JPH11236213A - Synthesis of hydrosodalite from diatomaceous earth - Google Patents

Abstract

PROBLEM TO BE SOLVED: To synthesize hydrosodalite in a short time on an industrial scale by putting diatomaceous earth and an alumina compd. in a soln. of sodium hydroxide, mixing them and heating the mixture at a low temp. or hydrothermally treating it in an autoclave. SOLUTION: Diatomaceous earth as a source of silica and a halogen-free alumina compd. such as aluminum hydroxide or basic aluminum carbonate are put in a soln. of sodium hydroxide or sodium carbonate having 3-10N concn. They are mixed at a room temp. for 1-30 min so as to attain an SiO2 to Al2 O3 molar ratio of 1.6-2.2 and an Na2 O to SiO2 molar ratio of 2.2. The mixture is then heated at 80-100 deg.C under atmospheric pressure for 1-12 hr or it is hydrothermally treated at 100-150 deg.C for 30 min in an autoclave. The diatomaceous earth may be a diatomaceous earth product or low purity diatomaceous earth generally called diatomaceous mudstone besides a raw ore.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for synthesizing hydrosodalite from diatomaceous earth.

[0002]

_2. Description of the Related Art The SiO ₂ / Al ₂ O ₃ molar ratio is set to 2;
It is known that hydrosodalite can be synthesized by heat treatment in excess sodium solution.

[0003]

The synthesis of hydrosodalite involves silica sand, fly ash, water glass, volcanic rock glass and the like as a silica source, aluminum hydroxide and the like as an alumina source, and sodium hydroxide and sodium carbonate as a sodium source. It can be synthesized using: But,
When raw materials such as silica sand, fly ash, water glass, and volcanic rock glass, which are inexpensive raw materials, are used as the silica source, 80-
At a temperature of 100 ° C. at normal pressure, a processing time of 24 hours or more is required, and even when a hydrothermal treatment is performed using an autoclave apparatus, at a temperature of 120 ° C., 5 hours or more. Need. For these reasons, the conventional method has low productivity and is disadvantageous in terms of cost, and it is difficult to produce hydrosodalite on an industrial scale at low cost. The present invention has been made to solve such a drawback.

[0004]

The present invention has been made in view of the above situation, and as a result of intensive research, it has been found that diatomaceous earth and aluminum hydroxide are put into sodium hydroxide or sodium carbonate solution and mixed at room temperature. , 80-100 ° C,
A series of techniques for inexpensively synthesizing hydrosodalite has been completed by heating at normal pressure or by placing the mixed solution in an autoclave and subjecting it to a hydrothermal treatment at a temperature of 100 to 150 ° C.

That is, the present invention provides the following (1) to
The present invention provides a synthesis method by each step of (5). _{(1) SiO 2 / Al 2} O 3 ( molar ratio) = 1.6 to 2.
2, preferably diatomaceous earth adjusted to SiO ₂ / Al ₂ O ₃ (molar ratio) = 2 and an aluminum compound as an alumina source, for example, basic aluminum hydroxide discharged from an aluminum sash maker, into a sodium compound solution, for example, To a 48% sodium hydroxide solution, which is a reagent for use. The concentration of the sodium compound solution is Na ₂ O / S
iO ₂ (molar ratio) = 2-5, preferably Na ₂ O / Si
O ₂ (molar ratio) = _{2.5 to} 3 is desirable.

[0006] Since hydrosodalite is synthesized in the presence of excess sodium, N is determined from the composition formula.
The a ₂ O / SiO ₂ (molar ratio) is 0.67, but requires a several-fold excess of sodium. However, since excessively added sodium is removed by filtration and washing after the synthesis, sodium which did not contribute to the synthesis is removed. Therefore, considering the production cost, the smaller the Na ₂ O / SiO ₂ (molar ratio), the better. desirable. However, if the amount of sodium added is small, the synthesis of hydrosodalite is difficult to proceed unless the reaction temperature is high or the reaction time is long, so that Na ₂ O / SiO ₂ (molar ratio) = 2-5,
Preferably, Na ₂ O / SiO ₂ (molar ratio) = 2.5-3
Is desirable.

