JPS6339538B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for producing a hardened material using coal ash discharged during coal combustion as a main raw material. A mixed powder obtained by adding / and molded anhydrous gypsum is kneaded with water,
The present invention relates to a method for producing a hydrated material with high mechanical strength by curing at room temperature. [Prior Art] In recent years, the development of alternative energy to petroleum in order to reduce dependence on petroleum has become a national issue in Japan, and coal energy is attracting attention as one of the pillars of energy. One of the challenges in the practical application of coal utilization technology to cope with the large consumption of coal as a primary energy source is the disposal of large amounts of coal ash generated during coal combustion. When burning coal, usually almost 10 to 20 of the coal usage
% coal ash is generated. The so-called pulverized coal combustion ash generated from a typical pulverized coal combustion boiler is classified into bottom ash, cinder ash, and fly ash depending on where it is generated, and the fly ash accounts for the majority of the amount generated. Traditionally in Japan, a portion of fly ash has been reused as cement admixtures, cement raw materials, etc.
The rest is disposed of in landfills. [Problems to be solved by the invention] However, it cannot be expected that the demand for coal ash will be sufficient to cope with the huge amount of coal ash that will be generated in the future by reusing the current method. As for the disposal of ash in landfills, it is becoming difficult to secure land for coal ash disposal due to stricter environmental regulations. It is expected that it will be difficult to dispose of all of the coal ash generated through this and effective utilization methods. Furthermore, when considering mass processing technology for coal ash, it is necessary to aim for reuse as much as possible without causing environmental pollution. This is because in a country with limited domestic resources and limited land, it is important to reuse coal ash as a resource rather than simply dumping it. In view of the above points, the present invention utilizes coal ash in large quantities in the civil engineering sector, such as as a soil material for sea surface reclamation and land reclamation, as a soil improvement material for soft ground, and as a road base material for road construction. This method was developed to produce a hardened clay body with high compressive strength using coal ash as a raw material, and contains 50 to 94% by weight of coal ash, preferably 60 to 80% by weight, slaked lime or/and quicklime (hereinafter referred to as (abbreviated as slaked lime, etc.) 5 to 40% by weight,
Preferably 15 to 30% by weight, 1 to 40% by weight of dihydrate gypsum, hemihydrate gypsum or/and type anhydrous gypsum (hereinafter abbreviated as dihydrate gypsum), preferably 5
When producing a cured product using a mixed powder of ~20% by weight as raw material, the amount of water mixed in is 10~60% by weight (100% by weight of powder).
After kneading the raw material powder in seawater (wt% of water added to wt%), or after kneading the mixed powder
0.1 to 3 parts by weight of sodium chloride,
After adding and kneading a chloride selected from the group consisting of potassium chloride and magnesium chloride and water in an amount of 10 to 60% by weight, the kneaded product is molded into a predetermined shape using a mold or a molding container. By curing at room temperature with or by directly putting this kneaded material into the construction target area and curing at room temperature in an amorphous state, a hardened soil body with high compressive strength can be produced in a short kneading time. The purpose is to provide a method to do so. [Means and effects for solving the problem] In order to achieve the above object, the method for producing a hardened body using coal ash as a main raw material according to the first invention of the present application uses 50% of coal ash discharged during coal combustion. ~94% by weight, slaked lime or/and quicklime 5-40% by weight, dihydrate gypsum, hemihydrate gypsum or/and type anhydrous gypsum 1
When producing a cured body using a mixed powder consisting of ~40% by weight as a raw material, for 100 parts by weight of the mixed powder.
0.1 to 3 parts by weight of sodium chloride, potassium chloride,
A chloride selected from the group consisting of magnesium chloride and water in an amount of 10 to 60% by weight are added and kneaded, then this kneaded product is molded using a mold or a molding container, and then left at room temperature. It comes from taking care of yourself. Further, the method for producing a hardened body using coal ash as a main raw material according to the second invention of the present application includes 50 to 94% by weight of coal ash discharged during coal combustion, 5 to 40% by weight of slaked lime or/and quicklime, and dihydrate gypsum. , hemihydrate gypsum or/
When producing a hardened body using a mixed powder consisting of 1 to 40% by weight of anhydrous gypsum and type anhydrous gypsum as a raw material, 0.1 to 3 parts by weight of sodium chloride, potassium chloride, and magnesium chloride are added to 100 parts by weight of the mixed powder. The method consists of adding and kneading a chloride selected from the group consisting of: and water in an amount of 10 to 60% by weight, and then curing the kneaded product at room temperature without shaping it into a specific shape. . In the method of the present invention, 0.1 to 3 parts by weight of a chloride selected from the group consisting of sodium chloride, potassium chloride, and magnesium chloride and 10 to 60% by weight of water are added to 100 parts by weight of the mixed powder. It is preferable to use seawater as the water. Hereinafter, the configuration of the present invention will be explained in detail. In general, the typical properties of coal ash, such as components, composition, and particle size distribution, greatly depend on the coal's production area and combustion history. First of all, it depends on the place where the coal is produced.
The proportions of ingredients such as SiO ₂ , Al ₂ O ₃ , CaO, Fe ₂ O ₃ , Na ₂ O, K ₂ O are different, and secondly, the coal ash currently generated in Japan is mainly pulverized coal combustion ash. Yes, the particle size distribution varies depending on the location and collection method. Therefore, when producing a hydrated material with high compressive strength using coal ash as the main raw material and curing at room temperature, the appropriate manufacturing conditions for the hydrated material may vary depending on the composition and particle size distribution of the coal ash. different. Factors that have a large contribution rate as manufacturing conditions are the mixing ratio of raw material powder, kneading time and kneading temperature, and room temperature curing time. The main component _of the hydrated hardened material produced by curing at room temperature is ettringite (3CaO・_Al2O3・_3CaSO4・
32H ₂ O) and various forms of calcium silicate hydrate (xCaO・ySiO ₂・zH ₂ O), but the one that contributes most to early strength development is ettringite.
For this reason, the appropriate mixing ratio of the raw material powder is the one most favorable for the production of ettringite, and the amount of slaked lime etc. to be added is 5 to 40% by weight, preferably 15 to 40% by weight.
30% by weight, and the amount of dihydrate gypsum added is limited to 1 to 40% by weight, preferably 5 to 20% by weight. Furthermore, the room temperature curing conditions are mainly due to the processing time. When cured at room temperature, it usually takes a few days to a week for ettringite to form and exhibit a compressive strength of several kg/cm ² or more, which is sufficient to withstand normal civil engineering work. The particle size distribution of coal ash also has a large effect on the properties of the hydrated hardened material. Generally, as the particle size of coal ash becomes smaller, that is, as the specific surface area becomes larger, the hydrated hardened material tends to exhibit a predetermined strength with a shorter curing time. This is because the formation reaction of ettringite is a through solution reaction, and the dissolution rate of alumina (Al ₂ O ₃ ) contained in coal ash is significantly lower than that of slaked lime and dihydrate gypsum. This is because it can be estimated that the production rate of ettringite depends on the dissolution rate of alumina. in this way,
The properties of the hydrated hardened product are determined by the components and composition of the coal ash,
It is greatly influenced by manufacturing conditions such as the amount of other raw material powders added, amount of water mixed, kneading method and kneading time, and room temperature curing period, and each manufacturing condition must be appropriately selected according to the required characteristics of the hydrated product. It is necessary to. In the present invention, by simultaneously kneading a mixed powder consisting of an appropriate blending ratio of each raw material powder and seawater, or by simultaneously kneading the mixed powder, a water-soluble chloride, and water, the initial The purpose is to produce a hydrated hardened product with high strength through a simple kneading process and by curing at room temperature under a short kneading time. In the present invention, the amount of mixed water is 10 to 60% by weight, but if the amount of mixed water is reduced, the strength will increase, but the moldability will deteriorate, and if the amount of mixed water is less than about 10% by weight, molding will not be possible. In addition, when the amount of mixed water is increased, the fluidity increases and it becomes difficult to solidify, and the amount of mixed water is about 60% by weight as the limit. Therefore, in the present invention, the desirable amount of water to be mixed is 30 to 50% by weight. Further, the present invention aims at increasing the initial strength of the hydrated and hardened product and shortening the room temperature curing period by using seawater or a similar aqueous solution as the kneading water. The strength of this hydrated hardened product is due to the formation of ettringite,
The presence of salts such as NaCl, KCl, MgCl ₂ increases the rate of ettringite formation and increases the strength of the hydrated hardened product. Next, Examples and Comparative Examples will be described.
The raw material coal ash in Examples and Comparative Examples is commercially available fly ash, and the composition and properties are shown in Table 1.

