JPH061675A - Manufacture of insulating fire-resisting sintered compact - Google Patents

Abstract

PURPOSE:To continuously obtain an excellent insulating fire-resisting sintered compact stabilized the quality by a simple process by mixing easily combustible coal to a fire resisting characteristic raw material and firing it. CONSTITUTION:The easily combustible coal is mixed to the fire resisting characteristic raw material and fired, thus the insulating fire sintered compact is produced. A single raw material such as clay of halloysite alumina, and silica, or the raw material to produce the fire resisting characteristic materials such as mullite and spinel after >=2 kinds raw materials are reacted or a mixture of both, are mentioned as the using fire resisting characteristic materials. Since the insulating fire-resisting sintered compact is mixed the easily combustible coal to the raw material and is molded, the combustible coal burns away in a short firing time and the easily combustible coal material vanishes perfectly before sintering of the molded body, and pores are formed. Beside in order to avoid disappearance of the pores accompanied by firing shrinkage, the combustible coal the particle size of which has been adjusted is used, the pores with a controlled diameter is surely formed and then the porous insulating fire-resisting sintered compact superior in a heat insulating property is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat insulating refractory sintered body suitable for heat insulating bricks, heat insulating castables and the like used in various kilns and the like.

[0002]

2. Description of the Related Art As a conventional method for producing a heat-insulating refractory sintered body, a method of mixing rice husks with refractory substances such as refractory clay, kaolin, and alumina, followed by molding and firing, or a slurry with a surfactant is used. How to introduce bubbles, tar pitch,
In some cases, oil coke or the like is mixed, molded, dried, calcined, and then sintered by main firing. However, since the main components of the material obtained by firing the rice husks are silica and carbon, when the refractory material is other than silica, there is a drawback that it is contaminated by silica and the fire resistance is lowered. Further, according to the method using tar pitch, oil coke, etc., since the combustion reaction is slow, it is necessary to perform calcination for a long time in order to completely burn the carbon material and obtain effective pores. At that time, since the calcination temperature is lower than the main calcination temperature, the strength of the calcination body is weak,
At the time of main firing in a continuous kiln such as a rotary kiln, or during other operations such as drying and moving until it is fired into a final product, the molded body is worn out and damaged, and the yield is remarkably increased. It lowers and reduces the pores that have been formed. If the calcination temperature is raised too high to avoid this, only the surface of the calcined body will sinter rapidly and the carbonaceous material inside cannot be removed by incineration. The result is that it is not desirable because it becomes a material far from the refractory heat insulating material. In addition, the process including the two-stage firing of calcination and main firing requires complicated operations and also reduces the economical efficiency. When air bubbles are introduced into the slurry, the molded body is extremely weak and there is a problem in handling. As another method, it is possible to avoid the above drawbacks by slowly firing in a tunnel kiln, a shuttle kiln or the like. However, it takes a long time of several days until the firing is completed, and there are problems such as inefficiency and high cost.

[0003]

The object of the present invention is to form a porous body which is most effective for the heat insulating effect on the refractory material, and has a good heat insulating fire resistance with stable quality by a simple process. It is to continuously produce a sintered body. To eliminate the calcination step and burn away the carbonaceous material for pore formation in one firing, and to subsequently sinter it, it is necessary to make the carbonaceous material into a fine powder and to promptly react with air to remove it. is there. However, in this case, the pores after burning the carbonaceous material become small as a result, so the pores are reduced or eliminated due to the shrinkage of the refractory material. As a result, the purpose of making pores inside the sintered body cannot be achieved, and when the remaining pores are too fine, the partition strength between the pores is weak, and when trying to obtain crushed particles as an aggregate of refractory material. However, the amount of fine particles, which is an unnecessary particle size, is remarkably increased. On the other hand, if the particles of the carbonaceous material are made coarse, unburned carbonaceous material remains in the sintered body in a continuous and highly efficient firing method such as a rotary kiln and a fluidized firing furnace, which causes a problem that the original purpose cannot be achieved. Have.

