JPH01270553A - Production of set material of coal ash - Google Patents

Abstract

PURPOSE:To simply reduce kinds of agents added and to shorten setting time by adding water to a mixture of a given amount of coal ash and alpha type hemihydrate, kneading and molding at normal temperature under normal pressure. CONSTITUTION:20-80 pts.wt. coal ash is blended with 80-20 pts.wt. alpha type hemihydrate to give 100 pts.wt. mixture, which is kneaded with 40-50 pts.wt. water to give mixed powder slurry. Then the slurry is cast into a mold at normal temperature under normal pressure to produce set materials.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for producing a hardened body that can be used for building boards and the like using coal ash.

(Conventional technology) It is said that the amount of coal ash emitted from the boilers of coal-fired power plants will reach 10 million tons per year in the near future, and although some of it is effectively used, the majority is landfilled. The waste is being disposed of as waste or being dumped in ash dumps. However, there are many issues related to compliance with the Waste Disposal Law, and it is desirable to develop technologies for utilizing coal ash.

Coal ash can be used effectively in cement, civil engineering, aggregate, and building materials, and can be roughly divided into whether it is used as a raw material in the form of powder or it is used after solidification.

As is well known, coal ash does not harden as it is, so many solidification methods have been proposed.
No. 2560 describes a method of adding lime and gypsum to coal ash and subjecting it to steam curing at 180°C; JP-A-55-36615 describes a method of kneading gypsum calcined at 450 to 600°C with coal ash; -134023 discloses a method for producing a porous hardened body by adding α hemihydrate gypsum and a foaming agent to coal ash;
Japanese Patent Publication No. 59-53228 describes a method of adding lime and gypsum to coal ash, Japanese Patent Publication No. 56-17961 discloses a method of mixing lime with coal ash and calcining the mixture at 1350 to 500°C, and Japanese Patent Publication No. 58-30262 discloses a method of adding lime and gypsum to coal ash. A method using coal ash, lime and strong alkali is shown.

In either case, lime is added to coal ash and assimilated using the slow Boduran reaction, or lime and gypsum are combined to form ettringite over a long period of time.
Alternatively, chemicals such as dissolved salts and blowing agents are added or heat treatment is performed, which shortens the production time of cured products.
There was no one that could meet the demands of (1) simplifying the process, and (2) reducing the amount of added drug crystal species.

(Problems to be Solved by the Invention) When producing a cured product that can be used as building materials such as boards from coal ash, ■ Simplifying the process for producing the cured product ■ Reducing the amount of inertia 11 drug crystal species ■ Curing speed The present invention solves the conventional problem of shortening the curing time without utilizing the slow process of coal ash and coal ash produced from coal-fired power plants. This method provides a method for producing hardened coal ash by using α-type hemihydrate gypsum, which can be produced from exhaust dihydrate gypsum obtained by flue gas desulfurization. It is possible to easily and quickly produce a hardened product that does not contain any of the following: a.

Instead of α-type hemihydrate gypsum, β is known as calcined gypsum.
It takes time to use mold hemihydrate gypsum and to manufacture the hardened body.
Since the strength of the hardened product is low, the hardened product that can be used for building materials such as boards is 111% when α-type hemihydrate gypsum is used.

(Means for Solving the Problems) The present invention mixes α-type handwash gypsum with coal ash, minimizes the amount of kneading water, and kneads and molds at room temperature and normal pressure to produce a high-strength hardened product. Here, the α-type hemihydrate liver can be used, which is produced from waste gypsum (dihydrate-K) from a thermal power plant by a 11-pressure water 7-volume liquid method. The method for producing a hardened body of coal ash according to the present invention is extremely convenient for use in a thermal power plant (Structure of the Invention) Therefore, the present invention provides: (1) a method for producing a hardened body using coal ash as a raw material; 100 parts by weight of a mixture consisting of 20 to 80 parts by weight of coal ash and 80 to 20 parts by weight of α-type hemihydrate gypsum and 40 to 50 parts by weight of water are mixed by weight and molded at room temperature and normal pressure. (2) A method for producing a hardened body using coal ash as a raw material, in which 100 parts by weight of a mixture consisting of 20 to 80 parts by weight of coal ash and 80 to 20 parts by weight of dihydrate gypsum and 45 to 45 parts by weight of water. 80 parts by weight
Then, while kneading under pressure and JJII heat, add dihydrate gypsum to α.
The present invention provides a method for producing a hardened product of coal ash, which is characterized in that the coal ash is converted into mold hemihydrate gypsum, and then molded under normal pressure and normal temperature.

