JPH0621029B2 - Method for producing raw material for kaolinite synthetic clay - Google Patents

Description

The present invention relates to a method for producing a raw material for industrially mass-producing a kaolinitic synthetic clay.

[Conventional technology and technical problems to be solved]

Conventionally, the following materials have been known as raw materials for obtaining kaolinite synthetic clay.

i. Highly crystalline silicate or aluminosilicate.

ii. Amorphous or low crystalline naturally occurring silicate or aluminosilicate.

iii. Easily reactive high-purity artificial reagents such as colloidal silica.

However, the following problems have been pointed out in the raw materials for producing such conventionally known kaolinite synthetic clay.

That is, when the silicate or aluminosilicate of the above i is used, a large amount of impurities such as free quartz and mica remain as they are, and 300 ° C or more is required to completely eliminate the impurities. Since it is necessary to carry out hydrothermal treatment at a high temperature for several tens of days or more for a long period of time, there is a problem in terms of productivity, and when the raw material of the above ii is used, elutriation classification is extremely efficient. Bad, it is necessary to perform a troublesome and troublesome selection process to select the raw materials, and further, in the method using the raw material iii, the yield is poor because it has to be processed in a very dilute liquid state, Moreover, the raw materials were extremely expensive and not economical.

The present invention has been made in view of the above-mentioned drawbacks in the conventional production technique of kaolinitic synthetic clay, and is a raw material suitable for efficient production of kaolinitic synthetic clay close to natural clay. It is a technical object to provide a new method capable of industrial mass production.

[Means for solving problems]

The present inventors have repeated trial and error test research for raw materials suitable for producing easily and inexpensively easily reactive kaolinite synthetic clay to solve the above technical problems, and by chance, I. When a hydrous silicate-based compound is exposed to an acidic atmosphere,
The fact that the connective tissue of silicic acid and lime is easily destroyed and hydrous silicic acid is liberated, ii. In addition, 500 rice husks derived from the production process of rice, wheat, etc.
It was discovered that when ashing is performed by oxidative firing at ~ 900 ° C, a powder containing almost no carbon and containing amorphous silicic acid as the main component is produced.

Therefore, in order to find a way to utilize the new facts obtained from this discovery in industrial technology, further research for practical application is carried out, and the hydrous silicic acid obtained by the above treatment i or the above ii As a result of performing a hydrothermal treatment by adding an easily reactive aluminum compound to amorphous silicic acid, the bottleneck in the production of the above-mentioned conventional kaolinite synthetic clay was solved at once and the present invention was reached. .

That is, the first method means adopted by the present invention to solve the above technical problems is to use quick lime or slaked lime in various siliceous raw material powders in a CaO / SiO ₂ + Al ₂ O ₃ molar ratio of 0.5 to 2.0. After mixing so that water is added to the mixture and hydrothermal reaction is carried out at 150 ° C or higher to generate hydrous silicate lime compound, by exposing it to an acidic atmosphere, difficult-to-react quartz is converted into easily-reactive silica. It is to change.

The siliceous raw material used as the starting material in the first method is not particularly limited as long as it has a large silicic acid content. Further, it is desirable to use powder quicklime or powder slaked lime as the calcareous raw material.

The hydrous silicate lime compound thus obtained is zonotolite.
(6CaO ・ 6SiO ₂・ H ₂ O) and 11Åtobermorite (5CaO ・ 6SiO ₂・ 5H
₂ O) and other crystalline substances, other gel-like substances, or Al,
There are various kinds of materials such as those containing respective ions such as Fe, K and Na depending on the difference in crystal structure, and all of them are effective as raw materials for kaolinite synthetic clay for achieving the object of the present invention.

Next, the second method means adopted by the present invention to solve the above technical problems is to easily react by burning rice husks of grasses in an oxidizing atmosphere at 500 to 900 ° C. for ashing. This is to generate a powder containing a crystalline amorphous silicic acid as a main component.

Therefore, as the rice husk of the Gramineae plant used as the starting material in the second method, the rice husk which is produced in large quantities as a by-product through rice cultivation in Japan and is difficult to dispose of due to smoke damage is preferable. By ashing such rice husks, it is possible to obtain high-quality amorphous silicic acid having a SiO ₂ content of 90% or more. In this case, the ashing condition is 500
It is desirable that the temperature is above ℃ and below 900 ℃. This is because carbon is likely to remain at 500 ° C or lower, and homomorphism of crystalline silicic acid such as cristobalite or tridymite is easily generated at 900 ° C or higher. In addition, in the ashing, it is necessary to supply sufficient oxygen to prevent carbon from remaining.

In the case of producing a kaolinite synthetic clay using the raw materials obtained by the above-mentioned first and second invention methods, first, the kaolinite composition ratio (Al / Si atomic ratio is about 1) To each of the above raw materials, an easily reactive aluminum source (eg, aluminum chloride, aluminum nitrate, gelled aluminum hydroxide, alumina sol, etc.) is added in an appropriate amount, and the pH is adjusted to 150 to 250 ° C. for several hours or more in an acidic region near pH 2. Hydrothermally react. When treated in this manner, a pure white, high-quality synthetic clay containing kaolinite as a main component can be easily obtained.

〔Example〕

The specific contents of the present invention will be described in more detail with reference to the drawings and by way of examples.

