JP2008049330A - Manufacturing method of fired product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of fired products which makes it possible to use waste, which particularly contain much arsenic, such as industrial waste. <P>SOLUTION: In manufacturing a fired product which keeps hydraulicity modulus (H. M.) smaller than 0.4 and is made from one or more materials selected from industrial waste, domestic waste and soil, an aqueous solution or suspension of one or more materials selected from a calcium salt, a magnesium salt and an iron-based powder material is sprayed to a fired product which is cooled to 800°C or lower; or in manufacturing a fired product, which keeps hydraulicity modulus (H. M.) smaller than 0.4 and is made from one or more materials selected from industrial waste, domestic waste and soil, a fired product, which is cooled to 800°C or lower, is fed to an aqueous solution or suspension of one or more materials selected from a calcium salt, a magnesium salt and an iron-based powder material. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a calcined product having a hydraulic modulus (H.M.) of less than 0.4, using industrial waste or construction waste as a main raw material.

The amount of soil and residual soil generated from construction sites and construction sites, industrial waste and general waste reaches millions of tons per year, most of which is landfilled without being effectively used. This is the current situation. In recent years, the landfill disposal site on the receiving side has become increasingly depleted, and all the generated waste cannot be received.
In addition, the costs necessary for disposing of these materials are also increasing year by year, and from such a situation, social problems such as illegal dumping of waste have also occurred.

Conventionally, as an effective use method of waste, coal ash is put into a rotary kiln controlled according to the operating conditions of firing temperature 1100-1400 ° C, residence time 20-120 minutes, kiln fullness 2-10%, depending on the type and properties Then, a method for producing an artificial aggregate that is fired while rolling granulation (Patent Document 1) or a method for producing an artificial aggregate by firing using fly ash as a raw material, wherein bentonite and a composition preparation material A mixture was prepared by mixing with ash, and the chemical composition after firing was adjusted to 20 to 80% by weight of silica and 10 to 35% by weight of calcium oxide. A method for producing an artificial aggregate characterized by firing (Patent Document 2) has been proposed.
However, the artificial aggregates described in Patent Documents 1 and 2 have a problem that the amount of arsenic eluted is large, and it is difficult to use waste containing a large amount of arsenic as a raw material.
Japanese Examined Patent Publication No. 62-24370 JP-A-10-29841

  Accordingly, an object of the present invention is to provide a method for producing a baked product that makes it possible to use industrial waste and the like, in particular waste containing a lot of arsenic.

  As a result of intensive investigations in view of such circumstances, the present inventors, as a result of manufacturing a fired product having a specific range of hydraulic modulus (HM), an aqueous solution of a specific metal salt or a fired product cooled to 800 ° C. or lower. It was found that the amount of arsenic elution from the calcined product can be reduced by spraying the suspension or charging the calcined product cooled to 800 ° C or lower into an aqueous solution or suspension of a specific metal salt. Completed the invention.

That is, in the production of a fired product having a hydraulic modulus (HM) of less than 0.4, using one or more selected from industrial waste, general waste and soil as a raw material,
A fired product cooled to 800 ° C. or lower is sprayed with one or more aqueous solutions or suspensions selected from calcium salts, magnesium salts, and iron-based powder materials.
In addition, the present invention, in the production of a fired product having a hydraulic modulus (HM) of less than 0.4 using one or more selected from industrial waste, general waste and soil as a raw material,
A fired product cooled to 800 ° C. or lower is charged into one or more aqueous solutions or suspensions selected from calcium salts, magnesium salts, and iron-based powder materials.

According to the present invention, waste containing a large amount of arsenic can be used as a raw material. In addition, the calcined product produced in the present invention is excellent in the ability to fix lead and Cr ⁶⁺ , and can be used in large quantities as a raw material containing a large amount of these, thus promoting the effective use of waste. Can contribute.

