JPS6385070A - Manufacture of porous ceramics - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION B) Industrial Application Field The present invention uses a natural natural resource with foaming expansion and fusing properties as a raw material, and uses no special binder, blowing agent, or fusing agent. This invention relates to a novel method for producing porous ceramics of arbitrary shape and size by firing.

(b) Conventional techniques and problems Conventionally known techniques for producing porous ceramics using natural inorganic raw materials are typified by the following. Namely, 1. A method in which gas-generating substances such as sawdust and rice hulls are added to silica stone and clay, kneaded, shaped, dried, and fired.

■A method in which air bubbles are mixed into a slurry-like ceramic material, molded, dried, and then fired. ■ A method of adding and mixing a plasticizer and a fusing agent to chamotte (sintered powder), shaping and firing the mixture.

In order to further explain their manufacturing methods in detail, the respective manufacturing steps are shown in FIGS. 1 to 3.

In this way, in order to obtain the desired product, all conventional technologies require the use of some kind of binder, gas generating substance, and fusing agent in the raw materials, and the manufacturing method also involves mixing, molding, drying, and baking. Even if this process is simplified to the maximum, porous ceramics cannot be obtained without going through the steps of mixing, molding, and firing. Therefore, unless these steps can be simplified, manufacturing costs cannot be reduced, which is a serious drawback.

(C) Problems to be Solved by the Invention As shown in Figure 4, the present invention greatly simplifies the manufacturing process by pulverizing natural inorganic raw materials, filling the pulverized raw materials into molds, and firing them. The purpose is to obtain porous ceramics that can reduce manufacturing costs by doing so.

(d) Means for Solving the Problems The present inventors produced porous ceramics using shale, which has foam expansion, as a raw material, among mudstones, which are abundant resources widely available in Hokkaido and Honshu. As a result of various studies, we found that these raw material powders and granules not only do not require a binder, but also can be fused together while foaming and expanding by simply filling them into a mold without applying pressure. However, the present invention was completed by discovering that it is possible to produce strong porous ceramics having the desired shape and dimensions.

Up until now, product development that utilizes the expansion properties of inorganic raw materials such as shale and volcanic ash has focused on shale as a lightweight aggregate,
Examples of volcanic ash include balloons and perlite. However, it goes without saying that these are all foam materials, and when manufacturing these foams, it is important to reduce the influence of the fusing properties of the raw materials in order to produce high-quality foams. Indeed, it has become an even more important technology. Therefore, in the case of the porous ceramics according to the present invention, we have discovered a mechanism in which the powder and granular raw materials foam and expand during the firing process and fuse themselves. The concept is completely different from the production of foam glass that is mixed into materials.

Below, the foaming expansion fusion mechanism of porous ceramic raw materials,
The present invention will be explained by examples.

The raw material targeted by the present invention has the following chemical composition.

That is, SiOAIO, basic composition 2 S 2
3 minutes (Ca○* MgOr NaO, 20, Fe
, 03), and is composed of gas generation sources such as C (carbon) and S (sulfur content). Table 1 shows the chemical composition as an example. These raw materials are mudstone (shale) that exists in large quantities in Hokkaido, and S i 0264~
71%, Al2O, 13-16%, basic component lO~1
3%, and the sum of C and S as gas generating sources is in the range of 0.2 to 2.4%, both of which have foaming expansion and fusing properties.

When these powders and granular raw materials are heated, they form a highly viscous glass phase capable of trapping gas, and are formed into foams with independent or continuous pores by gas-generating substances. integrated,
This results in a strong porous ceramic.

Example: Massive shale collected from an outcrop with a chemical composition as shown in Table 1 was adjusted to have a grain size of 1 to 4, and each of them was made into a refractory mold shape: square, dimensions: The raw material was filled into a container (inner dimensions: 30 x 30 x 4 cm) to a volume of 70%. Next, insert it into the heating furnace as it is, and as shown in Fig. 5, the heating rate is 200°C/h and the
℃, and the holding time at the maximum temperature was 1 hour. The porous ceramic thus obtained exhibited properties as shown in Table 2. As can be seen, the bulk specific gravity of the product ranges from 0.35 to 1.03, and the bending strength ranges from 17.6 to 52.3 ktf/cj. In addition, the physical properties of the product can be improved by appropriately changing the selection of raw materials and particle size composition according to the purpose of use. -Of course, it can be easily set as 2-geki red.

As is clear from the examples above, the manufacturing method according to the present invention makes effective use of the characteristics of the raw materials, and is very effective in producing porous ceramics with independent and continuous pores through the minimum steps of crushing, filling, and firing the raw materials. It has characteristics.

(e) Effects of the invention As detailed above, the present invention is significantly different from conventional porous ceramic manufacturing technology, and utilizes natural inorganic raw materials through an extremely simplified process. This made it possible to produce porous ceramics with physical properties.

Furthermore, due to its characteristics, the porous ceramics according to the present invention can be expected to have a wide range of uses, not only as building materials, but also as filter media in the chemical industry and water treatment.

At present, not only in Hokkaido but also in Japan, ceramic raw materials, mainly clay resources, are becoming depleted, and the present invention
By utilizing abundant and unused inorganic resources such as shale and volcanic ash, it has been possible to produce porous ceramics with high added value at low cost, improving livability by supplying it as a ceramic building material. This will greatly contribute to not only the improvement of the industry, but also the promotion of the locally-based kiln industry.

[Brief explanation of the drawing]

Figures 1, 2, and 3 are diagrams showing the currently used manufacturing method of porous ceramics, Figure 4 is a diagram showing the manufacturing method based on the present invention, and Figure 5 is a diagram showing the manufacturing method based on the present invention. , the country where the firing conditions were indicated.

Claims (1)

[Claims] Using powders and granules of natural inorganic substances that have foaming expansion and fusing properties as raw materials, filling them into molds with the desired shape and dimensions, and using special binders, blowing agents, and fusing agents. A method for producing porous ceramics, which is characterized by firing as is.