JPH06106153A - Cement solidification of incineration ash and cement solidified product of incineration ash - Google Patents

Abstract

PURPOSE:To produce a cement solidified product of incineration ash utilizable as resources, in producing the cement solidified product using incineration ash, by suppressing the elution of a harmful substance and enhancing the strength of the cement solidified product to a large extent. CONSTITUTION:A raw material containing the incineration ash of waste refuse or sewage sludge, cement, aggrigate and a water absorbable polymer having absorbed water is kneaded to prepare paste accelerated in initial hydration and this paste is molded. Pref., the raw material consisting of 100 pts.wt. of incineration ash, 65 pts.wt. or more of cement, 50 pts.wt. or more of aggregate and 0.5 pts.wt. or more of a water absorbable polymer (at the time of drying) and containing 25-45wt.% of water with respect to the sum amt. of incineration ash and cement is used.

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 incineration ash produced by incinerating garbage, sewage sludge and the like with cement, and more specifically, it has a low water cement ratio and does not elute harmful substances, The present invention relates to a method for treating incinerated ash that can obtain a solidified cement product.

[0002]

2. Description of the Related Art The amount of garbage and sewage sludge produced from cities has been increasing year by year. Regarding the incineration ash produced after incinerating such garbage and sewage sludge, the problem of securing landfill sites, the toxic heavy metals contained There is a problem of elution of ash, and technological developments such as stabilization, volume reduction, and resource recovery of incinerated ash are underway. For example, in the "Technology development project for stabilization of ash" conducted by the Waste Research Foundation, a method of solidifying incinerated ash with cement is being examined in detail (the project 1989 report).

In the above report, cement: incineration ash = 1
5-60: 100, Water: Cement = 110-570: 1
00 (water: incineration ash + cement = 24-119: 100)
After mixing raw materials with a mixing ratio (weight ratio) such as the above with an omni mixer or the like, the mixture is cemented into a block shape by extrusion molding or press molding, and the elution test and the strength measurement of harmful components such as heavy metals are performed. In this experimental method, the amount of cement is as small as 15 to 60 (against incineration ash), although the incineration ash has poor hydraulic properties, and a large amount of water is added for pressure molding. However, since the theoretical amount of water required for the hydration reaction of cement is around 25% in water-cement ratio, most of the water will evaporate as excess water that cannot contribute to the solidification reaction in the above experiment. In addition, many voids are generated, the specific surface area is increased, the elution of toxic components of heavy metals is increased, and the strength of molded products is decreased.Therefore, it is possible to obtain a cement-solidified product that has practically usable strength and is safe. Not not.

On the other hand, a method of melting incinerated ash in a thermal plasma melting furnace has been studied, but it is not general because the equipment becomes large and complicated and a large amount of energy is used. Furthermore, using incineration ash as a partial substitute for clay,
A method for producing a permeable tile by sintering has been studied, but there is a problem that the low melting point toxic substance in the incineration ash volatilizes during sintering, and since a large amount of energy is used, it is also considered as a resource. At present, the disadvantage is greater.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and suppresses elution of toxic substances when forming cement-solidified products using incinerated ash, and solidifies by molding. The purpose of the present invention is to produce a cement-solidified product of incinerated ash that can be used as a resource by significantly improving the strength of the product.

[0006]

[Means for Solving the Problems] The cement solidification method of incineration ash of the present invention which has achieved the above-mentioned object is a water-absorptive material that absorbs incineration ash such as dust and sewage sludge, cement, aggregate and water. The gist is that the raw material containing a polymer is kneaded to form a paste in which initial hydration is promoted, and then the molding is performed. The preferable mixing ratio of raw materials is 100 parts by weight of incinerated ash, 65 parts by weight or more of cement, 50 parts by weight or more of aggregate, and 0.5% by weight or more of water-absorbing polymer (dry).
Water: 25 to 45% by weight of the total amount of incinerated ash and cement, and a cement-solidified product of incinerated ash solidified by using the present method is also included in the present invention.

