 6 shows the physical property test results of the specific gravity and water absorption of the obtained fired body.

The firing temperature pattern is to raise the temperature from room temperature to 1000°C in 120 minutes, and to increase the maximum temperature of each firing from 1170°C to 1220°C in 75 minutes to 110 minutes depending on each temperature, and then, The holding time of each maximum firing temperature was 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, the specific gravity and water absorption rate are measured in accordance with JIS A 1110 (Testing method for density and water absorption rate of coarse aggregate), and the measurement is carried out using Shimadzu analytical balance AUX120 and specific gravity measurement kit SMK-401 (Shimadzu Co., Ltd. (manufactured by Seisakusho) was used. The specific gravity is a value measured using SMK-401, and is the same value as the value expressed in density (g/cm ³ ). Furthermore, the crushing strength was measured using a testing machine model 5566 (10 kN) manufactured by Instron Japan in accordance with JSCE-C505 (compressive load test method for high-strength fly ash artificial aggregate). Table 6 shows the specific gravity and water absorption rate of the fired body. Displays the average value of the measured values and does not take into account significant figures.

Table 7 shows the physical property test results of crushing strength (N). The crushing strength was the average value of the measurement results of 5 pieces of each granulated and fired product, and the maximum crushing strength of none exceeded the limiter setting of 4500N.

Effect of adding sewage sludge alone Changes in specific gravity and water absorption rate of the fired body Specific gravity was used as a measure of the overall densification of the fired body, and water absorption rate was used as a measure of the waterproof densification of the surface. In Experimental Example 1, the specific gravity varied within the range of 1.942 to 2.118 after six firings at the maximum firing temperature of 1170°C to 1220°C. Similarly, the change in water absorption was within the range of 10.244% to 15.576%. Moreover, the crushing strength was in the strength range of 776N to 1051N. In Experimental Example 2, the specific gravity after six firings increased from 2.066 to 2.660 during the heating process to the highest firing temperature, and the water absorption rate similarly decreased from 12.522% to 0.855%. Ta. Furthermore, the highest crushing strength was 3065N at the maximum firing temperature of 1210°C. In Experimental Example 3, the specific gravity after six firings was the highest at 2.369 when the maximum firing temperature was 1190°C, and the specific gravity gradually decreased in the process of increasing the maximum firing temperature thereafter. Similarly, the water absorption rate was the lowest at 2.757%, and then tended to increase. Furthermore, the highest crushing strength was 2864N at the maximum firing temperature of 1180°C.

The results of firing the granules in which blast furnace slag and sewage sludge incineration ash were blended in Experimental Examples 2 and 3 showed that densification was more pronounced than in Experimental Example 1. In addition, in Experimental Example 3, the amount of sewage sludge incineration ash was increased compared to Experimental Example 2, but Experimental Example 3 was superior in densification until the maximum firing temperature of 1190°C (effect of low firing melting temperature). In each firing up to 1220°C, Experimental Example 2 had superior results.

In other words, for a granulated product containing blast furnace slag and sewage sludge incineration ash, the firing melting temperature of the granulated product was lower than that for a granulated product fired from only blast furnace slag, and in Experimental Example 2, a remarkable improvement in densification was observed. It was done. However, even if the amount of sewage sludge incineration ash was increased, the increase in specific gravity was relatively small, and the effect of reducing water absorption peaked around Experimental Example 2. Note that even when blast furnace slag with a large particle size other than Esment was used, this tendency was remarkable, especially when the amount of sewage sludge incinerated ash was increased beyond Experimental Example 3, and especially when fired at a high temperature of 1180 ° C. or higher.

Effect of adding electric furnace oxidized slag alone Changes in the specific gravity and water absorption rate of the fired body In Experimental Example 4, the specific gravity increased from 2.047 to 2.641 and the water absorption rate increased from 13.385% to 2.64% after 6 firings. It dropped to 455%. Furthermore, the highest crushing strength was 2872N at the maximum firing temperature of 1200°C.
In Experimental Example 5, the specific gravity increased from 2.094 to 2.657 and the water absorption rate decreased from 12.349% to 2.058% after 6 firings. Furthermore, the highest crushing strength was 3045N at the maximum firing temperature of 1210°C.
In Experimental Example 6, after 6 firings, the specific gravity increased from 2.188 to 2.793 at the maximum firing temperature of 1210°C, and similarly, the water absorption rate increased from 10.444% to 0.9% at the maximum firing temperature of 1210°C. It was the lowest at 339%. Moreover, the crushing strength was around 2800N at a maximum firing temperature of 1200°C to 1220°C.
The firing results of the granules in which electric furnace oxidation slag was mixed with blast furnace slag in Experimental Examples 4, 5, and 6 showed that densification was more pronounced (effect of lower firing melting temperature) than in Experimental Example 1. became.