[Table] The test methods for coal ash and hydrated hardened bodies are shown below. The Blaine specific surface area was measured using a powder specific surface area measuring instrument SS-100 manufactured by Shimadzu Corporation, using the air permeation method. Bending strength test uses 20×20 as a test piece
For the compressive strength test, a 20 x 20 x 20 (mm) test piece was used as the test piece, and a universal testing machine manufactured by Instron was used as the testing device. The test method was based on the constant deflection method. In the Examples and Comparative Examples, room temperature curing was carried out indoors away from direct sunlight. Details of Examples and Comparative Examples are shown in Table 2. Example 1 85 parts of coal ash, 10 parts of slaked lime, 5 parts of dihydrate gypsum, and 40 parts of seawater were simultaneously kneaded to form a slurry, and this slurry was cured at room temperature for 7 days to obtain a hydrated hardened product. The properties of the hydrated and cured product were as shown in Table 2. Comparative Example 1 85 parts of coal ash, 10 parts of slaked lime, 5 parts of dihydrate gypsum, and 40 parts of tap water were simultaneously kneaded to form a slurry, and this slurry was cured at room temperature for 7 days to obtain a hydrated hardened product. The properties of the hydrated and cured product were as shown in Table 2. Example 2 85 parts of coal ash, 10 parts of slaked lime, 5 parts of dihydrate gypsum,
1.0 part of NaCl and 40 parts of tap water were simultaneously kneaded to form a slurry, and this slurry was cured at room temperature for 7 days to obtain a hydrated hardened product. The properties of the hydrated and cured product were as shown in Table 2. Example 3 85 parts of coal ash, 10 parts of slaked lime, 5 parts of dihydrate gypsum,
1.0 parts of MgCl ₂ and 40 parts of tap water were simultaneously kneaded to form a slurry, and this slurry was cured at room temperature for 7 days to obtain a hydrated hardened product. The characteristics of the hydrated hardened product are the second
It was as shown in the table. Comparative Example 2 85 parts of coal ash, 10 parts of slaked lime, 5 parts of dihydrate gypsum,
1.0 part of CaCl ₂ and 40 parts of tap water were simultaneously kneaded to form a slurry, and this slurry was cured at room temperature for 7 days to obtain a hydrated hardened product. The properties of the hydrated and cured product were as shown in Table 2.

