JP2002018411A - Ash solidification molding method - Google Patents

Abstract

(57) [Summary] [Problem] To produce inexpensively a solidified ash that has sufficient strength that can be effectively used as a construction material such as pavement material and has no problem of elution of heavy metals. . SOLUTION: In a method of adding and mixing cement and water to ash, and solidifying and molding the obtained mixture, ash is pulverized, and cement, water and a calcium compound are added to and mixed with the crushed ash.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for solidifying and shaping ash, and more particularly to a method for solidifying sludge incineration ash such as papermaking wastewater sludge and sewage sludge, which has sufficient strength to be effectively used as a construction material such as pavement material. And a method for inexpensively producing a molded article having no problem of elution of heavy metals.

[0002]

2. Description of the Related Art Conventionally, the effective use of waste,
Attempts have been made to incinerate waste and solidify the resulting incinerated ash for the purpose of preventing elution of heavy metals and the like, and these have already been put to practical use. Specifically, incineration ash is solidified or melt-processed in cement to be effectively used for pavement blocks, roadbed materials and the like.

[0003] In particular, many methods have been proposed for the cement solidification method because of its low processing cost. After mixing incinerated ash with waste soil, sand, gravel, cement and water,
Method of manufacturing pavement material by vacuum extrusion molding
55396), a method in which alumina cement and water are mixed into incinerated ash and then press molding is performed to produce a pavement material (Japanese Patent Application Laid-Open No. 6-218352). A method has been proposed in which powder, fine aggregate, ordinary Portland cement and water are added, mixed and solidified by press molding (Japanese Patent Laid-Open No. 11-322401).

As described above, when studying the effective use as a pavement material by adding and mixing a solidifying material to ash, the recycling ratio is increased by increasing the mixing ratio of the ash as much as possible, and a less expensive solidifying material is used. It is desired that the pavement material sufficiently satisfy the strength (bending strength of 50 kgf / cm ² or more) required as the pavement material.

[0005] Further, as a solidification treatment method carried out for landfill disposal of ash, cement and water are mixed with the ash, and the ash is mixed and solidified at the same time (including granulation into irregular particles).
The same applies hereinafter) or a method of molding and solidifying after mixing.

The method of molding and solidifying simultaneously with mixing is usually
It is implemented by an omni mixer and a vibration mixer, which have both the mixing action and the rolling action. The method of molding and solidifying after mixing is performed by a device such as a bread granulator or an extruder, which has a mechanism for extruding the mixture into a die for rolling operation or a predetermined shape.

[0007] In such ash solidification treatment for landfill disposal, ash is not scattered, heavy metals are not eluted, the capacity increase after the solidification treatment is small so as to extend the life of the landfill, and It is desired that the soil has sufficient soil strength to enable the subsequent disposal site to be used effectively. In particular, it is essential that the elution value of heavy metals meet the soil environmental standards (hereinafter referred to as "environmental standards"). For this reason, in order to prevent the elution of heavy metals, an auxiliary agent is added and used for solidifying the cement. For example, Japanese Patent Application Laid-Open No. 7-96363 discloses an auxiliary agent such as sodium ligninsulfonate, sodium stearate, sodium tripolyphosphate and the like. It has been proposed to use calcium aluminate hydrate or calcium aluminosulfate hydrate in some cases. Japanese Patent Application Laid-Open No. 8-215658 discloses sodium, potassium,
It has been proposed to use a compound containing calcium, iron and aluminum in an ionic state. Japanese Patent Laid-Open No. Hei 5
JP-A-329460 proposes to add calcium chloride and slaked lime in combination.

However, when considering the effective use of ash, the method described in Japanese Patent Application Laid-Open No. 9-255396 requires a large amount of waste soil and water to be mixed in order to facilitate molding. There was a problem in terms of reuse rate.
Further, in vacuum extrusion molding, there is a problem that the mixing conditions of the raw materials for achieving both the moldability and the required strength are narrow, and it is difficult to reproduce the moldability and the strength when the source of the raw materials is changed. . Further, there is a restriction that a curing agent mainly containing a special inorganic metal element is required.