The method for producing a fired product according to the present invention has a hydraulic modulus (HM) of less than 0.4 (preferably 0.25 or less, particularly preferably 0.2 or less) using at least one selected from industrial waste, general waste and soil as a raw material. In the production of the fired product, 1) spraying one or more aqueous solutions or suspensions selected from calcium salt, magnesium salt and iron-based powder material to the fired product cooled to 800 ° C. or lower, or 2) 800 ° C. The fired product cooled below is charged into one or more aqueous solutions or suspensions selected from calcium salts, magnesium salts, and iron-based powder materials.
When the hydraulic modulus of the fired product is 0.4 or more, it is necessary to add limestone or the like to the raw material for component adjustment, and the amount of waste or the like used as the raw material tends to decrease. In addition, a fired product having a hydraulic modulus of 0.4 or more has a high ability to fix arsenic, and thus there is little need to spray the specific aqueous solution or suspension.

As the chemical composition of the calcined product, CaO is preferably 1 to 28% by mass, particularly preferably 1 to 22% by mass, and more preferably 1 to 17% by mass; SiO ₂ is 30 to 80% by mass, particularly 35 to 75% by mass. Further, it is preferably 40 to 70% by mass; Al ₂ O ₃ is preferably 5 to 40% by mass, particularly preferably 10 to 35% by mass, and further preferably 15 to 30% by mass; Fe ₂ O ₃ is 1 to It is preferably 12% by mass, particularly 1 to 10% by mass, and more preferably 1 to 8% by mass. Within these ranges, it is suitable for obtaining a fired product having a hydraulic modulus of less than 0.4.

  As a raw material of the baked product, one or more selected from industrial waste, general waste, and soil can be used. Industrial waste includes, for example, raw consludge, various sludges (eg, sewage sludge, purified water sludge, construction sludge, steel sludge, etc.), construction waste, concrete waste, boring waste soil, various incineration ash (eg, coal ash, incineration) Fly ash, molten fly ash, etc.), foundry sand, rock wool, waste glass, blast furnace secondary ash and the like. Examples of the general waste include sewage sludge dry powder, municipal waste incineration ash, and shells. Examples of construction generated soil include soil and residual soil generated from construction sites and construction sites, waste soil and contaminated soil, and those classified.

Further, in the present invention, as the raw material of the fired product, CaO raw material such as limestone, quicklime and slaked lime, SiO ₂ raw material such as silica and clay, Al ₂ O ₃ raw material such as clay, Fe ₂ such as iron cake and iron cake O ₃ raw materials can be used.
In order to reduce the weight of the fired product, foaming aids (silicon carbide, carbon, etc.), foaming raw materials (pearlite, expanded shale, etc.) can be used.
In the present invention, from the viewpoint of promoting effective utilization of waste, it is preferable to use 70% by mass or more of at least one selected from industrial waste, general waste, and soil as a raw material for the fired product.

In the production of the fired product, first, the raw materials are blended and mixed so that the hydraulic modulus (HM) is less than 0.4. The mixing of the raw materials can be performed using a known mixer such as a Nauter mixer or an air blending silo, and may be either a continuous type or a batch type.
In addition, when using raw materials with coarse particles, or when it is desired to increase the degree of mixing, it is possible to use a tube mill or other pulverizer, and any known pulverizer can be either a continuous type or a batch type. It can also be used. The pulverization and mixing time is preferably about 30 minutes to 1 hour from the viewpoint of economy and mixing properties, and may be appropriately set according to the equipment used.

  The mixed raw material can be obtained in a powdery and / or granular state of 20 mm or less, preferably 10 mm or less, preferably in a rotary kiln and fired while granulating to obtain a fired product.

