JPH02204350A - Production of inorganic foamed material - Google Patents

Abstract

PURPOSE:To obtain a high-strength inorganic foamed material which is fine and lightweight and has continuous particle size and low water absorptive properties by heat-treating and expanding particles of amorphous by-product slag in the specified conditions which is obtained by partial oxidation of coal and has specified size. CONSTITUTION:Amorphous by-product slag which is obtained by partial oxidation of coal and contains particles having <=0.3mm particle diameter at >=90wt.% is heat-treated in a range within 500-1000 deg.C/min temp. rise velocity at 800-1000 deg.C and expanded. Fly ashes or particulate coal are addeted to the slag at the rate of <=20wt.% fly ash and/or <=10wt.% particulate coal for the above- mentioned slag. When this mixture is calcined in the reducing atmosphere, it is foamed and expanded in a short time and therefore production cost is preferably lowered.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to improvements in the manufacturing method of inorganic foams.

[Background of the Invention] Structures such as buildings are becoming lighter, stronger, and more insulated in order to save energy, save resources, and improve earthquake resistance. Of high quality! ! The problem is how to produce structural foams at low cost.

In particular, the quality is fine and continuous grain size in terms of high strength,
Moreover, there is a demand for inorganic foams that are lightweight and have low water absorption.

[Prior Art and Problems] Conventionally, regarding a method for manufacturing an inorganic foam using amorphous by-product slag obtained by partial oxidation of coal as a main raw material,
For example, JP-A-61-197479 and JP-A-6
A proposal has been made in Publication No. 1-251551.

From the claims of these methods, the former method [600%
The content of 8102 in the forming component is 60% by weight or more, the content of 8ρ203 is 20% by weight or more, and the content of CaO is type 5, which is expanded by heat treatment at a temperature of ℃ or higher. % or more," and the latter is "a method for producing an inorganic foam with an internal particle diameter of 2.57117 J or less obtained from partial oxidation of coal at 600°C.
The content of 5IOz is 60% by weight or less, characterized by expansion by heat treatment at a temperature above, AI! 203
The content of is 20% by weight or more, and the unit volume weight is 0.
6Kg/j! This is a method J for producing an inorganic foam which is higher than 1.2/j or less.

However, particles with a particle size of 0.311 #I or less
At present, the production of inorganic foams using amorphous by-product slag, which accounts for more than 1% by weight, as a raw material has not been commercialized. The main reason for this is that the inorganic foams produced using these known methods are very easy to fuse, so they are required to be fired at low temperatures and may contain particles that are not foamed sufficiently. Because of this, it is necessary to extend the heat treatment time, which may cause the inorganic foam to fuse with each other and form large lumps, or to fuse to the heat treatment equipment and hinder the smooth operation of the equipment. This is because there is a problem of

[Object of the Invention] The main object of the present invention is to provide a method for producing a high-strength inorganic foam that has fine and continuous particle size, is lightweight, and has low water absorption.

More specifically, the present invention addresses two issues: the effective use of particles with a particle size of 0.3 s or less among amorphous by-product slag obtained by partial oxidation of coal, and the increasing demand for high-quality inorganic foams. The purpose of the present invention is to provide a method for manufacturing an inorganic foam that is inexpensive, high quality, and useful for resource saving, and that solves the following problems at the same time.

[Summary of the Invention] The present invention is based on Japanese Patent Application Laid-Open No. 61-197, which the applicant has already filed.
479@ Publication and JP-A No. 61-251551, it relates to a method for producing an inorganic foam, and it is possible to produce 9 particles with a particle diameter of 0.3 mm or less, which was conventionally difficult to sinter.
Amorphous by-product slag with a weight of 0 weight or more is heated at a heating rate of 500
This is a method of manufacturing fine inorganic foam by heating and expanding it at a temperature range of 800 to 1000°C at a rate of 1000°C/min. Zarani's second invention is a method for more advantageously producing a high-strength inorganic foam with fine and continuous particle size and low water absorption by adding fly ash and/or pulverized coal and firing in a reducing atmosphere. .

[Effects of the Invention] The method for producing an inorganic foam of the present invention has a particle size of 0.3 #, which has not been commercialized as an inorganic foam in the past! II! It can be manufactured using an amorphous by-product slag containing 90% by weight or more of the following particles. Furthermore, by adding fly ash and/or pulverized coal, the foaming and expansion can be achieved in a short time, thereby reducing the manufacturing cost of the inorganic foam.