Further, in the method described in Japanese Patent Application Laid-Open No. 6-218352, in particular, since powder is not used, in order to obtain sufficient strength, the solidifying material is not usually Portland cement but expensive. Alumina cement needs to be used, and there is a disadvantage that the cost is high.

The method disclosed in Japanese Patent Application Laid-Open No. H11-322401 increases the recycling rate by increasing the amount of ash, and uses inexpensive ordinary Portland cement as a solidifying material to obtain the required strength as a pavement material. Japanese Patent Laid-Open No. 9-2553,
Although it was a more effective method than the method described in No. 96 or JP-A-6-218352, it requires inorganic powder and fine aggregate having a particle size corresponding to clay and silt, There was a limit in increasing the proportion of ash.

[0011] The problems in terms of strength and ash content are solved, the recycle rate is increased by increasing the ash content, and the required strength as a pavement material or the like is sufficiently satisfied. In order to provide a method for solidifying and molding ash capable of producing a molded article, the present applicant firstly added and mixed cement and water to ash, and solidified and molded the obtained mixture. (Japanese Patent Application No. Hei 11-1999).
241774. Hereinafter, it is referred to as “first application”. ).

According to the invention of the prior application, the ash is pulverized and solidified to thereby increase the mixing ratio of the ash so that sufficient strength can be exhibited without using auxiliary materials other than the ash and cement. became. That is, according to the invention of the prior application, the solidified molded body after molding is densified by the ash pulverization treatment, and the obtained molded solidified body can be obtained without using auxiliary materials such as inorganic powder and fine aggregate. Since the strength can be increased, the mixing ratio of the ash can be greatly increased.

[0013] In the invention of the prior application, the details of the mechanism for increasing the strength of the solidified compact after molding by the ash crushing process are not clear, but 1) Since ash is a porous powder, The voids inside the ash particles are reduced, and the density of the solidified molded body after molding is increased. 2) Since the particle size distribution is broadened by the pulverization, the voids between the ash particles are reduced, and the density of the solidified compact after molding is increased. 3) The ash particles having low strength are destroyed in advance by the pulverization treatment, thereby increasing the strength of the solidified molded body after molding. For such reasons, it is estimated that the strength improving effect is exhibited.

[0014]

In the effective use of ash, improvement of solidification strength and increase of the mixing ratio of ash are important requirements, but prevention of elution of heavy metals is also extremely important in terms of environmental protection.

In the above-mentioned prior application, in order to prevent the elution of heavy metals, the use of blast furnace cement with a small amount of chromium elution or the addition of a heavy metal elution inhibitor is described. The prevention effect is not sufficient, and its improvement is desired.

[0016] Among the conventional techniques in which various auxiliaries are added to prevent the elution of heavy metals, Japanese Patent Application Laid-Open No. 7-96363 describes
In the method described in the publication No. 6, the environmental standard of hexavalent chromium is achieved, but the amount of incinerated ash in this method is small,
It contains a large amount of non-combustible inorganic waste (iron, non-ferrous metal, glass, ceramics, etc.), and the effect of preventing hexavalent chromium elution when the incineration ash content is large is unknown.

In the method described in JP-A-8-215658, hexavalent chromium cannot achieve environmental standards.

Furthermore, in the method described in Japanese Patent Application Laid-Open No. 5-329460, an effect of preventing elution of hexavalent chromium is obtained. For this purpose, calcium chloride and slaked lime are added to 100 parts by weight of ash. In addition, 40 parts by weight or more, specifically, a large amount of 150 g of calcium chloride and 400 g of slaked lime are required for 600 g of ash, and the amount of ash is relatively reduced in addition to the increase in chemical cost, and There is a disadvantage that the solidification strength is not sufficient.