[0004]

The adiabatic refractory sintered body according to the present invention is a refractory porous body having a large number of closed pores, and its manufacturing process is efficient, low cost, and high-quality adiabatic. It becomes possible to manufacture a refractory sintered body. For pore formation,
Easily incinerated coal, that is, granulated fine carbonaceous material (hereinafter simply referred to as granulated finely divided coal), and / or activated with fine-grained carbonaceous material (hereinafter simply referred to as activated carbon), the outer diameter of the grain is adjusted. To use. Therefore, one of the reasons is that the combustion of the carbonaceous material is rapid, the combustion is started from the surface portion of the molded body, and the carbonaceous material in the deeper portion is burned in a short time while the trace of disappearance of the carbonaceous material is in the open pore state. Is possible. That is, since the sintering starts, the pores are formed inside the molded body before the shrinkage starts, and the molded body continues to become a sintered body. It is possible. Therefore, it becomes possible to perform firing in a kiln such as a rotary kiln. Further, one of them is that the easily incinerated coal, that is, the granulated pulverized coal and / or the activated carbon is used by adjusting the outer diameter of the particles, so that it is possible to form effective pores with few pores disappearing due to firing shrinkage. As a result, it has become possible to continuously produce a good adiabatic refractory sintered body with stable quality by a simple process.

In the present invention, the refractory raw material and the easily incinerated coal are mixed by a conventional method such as wet mixing, semi-dry kneading, and dry mixing. An organic or inorganic binder may be used in order to maintain the strength of the molded body during kneading and mixing.

As the molding method in the present invention, any of ordinary methods such as casting molding, press molding, extrusion molding and granulation by a pelletizer can be used, and the molded article is dried or dried without drying. By doing so, it is possible to obtain a porous adiabatic refractory sintered body having many effective pores and excellent in strength.

The refractory raw material used in the present invention is a simple raw material such as clay such as halloysite, alumina, silica or the like, or a raw material for reacting two or more kinds of raw materials to produce a refractory material such as mullite or spinel, Alternatively, a mixture of both can be used.

The proportion of the refractory raw material is 40 to 9
5% by weight, easy incineration charcoal 5 to 60% by weight, more preferably refractory raw material 60 to 90% by weight, easy incineration charcoal 10 to 40%
A weight% ratio is preferable in terms of the strength of the molded body and the combustion and incineration time of the easily incinerated coal. In addition, when kneading and mixing the refractory raw material and the easily incinerated coal, in order to maintain the strength of the molded product, water is used for clay materials such as kaolin and water glass, silica sol for low molding strength such as alumina. , Alumina sol,
Organic or inorganic binders such as starch, MC, CMC and PVA may be used. These materials are mixed by wet mixing, semi-dry kneading, dry mixing or the like, or kneaded, and are molded by casting, press molding, extrusion molding, granulation by a pelletizer, etc. and dried naturally or without heating or drying. , A rotary kiln, a fluidized bed kiln, etc. are fired at a temperature of 1100 to 1900 ° C. to produce an adiabatic refractory sintered body.

[0009]

The heat-insulating refractory sintered body of the present invention mixes and molds easily incinerated charcoal with a material, so that the combustion of the easily incinerated charcoal is completed in a short firing time, and the completely burned coal can be completely burned before sintering. Incinerator carbonaceous material disappears and pores are formed. In addition, easy incineration charcoal with an adjusted outer diameter is used to avoid the disappearance of pores due to firing shrinkage, so pores with a controlled diameter are reliably formed, and a porous adiabatic refractory sintered material with excellent heat insulation properties. The body is obtained.

[0010]

[Experimental Examples] The present invention will be described in detail below with reference to experimental examples.

[0011]

Experimental Example 1 Calcined alumina (Al ₂ O ₃ 99.6%,
Na ₂ O 0.35%, SiO ₂ 0.02%, Fe ₂ O
₃ 0.02%, Nippon Light Metal Co., Ltd. product name A-1
7) 19.5% by weight and 0.5% by weight of an organic binder (methyl cellulose manufactured by Shin-Etsu Chemical Co., Ltd.) in an alumina pot mill, specific surface area, plain 8050 cm ²
Specific surface area (B.I.) of commercially available activated carbon (Kuraray Co., Ltd., trade name: Kuraray Coal) as the activated carbon.
E. T method) 1 having 1100 to 1780 m ² / g
~ 0.5 mm, 0.5-0.3 mm, 0.3-0.15
mm, 0.15-0.106 mm, 0.106-0.0
05mm, each adjusted to 0.005mm or less 2
0% by weight, 10% by weight of water were added, mixed by a Hobart mixer, press-molded to 20 mm × 25φ, dried at 120 ° C., and gas furnace (volume 1800 cm ³ acetylene-oxygen type).
At 120 ° C., the temperature was raised to 1900 ° C., and the temperature was maintained at 1900 ° C. for 10 minutes. The apparent porosity, bulk specific gravity, and apparent specific gravity (J
IS method), amount of residual coal (0.045 mm for adiabatic fire resistant sintered body
Finely pulverize so that it can pass through the sieve of the
It is ignited for 30 minutes, and the weight loss after the weight becomes constant is expressed in% by weight. ) Is shown in Table 1.