〔Example〕

Specific examples of the present invention (1) will be described below. FIG. 1 shows, as a comparative example, the relationship between the coal ash blending ratio and the amount of water when kneading a mixed powder of coal ash and β-type hemihydrate gypsum. FIG. 2 shows a specific example of the present invention in which α-type hand plaster is applied to coal ash. Here, the parts by weight of mixed pure water added to 100 parts by weight of GJ mixed powder are shown. /Ft
In the method of obtaining a hardened product by spreading the slurry made by kneading the composite material with water into a mold and molding it, it is important that the slurry has sufficient fluidity in terms of ease of molding. be.

As shown in Figures 1 and 2, the minimum amount of mixed pure water to obtain a fluid slurry is 25 parts by weight per 100 parts by weight of the mixed powder when α-type hemihydrate gypsum is used. ~4
5 parts by weight, and 60 to 63 parts by weight for β-type hemihydrate stone. If the amount of kneading water is large, the setting time during molding will be delayed and a large amount of drying heat will be required. Therefore, if α-type hand plaster is used, it can be molded in a shorter time and furthermore, it dries and hardens with less heat. It is possible to obtain a body.

Table 1 shows the physical property measurement results of the cured product obtained by the present invention and the cured product using β-type hemihydrate gypsum.

Comparative Example 1 100 parts by weight of β-type hemihydrate gypsum without coal ash mixed with 61 parts of water
Add parts by weight and knead, and mix this into a 4 cm x 4 cm
A cured product was obtained by spreading and molding in a mold of 16 cm x 16 cm. The physical properties of this cured product were as shown in Table 1.

Comparative Example 2 Except that 60 parts by weight of water was added to 100 parts by weight of a mixed powder obtained by adding 50 parts by weight of β-type hemihydrate gypsum to 50 parts by weight of coal ash.
A cured product was obtained in the same manner as in Comparative Example 1.

The physical properties of the cured product were as shown in Table 1.

Comparative Example 3 Except that 60 parts by weight of water was added to 100 parts by weight of a mixed powder of 80 parts by weight of coal ash and 20 parts by weight of β-type hemihydrate gypsum.
A cured product was obtained in the same manner as in Comparative Example 1.

The physical properties of the cured product were as shown in Table 1.

Example 4 A cured product was obtained in the same manner as in Comparative Example 1 except that 45 parts by weight of water was added to 100 parts by weight of a mixed powder obtained by adding 50 parts by weight of α-type water gypsum to 50 parts by weight of coal ash. The physical properties of the cured product were as shown in Table 1.

Example 5 A hardened body was obtained in the same manner as in Comparative Example 1 except that 55 parts by weight of water was added to 100 parts by weight of a mixed powder of 80 parts by weight of coal ash and 20 parts by weight of α-type hemihydrate gypsum. .

The physical properties of the cured product were as shown in Table 1.

As shown in Table 1, a hardened body made of 80 parts by weight of coal ash and 20 parts by weight of α-type hemihydrate gypsum is mixed with a hardened body made of 80 parts by weight of coal ash and 20 parts by weight of β-type hemihydrate gypsum with the same mixing ratio. It has higher strength compared to other materials. It can also be seen that a hardened body made of 50 parts by weight of coal ash and 50 parts by weight of α-type hemihydrate gypsum has almost the same strength as a hardened body made of only β-type hemihydrate gypsum.

Table 1 * (β) represents β-type hemihydrate gypsum, and (α) represents α-carrying water gypsum.

As described above, according to the present invention (1), by adding α-type hemihydrate gypsum and a minimum amount of mixed pure water to coal ash, and performing kneading and molding at room temperature and normal pressure, a hardened coal ash product with high strength is obtained. It can be produced easily, without the use of additives to obtain hardened pozzolan or ettringite, and in a short curing time.

Next, examples related to the present invention (2) will be described below.

In the method of producing α-type hemihydrate gypsum from eliminated dihydrate gypsum by a pressurized aqueous solution method, 500 parts by weight of pure water is used for 100 parts by weight of eliminated dihydrate gypsum. If a dilute slurry of gypsum is simply added to coal ash, it is difficult to obtain a hardened material with sufficient strength. The present invention (2) involves converting dihydrate gypsum into α-type hemihydrate gypsum while pressurizing and heating and kneading a mixed powder obtained by adding expelled dihydrate gypsum to coal ash with the minimum amount of mixing water possible. This is a method of producing a hardened body of coal ash by molding it at room temperature and pressure. Therefore, as shown in Fig. 3, the relationship between the coal ash blending ratio and the amount of water per kneading was investigated when kneading a mixed powder of coal ash and removed dihydrate gypsum.

