JP3231197B2 - Method for producing ceramics from waste and ceramic firing furnace - 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 from wastes such as industrial wastes and a ceramic firing furnace.

[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 firing 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, the heating of the compact in the conventional firing 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. For this reason, there has been a problem that the time required for sintering increases as the size of the compact increases, and the amount of energy consumption increases.

[0004] Other heating means for heating the compact include:
There is a microwave firing furnace using microwaves. The microwave firing furnace has better thermal efficiency than conventional firing furnaces and does not require heat conduction time, so that the process time can be shortened.

[0005] However, the heating condition of the microwave firing furnace differs depending on the shape of the furnace and the size, shape, material and the like of the object to be heated. General ceramics are composites of different materials, and there are materials that absorb microwaves well and materials that hardly absorb microwaves depending on the materials used. Further, there is a material having a property of easily absorbing microwaves at a temperature equal to or higher than the critical temperature even when stable heating is performed. Among such materials, there is a material whose temperature rises runaway and melts. As described above, it is very difficult to stably obtain a sintered body from a heated object having a composite material.

The present invention solves the above-mentioned problems. By using a microwave heating means which is an internal heating method and a heating means of an external heating method together, an object to be heated made of a composite material can be efficiently used. It is an object of the present invention to provide a method for producing ceramics from a waste material that can be stably fired, and a ceramic firing furnace.

[0007]

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 waste molten glass,
A molded body containing the waste molten glass as a raw material component is formed, the molded body forming an object to be heated is arranged in a firing furnace, and the molded body is irradiated with microwaves from a microwave heating means, thereby being heated by microwave. 600 ° C in 30 minutes
Just before the compact melts due to the temperature gradient
The temperature is rapidly raised to this temperature, and then the external heating
The temperature of the molded product increases by 200 ° C in 4 hours.
Slowly raise the temperature to the sintering temperature
The molded body is heated to 600 ° C in 15 minutes by microwave heating.
The temperature gradient rises to an appropriate temperature just before the compact melts.
Temperature and then molded by external heating means
The body is sintered with a temperature gradient of 200 ° C in 3 hours
Either slowly raise the temperature to
A temperature rise of 850 ° C in 45 minutes by heat.
Rapidly rises to the appropriate temperature just before the molded body melts due to temperature gradient
And then heat the molded body at 4:00
Up to the sintering temperature with a temperature gradient of 100 ° C
Either increase the temperature slowly or use microwave heating.
Temperature gradient of 850 ° C in 30 minutes
The temperature rises quickly to the appropriate temperature just before the
After that, the molded body is heated by an external heating means for 10 hours in 2 hours.
Slowly rise to sintering temperature with a temperature gradient of 0 ° C
The ceramics are formed by sintering the components of the compact
To form .

A ceramic firing furnace according to the present invention is characterized in that a molded body containing waste molten glass as a raw material component is an object to be heated, and a closed space surrounded by a heat insulating wall forms a furnace chamber for storing the object to be heated. A microwave heating means for irradiating microwaves to the object to be heated in the furnace chamber to rapidly raise the temperature of the compact, and an external means for heating the object to be heated in the furnace chamber and applying heat to the object slowly. Heating means, and microwave heating means
With a temperature gradient in which the temperature rises to 600 ° C in 30 minutes,
Temperature rise by external heating means 200 ° C in 4 hours
Temperature gradient or microwave heating means
Temperature rise of 600 ° C in 15 minutes
The temperature is raised to 200 ° C in 3 hours by the external heating means.
This is a temperature gradient that increases in degree .

In the ceramic firing furnace of the present invention, a formed body containing waste molten glass as a raw material component is used as an object to be heated, and a drying zone is formed in a furnace chamber for storing the object to be heated from a furnace inlet to a furnace outlet. A furnace body in which a first baking region and a second baking region are continuously formed; a conveying means for conveying the object to be heated from the furnace inlet to the furnace outlet in the furnace chamber; Drying microwave heating means for irradiating waves, microwave heating means for irradiating the object to be heated with microwaves in the first firing area to rapidly raise the temperature of the molded body, and heating in the second firing area. External heating means for applying heat to the object to be heated and slowly heating the object,
Temperature rise by microwave heating means for firing is 850 in 45 minutes
A temperature gradient that raises the temperature by an external heating means
A temperature gradient where the temperature rises by 100 ° C in 4 hours
Or the temperature rise by the microwave heating means for firing is 3
External heating with a temperature gradient of 850 ° C in 0 minutes
The temperature at which the temperature rise by means increases the temperature by 100 ° C in 2 hours.
Is a degree gradient .