Example As a siliceous raw material, 44 low-grade porcelain stones (Sample: A) produced in Fukui Prefecture are used.
It was used after being pulverized to μ or less. The chemical composition of this porcelain stone powder is shown in Table 1, and the mineral composition is shown in the powder X-ray diffraction pattern of FIG. Slaked lime is added to the above-mentioned pottery stone powder by CaO / SiO ₂ +
The Al ₂ O ₃ molar ratio was mixed to 1 to 4 g, and water was added so that the weight ratio of the raw material and water was 1: 4, and the mixture was placed in a stainless steel container and placed in an autoclave at 180 ° C. In 1
It was hydrothermally reacted for 2 hours. The treated product thus obtained was suction-dewatered with a Buchner funnel and dried at 100 ° C. (Sample B).
As shown in the powder X-ray diffraction pattern of FIG. 1, most of this powder was changed to a hydrous silicate lime compound (in this case, the product was 11Åtobermorite), and no free quartz remained.

Next, add hydrochloric acid to this to adjust the pH to around 2, then add an appropriate amount of 2 mol of an aluminum chloride aqueous solution so that the kaolinite composition ratio (Al / Si atomic ratio ≈ 1) and put it in a Teflon container at 230 ° C. It was hydrothermally reacted for 48 hours. Then, the treated product was separated into individual pieces and liquid by a centrifuge and dried at 40 ° C. (Sample C). As shown in Table 1 and Figure 1, this powder is pure white and has a high content of Al ₂ O ₃ and kaolinite, and it is a high-quality kaolinite that does not contain impurities such as free quartz, microcline, and mica. It was confirmed to be synthetic clay.

Example A powder of a commercially available waste material (zonotolite) of hydrous silicate lime compound is used, and hydrochloric acid is added to the powder to adjust the pH to around 2. Further, as in the case of the example, chlorination is performed so that the kaolinite composition ratio is obtained. Aluminum was added and the mixture was placed in a Teflon container and hydrothermally reacted at 200 ° C. for 48 hours in an autoclave. The obtained powder was very similar to that obtained in the example, and was pure white kaolinite synthetic clay containing no impurities.

Example Rice husk ash (S) which was ashed by heating at 550 ° C. for 3 hours in an electric furnace
iO ₂ 93% content) was weighed in an amount of 4 g, and 15.2 ml of a 2 mol aqueous solution of aluminum chloride was added to adjust the pH to around 2.
Water was added and the ratio of raw material to water was not set to 1: 4. The mixture was placed in a Teflon container and hydrothermally treated at 230 ° C. for 96 hours in an autoclave. The treated product thus obtained was white fine powder containing kaolinite as a main component.

[Effects of the Invention] As described above with reference to the embodiments, according to the present invention,
The following effects can be obtained.

(1) When using a conventionally known raw material of kaolinite synthetic clay, when trying to obtain clay of a predetermined quality, not only high temperature and long time were required for the reaction, but also amorphous or low crystalline In addition to having to select and use the quality part carefully, it is necessary to use highly reactive reagents with high reactivity, and the selection range of raw materials was extremely limited, but in the present invention, It is possible to use most silicates and aluminosilicates such as raw materials with high crystallinity and difficult reactivity, low-grade raw materials with many impurities, and general commercially available hydrous silicate lime compounds, and even waste materials thereof.
The range of selection of raw materials is greatly expanded, and raw material costs can be extremely reduced.

(2) In the method of the present invention, the hydrothermal treatment conditions are relatively low, and the treatment can be performed for a short time. Therefore, the productivity is dramatically improved as compared with the conventional method, and the production cost is extremely high. Is reduced to.

The raw material produced by the method of the present invention is of excellent quality because impurities such as quartz and feldspar do not remain at all.

According to the present invention, it is possible to effectively use rice hulls, which have been difficult to process by secondary production in rice farming, as a raw material for kaolinite synthetic clay, and to effectively use resources. In addition to being useful, it also brings about the effects of two birds with one stone, such as reducing production costs.

Thus, the present invention, in addition to being able to solve the problems that have been bottlenecked in the manufacturing technology of the raw materials of this type of kaolinite synthetic clay in the past, in addition to the kiln industry which is concerned about the supply of high-quality raw materials. We can provide a new material source,
The use as a fine powder produced by the present invention such as a raw material for cosmetics and foods, a material for treating radioactive substances, and the like is infinitely widespread, and it can be said that its industrial utility value is extremely large.

[Brief description of drawings]

FIG. 1 shows low-grade porcelain stone as a starting material (Sample A), hydrous silicate lime compound (Sample B) obtained by hydrothermally treating it as in Example, and kaolinite synthetic clay (Sample C). FIG. 4 is a powder X-ray diffraction diagram measured under the same conditions for the purpose of comparing and explaining the production states of and. K: Kaolinite, M: Microcline feldspar, Q: Quartz, S: Sericite, T: 11Å Tobermorite, P: Slaked lime.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-53-106400 (JP, A) JP-A-52-6397 (JP, A) JP-A-60-191018 (JP, A)

Claims (1)

[Claims] 1. A method for producing a raw material for kaolinite synthetic clay, which comprises converting a hydrous silicate lime compound into an easily reactive silicic acid by exposing it to an acidic atmosphere.