The present invention solves such a problem and provides a molded product having sufficient strength that can be effectively used as a construction material such as a pavement material and has no problem of elution of heavy metals by a cement solidification method. It is an object of the present invention to provide an inexpensive method for producing a large amount of ash.

[0020]

The ash solidification molding method of the present invention is a method of adding and mixing cement and water to ash and solidifying and molding the obtained mixture, wherein the ash is pulverized. And adding and mixing cement, water and a calcium compound to the ash or ground ash.

According to the present invention, by pulverizing the ash, it is possible to obtain a high-strength solidified body while increasing the proportion of the ash by the above-mentioned effects.

Further, by adding a calcium compound to the ash or the ground ash together with cement and water, elution of hexavalent chromium can be surely prevented.

That is, the present inventors have conducted studies in order to prevent the elution of hexavalent chromium in the method of the prior application, and the elution of hexavalent chromium from commercially available blocks such as mortar and concrete has achieved environmental standards. On the other hand, blocks obtained by solidifying ash by the cement solidification method cannot achieve environmental standards. As a result of a dissolution test of the material alone, there was no dissolution of hexavalent chromium from sand and gravel, which are materials for commercially available blocks such as mortar and concrete. In addition, hexavalent chromium was not eluted from sludge incineration ash, which is a block material obtained by solidifying the ash. Hexavalent chromium was eluted under highly alkaline conditions, but no hexavalent chromium was eluted when the ash alone was exposed to alkaline conditions of pH 12.0. From these findings, it was presumed that hexavalent chromium from the solidified ash by the cement solidification method was due to elution from the cement hydrate.

By the way, sludge incineration ash as a raw material is roughly classified into lime-based ash added with iron salt and slaked lime and polymer-based ash added with an organic polymer based on the generation source.
In the dissolution test of the solidified cement made from these ashes, the solidified body using the lime-based ash always emitted a smaller amount of hexavalent chromium than the solidified body using the polymer-based ash.

Therefore, attention was paid to calcium salts of lime-based ash, and as a result of various studies, it was found that calcium salts, particularly calcium compounds such as calcium chloride, have a remarkable effect on elution of hexavalent chromium.

In the present invention, the details of the mechanism of the action of the calcium compound to prevent the dissolution of hexavalent chromium by the calcium compound are not clear, but the calcium compound added and mixed with the cement forms a hardly soluble crystal together with the cement mineral and hexavalent chromium. It is presumed to be due to

In the present invention, the addition ratio of the calcium compound is preferably 1 to 100 parts by weight, particularly preferably 2 to 50 parts by weight, based on 100 parts by weight of cement.

It should be noted that the addition and mixing of the calcium compound does not impair the strength of the obtained solidified product, and the addition ratio within the above range does not significantly reduce the mixing ratio of ash. .

Further, when calcium chloride is used as the calcium compound, corrosion of the reinforcing steel due to chloride ions poses a problem in the case of reinforced concrete, but there is no such problem in the case of a non-strength block such as a pavement block.

In the present invention, the molding is preferably performed by press molding, vacuum press molding or vibration molding, or extrusion molding or vacuum extrusion molding.

When the molding is carried out by press molding, vacuum press molding or vibration molding, the mixture is used as a base material, and a molded body having a multilayer structure of two or more layers is formed using a surface material different from the mixture. Can also.

Further, in the present invention, the dry density [rho _dA ash before grinding, to a dry density [rho _dB ash after grinding becomes larger, in particular, dry density [rho _dB ash pulverized pulverization The dry density ρ _dB of the ash after grinding is 0.2 g / cm ³ or more larger than the dry density ρ _dA of the previous ash, and 0.7 g / cm 3
^It is preferable to carry out the pulverization treatment so as to be ³ or more, especially 1.0 g / cm ³ or more.

