JPH06340417A - Production of zeolite composition - Google Patents

Abstract

PURPOSE:To obtain a high-value-added zeolite composition regardless of the kind of coal ash by mixing coal ash and >=1 kind of alkaline component among Na2CO3, NaOH, K2CO3 and KOH, thermally melting the mixture and then heat-treating the molten mixture. CONSTITUTION:Coal ash is mixed with >=1 kind of alkaline component among Na2CO3, NaOH, K2CO3 and KOH preferably in 0.5-1.5 molar ratio of the alkaline component to SiO2 contained in the coal ash. The mixture is heated, for example, at >=1000 deg.C for about 1hr in an electric furnace and melted. The molten mixture is then cooled and crushed, water is added in 50 molar ratio of H2O to Na2O and the admixture is heat-treated at about 100 deg.C for about 24hr in an autoclave, for exapmle. The coal ash of certain composition has not sufficiently been converted to zeolite so far, especially when the Al2O3 in coal ash exists as crystalline mullite. The coal ash difficult to convert to zeolite is converted to zeolite by this method.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a zeolite composition using coal as a raw material.

[0002]

2. Description of the Related Art Power generation by a coal-fired boiler is expected to increase in the future due to an increase in power demand and a reduction in energy cost. Coal contains some unburned ash, which remains as fly ash after burning. With the increase in the number of coal-fired power plants, the amount of coal ash emitted becomes large, and the treatment of the ash becomes a social problem.

At present, coal ash is mainly used as a raw material for landfill or cement at sea or on land. As another use, a method of obtaining a hardened product by blending with anhydrous gypsum (JP-A-53-27619) is also shown. Also,
Japanese Unexamined Patent Publication No. 64-24014 and Japanese Unexamined Patent Publication No. 2-221114 disclose methods for synthesizing zeolite having a higher added value using coal ash as a raw material.

[0004]

However, according to the prior art, depending on the composition of the coal ash, sufficient zeolite formation is not always possible, and particularly when Al ₂ O ₃ in the coal ash exists as crystalline mullite. It is difficult for zeolite to progress.

The present invention has been made in view of these circumstances. Compared with the prior art, coal ash that is difficult to be made into zeolite can be sufficiently made into zeolite, and a zeolite with high added value can be synthesized regardless of the type of coal ash. It is an object of the present invention to provide a method for producing a zeolite composition that can be used.

[0006]

This invention is directed to coal ash and N
a ₂ CO _3, NaOH, mixed K ₂ CO _3, at least one kind of alkaline components in the KOH, after further heating and melting the mixture, the manufacturing method of the zeolite composition, characterized in that the heat treatment Is.

In the present invention, the amount of the alkaline component mixed is 0.5 to 0.5 in terms of molar ratio with respect to the SiO ₂ content in the coal ash.
1.5 is preferable, and the heating and melting temperature is preferably 1000 ° C. or higher.

[0008]

According to the present invention, Al ₂ O ₃ , S in coal ash is
Regardless of the proportion of iO ₂ present as crystals of mullite, α-quartz, etc., sufficient zeolite formation proceeds.
The reason for this is that by mixing and melting coal ash with an alkaline component such as Na ₂ O ₃ in advance, crystals such as mullite and α-component existing in the coal ash disappear, and nepheline which easily undergoes zeolite formation, It is thought to be due to the change to minerals such as Carnegie stone.

[0009]

Embodiments of the present invention will be described below. (Examples 1 to 3) 1 g of Na ₂ CO ₃ was added to 30 g of coal ash having the chemical composition shown in the following “Table 1” collected from a coal-fired boiler.
7.6g, 35.2g, 52.8g were added and mixed, and it melted at 1000 degreeC x 1 hour in an electric furnace. Then, the melt was cooled and ground, water was added so that the H ₂ O / Na ₂ O molar ratio was 50, and heat treatment was carried out at 100 ° C. for 24 hours in an autoclave. The product after the treatment is filtered, washed with water and dried,
Zeolite composition A (Example 1), zeolite composition B
(Example 2) and a zeolite composition C (Example 3) were obtained.

[0010]

[Table 1]

(Comparative Example) 30 g of coal ash shown in Table 1 was mixed with 3N N
Add to 300ml aOH, 3kg / in autoclave
It was heated to a pressure of cm ² and treated for 5 hours. The treated product was filtered, washed with water and dried to obtain a zeolite composition D.

The mineral compositions of the zeolite compositions A, B, C and D obtained in Examples 1 to 3 and Comparative Example 1 were X.
It was identified by line diffraction. The X-ray diffraction patterns are shown in FIGS. Here, in FIGS. 1 to 4, the horizontal axis represents the diffraction angle 2θ (°) and the vertical axis represents the diffraction X-ray intensity (cps: co).
unt per second). In addition, mullite in the figure, α-
SiO ₂ (quartz) is a mineral species originally contained in coal ash. Also performs NH ₄ ⁺ ion exchanged with aqueous NH ₄ Cl, zeolite compositions A, B, C, an ion exchange capacity of D a (meq / g) was determined. The results are shown in "Table 2" below.

[0013]

[Table 2]

1 to 4, mullite and α-SiO ₂ remain in the zeolite composition D of the comparative example.
This is not seen in the zeolite compositions A, B, and C of Examples 1, 2, and 3, and zeolites such as gallonite and analcime are often formed. In addition, from Table 2, Example 1,
It can be seen that the few zeolite compositions A, B, and C have a larger ion exchange capacity than the zeolite compositions of the comparative examples, and are excellent.

[0015]

As described above in detail, according to the present invention,
It is possible to provide sufficient zeolite-forming for coal ash that is difficult to form into zeolite as compared with the conventional one, and it is possible to provide a method for producing a useful zeolite composition capable of synthesizing high-value-added zeolite regardless of the type of coal ash.

[Brief description of drawings]

FIG. 1 is a characteristic diagram of an X-ray diffraction pattern of a zeolite composition according to Example 1 of the present invention.

FIG. 2 is a characteristic diagram of an X-ray diffraction pattern of the zeolite composition according to Example 2 of the present invention.

FIG. 3 is a characteristic diagram of an X-ray diffraction pattern of the zeolite composition according to Example 3 of the present invention.

FIG. 4 is a characteristic diagram of an X-ray diffraction pattern of a conventional zeolite composition.

Claims (2)

[Claims] 1. Coal ash and Na ₂ CO ₃ , NaOH, K ₂
A method for producing a zeolite composition, which comprises mixing at least one alkaline component selected from CO ₃ and KOH, heating and melting the mixture, and then heat-treating the mixture. 2. The amount of alkali components mixed in the coal ash is Si.
The method for producing a zeolite composition according to claim 1, wherein the molar ratio to the O ₂ content is 0.5 to 1.5, and the heating and melting temperature is 1000 ° C or higher.