That is, the granules containing blast furnace slag and electric furnace oxidation slag have a lower firing melting temperature than Experimental Example 1 of the fired body in which only blast furnace slag is added, but Experimental Examples 4, 5, In Example 6, even if the amount of electric furnace oxidized slag was increased, the increase in specific gravity was small, and the water absorption rate in Experimental Examples 4 and 5 was inferior to that in Experimental Example 2. In Experimental Example 6, none had a crushing strength of 3000N. In particular, this tendency is remarkable in the results of using blast furnace slag with a large particle size other than Esment, and the effect of sewage sludge incineration ash alone exceeds the effect of adding electric furnace oxidized slag alone. It became.

Effect of addition of sewage sludge incineration ash and electric furnace oxidized slag Changes in specific gravity and water absorption of the fired body In Experimental Example 7, the specific gravity was the largest from 2.071 to 2.653 at the maximum firing temperature of 1210°C after 6 firings. Similarly, the water absorption rate decreased from 12.423% to 0.808% at the maximum firing temperature of 1210°C. Moreover, the crushing strength was the highest at 3370 N at the maximum firing temperature of 1200°C.
In Experimental Example 8, after 6 firings, the specific gravity increased from 2.178 to 2.629 at the maximum firing temperature of 1200°C, and similarly, the water absorption rate increased from 8.106% to 0.9% at the maximum firing temperature of 1210°C. It was the lowest at 719%. Moreover, the crushing strength was the highest at 3479N at the maximum firing temperature of 1190°C.
In Experimental Example 9, after 6 firings, the specific gravity ranged from 2.284 to 2.643 at the maximum firing temperature of 1190°C, and the water absorption rate increased from 8.106% to 0.6% at the maximum firing temperature of 1210°C. It was the lowest at 540%. Moreover, the crushing strength was the highest at 3599N at the maximum firing temperature of 1190°C.
In Experimental Example 10, after 6 firings, the specific gravity ranged from 2.334 to 2.659 at the maximum firing temperature of 1190°C, and the water absorption rate increased from 6.952% to 0.0% at the maximum firing temperature of 1210°C. It was the lowest at 226%. Moreover, the crushing strength was the highest at 3599N at the maximum firing temperature of 1190°C.

In other words, a granulated material made by adding 5 parts by weight of blast furnace slag and sewage sludge incineration ash and further adding electric furnace oxidized slag is the same as the sintered body experimental example 1 with only blast furnace slag added, and the addition amount of sewage sludge incineration ash. Compared to Experimental Example 2 of the fired body containing 5 parts by weight, Experimental Examples 7, 8, 9, and 10 all showed an increase in specific gravity and a decrease in water absorption at a lower maximum firing temperature, and the addition of electric furnace oxidized slag The water absorption rate decreased as the amount increased. The specific gravity remains stable even if the amount of electric furnace oxidized slag increases, and the overall densification changes are small. In addition, the crushing strength exceeded 3000N even at the lowest firing temperature. These results made it possible to set a wide range of firing temperatures during the production of artificial aggregates, making them suitable for use as artificial aggregates.

Effect of addition of sewage sludge incineration ash and magnetite or red iron oxide Changes in specific gravity and water absorption of the fired body The compositions of the magnetite or red iron oxide used are shown in Tables 8 and 9. To this additive material, predetermined amounts (unit: g) of the binder and water shown in Table 10 were added to produce granules (18 samples for each).

Granules having the composition shown in Table 10 were molded using starch paste as a binder and a predetermined amount of water. This was fired according to the firing pattern described above, with the upper limit of firing temperature set between 1170°C and 1220°C. Tables 11 and 12 show the physical property test results of specific gravity and water absorption of the fired body.