When the molding is performed by press molding, vacuum press molding or vibration molding, the mixing ratio of the cement is 10 to 80 parts by weight with respect to 100 parts by weight of the crushed ash.
The mixture preferably has a water content of 5 to 40%, and when molded by press molding or vacuum press molding, the molding pressure is 50 to 3000 kgf / cm ² (4.9 to 294MPa).
a) is preferred. In the case of molding by vibration molding, 0.5 to ¹ kgf / cm ² (4.9 × 10
^{-2 to} 9.8 × 10 ⁻² MPa).

When molding is carried out by extrusion molding or vacuum extrusion molding, the mixing ratio of cement is adjusted to 100 pulverized ash.
It is preferable to carry out extrusion molding or vacuum extrusion molding with the mixture being 10 to 80 parts by weight and the water content of the mixture being 10 to 80% by weight.

In the present invention, in particular, after at least a part of the cement and / or at least a part of water is added to the ash, more preferably, at least a part of the cement is added to the ash, and then the pulverizing treatment is performed. In the case where the treatment and the mixing treatment are performed at the same time, the ash and the cement come into contact with each other more efficiently than in the case where the ash that has been previously pulverized and the cement and the water are mixed, so that the strength is further increased or the amount of cement used Can be reduced.

On the other hand, there is no particular limitation on the timing of addition of the calcium compound. However, a calcium compound having high solubility in water, such as calcium chloride, is previously dissolved in water, and the solubility in water is reduced, as in slaked lime. It is preferred that the low calcium compound is previously mixed with the ash or cement.

In the present invention, a heavy metal fixing agent is further added to the ash in the ash crushing step, and the heavy metal fixing agent is added simultaneously with the ash crushing process, or the heavy metal fixing agent is added after the ash is crushed. Heavy metal fixing treatment.

When dioxins are contained in the ash, a dioxin decomposing agent is added to the ash in the ash crushing step, and the dioxin decomposing agent is mixed with the ash crushing process at the same time.
It is preferable that the dioxin decomposing agent is mixed with the dioxin decomposing agent by adding the dioxin decomposing agent after pulverizing the ash, and then the dioxin decomposing treatment is performed. In particular, after adding the dioxin decomposer to the ash, the temperature inside the pulverizer is changed from room temperature to 300 ° C.
By setting the value to be less than the above, efficient dioxin decomposition treatment can be performed simultaneously with pulverization of ash.

In the present invention, after the solidification molding, the obtained molded body may be subjected to a surface processing treatment.

The solidified ash product obtained by the ash solidification molding method of the present invention may be used as it is, or the ash solidified molded product obtained by this ash solidification molding method may be used. It can be used after crushing.

[0041]

Embodiments of the present invention will be described below in detail.

In the present invention, as a pulverizer for pulverizing ash, models classified into an intermediate pulverizer, a fine pulverizer, and an ultra-fine pulverizer can be used. In addition, since there is no unified and strict classification method for the classification of the crushers, the following will be described in the following by the Chemical Equipment Research Group, “Practical Knowledge of Chemical Equipment and Equipment” (published by Ohm Co., Ltd., 1997). ~
An example is described with reference to the description of “Pulverizer” on page 133.

Specific pulverizers include dodge crushers, cone crushers, double roll crushers, edge runners, disintegrators, hammer mills, impeller breakers, disk crushers, rotary crushers and the like as intermediate crushers, ball mills as fine crushers, and the like. Tube mill, rod mill, vibrating ball mill, high swing ball mill, ring roller mill,
Micronizer, Jetmizer, Magicak mill, Raymond vertical mill, Micro atomizer, Classification impact mill, Micron mill, Premier colloid mill, Charlotte colloid mill, etc. No.

In the present invention, since the purpose of the ash pulverization process is not to reduce the particle diameter, it is not always necessary to be able to pulverize to an ultra-fine pulverization region. Any crusher capable of crushing up to the crushing region may be used. However, when the ash particles are large, a pulverizer capable of handling up to the intermediate pulverization region is desirable. Also,
In the present invention, since the ash crushing process mainly aims at reducing the voids inside and between the particles, the crushing force is desirably a crusher that acts not only on impact but also on compression, friction and the like. Further, as described later, when a crushing and mixing treatment is performed by adding a cement, a calcium compound and water to ash, a crusher which has a mixing action and can cope with a wet process is desirable.
In addition, it is necessary to provide a pulverizing mechanism capable of coping with the amount of ash to be pulverized.