[0010]

According to the method of the present invention for producing ceramics from wastes, when a compact placed in a firing furnace is first irradiated with microwaves, the compact itself generates heat and heat is generated. Compared to the case where heat is transferred from the inner side to the outer side of the
The temperature of the molded body rapidly rises and reaches a suitable temperature shortly before melting. Thereafter, when the molded body is heated by the external heating means, heat is transmitted from the outside to the inside of the molded body, and the molded body is slowly heated to the final temperature and sintered.

Therefore, by using the microwave heating means and the external heating type heating means in combination, it is possible to easily stabilize the dense ceramics while using as a raw material a waste glass made of a variety of substances having inconsistent components. And can be formed in a short time.

According to the ceramic sintering furnace of the present invention, a pre-heating treatment for rapidly heating the compact to an appropriate temperature by the microwave heating means and a slow heating of the compact to the sintering temperature by the external heating means. Since the post-heating treatment is performed in combination, dense ceramics can be stably formed in a short time from waste molten glass.

According to the ceramic firing furnace of the present invention, the compact is moved from the furnace inlet to the furnace outlet in the furnace chamber by the transfer means. During this time, in the drying region, the molded body is dried while maintaining the molded body in a low temperature range by microwave heating. In the first sintering region, the preheating treatment is performed by rapidly heating to an appropriate temperature just before melting the molded body by microwave heating. In the second firing region, the compact is slowly heated to the final temperature by the external heating means and sintered. For this reason, dense ceramics can be continuously and stably formed from waste molten glass in a short time.

[0014]

An embodiment of the present invention will be described below. In FIG. 1, a microwave oscillator 3 is connected to a microwave firing furnace 1 via a waveguide 2 and an exhaust fan 5 is connected via a flue 4. An electric furnace 6 is arranged inside the microwave firing furnace 1. The furnace body 7 of the electric furnace 6 is formed of a heat insulating material 7a, and the inner surface of the heat insulating material 7a may be covered with a heating element suitable for microwave heating such as silicon carbide as needed. The furnace body 7 forms a furnace chamber 9 in which a closed space surrounded by a heat insulating material 7a houses a molded body 8 which is an object to be heated. A body 11 is provided. The molded body 8 is made of waste molten glass as a raw material.

In this embodiment, the waste molten glass includes general waste such as municipal waste, sewage sludge and fly ash, and industrial waste such as mine debris, river sediment, construction sludge and the like. Is obtained by cooling and solidifying a molten slag obtained by subjecting the waste to melting treatment, and is formed into a sintered material by pulverizing to a suitable particle size.

A molding material such as clay or cement is added to the powdery granules of the waste molten glass, mixed and kneaded to form a clay,
The molded body 8 is formed by drying. The mixing ratio between the molten glass waste and the molding material in this kneaded material can be set arbitrarily according to the characteristics of the target ceramics, and it is possible to add almost no molding material. It is also possible to add a molded foam material, a fired foam material, a sintered material, or the like as a component of the soil. Furthermore, it is also possible to add a fibrous reinforcing material or the like as a component of the clay, it is possible to combine various materials in addition to the above, not only conventional ceramic raw materials, but also unused resources and It is also possible to use the industrial waste as it is by pulverizing it to an appropriate particle size without turning it into a slag, or to combine refined raw materials, organic substances such as wood powder, and carbon.

In this embodiment, the compact 8 is made of a mixture of 80% municipal solid waste slag and 20% clay at 200 × 200 × 2.
It is formed in a 00 cube. Hereinafter, the operation of the above configuration will be described. FIG. 2 shows the relationship between the sintering temperature and the sintering time, in which the molded body 8 is sintered with a temperature gradient as shown in FIG. First, the microwave generated in the microwave oscillator 3 is guided to the microwave firing furnace 1 through the waveguide 2, and the formed body 8 arranged in the furnace chamber 9 of the electric furnace 6 is irradiated with the microwave. The molded body 8 is heated to an appropriate temperature (100 ° C.) by the microwave heating, and dried at this temperature for about 4 hours. Thereafter, the molded body 8 is heated to an appropriate temperature (700 ° C.) slightly before melting by pre-firing by strengthening the microwave heating. At this time, according to the microwave heating, the molded body itself generates heat, and heat is transmitted from the inside to the outside of the molded body 8,
The temperature of the molded body 8 is rapidly increased in a short time (about 30 minutes) as compared with the case where heat is transferred from another substance to the molded body 8. still,
When the heating element is arranged on the inner side surface of the heat insulating material 7a, the heating element generates heat by being irradiated with the microwave, and the heat can be used for heating the molded body 8.