(2) When the sodium mixed solution to which the silica source and the alumina source are added is subjected to a hydrothermal treatment by an autoclave apparatus, the mixing is carried out at room temperature for 1 to 30 minutes, preferably for about 10 minutes, using a homogenizer or a turbine blade. Perform with a stirrer attached. When performing synthesis in this state, heating is performed at 80 to 100 ° C. and heat treatment is performed for 1 to 12 hours, preferably 3 to 5 hours. When the hydrothermal treatment is performed using an autoclave device, the temperature is set to 100 to 1
At 50 ° C, preferably 120-130 ° C, the reaction time is 3
The hydrothermal treatment is performed for 0 minute to 3 hours, preferably for 1 to 2 hours.

The obtained hydrosodalite slurry is filtered, washed and dried to obtain hydrosodalite powder.

(3) Here, the diatomaceous earth as the silica source may be not only the raw ore but also a diatomaceous earth product. Not only high-purity diatomaceous earth having a silica content of 90% or more but also low-purity diatomaceous mudstone having a silica content of about 70% may be used. However, when the minerals contained as impurities include halogens, sulfates, etc., it is necessary to perform a treatment for removing these.

(4) By using a basic aluminum hydroxide discharged from an aluminum sash maker as an alumina source, hydrosodalite can be produced at lower cost. Or basic aluminum carbonate (eg, NaAlO (OH)
It can be synthesized using an aluminum compound such as HCO ₃ ). However, compounds containing halogen elements such as chlorine and sulfides and sulfates containing sulfur are not desirable.

(5) If the sodium source is a sodium compound such as sodium hydroxide or sodium carbonate, hydrosodalite can be synthesized. However, compounds containing halogen elements such as chlorine and sulfides and sulfates containing sulfur are not desirable.

[0012]

The present invention will be described more specifically below with reference to examples. However, the present invention is not limited to the examples.

Example 1 A diatomaceous earth raw material subjected to moisture, loss on ignition and chemical analysis was
With aluminum hydroxide weighed so that SiO ₂ / Al ₂ O ₃ (molar ratio) = 2, Na ₂ O / SiO ₂
(Molar ratio) = Pour into a sodium hydroxide solution adjusted to 2.5, and mix with a stirrer at room temperature for 10 minutes. The mixed solution is put into an autoclave and heated to 120 ° C. for 1 hour.
The temperature was raised over time and held for 1 hour. After the completion of the reaction, the slurry was taken out and subjected to filtration and washing.
And dried. FIG. 1 shows a powder X-ray diffraction chart of the obtained hydrosodalite of the present invention, and FIG. 2 shows a photograph observed by a scanning electron microscope.

In FIG. 1, (a) is a pattern of aluminum hydroxide as an alumina source, (b) is a pattern of diatomaceous earth as a silica source, and (c) is a pattern of hydrosodalite using diatomaceous earth as a silica source. .

In FIG. 2, (a) is diatomaceous earth,
(B) is hydrosodalite using diatomaceous earth as a silica source.

Example 2 A hydrosoda of the present invention was prepared in the same manner as in Example 1 except that each raw material was put in a stainless steel container and heated and stirred at 90 ° C. for 3 hours without using an autoclave apparatus. Got the lights. FIG. 3 shows a powder X-ray diffraction chart of the obtained hydrosodalite of the present invention.

In FIG. 3, (a) is a pattern of aluminum hydroxide as an alumina source, (b) is a pattern of diatomaceous earth as a silica source, and (c) is a pattern of hydrosodalite using diatomaceous earth as a silica source. .

Comparative Example 1 As a silica source, volcanic rock glass, silica sand (# 100), 3
FIG. 4 shows a powder X-ray diffraction chart of the obtained product in the same manner as in Example 1 except that sodium silicate was used.