From the above viewpoints, when sludge incineration ash is used, it is particularly preferable to use a ball mill, a tube mill, a rod mill, a vibrating ball mill, a roller mill, or the like as a pulverizer.

In the present invention, the degree of pulverization of the ash is such that the dry density ρ _dB of the ash after the pulverization is larger than the dry density ρ _dA before the pulverization, preferably ρ _dB ≧ ρ
_The target is to be _dA + 0.2 g / cm ³ .

The dry density of the ash is determined according to JIS-A-12.
10 According to the calculation method of “dry density of compacted soil” described in “Test Method for Compaction of Soil by Compaction”, it is defined as the following equation (1). ρ _d = ρ _w / (1 + w / 100) (1) where ρ _d : dry density of ash ρ _w : wet density of ash w: water content of ash (%)

Here, ρ _w is not a density when compacted as described in JIS-A-1210, but a value as a tap bulk density. It should be noted that the value of the tap bulk density ρ _w is calculated by the following equation (2). ρ _w = m _w / v _t (2) where, m _w : mass (g) of about 100 ml of ash collected in a 100 ml measuring cylinder with a tangible water content v _t : tapping the measuring cylinder Ash volume when the ash volume in the cylinder becomes constant (cm ³ )

The ash is used for the properties (origin, chemical composition,
The properties vary greatly depending on the shape of the incinerator, the type of incinerator, operating conditions of the incinerator, the method of collecting dust, and the like, but generally have a porous structure having voids inside the ash particles. Therefore,
If the voids inside the ash particles can be reduced by the pulverizing treatment, the dry density of the ash decreases. However, the dry density of the pulverized ash depends on the properties of the ash before pulverization (origin, chemical composition, water content, shape, structure, etc.), the type of pulverization equipment, the use of pulverization aids, and the operating conditions of the pulverization equipment. Since ρ _dB may not always be larger than the dry density ρ _dA of the ash before pulverization, it is necessary to perform an appropriate pulverization treatment.

The degree of pulverization of the ash may be adjusted according to the strength required for the intended use so that the dry density of the ash is higher than before the pulverization. As for the ash, the higher the dry density after the crushing treatment, the higher the density of the solidified compact after molding. It is necessary to increase the density.

In the same manner as described for soil in JIS-A-1210 "Test method for compaction of soil by compaction", the maximum dry density under certain compaction conditions for ash Can be requested. If the conditions at the time of molding are ash compaction conditions, the maximum dry density of the crushed ash under the conditions at the time of molding can be obtained.
In general, the maximum dry density of a granular material is affected by the amount of compaction energy and the particle size distribution of the granular material to be compacted, and the larger the amount of compaction energy, the larger the maximum dry density that can be obtained. The maximum dry density obtained becomes smaller as the particle size distribution becomes smaller. Therefore, it is necessary to adjust the ash pulverization treatment so that the maximum dry density obtained when the particle size distribution is too fine is not reduced.

[0052] Using the sludge incineration ash, if solidified molded body after molding and to obtain a strength of about equal to the interlocking blocks, dry density after pulverizing the ash [rho _{d B} is 0.7g / Cm ³ or more, especially 1.0 g / cm ³
It is preferable to pulverize so as to be as described above.

In the present invention, the mixing ratio of the crushed ash to the cement is preferably 10 to 80 parts by weight of the cement with respect to 100 parts by weight of the ash after the pulverization. If the amount of cement is more than the above range, the cost is high and the amount of ash that can be reused is relatively small. If the amount of cement is less than the above range, the equipment required for obtaining sufficient strength becomes excessive.