The raw material can be put into the rotary kiln in the form of powder, but there are problems in handling such as when dusting and the surrounding environment need to be taken into consideration, such as when feeding it into the kiln through a belt feeder from an outdoor hopper. If there is a possibility that it will occur, the raw material powder may be sized to a particle size of 20 mm or less, preferably 10 mm or less, and charged into a rotary kiln.
At this time, a pan pelletizer or an extrusion molding machine can be used for sizing, but these are not preferable from the viewpoint of the skill required and equipment cost, for example, using a pug mill or a screw feeder, It is preferable to spray water directly on the raw material transport route or the raw material being sized because the equipment can be simplified and no special skills are required. In addition, the control of the particle size of the sized product can be adjusted by the amount of water spray, and the optimal water spray amount varies depending on the fineness and water content of the raw material powder. It is preferable to do this.

  The granulated product of the raw material powder may have any shape as long as the particle size is 20 mm or less, and after sizing, a product adjusted to 20 mm or less by crushing or classification may be used. If the particle size of the sized product is 20 mm or less, it can be fired uniformly to the inside, which is preferable.

The powdery raw material thus mixed or the granular raw material adjusted to 20 mm or less is preferably fired in a rotary kiln.
When a rotary kiln is used, it is easy to obtain a fired product of stable quality continuously, and it is suitable for industrial production. In addition, a synergistic effect by adjusting the blending of the above raw materials is combined to produce a fired product extremely stably. It becomes possible to do. It is also preferable from the viewpoint of effective utilization of idle facilities in the cement industry.

Firing of the fired product using the rotary kiln is preferably performed at 800 to 1500 ° C., particularly 1150 to 1350 ° C. If the quality of the desired fired product (absolute density, water absorption rate, etc.) is taken into consideration, it can be adjusted appropriately. good.
If the firing temperature is less than 800 ° C., sufficient firing is not performed, and there is a concern that the raw material may be discharged without being granulated, which is not preferable, and if it exceeds 1500 ° C., the raw material is melted, which hinders operation. Therefore, it is not preferable.

The rotary kiln may be provided with a raw material circulation preheating facility such as a cyclone, a preheater, a waste heat boiler, a pulverizing facility, a drying facility, a dust collecting facility, etc. in the exhaust system. Moreover, what provided the lifter in the kiln bottom, and what added processing, such as narrowing or expanding the internal diameter of a rotary kiln on the way, may be used.
In the firing of the fired product of the present invention, acid gas may be generated, so it is desirable to attach an exhaust gas purification treatment facility to the rotary kiln.

  As fuel, if it is generally used, such as heavy oil, pulverized coal, reclaimed oil, LPG, NPG, etc., it can be used individually or in mixture, and the amount of penetration is set so that it may become a predetermined calcination temperature. adjust. In recent years, waste plastics, waste tires, waste wood, meat and bone powder and the like have been used as a fuel substitute in cement kilns, but these may be used as part of the fuel.

The firing time in the rotary kiln is preferably approximately 15 to 120 minutes from the viewpoint of economy, and may be appropriately adjusted so that a fired product of a predetermined quality is obtained. Further, the O ₂ partial pressure in the rotary kiln at the time of firing is not particularly limited, and may be adjusted to 1 to 12% which is a general firing range. Also, when firing in a rotary kiln that does not have a material circulation system such as a cyclone, adjust the wind speed at the bottom of the rotary kiln kiln to approximately 5 m / s or less in order to prevent the material from scattering outside the system. Is preferred.

During firing, an anti-fusing material can be blown from before the kiln of the rotary kiln for the purpose of further improving the quality of the fired product and for more stable operation.
As the anti-fusing material, silica powder, alusite, alumina, cement powder, alite, belite powder and the like, which are the main minerals of cement, can be used.

  It is preferable to use an anti-fusing material having an average particle size of 10 to 1000 μm because the anti-fusing effect is easily obtained, and the higher the purity, the better. If the average particle size of the anti-fusing material is less than 10 μm, it is highly likely that it will be used as a raw material during firing and incorporated into the sintered product, reducing the effect as an anti-fusing material and reducing the quality of the fired product. It is not preferable to occur. When the average particle size of the anti-fusing material exceeds 1000 μm, the wear of the feeding site and the like is remarkable, and replacement of these consumable sites and parts is not preferable. Further, if the average particle diameter of the anti-fusing material exceeds several millimeters, the effect as the anti-fusing material is reduced, and separation from the one fused to the fired product becomes difficult.