〔Effect of the invention〕

As explained above, according to the present invention, coal ash, which is an exhaust product during coal combustion, slaked lime and/or quicklime, which is an inexpensive raw material, dihydrate gypsum, hemihydrate gypsum, and/or type anhydrous gypsum are used, By kneading in seawater or a similar aqueous solution and then curing at room temperature, it is possible to easily and inexpensively produce a hydrated material with high compressive strength. It is useful as a technology that contributes to the production of soil materials for reclamation, land reclamation, road construction, etc. in the fields of civil engineering and construction. Furthermore, since the method of the present invention simultaneously kneads the raw material powder and seawater or a similar aqueous solution, the process is extremely simplified, the kneading time is shortened, and the hydrated hardened product can be produced at a lower cost. It has the effect of being able to

Claims (1)

[Claims] 1. 50-94% by weight of coal ash discharged during coal combustion, 5-40% by weight of slaked lime or/and quicklime,
When producing a hardened body using a mixed powder consisting of 1 to 40% by weight of dihydrate gypsum, hemihydrate gypsum, or/and type anhydrous gypsum as a raw material, 0.1 to 3 parts by weight per 100 parts by weight of the mixed powder. A chloride selected from the group consisting of sodium chloride, potassium chloride, and magnesium chloride and water in an amount of 10 to 60% by weight are added and kneaded, and then this kneaded product is molded using a mold or a molding container. A method for producing a hardened product using coal ash as a main raw material, which is characterized by curing at room temperature after curing at room temperature. 2. Chloride selected from the group consisting of sodium chloride, potassium chloride, magnesium chloride in an amount of 0.1 to 3 parts by weight per 100 parts by weight of the mixed powder, and 10 to 60 parts by weight
2. A method for producing a hardened body using coal ash as a main raw material according to claim 1, wherein seawater is used as the water in the amount of water mixed in % by weight. 3 50-94% by weight of coal ash discharged during coal combustion, 5-40% by weight of slaked lime or/and quicklime,
When producing a hardened body using a mixed powder consisting of 1 to 40% by weight of dihydrate gypsum, hemihydrate gypsum, or/and type anhydrous gypsum as a raw material, 0.1 to 3 parts by weight per 100 parts by weight of the mixed powder. A chloride selected from the group consisting of sodium chloride, potassium chloride, and magnesium chloride and water in an amount of 10 to 60% by weight are added and kneaded, and then the kneaded product is heated at room temperature without forming it into a specific shape. A method for producing a hardened material using coal ash as a main raw material, which is characterized by curing in a . 4 0.1 to 3 parts by weight of a chloride selected from the group consisting of sodium chloride, potassium chloride, and magnesium chloride per 100 parts by weight of the mixed powder, and 10 to 60 parts by weight
4. The method for producing a hardened body using coal ash as a main raw material according to claim 3, wherein seawater is used as the water in the weight percent water content.