[0007]

The present inventors have studied to make incinerated ash having poor hydraulic properties into a solidified product having a strength that can be used as a resource, and as a result, use a water-absorbing polymer to reduce the water-cement ratio as much as possible. The amount of cement with respect to the incinerated ash is preferably 65 parts by weight or more for strength development. When mixing the raw materials, it is preferable to use a mixer having a high kneading effect due to compression or shearing action, in order to promote initial hydration. The present invention has been accomplished by clarifying the above points. The details will be described below.

In the present invention, the incineration ash is generally trash obtained in the city, ash obtained after incinerating sludge in sewage, or coal ash produced by a thermal power plant. Municipal solid waste incineration ash generally has a larger ash particle size than sewage sludge incineration ash and coal ash. Therefore, in order to improve the compactness of cement solidified products, municipal solid waste incineration ash and sewage sludge incineration ash / coal can be improved. It is preferable to use a mixture of ash as appropriate because the closest packing effect can be obtained.

This incinerated ash is kneaded together with cement, aggregate and water-absorbing polymer that has absorbed water to form a paste. As a method for preparing the raw material paste, a water-absorbing polymer having absorbed a predetermined amount of water, incineration ash, aggregate, and a sufficient amount of cement together with a universal mixer, kneader, forced kneading mixer, etc. have a high kneading effect. Knead with a mixer.

Since the water-absorbing polymer that has absorbed water is in a powder state, initially the incinerated ash, aggregate, cement particles and polymer particles are very well dispersed as a powder. In addition, granules and aggregates in the incinerated ash particles and cement particles are destroyed by the compressive stress and the shear stress. In particular, ash with a small particle size, such as sewage sludge incineration ash, is easy to granulate due to moisture absorption, etc.
Since this granulation cannot be crushed with an omni mixer, which is mainly a shaking mixer, it should be kneaded with a mixer having a high kneading effect. If the granulated product remains, a uniform solidified product cannot be obtained, which is not preferable because it causes strength reduction and elution of toxic components.

Among the incinerated ash, aggregate, cement particles, and polymer particles that are well and uniformly dispersed, the cement particles and the water-absorbing polymer particles come into contact with each other, so that the polymer particles start water discharge under the influence of the alkali ions of the cement particles.
This is because the water-absorbed polymer is difficult to release water only by pressure and releases water due to the presence of alkali ions. The ionic equilibrium state on the surface of polymer particles is destroyed by kneading, and water discharge is further promoted, so that cement particles can be sufficiently wetted with water in a short time, and the incinerated ash can be easily made into a paste by this wet cement. Of. In addition, according to the method of the present invention, since the polymer particles are discharged quickly because a mixer having a high kneading effect is used, when the incinerated ash with many granules is used, the addition time of the polymer particles is delayed a little, It is also effective to carry out kneading for a while in a physical condition.

When the cement particles get wet with water, a hydration reaction is started. Since the cement particles and the polymer particles, the incinerated ash, and the aggregate are uniformly dispersed, the hydration reaction proceeds throughout the system. For this reason, the raw material paste becomes more dense as the hydrate is formed, and the finally solidified cement product has high strength. The conventional method of simply shaking the mixture with an omni mixer cannot enjoy the advantages of promoting the initial hydration in the present invention as described above. Therefore, in the conventional method, the powder is compacted in the conventional method to increase the internal voids, and only a solidified product having low strength can be obtained.

The water-absorbing polymer used in the present invention is not particularly limited as long as it has a maximum water absorption capacity of about 50 to 300 times (based on the dry polymer weight), but it maintains an independent granular form even after water absorption. Those having characteristics are preferably used. The amount of water absorbed by the water-absorbent polymer (water / water-absorbent polymer ratio) is preferably 30 to 200 times the polymer dry weight. If the amount of water absorption is less than 30 times, water is not discharged in a short time even in a strong alkaline state, and about 10 times as much water remains in the polymer,
The cement cannot be fully hydrated. On the other hand, if the water absorption exceeds 200 times, the amount of water adhering to the surface of the polymer will be so large that the polymer will be suspended in water, making it difficult to handle as a powder, and evenly mixing when preparing the raw material paste. become unable. The amount of the water-absorbing polymer used is appropriately selected depending on this water absorption capacity and the necessary amount of water described later. Generally, it is used in a dry weight of 0.5 parts by weight or more.