The method for blowing the anti-fusing material is not particularly limited as long as a predetermined amount of the anti-fusing material can be sprayed on the burning point. It is preferable to insert and blow the anti-fusing material with a pneumatic pump such as an ejector or a transport pump such as a mono pump because the apparatus can be simplified.
Moreover, it is preferable that the blowing amount of the anti-fusing material is 3 to 10% by mass with respect to the mixed raw material fed into the rotary kiln because the effect as the anti-fusing material can be sufficiently obtained.

  A sintering aid can be used in firing the fired product. Sintering aid is added to promote the sintering reaction. If the waste, which is the main raw material, already has sinterability, it is not necessary to add it. When it is not possible to ensure sufficient sinterability, it is preferable to add a sintering aid.

Examples of the sintering aid include clay, kaolin, bentonite, various Al ₂ O ₃ sources, cement, and the like. MgO also has an effect of promoting sintering, and Mg (OH) ₂ and MgCO ₃ , or CaCO ₃ · MgCO ₃ (dolomite), MgO · Al ₂ O containing MgO as well as MgO. ₃ (spinel), 2MgO · SiO ₃ (forsterite), etc. are also suitable. Further, ferronickel slag, which is a steel by-product, is not only a high content of MgO but also a more suitable material from the viewpoint of its effective use.

  It is known that oxides and composite oxides of alkali metals such as potassium and sodium, such as sodium carbonate and potassium carbonate, also have an effect of promoting the sintering reaction. Also suitable are feldspars such as feldspars, nitrates, mica and meteorites. Waste glass and red mud are also suitable materials from the viewpoint of their effective use.

The particle size of the sintering aid is preferably an average particle size of 1 to 300 μm, particularly preferably an average particle size of 1 to 50 μm, in view of reactivity with wastes and the like. When exceeding 300 micrometers, what adjusted the particle size by grinding | pulverization etc. can be used.
If the particle size of the sintering aid is less than 1 μm, the cost of pulverization and the like will increase, which is not preferable, and if it exceeds 300 μm, the reactivity with the waste etc. will deteriorate and the effect as a sintering glaze will not be obtained. It is not preferable.

The addition amount of the sintering aid is preferably 0.1 to 10% by mass for MgO and 0.1 to 10% by mass for R ₂ O as oxide-converted values of the sintering aid component elements in the fired product. R ₂ O is a generic name for alkali metal oxides, and can be expressed as R ₂ O (mass%) = Na ₂ O (mass%) + 0.685 K ₂ O (mass%).
If MgO is 0.1 to 10% by mass, the effect as a sintering aid is sufficiently obtained, which is preferable. When R ₂ O is 0.1 to 10% by mass, the effect as a sintering aid is sufficiently obtained, and the generation of a liquid phase at the time of firing is not abrupt, and stable operation can be performed.

The fired product fired in the rotary kiln is cooled using, for example, an air quenching cooler used in a cement clinker manufacturing plant.
In the present invention, 1) one or more aqueous solutions or suspensions selected from calcium salts, magnesium salts and iron-based powder materials are sprayed on the fired product cooled to 800 ° C. or lower, or 2) at 800 ° C. or lower. The cooled fired product is put into one or more aqueous solutions or suspensions selected from calcium salts, magnesium salts, and iron-based powder materials.
By spraying an aqueous solution or suspension of the specific metal salt, the amount of arsenic eluted from the fired product can be reduced.
The temperature of the calcined product when spraying an aqueous solution or suspension of the specific metal salt is 800 ° C. or less (preferably 600 ° C. or less, particularly preferably 400 ° C. or less). If the temperature of the calcined product exceeds 800 ° C, when spraying an aqueous solution or suspension, cracks, etc. occur in the calcined product, causing an increase in the water absorption rate and the reduced pressure water absorption rate, and a decrease in the crushing load. This is not preferable.

