JP3036574B2 - Manufacturing method of ceramics from waste materials - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to municipal solid waste, sewage sludge,
The present invention relates to a method for producing ceramics using waste such as industrial waste as a raw material.

[0002]

2. Description of the Related Art In recent years, various researches have been conducted for the purpose of disposing and reusing waste such as municipal solid waste, sewage sludge, industrial waste, and the like.
As described in Japanese Patent Publication No. 7, there is a method in which waste such as municipal waste and sewage sludge is melted and vitrified, and a ceramic is produced using the glass as a raw material. In this method, a formed body containing waste molten glass as a raw material component is formed, and the formed body is placed in a sintering furnace and fired to sinter the raw material component.

[0003]

In the above structure, when firing a molded body, it is necessary to gradually raise the temperature of the molded body to about 800 ° C. to 1100 ° C. On the other hand, heating of a compact in a conventional sintering furnace is a so-called external heating method in which heat is applied from the outside. In this method, heat is transferred from a substance other than the object to be heated to the molded body which is the object to be heated, so that a time for heat transfer is inevitably required.

[0004] For this reason, there has been a problem that the time required for sintering becomes longer and the amount of energy consumption increases as the size of the compact increases. SUMMARY OF THE INVENTION The present invention solves the above-mentioned problem. By using microwave heating as a heating means, wastes that can be efficiently heated and fired in a short time even in a large and thick molded body. It is an object of the present invention to provide a method for producing ceramics using as a raw material.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a method for producing ceramics using waste as a raw material according to the present invention comprises melting and processing waste such as municipal waste, sewage sludge, and fly ash. After cooling and solidifying to produce a waste molten glass, a molded body containing the waste molten glass as a raw material component is formed, and the molded body is microwave-heated to 800 to 1100 ° C. to reduce the components of the molded body. The ceramics are formed by sintering.

[0006]

According to the above construction, when microwaves are irradiated on the molded body, the molded body itself generates heat, and the heat is transmitted from the inside to the outside of the molded body. The sintering can be performed in a very short time as compared with the case where heat is transferred to a molded object to be heated. At this time, the waste molten glass forming the molded body has a large heat loss due to a large dielectric loss. Therefore, by microwave heating the compact, sintering can be performed taking advantage of the property of waste molten glass, which has a large dielectric loss, and energy loss can be suppressed even when the compact has a large thickness. And can be efficiently sintered.

Furthermore, sintering by microwave heating has the property of densifying the sintered body. Therefore, by using microwaves as the heating means, it is possible to reduce waste glass, which is a miscellaneous material having a variable component. While using such a material as a raw material, dense ceramics can be easily formed, and the usefulness of ceramics formed from unnecessary materials such as wastes can be expanded.

[0008]

An embodiment of the present invention will be described below. In the present embodiment, waste molten glass refers to general waste such as municipal waste, sewage sludge, and fly ash, and industrial waste such as mine debris, river sediment, and construction sludge. Is obtained by cooling and solidifying a molten slag obtained by subjecting the slag to a melting process, and is formed into a sintered material by pulverizing to a suitable particle size.

[0009] A molding material such as clay or cement is added to the granular material of the molten glass waste and mixed and kneaded to form a clay. At this time, the mixing ratio between the waste molten glass and the molding material can be arbitrarily set according to the characteristics of the target ceramics, and it is possible to add little molding material. When the target ceramic is a foam, a molded foam, a fired foam, a sintered material, or the like can be added as a component of the clay. Furthermore, when ceramics are formed into a composite to give strength, a fibrous reinforcing material or the like can be added as a component of the clay. The fibrous reinforcement is made of metal (iron, stainless steel,
Other metal fibers) and inorganic materials (glass fibers, carbon fibers, etc.). As the component for forming the kneaded material, various materials other than the above can be combined, and it is appropriate to use not only conventional ceramic raw materials but also slag of unused resources and industrial wastes. It is also possible to use the material after pulverizing it to a particle size, or to combine a refined raw material, an organic substance such as wood powder, carbon and the like. Further, it is possible to form a carbonized sintered body by blowing a carbon dioxide gas as an atmosphere gas at the time of sintering to be described later, or to form a nitrided sintered body by blowing a nitrogen gas.

Next, the kneaded clay is formed into a desired ceramic shape and dried to form a formed body. The compact is placed in a sintering furnace, the compact is irradiated with microwaves, and the components of the compact are sintered by microwave heating to form ceramics.

The radio waves that can be used are 915 (MH)
_{Z), 2.45 (GH Z)} , microwave or, 22.125 (GH _Z of _{5.80 (GH Z)), 28.00} (GH
_Z ) and 53.00 (GH _Z ), and 2.45 (GH _Z ) is used in this embodiment.

According to the microwave heating, the molded body itself generates heat, and the heat is transmitted from the inside to the outside of the molded body to heat the inside of the molded body. Sintering can be performed in a very short time as compared with the case where heat is transferred to a molded body that is an object to be heated.

[0013] At this time, the waste molten glass constituting the molded body has a large heat loss due to a large dielectric loss. FIG. 1 shows the dielectric loss of various ceramics.
As is clear from FIG. 1, crotiles (meaning black tiles) and the like made of sewage sludge as raw materials have physical properties with remarkably large dielectric loss as compared with conventional alumina porcelain and the like.
Therefore, conventionally, when performing microwave heating, silicon carbide (SiC) is added as a heat-generating auxiliary material in order to increase the dielectric loss of the object to be heated, or silicon carbide (SiC) is added around the object to be heated. And the like.