Further, the inorganic foam produced by the production method of the present invention has a fine and continuous particle size, is lightweight, has a low water absorption rate, and has high strength.

In addition, it has excellent fire resistance and low thermal conductivity, so it also has good heat insulation properties. Therefore, it is much more versatile than previous FI foams.

[Detailed Description of the Invention] Conventional inorganic foam manufacturing technology involves crushing and sieving amorphous by-product slag obtained by partial oxidation of coal using a ball mill, resulting in particle sizes of 0.3 to 5. .0IIur1 raw material is fired in a rotary kiln (φ1, 3 x 31.5 m). However, particles with a particle size of 0.3 s or less or particles with a particle size of 0.3 s or less of the amorphous by-product slag generated in large quantities when preparing the raw material particle size above are 90%
The above amorphous by-product slag (hereinafter sometimes referred to as particles with a particle size of 0.3% or less) is still not used as an inorganic foam due to its poor foamability, and is instead used as a substitute for cement raw materials or as a raw material for cement. It is disposed of in landfills, etc., and its added value is not increased.

The present inventors first investigated the reason why a high-quality inorganic foam cannot be obtained when particles of amorphous by-product slag with a particle size of 0.3 s or less are used as a raw material in an inorganic foam manufacturing technology.

As a result, for amorphous by-product slag raw materials with a particle size of 0.3 to 5#, even if the temperature increase rate is 150℃/llin or less, there is almost no effect due to the particle size, and high-quality inorganic foam can be produced. Obtained. However, when the raw material of the amorphous by-product slag particles with a particle size of 0.3M or less was heated at a heating rate of 150°C,'m
If the heat treatment is carried out at a temperature of less than 800°C, the particles tend to fuse together, so the heat treatment temperature is limited to less than 800°C, and the unit volume weight o:
It was difficult to obtain an inorganic foam with o1 to 0.80 ffg/l.

Therefore, we investigated the physical properties of particles of amorphous by-product slag with a particle size of 0.3 seconds or less, and investigated a firing method suitable for the raw material.

As a result, if heat treatment is performed at a heating rate of 500 to 800°C and a heating temperature of 800 to 1000°C, high-quality inorganic foam can be produced using particles with a particle size of 0.3 #I or less as raw material. It turned out that it was possible to obtain

If the temperature increase rate is less than 500°C/l1lin, as described above, the heat treatment temperature is limited to less than 800°C, so the foam does not expand effectively, and unexpanded particles are mixed into the inorganic foam. On the other hand, if the heating rate exceeds 1000°C/min, the firing will occur at a rapid high temperature, and the inorganic foams separated by 1q will collide with each other! ! ! The particles may turn into large lumps or may fuse to the heat treatment equipment, interfering with the smooth operation of the equipment.

Further, the heat treatment temperature is preferably in the range of 800 to 1000°C. If it is below 800℃, the particle size of amorphous by-product slag is 0.
．． Particles of 3 # or less do not expand effectively, resulting in unexpanded particles being mixed into the inorganic foam, and when the temperature exceeds 1000°C, the resulting inorganic foam may fuse together and form large lumps, or heat treatment may occur. This may interfere with the smooth operation of the device.

Next, the particles of the crushed amorphous by-product slag with a particle size of 0.3 s or less and the particles of the unpulverized amorphous by-product slag with a particle size of 0.3 #l
As a result of comparing particles of f or less, it was found that the physical properties were different as follows. In other words, the pulverized products had almost no difference in chemical composition, but the unfired carbon content had almost disappeared. ■The particle shape becomes distorted and the actual volume ratio increases, resulting in a higher unit volume weight. and ■ The amount of pores inside the particles is reduced. Taking this into consideration, we further investigated the heat treatment method.

Particles of the crushed amorphous by-product slag with a particle size of 0.3171#1 or less have a low unfired carbon content, so they are fired in an oxidizing atmosphere, resulting in poor foaming properties, and they are fired at a high temperature, resulting in inorganic foaming. It was found that it was necessary to fire in a reducing atmosphere because the bodies tend to fuse together and the quality tends to vary.