In the present invention, calcium hydroxide, calcium phosphate, and the like can be used as the calcium salt. Among these, calcium hydroxide is preferable from the viewpoint of reducing arsenic elution.
As the magnesium salt, magnesium hydroxide, magnesium phosphate, or the like can be used. Among them, magnesium hydroxide is preferable from the viewpoint of reducing arsenic elution. Iron-based powder materials include iron oxide (FeO, Fe ₂ O ₃ etc.), iron powder, iron sulfate (FeSO ₄ , Fe ₂ (SO ₄ ) ₃ etc.) and iron chloride (FeCl ₂ , FeCl ₃ etc.) Among them, iron powder or a divalent iron compound is preferable from the viewpoint of reducing arsenic elution, and iron powder or ferrous chloride (FeCl ₂ ) is particularly preferable. Of these, those that are hardly soluble in water such as calcium hydroxide, magnesium hydroxide and iron powder are used in suspension (dispersion medium is water) and are soluble in water such as ferrous sulfate and ferrous chloride. The salt of is used in an aqueous solution.

  In the present invention, when the aqueous solution is sprayed on the fired product or when the fired product is put into the aqueous solution, the amount of the metal salt per 100 kg of the fired product is 0.01 to 10 kg (more preferably 0.1 to 7 kg, particularly preferably 0.2 to It is preferable to adjust the concentration of the aqueous solution, the spray amount of the aqueous solution, and the input amount of the fired product into the aqueous solution so as to be 5 kg. If the amount of the metal salt per 100 kg of the fired product is less than 0.01 kg, the effect of reducing the arsenic elution amount from the fired product is reduced, which is not preferable. Even if the amount of the metal salt per 100 kg of the baked product exceeds 10 kg, the effect of reducing the amount of arsenic eluted from the baked product is not improved.

In the present invention, when a suspension is used, the average particle diameter of the metal salt or the like in the suspension is preferably 1 to 100 μm, and more preferably 5 to 60 μm. If the average particle size of the metal salt or the like is less than 1 μm, the cost for pulverization or the like increases, which is not preferable. If the average particle diameter of the metal salt or the like exceeds 100 μm, the metal salt or the like is liable to precipitate, making it difficult to prepare a suspension and spraying the suspension becomes difficult.
When the suspension is sprayed on the fired product or when the fired product is put into the suspension, the amount of metal salt, etc. per 100 kg of the fired product is 0.01 to 10 kg (more preferably 0.1 to 7 kg, particularly preferably 0.2. It is preferable to adjust the concentration of the suspension, the spray amount of the suspension, and the amount of the fired product to be introduced into the suspension so that the amount is 5 kg). If the amount of metal salt or the like per 100 kg of the fired product is less than 0.01 kg, the effect of reducing the arsenic elution amount from the fired product is reduced, which is not preferable. Even if the amount of metal salt or the like per 100 kg of the baked product exceeds 10 kg, the effect of reducing the amount of arsenic eluted from the baked product is not improved. In addition, when spraying suspension, it is preferable to make the density | concentration of suspension into 40 mass% or less. When the concentration of the suspension exceeds 40% by mass, the viscosity of the suspension increases and it becomes difficult to spray.

The fired product produced in the present invention may be dried after spraying the above-mentioned specific aqueous solution or suspension, or may not be dried. However, in order to improve conveyance and handling properties, the fired product is dried. It is preferable to do. The drying method is not particularly limited.
In the present invention, when spraying an aqueous solution or suspension onto the fired product, or when the fired product is put into an aqueous solution or suspension and then dried, the temperature of the fired product is 120 ° C. or higher. It is preferable that it is 150 degreeC or more. If the temperature of the fired product is 120 ° C. or higher, the subsequent drying period and labor can be reduced.

