JPS5969453A - Manufacture of hardened body from coal ash - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a hardened material using coal ash as a main raw material discharged during coal combustion. The present invention relates to a method for producing a hydrated hardened body having high mechanical strength by kneading a mixed powder containing water gypsum and/or (2) type water gypsum and curing at room temperature.

In recent years, the development of alternative energy sources for oil to reduce our dependence on oil has become a national issue in our country, 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 an energy source is the treatment of large amounts of coal ash generated during coal combustion.

During coal combustion, coal ash is usually generated which is approximately 10 to 20% by weight of the amount of coal used. The so-called pulverized coal combustion ash generated from ordinary pulverized coal combustion boilers is classified into bottom ash, cinder ash, and fly ash, depending on where it is generated, and the inner fly ash accounts for the majority of the amount generated. Conventionally, in Japan, a portion of fly ash is reused as a cement mixture or as a raw material for cement, and the rest is disposed of in landfills.

However, it is not possible to expect enough demand to meet the huge amount of coal ash that will be generated in the future by reusing the current method alone. Due to tightening environmental regulations, it is becoming increasingly difficult to secure land for coal ash disposal, and when a full-scale coal-fired power plant goes into operation, the current methods of disposing and effectively utilizing coal ash will It is expected that it will be difficult to process all of the coal ash. In addition, when considering mass processing technology for coal ash, it is necessary to aim for reuse as much as possible without polluting the environment. 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-mentioned points, the present invention utilizes coal ash in large quantities in the civil engineering sector, such as soil removal for sea surface reclamation and land reclamation, soil improvement targeting soft ground, and road base material for road construction. This was done with the aim of manufacturing a hardened soil with high compressive strength using coal ash as a raw material.
Coal ash 50-94% by weight, preferably 60-80% by weight
, slaked lime or/and quicklime (hereinafter abbreviated as slaked lime, etc.) 5 to 40% by weight, preferably 15 to 30% by weight, 2
Water gypsum, hemihydrate gypsum or/and type water gypsum (
When manufacturing a hardened body using a mixed powder of 1 to 40% by weight, preferably 5 to 20% by weight (hereinafter abbreviated as dihydrate gypsum, etc.), an amount of mixed water of 10 to 60% by weight (powder 10% by weight) is used as a raw material.
Heavy use of water added to 0% by weight.

%) of water, the kneaded product is shaped into a predetermined shape using a mold or a molding container, and cured at room temperature, or this kneaded product is directly applied to the construction target. The present invention provides a method for manufacturing a hardened soil body with a large compressive strength by putting it into a location and curing it at room temperature in an irregular shape.

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, depending on where the coal comes from, 5i02, A], 201, O
The blending proportions of components such as aOXFe20g, Na2O, K2O are different, and "Secondly, the coal ash currently generated in Japan is mainly pulverized coal combustion ash, and the particle size distribution differs depending on the hot spring and collection method. Therefore, when producing a hydrated hardened material with high compressive strength using coal ash as the main raw material and cured at room temperature, the optimum manufacturing conditions for the hydrated hardened material differ slightly depending on the composition and particle size distribution of the coal ash. Factors that have a large contribution rate are the mixing ratio of raw material powder, kneading time, kneading eddy electric current, and room temperature curing time.

The main component of the hydrated hardened product produced by curing at room temperature is ettringite (30aO...A120B/3
0aSO4・Ro21120) and various forms of calcium silicate hydrate (XCaO・ysi02・ZH20), but the one that contributes most to early strength development is ettringite. For this reason, the blending ratio of the raw material powder is the most favorable for the production of ettringite, and the amount of slaked lime added is 5 to 40% by weight, preferably 15 to 30% by weight.
The amount of weight M%, dihydrate gypsum, etc. added is limited to 1 to 40% by weight, preferably 5 to 20% by weight. In addition, curing at room temperature is the main cause of the processing time. When curing at room temperature, it usually takes 2.3 days to 1 day for ettringite to form and exhibit a compressive strength higher than that of the dispersed form, which is sufficient to withstand normal civil engineering work.
It takes a week.

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 the /f= formation reaction of ettringite.
n reaction), and the dissolution M rate of alumina (A120+1) contained in coal ash is slaked lime, 2
This is because it is significantly smaller than hydrogypsum, and the production rate of ettringite can be estimated to depend on the dissolution rate of alumina. In this way, the properties of hydrated hardened products are greatly influenced by manufacturing conditions such as the components and composition of coal ash, the amount of other raw material powders added, the amount of water mixed, the kneading method and kneading time, and the curing period at room temperature. It is necessary to appropriately select each manufacturing condition according to the required characteristics of the Japanese hardened product.