Effect of adding Kurohama (magnetite) or red iron oxide (iron oxide) Changes in specific gravity and water absorption rate of fired product Experimental example 11 (Kurohama blend) was fired six times. The specific gravity increased from 2.142 to 2.654 at the maximum firing temperature of 1210°C, and similarly, the water absorption decreased from 11.315% to the lowest at 2.131% at the maximum firing temperature of 1220°C. In addition, Experimental Example 13 (compounded with Red Red Garlic) was fired six times. The specific gravity increased from 2.167 to 2.672 at the maximum firing temperature of 1210°C, and similarly, the water absorption decreased from 10.887% to the lowest at 1.615% at the maximum firing temperature of 1220°C.

For both, the specific gravity increased and the water absorption rate decreased as the maximum firing temperature increased. Further, although there is a wide firing temperature range in which a specific gravity of 2.5 or more and a water absorption of 3% or less can be stably obtained, it was not possible to achieve a water absorption of 1% or less.

Effect of addition of sewage sludge incineration ash and Kurohama (magnetite) or red iron oxide (iron oxide) Changes in specific gravity and water absorption rate of fired body Experimental example 12 (Kurohama combination) was fired six times. The specific gravity increased from 2.137 to 2.684 at the maximum firing temperature of 1190°C, and similarly, the water absorption rate decreased from 11.009% to the lowest of 0.170% at the maximum firing temperature of 1200°C. In addition, Experimental Example 14 (compounded red iron oxide) was fired six times. The specific gravity increased from 2.172 to 2.638 at the maximum firing temperature of 1190°C, and similarly, the water absorption rate decreased from 11.094% to the lowest at 0.341% at the maximum firing temperature of 1210°C.

Both were melted at a relatively low maximum firing temperature, had a specific gravity of over 2.6, and a water absorption rate of less than 1.0%, which were suitable for use as aggregates.

Particle size dependence of granules Spherical granules (10 samples each, unit: g) of the composition shown in Table 13 were fired at a maximum firing temperature of 1200°C to obtain an average particle size of 8.8 mm to 16 mm. A sintered body for artificial aggregate of .7 mm was produced. Table 14 shows the measurement results of particle size shrinkage, specific gravity, water absorption, and crushing strength.

To 100 parts by weight of blast furnace slag (Esment), 5 parts by weight of sewage sludge incineration ash was added, and to this were added 5 parts by weight of electric furnace oxidized slag (Experimental Examples 15, 16, 17) and 7.25 parts by weight (Experimental Examples 15, 16, 17). This is the composition in which Examples 18, 19, and 20) were added. The shrinkage rate is stable at around 0.87 regardless of the particle size. Further, even if the particle size is changed, the specific gravity remains at 2.5 to 2.6, and the water absorption rate is low at less than 3.0%. In all experimental examples, the crushing strength increased as the particle size increased.

As a result, by using materials obtained by crushing or pulverizing industrial waste such as blast furnace slag, sewage sludge incineration ash, electric furnace oxidation slag, etc., and forming it into granules or flat plates, etc., and manufacturing fired bodies, Furthermore, the use of industrial waste as resources has increased.

Claims (7)

For firing, which is characterized by containing 100 parts by weight of pulverized blast furnace slag powder (a) as the main material and 5 to 20 parts by weight of sewage sludge incineration ash (b) as a medium to promote densification by firing. Composition. Using 100 parts by weight of blast furnace slag pulverized powder (a) as the main material, 5 to 20 parts by weight of sewage sludge incineration ash (b) as a medium to promote densification by firing, and an iron oxide-containing component, an electric furnace A firing composition comprising (c) one or more selected from among oxidized slag, Kurohama (magnetite), and red iron. It is characterized in that it is obtained by adding a binder to the composition for firing according to claim 1 or claim 2, granulating it or molding it under pressure in a mold, and then firing it in the atmosphere. A method for producing a fired body. 4. The method for producing a fired body according to claim 3, wherein the iron oxide component (c) in the medium is in an amount of 3 to 20 parts by weight in the firing composition. The sewage sludge incineration ash (b) in the medium is 5 to 10 parts by weight in the firing composition, and the iron oxide component (c) is 5 to 10 parts by weight in the firing composition. 2. The method for producing a fired body according to claim 2, characterized in that: The fired product according to any one of claims 3 to 5, wherein the granulated product has a particle size of 6 mm to 24 mm, and is used as an artificial aggregate by being fired in the atmosphere. manufacturing method. Claims 3 to 3, characterized in that the firing temperature in the atmosphere is 1180°C to 1220°C, the specific gravity after firing is 2.5 or more, the water absorption is 3.0 parts by weight or less, and the crushing strength is 3000N or more. The method for producing a fired body according to claim 6.