Calcined product produced in the present invention, absolute dry density 0.4~2.5g / cm ^3, in particular 0.5 to 2.5 g / cm ^3, still more preferably from 0.6 to 2.5 g / cm ^3. Within this range, the amount of arsenic elution can be reduced and the ability to fix lead and Cr ⁶⁺ is also excellent, so concrete aggregate, roadbed material, backfill material, and asphalt bone It can be suitably used as a material, embankment material, or filler.

The fired product of the present invention preferably has a 24-hour water absorption and a reduced-pressure water absorption of 0.1 to 30%. The crushing load of the fired product having a diameter of 5 to 10 mm is 0.2 kN or more, particularly 0.4 kN or more, or the crushing load of the fired product having a diameter of 10 to 15 mm is preferably 0.3 kN or more, particularly 0.5 kN or more. .
In particular, when the fired product of the present invention is used as an aggregate for concrete, a roadbed material, an aggregate for asphalt, or a banking material, it is preferable that the 24-hour water absorption rate and the reduced-pressure water absorption rate are 0.1 to 15%. Also, the crushing load of the fired product having a diameter of 5 to 10 mm is 0.2 kN or more, particularly 0.4 kN or more, and further 0.5 kN or more, or the crushing load of the fired product having a diameter of 10 to 15 mm is 0.5 kN or more, particularly 0.7 kN or more. Further, it is preferably 0.9 kN or more.

Here, the reduced-pressure water absorption is a method of forcibly absorbing water under a certain reduced pressure. Specifically, the fired product is submerged in a sealed container and the inside of the container is decompressed to −400 mmHg with a vacuum pump. Then, after standing for 15 minutes, it was gradually opened to the atmosphere, and the water absorption at the time of depressurization was measured from the amount of water contained in the fired product.
This reduced water absorption is an index for inferring the water absorption of the aggregate in the pipe when pumping concrete, and when using the fired product as an aggregate for concrete, In order to ensure good workability, it is important to reduce not only the 24-hour water absorption rate but also the reduced-pressure water absorption rate.

  EXAMPLES Next, although an Example is given and this invention is demonstrated further in detail, this invention is not restrict | limited to these at all.

Example 1
(1-1) Production of fired product:
The fired products shown in Table 1 were produced using construction-generated soil, coal ash, waste A, and limestone. In the production of the fired product, the raw materials shown in Table 2 were blended so as to have the hydraulic modulus shown in Table 1, and 5 kg was pulverized and mixed with a ball mill for 1 hour. The raw material was put into an external heating kiln (inner diameter 0.13 m, length 1.84 m) at 1.5 kg / hr and fired at 1150 to 1250 ° C. After firing, after cooling in air to 300 ° C, Ca (OH) ₂ suspension (dispersion medium is water), Mg (OH) ₂ suspension (dispersion medium is water), Fe suspension (dispersion medium) Water), FeSO ₄ aqueous solution, FeCl ₂ aqueous solution, Fe ₂ (SO ₄ ) ₃ aqueous solution or FeCl ₃ aqueous solution were sprayed to produce a fired product.
Reagents (primary) were used for Ca (OH) ₂ , Mg (OH) ₂ , Fe, FeSO ₄ , FeCl ₂ , Fe ₂ (SO ₄ ) ₃ , and FeCl ₃ .
Further, Ca (OH) ₂ , Mg (OH) ₂ , and Fe having an average particle diameter of 10 μm were used.
The concentration of the aqueous solution or suspension was 20% by mass, and the spray amount was adjusted so that the amount of metal salt or the like per 100 kg of the fired product was 1 kg.