Thereafter, the molded body 8 is heated to a sintering temperature by electric resistance heat generated from the electric heating element 11, and ceramics are formed by sintering the components of the molded body 8. At this time, heat is transmitted from the outside to the inside of the molded body 8, and is slowly fired (4 hours) until it reaches the sintering temperature (900 ° C.). ) And sinter. The electric furnace 6 is preheated as required.

Therefore, by using the heating from the inside by the microwave and the heating from the outside by the electric heating element 11 in combination, it is possible to use the waste molten glass as a raw material, which is composed of various substances whose components are not fixed. Dense ceramics can be easily and stably formed in a short time.

At the time of firing, the time in the furnace can be reduced by reducing the atmosphere in the furnace to a reduced pressure or a vacuum by means of the exhaust fan 5 or other means. FIG. 3 shows the relationship between the sintering temperature and the sintering time when the inside of the furnace is in a reduced pressure state.

FIG. 4 shows the configuration of a continuous firing furnace according to another embodiment of the present invention. The continuous firing furnace 21 includes a microwave drying furnace 22 serving as a drying area, a microwave firing furnace 23 serving as a first firing area, and a gas firing furnace 24 serving as a second firing area, and forms a continuous space. I have. A microwave oscillator 26 is connected to the microwave drying furnace 22 and the microwave firing furnace 23 via a waveguide 25, and a fixed heat insulating material 23a is arranged in the microwave firing furnace 23. A gas burner 27 is provided in the gas firing furnace 24, and an exhaust fan 29 is connected via a flue 28.

A plurality of carts 30 are arranged in the furnace from the furnace inlet to the furnace outlet. The carts 30 constitute a conveying means for conveying a molded body 31 to be heated, and are formed by a heat insulating material 32. A furnace chamber 33 is provided. The electric wave absorber doors 34 are provided at the furnace entrance and the furnace exit. The molded body 31 in the present embodiment is obtained by forming a mixture of fly ash slag 60% and clay 40% into a 200 × 200 × 200 cube.

The operation of the above configuration will be described. FIG. 5 shows the relationship between the firing temperature and the firing time, in which the compact 8 is fired with a temperature gradient as shown in FIG. The compact 31 is placed in the furnace chamber 33 of the truck 30 and a plurality of trucks 30 are sequentially fed into the furnace to form the compact 3.
1 is moved from the furnace inlet to the furnace outlet by the carriage 31. During this time, the microwave drying furnace 22 forming the drying area
In, the compact 31 is dried by irradiating the compact 31 with microwaves emitted from the microwave oscillator 26 and maintaining the compact 31 in a low temperature range (100 ° C.) for 4 hours. In the microwave firing furnace 23 forming the first firing area, the molded body 31 is heated by microwave heating to an appropriate temperature (950) just before melting.
(° C.) to perform preliminary firing. In the gas firing furnace 24 forming the second firing area, the gas burner 27
The molded body 31 is slowly heated to the final temperature (1
(050 ° C.), and the main firing is performed, and thereafter, the leveling firing is performed for 1 hour to sinter the components of the molded body 31. For this reason, dense ceramics can be continuously and stably formed from waste molten glass in a short time.

At the time of firing, the time can be shortened by reducing the atmosphere in the furnace to a reduced pressure state or a vacuum state by exhausting by the exhaust fan 29 or other means. FIG. 6 shows the relationship between the firing temperature and the firing time when the inside of the furnace is in a reduced pressure state.

[0025]

As described above, according to the present invention, by using a microwave heating means and an external heating type heating means together, it is possible to use a raw material made of a variety of materials having a variable component called waste molten glass. However, dense ceramics can be easily and stably formed in a short time.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a ceramic firing furnace according to an embodiment of the present invention.

FIG. 2 is a graph showing a relationship between a sintering temperature and a sintering time when the inside of a furnace is in a normal pressure state in the embodiment.

FIG. 3 is a graph showing a relationship between a sintering temperature and a sintering time when the inside of the furnace is in a reduced pressure state in the example.

FIG. 4 is an overall configuration diagram of a continuous ceramic firing furnace according to another embodiment of the present invention.

FIG. 5 is a graph showing a relationship between a sintering temperature and a sintering time when the inside of the furnace is in a normal pressure state in the example.