The amount of water absorbed by the water-absorbent polymer is preferably in the range of 25 to 45% by weight based on the total amount of incinerated ash and cement. Since the theoretical amount of water required for the hydration reaction of cement is about 25% by weight with respect to the cement, it is slightly excessive by the amount of incinerated ash, but a slight hydration reaction also occurs in the incinerated ash, resulting in a hydrate. Therefore, excess water cannot be a problem with the low water content of the present invention. The above water content is optimal for incorporating incinerated ash into cement paste to produce a dense solidified product.

The amount of water is 25% of the total amount of incinerated ash and cement.
If the content is less than wt%, especially the ash having a small particle size such as sludge incineration ash has a large specific surface area and thus the required water content is large, so that it is difficult to completely incorporate the ash into the cement paste. On the other hand, if the amount of water is more than 45% by weight, the amount of water required for ash having a large particle size, such as incineration ash of municipal solid waste, is small, which is contrary to the above. For example, in the above-mentioned conventional example, a large amount of water having a water-cement ratio of 110% or more is added, so that water in which toxic components are dissolved is released during pressure molding and water treatment is required, or a void is generated in a molded product. However, this causes inconveniences such as the toxic components being eluted from the voids and the strength being lowered.

The cement used in the present invention is a matrix material which hardens incinerated ash and prevents heavy metals, which are toxic components, from eluting. In the present invention, the type of cement is not particularly limited, and commonly used cement such as Portland cement, white cement, slag cement, and alumina cement can be applied. The amount of cement is incinerated ash 1
It is necessary to use 65 parts by weight or more with respect to 00 parts by weight. If the amount is less than 65 parts by weight, the surface of the incinerated ash cannot be sufficiently wetted with the cement paste, so that a dense molded product cannot be obtained and the harmful components cannot be fixed with cement.

Examples of the aggregate include crushed stones such as andesite, silica sand, and an inorganic fine powder filler, and the amount of the aggregate used is preferably 50 parts by weight or more with respect to 100 parts by weight of incinerated ash. If the amount of aggregate used is less than 50 parts by weight, the aggregate cannot cover shrinkage due to hydration of cement, and thus cracks may occur in the molded product.

In the present invention, the paste after kneading is solidified and molded by a known method such as pressure molding, extrusion molding, casting / casting, etc., so that the paste is compact and has high strength and practical use without toxic component elution. An excellent cement-solidified product of incinerated ash can be obtained. If the mold used for this shaping and the surface of the mold have a smooth mirror surface specification, the paste-like raw material will solidify while compacting without shrinkage due to desorption of excess water, so that the surface gloss It is possible to obtain an excellent solidified product. Therefore, the cement-solidified product which can be used only for conventional landfill can be used for tiles, interblocking blocks, etc., and the range of resource utilization is further expanded.

[0019]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the following examples do not limit the present invention, and various modifications may be made without departing from the spirit of the above and the following. Are all included in the technical scope of the present invention. still,
Unless otherwise specified, "part" and "%" mean "part by weight" and "% by weight", respectively.

Example 1 Material: 100% by weight of municipal waste incinerated ash Portland cement 150 〃 (cement / incinerated ash = 150%) Aggregate (No. 5 silica sand) 100 〃 Water 75 〃 (water / cement = 50%; water / (Cement + Incinerated ash) = 30%) Water-absorbent polymer 0.75 〃 [Osaka Organic Chemical Industry Co., Ltd. BL-100; particle size 70-100 µm; 100 times water absorption]

Of the above materials, 75 parts of water (tap water) was placed in a container, and 0.75 part of a water-absorbent polymer was gradually added with stirring. Stirring was continued for 5 minutes to absorb water, stirring was stopped, and a powdered polymer after water absorption was obtained. Other materials were kneaded with a 5-liter kneader (vacuum universal stirring mixer manufactured by Dalton Co., Ltd.) for 1 minute, and then powdered water was added and kneaded for 10 minutes to obtain a paste-like raw material.

