JPH0629131B2 - Method for producing high-purity kaolinite-like minerals - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention is widely used as a raw material for ceramics, a binder for ceramics, a filler for papermaking, and the like, and is a high-purity kaolinite that has been attracting attention as a new functional material. It is related to a method for producing such minerals.

[Conventional technology]

Conventionally, natural clay containing kaolinite as a main component has been used as a raw material for ceramics. This kaolinite is the main mineral of kaolins in clay minerals,
It is a white, gray or yellow high alumina mineral. On the other hand, the production of high-quality natural clay mainly composed of kaolinite, especially Kibushi Clay and Frogme Clay, which are produced in the Seto area of Aichi Prefecture, has been decreasing due to rapid housing development in recent years. The research and development of artificial clay is being promoted as a material that replaces the natural clay, and as a new functional material utilizing its layered structure.

A hydrothermal synthesis method is usually used as a method for producing kaolinite. This hydrothermal synthesis method is a method of obtaining a desired mineral by hermetically sealing raw materials in an autoclave in the presence of water and maintaining a high temperature and high pressure for a certain time, and is widely used as a synthetic means for various artificial minerals. ing. As a method for producing kaolinite by such a hydrothermal synthesis method,
Method of mixing silica sol and alumina sol by Clays and Clay Minerals (1983) and using as raw material, allophane, diatomaceous earth, montmorillonite,
A method is known in which zeolite or the like and an aluminum compound are mixed and used as a raw material.

However, the above method has a problem that since the silica raw material and the alumina raw material are solid mixed or solid / liquid mixed, there is a non-reactive portion, so that the reaction does not proceed 100% and the kaolinite content does not increase. . Further, when a natural raw material is used, impurities such as metal oxides and quartz contained in the raw material remain in kaolinite, which causes problems such as deterioration of clay characteristics and coloring. For example, when silica sol and alumina sol, which are synthetic products, are mixed and used as a raw material, there is no mixing of impurities such as metal oxides and quartz, but the kaolinite content is about 90% regardless of the hydrothermal treatment temperature and hydrothermal treatment time. The reaction is completed and unreacted silica and alumina remain. This is because the silica and alumina raw materials were mixed in a solid state and therefore were not homogeneously mixed, and because there was a non-reactive portion due to firing for removing the stabilizer in the method. Conceivable. The remaining unreacted silica and alumina cause agglomeration of kaolinite, resulting in deterioration of clay characteristics. Further, when diatomaceous earth and aluminum chloride are mixed and used as a raw material, quartz, iron, and other metal oxides are mixed as impurities in kaolinite, and the raw material diatomaceous earth also remains.

[Problems to be Solved by the Invention]

An object of the present invention is to provide a method capable of producing a high-purity kaolinite-like mineral containing no impurities and unreacted substances as compared with the conventional method.

[Means for Solving the Problems]

As a result of intensive studies to solve the above problems, the present inventors have arrived at the method for producing a kaolinite-like mineral of the present invention. That is, according to the present invention, a sodium silicate aqueous solution and an aluminum sulfate aqueous solution are uniformly mixed and gelled while maintaining pH = 4 to 12, and then sodium ions contained therein are ion-exchanged with protons using an ion exchange resin, and then the gel is water-exchanged. It is a method for producing a high-purity kaolinite-like mineral characterized by heat treatment.

Hereinafter, the present invention will be specifically described.

The kaolinite-like mineral in the present invention has a chemical formula {Al ₂
It is a layered aluminosilicate in which a silica layer represented by Si ₂ O ₅ (OH) ₄ } and an alumina layer are constituted by 1: 1.
Specific examples thereof include kaolinite, dickite, halloysite and the like.

In the present invention, the sodium silicate aqueous solution and the aluminum sulfate aqueous solution are uniformly mixed and gelled while maintaining pH = 4 to 12. Gelation in a pH range other than the above results in a dissolution region of silica or alumina, so that a uniform silica-alumina gel cannot be obtained. Therefore, gelation is performed at pH 4 to 12, preferably pH 6 to 8, and alkali and acid can be added if necessary. The mixing method is not particularly limited, but continuous mixing is preferably performed with stirring in order to improve the dispersibility of silica and alumina. Further, Si / Al in the synthetic gel is S for suppressing by-products in hydrothermal treatment.
It is preferably close to i / Al = 1.

The ion exchange resin used for the ion exchange in the present invention is a cation exchangeable ion exchange resin having a sulfonic acid group or a carboxylic acid group as a functional group. The ion exchange capacity and the like are not particularly limited except that the ion exchange resin is a proton type, and can be selected depending on the amount of sodium in the gel used for ion exchange. As an ion exchange method,
Although there is no particular limitation such as batch type and flow type, it is preferable to perform ion exchange so that Na / Al is 0.1 or less in order to promote crystallization because residual sodium inhibits crystallization in hydrothermal treatment. The amount of ion-exchange resin and the reaction temperature are set so that the dissolution of aluminum is promoted by the excessive use of the ion-exchange resin or the ion-exchange at high temperature.
It is preferable to carry out the treatment under mild conditions because it causes a change in composition. For example, an ion exchange resin having an amount equal to or less than twice the content of sodium is used, and ion exchange can be carried out to a proton type without changing the composition by repeating ion exchange several times at room temperature.

The hydrothermal treatment in the present invention can be carried out using an ordinary autoclave or a high pressure cup. The slurry concentration, reaction temperature, and reaction time in the hydrothermal treatment are not particularly limited, but the slurry concentration is preferably 1 to 30 wt%, the reaction temperature is 100 ° C. or higher, and the reaction time is 1 hour or longer. If necessary, the reaction time can be shortened by performing stirring and / or adding seed crystals.