In FIG. 4, (a) shows a pattern of hydrosodalite using volcanic rock glass as a silica source, and (b)
(A) is a pattern of hydrosodalite using silica sand (# 100) as a silica source, and (c) is a pattern of hydrosodalite using silica sand of No. 3 sodium silicate.

Example 3 and Comparative Example 2 Hydrosodalite has a performance of adsorbing hydrogen chloride gas at a high temperature (300 ° C. or higher) and replacing hydroxyl groups in the structure with chlorine ions to change to sodalite. .
Thus, a test was conducted to determine whether hydrosodalite adsorbs chlorine in the heated state.

The test method was as follows. The hydrosodalite synthesized in Examples 1 and 2 was placed in a heated electric furnace, and hydrogen chloride gas whose concentration was adjusted with air was flowed therein for a predetermined time, and hydrogen chloride discharged from the electric furnace was discharged. The gas containing gas was sampled at a constant flow rate, and the hydrogen chloride gas concentration was measured. Table 1 shows the results.

As Comparative Example 2, calcium hydroxide, which is currently used in a municipal garbage incineration plant, as a hydrogen chloride gas adsorbent, was supplied with hydrogen chloride gas in the same manner as in Example 3,
The concentration of hydrogen chloride gas discharged from the electric furnace was measured. Table 1 shows the results.

As shown in Table 1, when the sample was placed in an electric furnace heated to 400 ° C. or higher and hydrogen chloride gas was flowed, the hydrosodalite synthesized in Examples 1 and 2 was compared with Comparative Example 2 The passage of the gas showed a lower hydrogen chloride gas concentration at the outlet side. However, this is 200
At a low temperature of not more than ° C., Comparative Example 2 shows a larger amount of adsorption of chlorine amount than Examples 1 and 2. The above results show that the synthesized hydrosodalite has excellent ability to recover hydrogen chloride at a high temperature of 400 ° C. or higher.

[0024]

[Table 1]

[0025]

According to the present invention, diatomaceous earth can be produced at a low temperature and in a short time by using diatomaceous earth as a silica source. Use) is obtained.

[Brief description of the drawings]

FIG. 1 is an X-ray diffraction chart of a powder in each step of synthesizing a hydrosodalite obtained according to the present invention.

FIG. 2 is an X-ray scanning electron microscope observation photograph of a powder in each step of synthesizing a hydrosodalite obtained according to the present invention.

FIG. 3 is an X-ray diffraction chart of the powder in each step of synthesizing the hydrosodalite obtained according to the present invention.

FIG. 4 is an X-ray diffraction chart of the same powder as FIG. 1 in the case of using volcanic rock glass, silica sand (# 100) and No. 3 sodium silicate as a silica source as a comparative example.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kenji Suzuki 259 Minase, Minano, Oguchi-cho, Niwa-gun, Aichi Prefecture (72) Inventor Yasuhiko Noguchi 36 Minami-Showa-cho, Kurayoshi City, Tottori Prefecture

Claims (2)

[Claims] A diatomaceous earth is used as a silica source, and an aluminum compound such as aluminum hydroxide or basic aluminum carbonate which does not contain a halogen element such as chlorine is used as an alumina source. After placing in a sodium carbonate solution of the same concentration and mixing at room temperature for 1 to 30 minutes, the mixture is heated at 80 to 100 ° C. and normal pressure for 1 to 12 hours, or the mixed solution is placed in an autoclave apparatus and 100 to 150 ° C. For 30 minutes to 3 hours to synthesize hydrosodalite. 2. A composition of a mixture of diatomaceous earth, an alumina source and a sodium solution has an oxide molar ratio of SiO ₂ / Al ₂ O ₃ = 1.6 to 2.2 Na ₂ O / SiO ₂ = 2 to 5 A method for synthesizing hydrosodalite according to claim 1.