30 kg of this raw material paste is charged into a mold in which mineral oil is thinly applied to a S45C (▽▽ finish) mold material.
10 x 160 mm x 40 mm x 12 mm at a molding pressure of f / cm ²
Press molded for minutes. The molded product was aged at room temperature for 2 days while being kept in the mold. Bending / testing and measurement of total pore volume and gloss were performed on the obtained molded and solidified product. Bending strength is 100 mm in span of 2 days old,
It is the result of 3-point bending with an Instron universal test material, and the pore volume was determined by the mercury injection method using a Shimadzu Poiserizer 9310 type. Also, the glossiness is GM-060, a gloss meter manufactured by Minolta Camera.
Was measured using. The measurement results are shown in Table 1.

Example 2 Molding and evaluation were carried out in the same manner as in Example 1 except that the mold surface was hard chrome plated and buffed. Example 3 Under the conditions of Example 2, molding and evaluation were performed in the same manner except that the material composition was changed as follows.

Material: 100 parts by weight of municipal waste incineration ash (average particle size: about 0. 1 mm) Polymer-based sludge incineration ash 25 〃 (average particle size about 4 μm) Portland cement 150 〃 (average particle size about 10 μm) (cement / incineration ash = 120%) Aggregate (No. 5 silica sand) 100 〃 (average particle size About 0. 5mm) Water 80〃 (water / cement = 50%, water / (incineration ash + cement) = 29%) Water-absorbent polymer 0. 8 〃

Comparative Example Material: 100% by weight of municipal waste incinerated ash Portland cement 30 〃 (cement / incinerated ash = 30%) Water 50 〃 (water / cement = 167%, water / (incinerated ash + cement) = 38%)

Of the above materials, incinerated ash and cement were placed in an omnimixer OM-5 manufactured by Chiyoda Giken Kogyo Co., Ltd.
After stirring for 0 seconds, water was added and the mixture was stirred for 120 seconds. 3 mm
A powdery mixture was obtained which was granulated to a degree. This mixture was press-molded under the same conditions with the same mold as that used in Example 1. However, after the press molding, the mold was disassembled and immediately released from the mold, and the molded product was aged at room temperature for 2 days for evaluation. The evaluation results of Examples 1 to 3 and Comparative Example are also shown in Table 1. Further, with respect to Example 1 and Comparative Example, a heavy metal dissolution test was carried out based on the Environmental Agency Public Notice No. 13 test, and the results are shown in Table 2.

[0027]

[Table 1]

[0028]

[Table 2]

It can be seen from Table 1 that the examples of the present invention have a total pore volume of 1/10 or less that of the comparative examples and are dense, so that the bending strength is improved 6 to 7 times. Also,
In Examples 2 and 3 in which the mold was mirror-finished and molded, solidified products having a clean gloss were obtained. Further, from the results of Table 2, it was proved that the examples of the present invention are excellent in the elution prevention effect of toxic substances.

[0030]

EFFECTS OF THE INVENTION The present invention is configured as described above, and by using a raw material paste whose initial hydration is promoted at a low water cement ratio, a cement solidified product of incineration ash having high strength, compactness and safety. I was able to get Also, by making the mold surface a smooth mirror surface, it is possible to obtain a cement-solidified product with excellent surface gloss, and we succeeded in expanding the possibilities of resource utilization of incinerated ash.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location C04B 24:24) Z 2102-4G (72) Inventor Saburo Sawada 1 Wakihama-cho, Chuo-ku, Kobe-shi, Hyogo Chome 3-18 Kobe Steel, Ltd. Kobe Head Office

Claims (3)

[Claims] [Claim 1] Incinerated ash of waste, sewage sludge, cement,
A method for solidifying cement of incinerated ash, which comprises kneading an aggregate and a raw material containing a water-absorbing polymer that has absorbed water to form a paste in which initial hydration is promoted, and then forming the paste. 2. The raw material according to claim 1 is incinerated ash 100.
Cement: 65 parts by weight or more with respect to parts by weight, aggregate: 50
The cement solidification method for incinerated ash according to claim 1, wherein the content of water-absorbent polymer (when dried): 0.5 part by weight or more and water: 25 to 45 wt% of the total amount of incinerated ash and cement. 3. A cement-solidified product of incineration ash, which is solidified by using the method according to claim 1.