As the type of cement used in the present invention, hydraulic cement and air-hardened cement can be used in general, and are selected and used depending on the use of the molded article. Specifically, as hydraulic cement, ordinary Portland cement, moderate heat Portland cement, early-strength Portland cement, ultra-high-strength Portland cement, sulfate-resistant Portland cement, white Portland cement, oil well cement, colloid cement, blast furnace cement, Fly ash cement, silica cement, ultra-low heat cement, high-strength cement, geothermal well cement, RCCP cement, alumina cement, ultra-rapid hardening cement, low alkali cement for GRC, etc., and as the air-hardening cement, slaked lime, Gypsum, magnesia cement and the like can be mentioned.

Of the above-mentioned cements, it is desirable to use inexpensive ordinary Portland cement, blast furnace cement, and fly ash cement unless there is any particular problem.

When a blast furnace cement or a fly ash cement with a small amount of hexavalent chromium eluted is used, the effect of preventing the elution of hexavalent chromium can be further enhanced.

The mixing ratio of the ash and the calcium compound after pulverization is preferably 1 to 100 parts by weight, more preferably 2 to 50 parts by weight, of the calcium compound per 100 parts by weight of the cement. If the amount of the calcium compound is less than the above range, the effect of preventing dissolution of hexavalent chromium is not sufficient, and conversely, even if the amount is greater than this range, no significant improvement is observed in the effect of preventing dissolution of hexavalent chromium, The amounts of ash and cement are relatively small, resulting in a decrease in the ash recycling rate, a decrease in the strength of the obtained solidified body, and an increase in the cost of chemicals.

The calcium compounds include calcium chloride, calcium nitrite, calcium nitrate, calcium sulfite, calcium sulfate, calcium oxide, calcium carbonate, calcium phosphate, calcium aluminate,
Calcium silicate, calcium cyanate, calcium borate, calcium formate, calcium acetate, calcium acrylate, calcium gluconate, calcium citrate, calcium tartrate, calcium glutamate, calcium lignin sulfonate, calcium humate, calcium polyacrylate, Calcium rhodanate, condensate of calcium naphthalene sulfonate, condensate of melanin resin calcium sulfonate, modified calcium lignin sulfonate and the like can be used. Among them, those which have high solubility and are inexpensive are particularly preferable.

In the present invention, it is advantageous to use a calcium compound having a high water solubility as the calcium compound. As is clear from the results of the examples described later, slaked lime which is a calcium compound having a low solubility in water is used. When using, a large amount of addition is required to prevent hexavalent chromium from being eluted, which raises the problem of soaring drug costs, a decrease in the relative amount of ash, and a decrease in the ash recycling rate. In addition, the strength of the solidified body is reduced, and it is necessary to increase the amount of cement to secure the strength. However, it is applicable to applications that do not require strength.

In the present invention, when the molding is carried out by press molding, vacuum press molding or vibration molding, the ash, cement and calcium compound pulverized preferably have a water content of 5%.
It is preferred to add water so as to be ~ 40%. When the water content exceeds 40%, a predetermined press pressure cannot be applied because of too much water, and sufficient strength cannot be exhibited. Conversely, if the water content is less than 5%, the hydration reaction of the cement does not sufficiently proceed, and sufficient strength cannot be exhibited.

In the case of extrusion molding or vacuum extrusion molding, it is preferable to add water to the pulverized ash, cement and calcium compound so that the water content is preferably 10 to 80%. If the water content exceeds 80%, the W / C increases and sufficient strength cannot be exhibited. Conversely, when the water content is less than 10%, the amount of water is too small, and the water is not discharged from the extruder, and molding is difficult.

The water content ratio is the weight ratio (% by weight) of the total amount of water to all the dry raw materials in the mixture.

In the present invention, the procedure for mixing the ground ash, cement, calcium compound and water is not particularly limited, and water is added and mixed after the ground ash, cement and calcium compound are mixed. Alternatively, a part of the pulverized ash, cement and calcium compound may be mixed in advance with water, and the remaining raw materials may be added and mixed.