By such a hydrothermal treatment, a kaolinite-like mineral can be produced at a production rate close to 100% as compared with the production rate of about 90% in the conventional method.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited thereto.

Example 1 No. 3 water glass (SiO ₂ = 29.3 wt%, Na ₂ as a raw material)
O = 9.35 wt%) and aluminum sulfate (Al ₂ O ₃ = 8.02)
wt%), and the raw materials were continuously mixed while stirring so that Si / Al = 1. At the same time, a silica-alumina gel was prepared by adding sodium hydroxide and neutralizing it so that the reaction pH became 6-8. When the composition of this gel was analyzed, Si / Al = 1 and Na / Al = 0.25.

Next, sodium in the gel was ion-exchanged for protons using an ion-exchange resin. As the ion exchange resin, cation exchange resin Amberlite 200C (functional group = sulfonic acid, ion exchange capacity = 1.75 mep) manufactured by Organo was used in an amount twice as much as that of sodium in the gel, and ion exchange was performed at room temperature. When the composition of this gel was analyzed again, Si / Al =
1, Na / Al = 0.01.

The above raw material gel was charged into an autoclave so that the slurry concentration was 5 wt%, and hydrothermal treatment was performed at 220 ° C. for 10 days.
After cooling, it was washed with water and dried to obtain a product. The X-ray diffraction result of the obtained product is shown in FIG.

The product showed only an X-ray pattern of kaolinite-like minerals. Further, the weight loss of kaolinite due to dehydration of structured water was measured by thermogravimetric analysis (TG) to quantify the amount of kaolinite produced, and the content of kaolinite in the product was 98%.

Example 2 A product was obtained by performing the same operation as in Example 1 except that the cation exchange resin Amberlite IRC-84 (functional group = carboxylic acid, ion exchange capacity 3.5 mep) manufactured by Organo was used as the ion exchange resin. . When the composition of the gel after ion exchange was analyzed, Si / Al = 1, Na / Al = 0.03
Met. The X-ray diffraction result of the obtained product is shown in FIG.

As in Example 1, it can be seen that the product is a high-purity kaolinite-like mineral. The content of kaolinite in the product was 97% by thermogravimetric analysis.

Comparative Example 1 A product was obtained by performing the same operation as in Example 1 except that ion exchange was not performed. The X-ray diffraction result of the obtained product is shown in FIG.

As is clear from FIG. 3, the peak of the kaolinite-like mineral does not appear in the X-ray diffraction pattern, and it is understood that the kaolinite-like mineral is not formed.

Comparative Example 2 A product was obtained by performing the same operation as in Example 1 except that hydrochloric acid was used instead of the ion exchange resin. When the composition of the gel after ion exchange was analyzed, Si / Al = 1.
8, Na / Al = 0.10, indicating that aluminum is melting. The X-ray diffraction result of the obtained product is shown in FIG.

As in Example 1, it can be seen that the product is only kaolinite-like minerals. Further, the thermogravimetric analysis revealed that the kaolinite content in the product was 45%.

Comparative Example 3 Using colloidal silica (SiO ₂ = 20 wt%) and alumina sol (Al ₂ O ₃ = 10 wt%) as raw materials, Si / Al
They were mixed and stirred so that = 1. Then, the raw material gel was dried and calcined at 600 ° C. for 1 hour to remove acetic acid as a stabilizer to obtain a raw material gel used for hydrothermal treatment.

The above raw material gel was charged into an autoclave so that the slurry concentration was 5 wt%, and hydrothermal treatment was performed at 220 ° C. for 10 days.
After cooling, it was washed with water and dried to obtain a product. The X-ray diffraction result of the obtained product is shown in FIG.

The product showed only the X-ray diffraction pattern of kaolinite-like minerals. Moreover, the kaolinite content in the product was 90% by thermogravimetric analysis.

Comparative Example 4 Si / Al = using diatomaceous earth and aluminum chloride as raw materials
The mixture was mixed and stirred so as to be 1. Then, it was charged into an autoclave and subjected to hydrothermal treatment at 220 ° C. for 10 days. After cooling, it was washed with water and dried to obtain a product. The X-ray diffraction result of the obtained product is shown in FIG.

The product showed an X-ray diffraction pattern of kaolinite-like mineral and quartz as an impurity. The kaolinite content in the product was 50% by thermogravimetric analysis.

[Effects of the Invention] As described above, according to the present invention, a sodium silicate aqueous solution and an aluminum sulfate aqueous solution are mixed and neutralized to uniformly mix and gelate the sodium silicate aqueous solution and the aluminum sulfate aqueous solution while maintaining the pH at 4 to 12. Then, by performing ion exchange of the contained sodium ions into protons using a cation exchange resin and then performing hydrothermal treatment, it is possible to synthesize a high-purity kaolinite-like mineral containing no impurities and unreacted substances as compared with the conventional method. .

[Brief description of drawings]

1 to 6 show Examples 1-2 and Comparative Examples 1-4.
It is a figure which shows each result of the X-ray-diffraction measurement obtained by.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kyo Osaki 1-226-22 Ogami, Shinnanyo-shi, Yamaguchi Prefecture (72) Inventor Soichiro Samejima 2-6-10 Miyanoma, Shinnanyo-shi Tosoh Jijo Dormitory ( 72) Inventor Shigeo Satokawa 2-14-8 Tabata, Kita-ku, Nagoya, Aichi Prefecture

Claims (1)

[Claims] 1. A sodium silicate aqueous solution and an aluminum sulfate aqueous solution are uniformly mixed and gelled while maintaining pH = 4 to 12,
Next, a method for producing a high-purity kaolinite-like mineral, which comprises subjecting the gel to ion exchange of contained sodium ions with a cation exchange resin, and then subjecting the gel to hydrothermal treatment.