[0012]

[Experimental Example 2] Kaolin clay (SiO ₂ 46.3%, A
l ₂ O ₃ 36.1%, Fe ₂ O ₃ 2.1%, fire resistance
80% by weight of SK36) as carbon material, carbonized fine powder granules of paper, specific surface area of 20 m ^{2 /} g (BET method),
Outer diameter of grain is 0.5 to 0.15 mm. Carbonized fine powder granules of wood chips,
Specific surface area 4 m ^{2 /} g (BET method), grain outer diameter 0.5 to
0.15 mm. Oil coke fine granules, specific surface area 5
m ^{2 /} g (BET method), particle outer diameter 0.5 to 0.15 m
m. Oil coke fine powder granules, specific surface area 8 m ² / g
(BET method), 20% by weight of each of four types having an outer diameter of 0.5 to 0.15 mm and 30% by weight of water were added, mixed by a Hobart mixer, and pressed into 20 mm × 25φ.
After drying at 0 ° C., a gas furnace (volume of 1800 cm ³ acetylene-oxygen type) was heated to 1420 ° C. for 120 minutes at 1420 ° C.
Firing was performed at 10 ° C. for 10 minutes. The apparent porosity, bulk specific gravity, apparent specific gravity, and amount of residual coal of the heat-insulating fire-resistant sintered body obtained at this time are shown in Table 2 together with the properties of the carbonaceous material-free product for reference.

[0013]

[Table 1]

[0014]

[Table 2]

From the results of Tables 1 and 2, refractory material 8
20% by weight of easily incinerated coal to 0% by weight of 1 to 0.5 of the outer diameter of the grain
mm, 0.5 to 0.3 mm, 0.3 to 0.15 mm,
0.15-0.106 mm, 0.106-0.005 m
m, 0.005 mm or less of 6 kinds of outer diameter of the particles are adjusted, and each is mixed, molded, dried, fired, and cooled.
No. 2, No. 3, that is, the outer diameter of the grain is 0.5 to 0.
Those adjusted to 3 mm and 0.3 to 0.15 mm have a large porosity, a low bulk specific gravity, and a small amount of residual coal. In addition, No. 4, No. 5, No. 6 or 0.15
.About.0.106 mm, 0.106 to 0.005 mm, 0.
No. 5 of Experimental Example 1 was adjusted to 005 mm or less.
2, No. Compared with No. 3, the porosity is small, the bulk specific gravity is large, and the amount of residual coal is slightly large. This means that by using easy-burning coal whose grain outer diameter is adjusted to form pores, it is possible to use 0.5 to 0.3 of the easy-burning coal whose combustion is adjusted for grain outer diameter.
mm and 0.3 to 0.15 mm are N of Experimental Example 1
o. 4, No. 5, No. Since the combustion is faster than that of the grain outer diameter adjusted product of 6, the combustion starts from the surface portion of the molded body, and the entire combustion starts while the disappearance traces of the easily incinerated coal are open pores, that is, the fired body. It is possible to form a porous body because the pores are formed before the contraction starts, and one is the pores of easily incinerated coal that disappear by sintering because the outer diameter of the grain is adjusted. Effective pores can be formed due to the small amount. This is because the No. 4, No. 5, N
o. No. 6 grain outer diameter 0.15-0.106 mm, 0.106
Disappearance of generated pores becomes remarkable when the thickness is 0.005 mm or less and 0.005 mm or less. No. 1 in Experimental Example 1 In No. 1, the large pores are conspicuous, and the apparent porosity is slightly low.

No. 2 of Experimental Example 2 was prepared by mixing 80% by weight of the refractory material with 20% by weight of easy-burning coal having a different specific surface area, molding, drying, firing and cooling. 6 ie specific surface area 2
In the case of 0 m ² / g, the porosity was large, the amount of residual coal was small, and the bulk specific gravity was also appropriate, but No. 7 specific surface area of 4 m ² / g, No. 7 of Experimental example 2. 8 Specific surface area 5 m ² /
g, No. 2 of Experimental Example 2. 9 With a specific surface area of 8 m ² / g, the porosity is small and the amount of residual coal is large. This means that the specific surface area is 20
In the case of less than m ² / g, the surface of the molded body is sintered faster than the disappearance rate of the carbonaceous material, unburned carbonaceous material remains inside the molded body, and the amount of residual carbon increases. Further, the relationship between the outer diameter of the grain of each charcoal and the incineration time differs depending on the specific surface area of the easily incinerated charcoal used for forming pores.