Further, in the present invention, the procedure for pulverizing the ash and mixing it with the cement, calcium compound and water is not particularly limited. The ash may be pulverized and then mixed with the cement, the calcium compound and water. After mixing the ash, cement, calcium compound and water, the mixture may be further pulverized and mixed. Further, the whole amount of cement, calcium compound and water may be added and pulverized while pulverizing the ash. May be further added and mixed. In particular, at least part of the cement and / or
Or after adding at least a portion of water, more preferably after adding at least a portion of the cement to the ash, crushing, in the case of simultaneously performing the crushing process and the mixing process, the crushed ash and cement in advance As compared with the case of mixing water, the ash and the cement are in efficient contact, so it is possible to further increase the strength or reduce the amount of cement used,
preferable.

There are no particular restrictions on the timing of the addition of calcium compounds, but those having high solubility in water are added to water, and those having low solubility in water are added to ash or cement in advance. Is preferred.

In the present invention, molding is basically performed using ash, cement, a calcium compound and water as raw materials. Further, if necessary, inorganic powder, aggregate, pigment and other additives may be added. You may mix | blend as a forming raw material.

If the ash contains harmful heavy metals other than hexavalent chromium, another heavy metal fixing agent is added to the ash in the ash pulverization step, and the heavy metal fixing processing is performed simultaneously with the ash pulverization processing. After the ash is pulverized, it is preferable to perform a heavy metal fixing treatment by adding a heavy metal fixing agent.

When dioxins are contained in the ash, a dioxin decomposer is added to the ash in the ash pulverization step to mix the dioxin decomposer simultaneously with the ash pulverization.
It is preferable that the dioxin decomposing agent is mixed with the dioxin decomposing agent by adding the dioxin decomposing agent after pulverizing the ash, and then the dioxin decomposing treatment is performed. In particular, after adding the dioxin decomposer to the ash, the temperature inside the pulverizer is changed from room temperature to 300 ° C.
By setting the value to be less than the above, efficient dioxin decomposition treatment can be performed simultaneously with pulverization of ash.

In the present invention, a mixture obtained by mixing crushed ash, cement, calcium compound, water and the like at a predetermined ratio is filled in a mold and subjected to press molding, vacuum press molding or vibration molding. , And supplied to an extruder or a vacuum extruder for molding.

In the case of press molding or vacuum press molding, the pressing pressure is 50 to 3000 kgf / cm ² (4.9 to
294 MPa). If the pressing pressure is less than 4.9 MPa, a molded article having sufficient strength cannot be obtained, and the use of the molded article is limited. On the other hand, if the pressing pressure exceeds 294 MPa, the equipment for press molding becomes excessively large, which is not practical. Practically 100-1000kg
A press pressure of f / cm ² (9.8 to 98 MPa) is preferable, and in particular, 150 to 400 kgf / cm ² (14.
7 to 39.2 MPa) is particularly preferred.

When performing the vibration molding, the molding pressure can be as low as about 0.5 to ¹ kgf / cm ² . That is, the vibration molding is to press at a low pressure while applying vibration. As a result of increasing the packing density by simultaneously using the vibration together with the press, 0.5 to 1
kgf / cm ² (4.9 × 10 ^{−2 to} 9.8 × 10 ⁻²⁾
Even at a pressure of about MPa, which is significantly lower than the molding pressure of press molding, strength equivalent to that of press molding is exhibited.

In the case of press molding, vacuum press molding, or vibration molding, a mixture obtained by mixing crushed ash, cement, calcium compound, water, etc. at a predetermined ratio is used as a base material, and separately prepared separately. By using the above surface layer material, a molded article having a multilayer structure of two or more layers can be formed.

In the present invention, the molding method is not limited to press molding, vacuum press molding, vibration molding, extrusion molding, and vacuum extrusion molding, and other molding methods such as cast molding can be adopted.