However, in the present invention, since the waste molten glass itself has a large dielectric loss, the molded body is microwave-heated without using a heat-generating auxiliary material separately, so that the waste molten glass has a unique characteristic. Efficient sintering can be performed by taking advantage of the characteristic that the dielectric loss is large. For this reason, even if it is a molded object with a large thickness, it is possible to suppress the energy loss and efficiently sinter.
Incidentally, depending on the shape of the molded body, a heat generating auxiliary material or a heat generating element such as SiC can be used in combination.

Further, since sintering by microwave heating has the property of densifying a sintered body, the use of microwaves as a heating means makes it possible to remove waste glass, which is a non-uniform material having a variable component. While using such a material as a raw material, dense ceramics can be easily formed, and the usefulness of ceramics formed from unnecessary materials such as wastes can be expanded.

FIGS. 2 to 4 show a comparison between a ceramic obtained by using a conventional sintering furnace and a ceramic obtained by microwave heating, using a water absorption rate as one index indicating the physical properties of the ceramic. Things. 2 shows a case where sewage sludge slag is used as a raw material of molten glass of waste, FIG. 3 shows a case where municipal solid waste slag is used as a raw material of molten glass of waste, and FIG. It shows a case using fly ash slag.
The Kuboflux in FIGS. 2 and 3 uses municipal solid waste incineration fly ash as a raw material for molten glass of waste and stabilizes it by adding a component adjusting material such as boric acid during melting. Reference numeral 1 denotes a general chemical component of Kubo flux, and Table 2 is a component list of Kubo flux used in this example.

[0017]

[Table 1]

[0018]

[Table 2]

As apparent from FIGS. 2 to 4, the sample subjected to microwave heating can be sintered at a lower temperature than the sample subjected to electric furnace heating, and has a characteristic of low water absorption. doing. The superiority of the sample subjected to the microwave heating is the same whether the mixing ratio of slag and clay is 80:20 or 60:40. In addition, the sample using Kuboflux has the lowest water absorption and is dense. Further, the time required for heating is 36 ° C./min for microwave heating, while the heating time for electric furnace heating is 3 ° C./min.
At 0 ° C./min, the time can be significantly reduced as compared with the conventional case. Thus, the advantage of microwave heating the molded body made of waste molten glass is obvious.

[0020]

As described above, according to the present invention, it is possible to perform efficient sintering by microwave heating, taking advantage of the characteristic that the dielectric loss, which is a unique property of waste molten glass, is large. Even a compact having a large thickness can be efficiently sintered while suppressing energy loss. Also,
The use of microwaves as the heating means makes it possible to easily form dense ceramics while using waste molten glass made of various substances with inconsistent components as raw materials, and the usefulness of unnecessary waste materials Can be expanded.

[Brief description of the drawings]

FIG. 1 is a diagram showing a comparison of dielectric loss of various ceramics in an example of the present invention.

FIG. 2 is a view showing a comparison of water absorption when a sample using sewage sludge slag as a raw material of molten glass of waste is heated in a microwave and in an electric furnace in the same example.

FIG. 3 is a diagram showing a comparison of water absorption when a sample using municipal waste slag as a raw material of molten glass of waste is heated in a microwave and in an electric furnace in the example.

FIG. 4 is a diagram showing a comparison of water absorption when a sample using fly ash slag as a raw material for molten glass waste is heated by microwave heating and by electric furnace heating in the same example.

[Explanation of symbols]

A is a water absorption-temperature relationship line in a sample in which the mixing ratio of slag and clay is 80:20 and microwave heating is performed. B is a water absorption-temperature relationship line for a sample in which the mixing ratio of slag and clay is 80:20 and heated by an electric furnace. C is a water absorption-temperature relationship line for a microwave heated sample having a mixing ratio of slag and clay of 60:40. D is a water absorption-temperature relationship line for a sample having a mixture ratio of slag and clay of 60:40 and heated by an electric furnace. E It is a water absorption-temperature relationship line in a microwave heated sample having a mixing ratio of Kuboflux and clay of 80:20.

Continued on the front page (72) Inventor Shiro Uebayashi 2-47, Shikitsu Higashi 1-chome, Namiwa-ku, Osaka-shi, Osaka (72) Inventor Yasushi Terao Yasushi 1-chome, Shikitsu-higashi, Namiwa-ku, Osaka, Osaka No. 47 Kubota Co., Ltd. (72) Inventor Shoji Okada 2-47, Shikitsu Higashi 1-chome, Namiwa-ku, Osaka, Osaka 2-7 Inventor Hirohito Yoshioka, Hirohito Yoshioka Higashiichi Shikitsu, Naniwa-ku, Osaka, Osaka No. 2-47, Kubota Co., Ltd. (72) Inventor Hiroshi Tajima 2-47, Shikitsu Higashi, Naniwa-ku, Osaka-shi, Osaka (56) References JP-A-56-96782 (JP, A) (58) Fields surveyed (Int. Cl. ⁷ , DB name) C04B 35/00 C04B 35/64

Claims (1)

(57) [Claims] 1. A waste such as municipal solid waste, sewage sludge, fly ash and the like is melt-processed, then cooled and solidified to form a waste molten glass, and a molded body containing the waste molten glass as a raw material component is formed. A method for producing ceramics from waste materials, comprising sintering the components of the molded body by microwave heating the molded body to 800 to 1100 ° C. to form ceramics. .