The present invention is capable of producing a hydrated material with high initial strength in a simple kneading process and in a short kneading time by simultaneously kneading a mixed powder consisting of an appropriate blending ratio of each raw material powder and water. It is intended to be manufactured by curing at room temperature.

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. Furthermore, if 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 or the limit. Therefore, in the present invention, the desirable amount of mixed water is 30 to 50
Weight%.

Next, Examples and Comparative Examples will be described.

The raw material coal ash used in Examples and Comparative Examples is commercially available fly ash, and its composition and properties are shown in Table 1.

(Margin below) The test methods for coal ash and hydrated bodies are shown below.

The Blaine specific surface area was measured by the air permeation method using a powder specific surface area measuring device 5S-100 manufactured by Takafusa Seisakusho.

The bending strength test uses 20X20xso (mx) as a test piece.
The compressive strength test was performed using 20X as a test piece.
20 x 20 (HA) was used, and a universal testing machine manufactured by Instron was used as the testing device. The test method was the constant deflection method. In Examples and Comparative Examples, room temperature curing was carried out indoors without direct sunlight. Details of Examples and Comparative Examples are shown in Table 2.

Example 1 88 parts of coal ash, 10 parts of slaked lime, 2 parts of dihydrate gypsum, 40 parts of water
The components were simultaneously kneaded to form a slurry, and this slurry was cured indoors 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, 40 parts of water
These parts were kneaded simultaneously to form a slurry, and this slurry was cured indoors at room temperature for 7 parts to obtain a hydrated hardened product. The properties of the hydrated and cured product were as shown in Table 2.

Example 90 parts of coal ash, 5 parts of slaked lime, 5 parts of dihydrate gypsum, and 40 parts of water were simultaneously mixed and kneaded to form a slurry, and this slurry was cured at room temperature for 711 days to obtain a hydrated hardened product.

The properties of the hydrated and cured product were as shown in Table 2.

Example 4 80 parts of coal ash, 15 parts of slaked lime, 5 parts of dihydrate gypsum, 40 parts of water
The components were simultaneously kneaded to form a slurry, and this slurry was cured indoors 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 1 90 parts of coal ash, 10 parts of slaked lime, and 40 parts of water were simultaneously kneaded to form a slurry, and this slurry was cured at room temperature for 711 days to obtain a hydrated hardened product. The properties of the hydrated and cured product were as shown in Table 2.

Comparison Example 2 95 parts of coal ash, 5 parts of dihydrate gypsum, and 40 parts of 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.

(The following is a blank space) From Table 2, it can be seen that a hydrated hardened product with high initial strength can be produced by simultaneously kneading the raw material powder and water and then curing at room temperature.

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 water gypsum are used. However, by kneading it in water and curing it at room temperature, it is possible to easily and inexpensively produce a hydrated material with high compressive strength.The present invention makes effective use of coal ash and can be used in civil engineering and construction. It is useful as a technology that contributes to the production of earthworks for reclamation, land preparation, road construction, etc. in the field. In addition, since the method of the present invention kneads the raw material powder and water at the same time, the process is extremely simplified, the kneading time is shortened, and the hydrated hardened product can be produced at a lower cost. are doing.

Representative Patent Attorney Makoto Shiide ,7'

Claims (1)

[Claims] 1. 50 to 94% by weight of coal ash discharged during coal combustion,
Slaked lime or/and quicklime 5-40% by weight, dihydrate gypsum, hemihydrate gypsum or/and type water gypsum 1-40%
When producing a cured product using a mixed powder consisting of A method for producing a hardened product using coal ash as the main raw material, which is characterized by forming it using coal ash or the like and then curing it at room temperature. 2 50-94% by weight of coal ash emitted during coal combustion,
Slaked lime or/and quicklime 5-40% by weight, dihydrate gypsum, hemihydrate gypsum or/and type water gypsum 1-40%
When producing a cured product using a mixed powder consisting of 10% to 071% by weight as a raw material, water in an amount of 10% to 071% by weight is added to the mixed powder and thoroughly kneaded, and the kneaded product is shaped into a specific shape. A method for producing a hardened product using coal ash as the main raw material, which is characterized by curing at room temperature without molding.