(1-2) Evaluation of fired product:
The obtained fired product was sieved with openings of 5, 10, and 15 mm, and the content of lead, chromium, and arsenic was measured for the fired product of 5 to 15 mm.
The lead and chromium contents were measured by ICP emission analysis after pretreatment with JCAS I-51. The arsenic content was measured by hydride generation atomic absorption after pretreatment with JCAS I-51.
Moreover, the absolute dry density and the water absorption rate were measured based on JIS A1110 about the 5-15 mm baked product. Moreover, the crushing load of the fired product of 10 to 15 mm was measured in accordance with the crushing load test method for high-strength fly ash artificial aggregates of the Japan Society of Civil Engineers. In addition, the content of lead and Cr ⁶⁺ in the fired product in accordance with Ministry of the Environment Notification No. 19 and the elution amount of lead, Cr ⁶⁺ and arsenic from the fired product in accordance with the Ministry of the Environment Notification No. 46 method are measured. did.
The results are shown in Tables 3-5.

From Tables 3 to 5, Ca (OH) ₂ suspension, Mg (OH) ₂ suspension, Fe suspension, FeSO ₄ aqueous solution, FeCl ₂ aqueous solution, Fe ₂ (SO ₄ ) ₃ aqueous solution or FeCl ₃ aqueous solution It can be seen that the fired product produced by spraying has a small amount of arsenic elution. Moreover, it turns out that this baked product is excellent in the fixing ability of lead and Cr6 ⁺ .

Example 2
(2-1) Production of fired product:
Using the raw materials shown in Table 2 and SiC (Kanto Chemical Reagent), the fired products shown in Table 6 were produced. In the production of the fired product, the raw materials shown in Table 2 were blended so as to have the hydraulic modulus shown in Table 6, and SiC was added in the amount shown in Table 6, and 5 kg was pulverized and mixed for 1 hour with a ball mill. The raw material was put into an external heating kiln (inner diameter 0.13 m, length 1.84 m) at 1.5 kg / hr and fired at 1150 to 1250 ° C. After calcination, after cooling in air to 300 ° C, spray the Ca (OH) ₂ suspension (dispersion medium is water), Fe suspension (dispersion medium is water) or FeCl ₂ aqueous solution, Manufactured.
Ca (OH) ₂ and Fe having an average particle diameter of 10 μm were used.
The concentration of the aqueous solution or suspension was 20% by mass, and the spray amount was adjusted so that the amount of metal salt or the like per 100 kg of the fired product was 1 kg.

(2-2) Evaluation of fired product:
The obtained fired product was evaluated in the same manner as in the above (1-2).
The results are shown in Table 7.

From the results in Table 7, it can be seen that the calcined product produced by spraying Ca (OH) ₂ suspension, Fe suspension, and FeCl ₂ aqueous solution has a small amount of arsenic elution. Moreover, it turns out that this baked product is excellent in the fixing ability of lead and Cr6 ⁺ .

Claims (6)

In manufacturing a fired product having a hydraulic modulus (HM) of less than 0.4 using one or more selected from industrial waste, general waste and soil as raw materials,
A method for producing a calcined product, comprising spraying a calcined product cooled to 800 ° C. or less with one or more aqueous solutions or suspensions selected from calcium salts, magnesium salts and iron-based powder materials. In manufacturing a fired product having a hydraulic modulus (HM) of less than 0.4 using one or more selected from industrial waste, general waste and soil as raw materials,
A method for producing a calcined product, wherein the calcined product cooled to 800 ° C. or lower is charged into one or more aqueous solutions or suspensions selected from calcium salts, magnesium salts and iron-based powder materials.   The method for producing a fired product according to claim 1 or 2, wherein the iron-based powder material is iron powder or a divalent iron compound.   The method for producing a fired product according to claim 1 or 2, wherein the calcium salt is calcium hydroxide.   The method for producing a fired product according to claim 1 or 2, wherein the magnesium salt is magnesium hydroxide.   The manufacturing method of the baked product in any one of Claims 1-5 which performs baking using a rotary kiln.