From FIG. 3, it was found that the minimum ratio of mixed pure water required for the mixed powder to become a fluid slurry was 32 to 47 parts by weight per 100 parts by weight of the mixed powder.

Table 2 shows an example of the physical property measurement results of the cured product obtained according to the present invention (2).

Example 6 50 parts by weight of coal ash and 5 parts by weight of removed dihydrite in an autoclave
A mixed powder consisting of 0 parts by weight is charged, and this mixed powder 10
0 parts by weight, 0.04 parts by weight of sodium citrate as a crystal modifier
After adding 88 parts by weight of water, the autoclave was sealed, and the raw materials inside the autoclave were heated by heating from the outer wall of the autoclave without kneading.

Pressure = 3, 1 kg/cm 2+ /l! ! After kneading for about 1.5 hours at 132°C, the mixture of coal ash and α-type hemihydrate gypsum was mixed into 4 cm x 4 at normal pressure and room temperature.
The mixture was spread and molded into a mold of cm x 16 cm to obtain a cured product.

The physical properties of this cured product were as shown in Table 2.

Example 7 A mixed powder consisting of 80 parts by weight of coal ash and 20 parts by weight of JJI dehydrated gypsum was placed in an autoclave, and 0.04 parts by weight of sodium citrate and 80 parts by weight of water were added to 100 parts by weight of this mixed powder. Parts by weight were added and mixed by heating in the same manner as in Example 6. Pressure・3.2kg/cm2. Temperature/132°
About 1. After Ohr kneading, the mixture was spread and molded at room temperature and pressure in the same manner as in Example 6 to obtain a cured product.

The physical properties of this cured product were as shown in Table 2 LJ.

As shown in Table 2, the cured product of the present invention (2) was found to have a strength that can be used as a building material, etc.

In the present invention (2), sodium citrate is preferred as the modifier, and the amount thereof is 0 to 100 parts by weight of the mixed powder.
, 02 to 0.3 g parts by weight are suitable. Furthermore, since a slurry with a small amount of mixed pure water is stirred, a stirrer with strong torque and stirring blades of an appropriate shape are used. Is the 11iA dihydrate gypsum α type in the second table? The reaction conditions for conversion to hydrated gypsum are pressure = 3.0 to 4.5 kg/cm2.
? mr degree, 130-145°C is suitable.

Note 11 As the heating method, direct heating of the raw material using steam and indirect heating using a steam jacket can be used.

(Effects of the Invention) As described in 2 below, according to the present invention, removed dihydrate gypsum and a minimum amount of mixed pure water are added to coal ash, and dihydrate K is added to the coal ash while kneading under pressure and heat. Convert to α carrier water stone, then mold under normal pressure? 7a, it can be produced easily, with fewer medicinal crystal species added, and in a shorter curing time.

[Brief explanation of the drawing]

FIG. 1 is a graph of a comparative example showing the relationship between the coal ash blending ratio and the kneading mercury when kneading a mixed powder of coal ash and β-carrying water gypsum, which is a comparative example of the present invention; Fig. 2 shows one embodiment of the present invention in which α-type hemihydrate gypsum is added to coal ash. FIG. 2 is a graph showing the relationship between the mixing ratio of coal ash and the mixing water (2) in the gap in which the mixed powder to which water gypsum is added is kneaded.

Claims (2)

[Claims] (1) In a method for producing a hardened product using coal ash as a raw material, 20 to 80 parts by weight of coal ash, 80 to 20 parts by weight of α-type hemihydrate gypsum
A method for producing a hardened body of coal ash, which comprises adding 40 to 50 parts by weight of water to 100 parts by weight of a mixture consisting of 100 parts by weight, and performing kneading and molding at room temperature and normal pressure. (2) In a method for producing a hardened body using coal ash as a raw material, 45 to 80 parts by weight of water is added to 100 parts by weight of a mixture consisting of 20 to 80 parts by weight of coal ash and 80 to 20 parts by weight of dihydrate gypsum. A method for producing a hardened coal ash product, which comprises converting dihydrate gypsum into α-type hemihydrate gypsum while kneading under pressure and heat, and then molding at normal pressure and room temperature.