After molding, curing is preferably performed until sufficient strength is developed. Curing methods include aerial curing, underwater curing, and steam curing, although there is no particular limitation on the curing method.
Aerial curing is desirable because the cost is low, and the curing conditions in this case are a temperature of 5 to 30 ° C. and a humidity of 30 to 7
It is about 1 day to 4 weeks at 0%. In the case of performing aerial curing, it is preferable to perform accelerated curing using the heat of hydration of cement by curing the molded body as tightly as possible.

By the method as described above, the bending strength is 50 kgf / cm ² according to the interlocking block.
(4.9 MPa) or more, compressive strength 330 kgf / cm ²
(32.34 MPa) or more, it is possible to obtain a solidified compact that can be effectively used as a pavement material.

The obtained solidified compact may be subjected to a surface treatment such as comb stitching. This solidified product is used in a fixed shape such as a plate shape.
It can be crushed to a size of about m and used as aggregates such as chestnut stone as crushed materials.

[0077]

The present invention will be described more specifically below with reference to examples and comparative examples.

Examples 1 to 9, Comparative Examples 1 and 2 Polymer sludge incineration ash, cement (ordinary Portland cement) pulverized for 2 hours using a ball mill,
A calcium compound and water were mixed at a blending amount and a water content of 20% shown in Table 1 (however, no calcium compound was blended in Comparative Examples 1 and 2), and this mixture was 200 kgf / cm ^2.
Press molding was performed at a press pressure of (19.6 MPa). However, in Example 5, after adding cement and a water-soluble calcium compound to the ash, pulverized and mixed for 2 hours using a ball mill, and mixed with water having a water content shown in Table 1,
This mixture was press-molded under the same conditions. The dry density of the ash before the crushing treatment was 0.9 g / cm ² , and the dry density of the ash after the crushing treatment was 1.3 g / cm ² .

After demolding, the obtained molded body was cured in the air at a temperature of 20 ° C. and a humidity of 70% for 4 weeks, and then 10 cm × 20 cm × 6.
A pavement material of cm thickness was produced.

For this pavement material, the elution concentration of hexavalent chromium was measured by the Environment Agency Notification No. 46, and the flexural strength was measured by the test method specified by the Interlocking Block Pavement Technology Association. The results are shown in Table 1. Indicated.

[0081]

[Table 1]

As is clear from Table 1, by adding calcium chloride which is a calcium compound having high solubility in water, the environmental standard can be achieved by adding 10% by weight to the cement, and Also, the standard strength of the interlocking block can be sufficiently achieved.

Even when slaked lime having low solubility in water is used, the environmental standard can be achieved by adding 50% by weight to the cement. It can be used for other construction material applications that do not require high strength.

[0084]

As described above in detail, according to the present invention, when the ash is solidified with cement and reused, the ash is pulverized and a calcium compound is added, so that the ash can be compared with the conventional method. It has become possible to prevent the dissolution of hexavalent chromium reliably, after significantly increasing the mixing ratio of chromium and sufficiently satisfying the strength required for the pavement material. For this reason, according to the present invention, it is possible to provide a cheap and highly safe pavement material by greatly reducing the molding cost while significantly improving the ash recycling rate.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B02C 19/12 C04B 28/02 C04B 28/02 (C04B 28/02 // (C04B 28/02 18:10 Z 18:10 22:12 22:12 22:06) Z 22:06) 111: 60 111: 60 B09B 3/00 ZAB F term (reference) 4D004 AA36 AB03 AB07 AC04 BA02 CA04 CA14 CA15 CA45 CB13 CC11 CC13 CC20 4D067 CG06 GA20 4G012 PA26 PB03 PB09 PC12 4G035 AB43 AB48

Claims (1)

[Claims] 1. A method of adding and mixing cement and water to ash and solidifying and shaping the resulting mixture, wherein the ash is pulverized, wherein cement, water and a calcium compound are added to the ash or pulverized ash. Ash solidification molding method characterized by adding and mixing the following.