JPH064486B2 - Zeolite synthesis method from fly ash - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for synthesizing zeolite from fly ash.

(Problems to be Solved by Prior Art and Invention) It is known that a mixed slurry of an aqueous NaOH solution and fly ash is boiled to form a zeolite.

In such processing, high base exchange capacity (250me
In order to obtain q / 100 g or more), a long boiling process is required.

For example, when 100 g of 4N-NaOH aqueous solution added with 50 g of fly ash is boiled at 100 ° C., zeolite production is as shown in the table below.

As shown in the above table, in order to obtain a zeolite with a high base exchange capacity, a boiling treatment time of about 15 hours or more is required.

For this reason, there are drawbacks such that productivity is extremely low, cost is disadvantageous, and operation on an industrial scale is impossible.

The present invention has been made to advantageously solve these drawbacks.

(Means and Actions for Solving the Invention) The present invention is to add 20 to 100 g / (SiO ₂ conversion) of silicate ions to a mixed slurry of an aqueous NaOH solution and fly ash, and then subject it to boiling treatment and an aqueous NaOH solution and fly ash. A method for synthesizing zeolite from fly ash, which comprises adding reactive SiO ₂ -containing rock to the mixed slurry of, and then boiling the mixture.

Here, the above-mentioned NaOH aqueous solution may be any one that can boil a conventionally known mixed slurry with fly ash, for example, NaOH: 80 to 160 g /
An aqueous solution is suitable, and the mixing ratio with fly ash may be a conventional mixing ratio for zeoliticization.
Is appropriate.

20 to 100 g of silicate ions /
Although (SiO ₂ equivalent) is added, if it is less than 20 g /, there is almost no effect, and even if it does not exceed 100 g /, a sufficient effect is obtained.

As the silicate ion, for example, sodium metasilicate is suitable.

In addition to such silicate io, rocks containing reactive SiO ₂ can be used. As the SiO ₂ source, rock containing cristobalite, silicate glass or the like can be used, and the addition amount is 2-1 to the fly ash.
0% is sufficient.

The reason why the zeoliticization is rapidly performed by adding the silicate ion or the reactive SiO ₂ -containing rock to the mixed slurry of the NaOH aqueous solution and the fly ash in the present invention is considered as follows.

That is, fly ash includes mullite, quartz, and amorphous S.
It is made from iO ₂ (glass).

An example of the composition of fly ash is SiO ₂ 7
0%, Al ₂ O ₃ 15%, CaO 0.6%, Na ₂ O
0.4%, K ₂ O 0.2%, TC 3.5%, MgO
0.4%, the balance is other, and an example of the mineral composition (X-ray diffraction) is as follows: quartz 30%, mullite 17%, amorphous S
It consists of 38% of iO _{2, the} balance of others.

Of this, the amorphous SiO _{2 component} is once dissolved by boiling treatment in an aqueous NaOH solution. The dissolved amorphous SiO ₂ exists in the aqueous solution as silicate ions, and the silicate ions react with the remaining fly ash and Na ₂ O ions to produce zeolite. It takes a long time to dissolve the high-quality SiO ₂ , and therefore the zeolite synthesis (production) also takes a long time.

Therefore, as in the present invention, by adding the silicate ion or reactive SiO ₂ before the boiling treatment as described above, the time required for the silicate ion to exist in the aqueous solution becomes shorter, and the zeolite is more likely to be synthesized. Zeolites with a high base exchange capacity (about 200 meq / 100 g or more) can be stably synthesized in a short time.

(Example) Next, the Example of this invention is given with a comparative example.

Note 1: The amount of SiO ₂ added is silicate ion (sodium metasilicate) (SiO ₂ conversion) added in Examples 1 to 3, and Example 4
For Nos. 6 to 6, rock powder (44 μ>) containing 90% of cristobalite was added as a reactive SiO ₂ ion.

Note 2: Boiling is 100 ° C. Note 3: Fly ash composition (%) is SiO ₂ : 72.
0, Al ₂ O ₃ : 15.3, CaO: 0.6, Na
₂ O: 0.4, K ₂ O: 0.2, TC: 3.5, Mg
O: 0.4.

Note 4: Fly ash mineral composition (%) is quartz: 30.
4, mullite: 17.1, amorphous SiO ₂ : 38.4,
Other 14.1.

Note 5: CPS is the diffraction intensity of 2θ = 12.5 ° in the X-ray diffraction peak of phillipsite.

Note 5: meq / 100g is base exchange capacity.

(Effect of the invention) According to the present invention, a zeolite having a high base exchange capacity can be stably obtained. In addition, since it can be produced by boiling for a short time, it can be produced while maintaining high productivity, and excellent effects such as a great industrial effect can be obtained.

Claims (2)

[Claims] 1. Silica ion 20 to 100 g / (SiO ₂ conversion) in a mixed slurry of NaOH aqueous solution and fly ash.
A method for synthesizing zeolite from fly ash, which comprises adding water, followed by boiling treatment. 2. A method for synthesizing zeolite from fly ash, which comprises adding reactive SiO ₂ -containing rock to a mixed slurry of an aqueous NaOH solution and fly ash, and then performing boiling treatment.