Inorganic materials such as fly ash, pulverized coal, and iron oxide and C are used as reducing substances for firing in a reducing atmosphere.
Examples include gaseous substances such as O and H2, and liquid substances such as heavy oil, but from the viewpoint of economy, workability, and product quality, it is preferable to use inorganic fly ash and/or pulverized coal. suitable.

Further, fly ash and pulverized coal combustion ash have almost no harmful effects even if mixed into the inorganic foam, and on the contrary, they act effectively as a fine powder filler.

The amount of fly ash added is preferably 20% by weight or less, judging from the particle size structure of the inorganic foam, and the unburned carbon content of the fly ash is preferably 4 to 10% by weight. Additionally, if the amount of pulverized coal added exceeds 10%, self-combustion will occur at low temperatures, causing a rapid temperature rise in the furnace, making it difficult to control the heat treatment temperature, and resulting in inconsistent quality.
It is preferably 10% by weight or less. The particle size of the fly ash is 2500 to 2,500 b based on the Blaine specific surface area.The particle size of the pulverized coal is 88 μm, with a residual content of 5 to 12% by weight.

Add 20% by weight or less of fly ash and/or 10% of pulverized coal to amorphous by-product slag particles with a particle size of 0.3# or less
% or less to increase the temperature increase rate from 5QO to 1000℃/
min(7) range: heating 9n temperature to 800~
By performing heat treatment at 1000°C, it became possible to obtain an even better quality inorganic foam.

That is, particles of amorphous by-product slag obtained by partial oxidation of coal with a particle size of 0.381 or less are heat-treated at a temperature of 80
0~1ooo℃, heating rate 500~1000℃/min
By adding a reducing substance and heat-treating in a reducing atmosphere, it is possible to foam and expand more effectively.
The operation of the heat treatment equipment is much easier, and at the same time, the product yield during manufacturing is also increased.

Conventional methods for producing inorganic foams gradually foam and expand, whereas the method for producing inorganic foams of the present invention rapidly foams and expands, which shortens the holding time at the heat treatment temperature, making production easier. It's easy.

In addition, in the manufacturing method of the present invention, even if particles larger than 0.3 # are mixed within a range of 10ffii% or less, there is no effect, and a high-quality inorganic foam can be manufactured.

By the production method of the present invention, particles with a particle diameter of 0.3s or less
Inorganic foam obtained when using non-quality by-product slag with a content of 5% or more as a raw material generally has a particle size of 600% or more.
μm or less, the average particle size is 250 μm or less, and when fly ash and/or pulverized coal is used as an additive, the average particle size is 200 μm or less, and usually the average particle size is in the range of 150 μTrL to 200 μm. It is an inorganic foam.

In addition, this fine inorganic foam is light in weight and usually has a unit volume weight of 0.4 to 0.8 Kg/, i! within the range of Note that when expressed in terms of apparent specific gravity, it is in the range of 0.8 to 1.6.

Roughly speaking, the inorganic foam of the present invention has a compressive load of 250 mm when the compressive displacement is 10 m. ! RYF, it was 50 Kyf, which is about 5 times stronger than that of conventional inorganic foam.

Therefore, the inorganic foam produced by the production method of the present invention is
Since it is lightweight and has high strength, it can be used, for example, as lightweight structural and non-structural members.

The inorganic foam produced by the production method of the present invention has air bubbles in its particles. Since air bubbles are made up of closed cells, the 24-hour water absorption rate is extremely low at less than 5%, making it possible to reduce the amount of mixed water used when mixing with cement as a light aggregate. The hardened cement mixture exhibits high strength and excellent durability against freezing and thawing. In addition, since it contains many air bubbles, its thermal conductivity is low, usually 0.05 Kcal/m・
It has a good heat insulating property and can be used as a heat insulating material.

The production method of the present invention is very inexpensive because it can use amorphous by-product slag particles with a particle size of 0.3 m or less, which are produced during partial oxidation of coal, for which no effective use has been developed in the past. high quality inorganic foam can be produced.

In addition, the inorganic foam obtained by the production method of the present invention is
Other uses that take advantage of the foam, such as insulation,
Of course, it can also be used as a lightweight aggregate, fertilizer, filler for detergents or paints, soil improvement material, etc.

Next, examples of the present invention will be shown.