[0017]

EXAMPLES The present invention will now be described in more detail by way of examples.

[0018]

Example 1 Kaolin Clay (SiO ₂ 46.3%, A
l ₂ O ₃ 36.1%, Fe ₂ O ₃ 2.1%, fire resistance
90% by weight of SK36) as activated carbon, and the specific surface area (BET method) of commercially available activated carbon (Kuraray Co., Ltd., trade name: Kuraray Coal), 1100 to 1780 m ² / g, outer diameter of grain: 0.3 to 0 15mm 10% by weight and water 30% by weight
Add and mix with Hobart mixer. Then, this material was tumbled and granulated at 20φ with a pelletizer to obtain 120
Dry at a temperature of ℃, rotary kiln (inner diameter 500φ
It was fired at a burning point temperature of 1420 ° C. in a length of 9 m) for 50 minutes from charging to discharging, and cooled in a cooler. Table 3 shows the apparent porosity, bulk specific gravity, apparent specific gravity, and amount of residual coal of the heat-insulating fire-resistant sintered body obtained at this time.

[0019]

Example 2 Kaolin Clay (SiO ₂ 46.3%, A
l ₂ O ₃ 36.1%, Fe ₂ O ₃ 2.1%, fire resistance
SK36) as 80% by weight as granulated pulverized coal, specific surface area 162 m ^{2 /} g (BET)
Method) was adjusted to 0.3 to 0.15 mm, and 20% by weight of water was added to 30% by weight of water, and the mixture was mixed by a Hobart mixer, and was molded into a long column of 20 mm × 25φ by an extrusion molding machine, which was naturally dried. , With a rotary kiln (inner diameter 500φ, length 9m) at a burning point temperature of 1420 ° C.
It was fired at 0 minutes and cooled by a cooler. Table 3 shows the apparent porosity, bulk specific gravity, apparent specific gravity, and amount of residual coal of the heat-insulating fire-resistant sintered body obtained at this time.

[0020]

Example 3 Calcined alumina (Al ₂ O ₃ 99.6%,
Na ₂ O 0.35%, SiO ₂ 0.02%, Fe ₂ O
₃ 0.02%, Nippon Light Metal Co., Ltd. product name A-1
49.5 wt% of 1) and 0.5 wt% of an organic binder (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd. carboxylmethylcellulose) in a tube mill (specific surface area, plain 6980).
cm ² / g) and the specific surface area (BET method) 1100 to 1780 m ² / g of commercially available activated carbon (Kuraray Co., Ltd., trade name: Kuraray Coal) as activated carbon having an outer diameter of 0. 50% by weight adjusted to 0.5 to 0.15 mm and 10% by weight of water were added, mixed with a Hobart mixer, press-molded to 20 × 34 × 30 mm, air-dried, and then rotary kiln (inner diameter 500φ length 9 m). It was fired at a firing point temperature of 1900 ° C. for 100 minutes from charging to discharging, and cooled in a cooler. Table 3 shows the apparent porosity, bulk specific gravity, apparent specific gravity, and amount of residual coal of the heat-insulating fire-resistant sintered body obtained at this time.

[0021]

[Table 3]

[0022]

The adiabatic refractory sintered body according to the present invention has a specific surface area of 20 m ^{2 /} g (BET method) of easily incinerated coal, that is, granulated pulverized coal and / or activated carbon, for forming pores. By using a carbonaceous material whose grain outer diameter is adjusted to 0.005 mm or more, one of them is that the combustion of easy-burning coal is rapid, so combustion starts from the surface of the molded body, and the trace of disappearance of easy-burning coal Since the entire carbonaceous material finishes burning while is an open pore,
That is, it becomes possible to form a porous body because pores are formed before the entire combustion starts and the molded body starts contracting. One is that the outer diameter of the easily incinerated coal is adjusted according to the shrinkage amount of the refractory material so that the most effective pore diameter and pore volume for heat insulation can be set and the pores that disappear Good adiabatic fire resistance with stable quality due to a simple process by using a kiln such as a rotary kiln because it is possible to form a small number of effective pores and to have a required sintered body strength in a short time. It has become possible to continuously produce sintered bodies.

Claims (1)

[Claims] 1. A method for producing an adiabatic refractory sintered body by mixing easily incinerated coal with a refractory raw material and sintering the mixture.