FIG. 6 is a graph showing a relationship between a sintering temperature and a sintering time when the inside of the furnace is depressurized in the example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Microwave firing furnace 3 Microwave oscillator 6 Electric furnace 9 Furnace room 11 Electric heating element

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shoji Okada 2-47, Shikitsuhigashi, Namiwa-ku, Osaka-shi, Osaka Prefecture Inside Kubota Corporation (72) Inventor Satoru Shibaken Shikitsu-higashi, Namiwa-ku, Osaka, Osaka 1-2-47, Kubota Co., Ltd. (72) Hiroshi Tajima, Inventor Hiroshi Tajima 1-2-47, Shibutsu Higashi, Naniwa-ku, Osaka, Osaka (72) Inventor Tetsuo Kiyota, Naniwa-ku, Osaka, Osaka No. 2-47 Tsuto Kubota Co., Ltd. (56) References JP-A-6-87677 (JP, A) US Patent 4,375,441 (US, A) (58) Fields investigated (Int. Cl. ⁷ , DB Name) C04B 35 / 00,35 / 64 B09B 3/00

Claims (3)

(57) [Claims] 1. A waste product such as municipal solid waste, sewage sludge, fly ash and the like is melt-processed, then cooled and solidified to produce a waste molten glass, and a molded body containing the waste molten glass as a raw material component is formed. and, placed in a firing furnace the molded body forming the object to be heated is irradiated with microwaves in the molded body from the microwave heating means, of 600 ° C. for 30 minutes moldings by microwave heating temperature
A suitable temperature immediately before the compact melts due to the temperature gradient
Temperature rapidly, and then external heating means
The molded body is heated at a temperature gradient of 200 ° C. in 4 hours.
Either slowly raise the temperature to the sintering temperature, or heat the compact by microwave heating for 6 minutes in 15 minutes.
Immediately after the molded body melts due to a temperature gradient of a temperature rise of 00 ° C
Rapidly raise the temperature to the appropriate temperature before, and then externally heat
The temperature of the molded body is increased by 200 ° C. in 3 hours by means of
The temperature is gradually increased to the sintering temperature by a temperature gradient, or the molded body is heated by microwave heating for 8 minutes in 45 minutes.
Immediately after the compact is melted by a temperature gradient that raises the temperature by 50 ° C.
Rapidly raise the temperature to the appropriate temperature before, and then externally heat
The temperature of the molded body is increased by 100 ° C. in 4 hours by means of
The temperature is gradually increased to the sintering temperature by a temperature gradient, or the molded body is heated by microwave heating for 8 minutes in 30 minutes.
Immediately after the compact is melted by a temperature gradient that raises the temperature by 50 ° C.
Rapidly raise the temperature to the appropriate temperature before, and then externally heat
The molded body is heated to 100 ° C. in 2 hours by means
Slowly raise the temperature to the sintering temperature with a temperature gradient to form the components of the compact.
A method for producing ceramics from waste materials, characterized in that ceramics are formed by densely sintering ceramics . 2. A furnace body which comprises a molded body containing waste molten glass as a raw material component, and a closed space surrounded by a heat insulating wall forms a furnace chamber for accommodating the heated object; Microwave heating means for irradiating the object with microwaves to rapidly raise the temperature of the molded body, and external heating means for heating the object to be heated, which is located in the furnace chamber and slowly heating the object, Temperature rise of 600 ° C in 30 minutes by microwave heating means
The temperature rise by the external heating means is 4 degrees.
Time temperature gradient der forms a temperature increase of 200 ° C. Luke, or heating by microwave heating means 15 min 60
With a temperature gradient of 0 ° C, with external heating means
A temperature gradient in which the temperature rises to 200 ° C in 3 hours.
Ceramics firing furnace, characterized in that that. 3. A molded object containing waste molten glass as a raw material component is to be heated, and a drying zone, a first firing zone, and a second firing zone are provided from a furnace inlet to a furnace outlet in a furnace chamber for storing the heated object. A furnace body formed continuously with a firing region, a conveying means for conveying the object to be heated from the furnace inlet to the furnace outlet in the furnace chamber, and a drying unit for irradiating the object with microwaves in the drying region. A microwave heating means, a firing microwave heating means for irradiating the object to be heated with microwaves in the first firing region to rapidly raise the temperature of the molded body, and a second heating means.
External heating means for applying heat to the object to be heated in the firing region to slowly heat the object, and the temperature rise by the microwave heating means for firing is 850 in 45 minutes.
A temperature gradient that raises the temperature by an external heating means
A temperature gradient where the temperature rises by 100 ° C in 4 hours
Or, alternatively the heating 30 minutes by firing for microwave heating means
External heating means with a temperature gradient of 850 ° C.
Temperature rise of 100 ° C in 2 hours
Ceramics firing furnace which is a distribution.