[Example 1] As the raw material, amorphous by-product slag discharged from a coal gasification furnace using the Texaco method was sieved to contain 95% by weight or more of particles with a particle size of 0.3 an or less. . The chemical composition of the by-product slag used is shown in Table 1, and the particle size distribution is shown in Table 2.

Incidentally, as a result of X-ray diffraction, this by-product slag was confirmed to be amorphous.

The resulting by-product slag, in which 95% by weight or more of particles with a particle size of 0.3 s or less, is heated in a small external heating rotary electric furnace (φ60
An inorganic foam was produced by raising the maximum temperature of the heat treatment by 950°C at a heating rate of 900'C/min.

The unit volume weight of the obtained inorganic foam is 0.63 kg/
The 24-hour water absorption rate of L was 3.8% by weight. The chemical composition of the obtained inorganic foam is shown in Table 1, and the particle size distribution is shown in Table 2.

Note that the above measurements were performed using the method and apparatus described below.

[Measurement method] Unit volume weight ■ Prepare a 100 d graduated cylinder or 2 g mass, take the particles to be measured into this graduated cylinder or mass,
The mold opening of this particle was measured.

Specific gravity and water absorption Measured according to JIS A 1134.

First blood at school Measured according to JIS A 1102.

The plate is destroyed It was analyzed according to JIS M 8852.

The load at which 5% by weight of particles broke was measured by a simple method according to Koukibokan B, 5812.

[Example 2.3 and Comparative Example 1.2] Heat treatment temperatures were set at 500"C (Comparative Example 1), 875"C (Example 2>), 1000"C (Example 3) and 1200"C (
A heat treatment experiment was conducted in the same manner as in Example 1, except that Comparative Example 2) was used.

Table 3 shows the physical properties of the obtained inorganic foam.

[Example 4 and Comparative Example 3] Temperature increase rate 20°C/min (Comparative Example 3) and 500”
C/min (Example 4), except that the heat treatment experiment was conducted at the highest heat-treatable temperature.

Table 3 shows the physical properties of the obtained inorganic foam.

[Example 5] As a raw material, by-product slag discharged from a coal gasifier using the Texaco method had a particle size of 0.37111I! The above particles were pulverized with a ball mill and the particles having a particle diameter of 0.3M or less accounted for 95% by weight or more were used. The chemical composition of the by-product slag used is shown in Table 1, and the particle size distribution is shown in Table 2.

Particles with a particle size of 0.3 mm or less obtained by pulverization are 95
A heat treatment experiment was conducted in the same manner as in Example 1, except that by-product slag having a weight of 5% or more was used.

The chemical composition and particle size distribution of the obtained inorganic foam are shown in Tables 1 and 2, and the physical properties are shown in Table 3.

[Examples 6 to 8] 15% by weight of fly ash (Example 6) and 5% by weight of pulverized coal (Example 7) were added to the raw materials used in Example 5 as additives.
) added. Zara, 10% fly ash by weight
A heat treatment experiment was conducted in the same manner as in Example 1, except that 5% by weight of pulverized coal (Example 8) was added.

Table 3 shows the physical properties of the obtained inorganic foam.

[Comparative Example 4] 15% by weight of pulverized coal was added as an additive to the raw material used in Example 5.
A heat treatment experiment was carried out in the same manner as in Example 1, except that the addition of C.

Table 3 shows the physical properties of the obtained inorganic foam.

[Examples 9 and 10] A heat treatment experiment was conducted using the raw materials and combustion conditions of Examples 1 and 6 using a rotary kiln with an effective inner diameter of 1.3 m and a length of 3.5 m.

Table 4 shows the physical properties of the obtained inorganic foam.

Claims (2)

[Claims] (1) Particle size 0.3 mm obtained by partial oxidation of coal
Amorphous by-product slag containing 90% by weight or more of the following particles was heated to 800°C at a heating rate of 500 to 1000°C/min.
A method for producing an inorganic foam, the method comprising expanding the inorganic foam by heat treatment in a temperature range of ~1000°C. (2) Fly ash is 20% by weight based on the above slag.
The method for producing an inorganic foam according to claim 1, characterized in that fly ash or pulverized coal is added so that the amount of pulverized coal is 10% by weight or less, and the pulverized coal is fired in a reducing atmosphere.