JPS60155556A - Manufacture of lightweight aggregate - Google Patents

Abstract

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

Description

DETAILED DESCRIPTION OF THE INVENTION More particularly, the present invention relates to a method of producing ultra-lightweight aggregates.

Conventionally, the manufacturing method of lightweight aggregate using shale as raw material is as follows:
A method in practical use is to crush a shale block to a density of 100 mesh, add water to it, adjust the humidity, and then granulate it, dry it, and fire it.

However, the fired pellets obtained by this method have sufficient crushing strength (50 or more for a diameter of 7 mm) and water absorption resistance (water absorption rate of 5 to 7 weight N%) as aggregates, but their apparent specific gravity There was a problem that the weight was relatively heavy at about 1.25.

In recent years, there has been a demand for lighter weight construction materials and stronger thermal insulation performance, and there is also a need for fire-resistant, strong, and low-density aggregates.

Therefore, a novel method for producing lightweight aggregate has been proposed (Japanese Unexamined Patent Application Publication No. 1989-98923) which efficiently and significantly reduces the above-mentioned apparent specific gravity (hereinafter simply referred to as specific gravity).

This method involves adding and mixing 10 to 30 parts of valve sludge to 100 parts of shale or right-wing rock, granulating it, and pulverizing it into 800 parts.
By firing at ~1150 C, the specific gravity is 0.7
It is assumed that the aggregate of

However, the additives used in the above method are made by evaporating a huge amount of water from pulp sludge (see Example 1 of JP-A-50-105718) generated in paper mills with a water content of about 85% by weight using a large dryer. and moisture content 10
It has to be used after drying to about % by weight, which not only results in impractically high costs, but also has drawbacks such as not contributing at all as a filler.

An object of the present invention is to provide a method for producing aggregate that can eliminate the above-mentioned drawbacks and further reduce the specific gravity of the resulting fired product.

In order to achieve this objective, the inventors of the present application have conducted various studies and found that fine powdered shale is mixed with an appropriate amount of ferric oxide and silicon carbide or polyvinyl alcohol (hereinafter referred to as P, 'V, A).
), carboxymethylcellulose (hereinafter referred to as 0.
(abbreviated as M, O), styrene-butadiene latex (
We found that the specific gravity of the fired product can be significantly reduced by adding, mixing, and granulating one or more of the following (hereinafter abbreviated as S, B, and 'R latex) as fine particles or liquid, and firing at an appropriate temperature and atmosphere. They each applied.

In the above method, the grain size of the raw material shale is 15 μm on average.
Add an inorganic blowing agent or an organic blowing agent with an average particle size of 10 μm or less to the shale by 0.1 to 2.
．． 5% by weight, 2% by weight or less and 1, same internal division as 2 to 10
Ferric oxide having a weight percentage of 10 μm or less is added, mixed according to a known method, and after humidity conditioning, granulated with a pelletizer or the like and fired at 1050 to 1120 C.

According to this method, it is possible to produce lightweight aggregate with a specific gravity that is about half that of conventional methods.

An object of the present invention is to provide a method for producing ultra-lightweight aggregates that can further reduce the specific gravity of the above-mentioned lightweight aggregates.

In order to achieve this objective, the inventors of the present application have conducted extensive research to further improve the above method, and have found that, instead of the conventional method of blending raw materials and additives, they are prepared by separately pre-pulverizing the raw materials and additives. , the powder obtained by pulverizing shale to a certain extent and each additive are simultaneously pulverized, and the resulting fine powder is subjected to humidity conditioning, granulation,
We have achieved a method of obtaining aggregate that is significantly lighter in weight by firing it.

That is, in the method of the present invention, shale is first crushed to a size of 60 mesh or less, and then 2 to 10% by weight of iron oxide, preferably oxidized Second iron and internal division 0.1 to 2.5
% by weight of silicon carbide of the same particle size, or 2% by weight or less, preferably 0.1 to 1.0% by weight of lignin, P, V,
After adding one or more of A, O, M, O, S, B, and R latexes, they are pulverized to 15 μm or less, preferably 10 μm or less using a tube mill, and mixed together.

Next, this mixture is mixed with water to adjust its humidity by a known method, and then granulated using a pan-type pelletizer to obtain the desired particle size. After sufficient drying, the mixture is ready for baking. The temperature is preferably 1050 to 1120C, more preferably 1100 to 1115tll's, and the oxygen concentration is 8
~10% by volume, temperature of raw material green pellet charging port 6
300%, and the residence time in the firing zone is about 20 to 30 minutes at the same oxygen concentration of 12 to 13% by volume.

In the method of the present invention, the styrene-butadiene latex (S, B, R latex) used as an additive is not specified, but the product name is LX531B (
(manufactured by Nippon Zeon), Crossren (manufactured by Shikinichi Pharmaceutical Co., Ltd.), Onoda SXB (manufactured by Nippon Unilon), J, S, R06
7,0 (manufactured by Japan Synthetic Rubber) etc. are preferable.

In the method of the present invention, the shale is first coarsely pulverized, then additives are added, and then finely pulverized. Although it depends on the pulverizing equipment, it is not efficient even if the shale is charged into a tube mill in a very coarse state. This is because pulverization is not good and requires a long time for pulverization.

After reducing the shale to 60 meshes or less, the average grain size is 20 μm.
Iron oxide preferably has a diameter of 10 μm or less and an average particle size of 2
2 to 10% by weight of silicon carbide with a diameter of 0 μm or less,
0.1 to 2.5% by weight, or the same amount of iron oxide as above, and at least 2% by weight of one or more of lignin, P, V, A, O, M, OXS, E, R5 Tenx, preferably 0 .1~1
The reason for adding each weight percent is that if the amount added is less than this amount, the effect of reducing the specific gravity of the firing zone will not be significant, and if the amount added is more than this amount, the above-mentioned effect will not be particularly improved.

The reason why an appropriate amount of additive is added to shale and then pulverized to an average particle size of 15 μm or less, preferably 10 μm or less is to improve the reactivity when firing the pellets.

Mixing and pulverization of shale and additives according to the method of the present invention is not necessarily constant depending on the pulverizing equipment, but in the case of a normal mill, 30 minutes to 1 hour is sufficient.

However, the degree of pulverization is important in order to obtain a sintered body with a light specific gravity.The finer the particles, the more stable a sintered body with a low specific gravity can be obtained, so it is necessary to measure the particle size of the fine powder and set the pulverization conditions. There is a need to. If a particle size coarser than the above-mentioned particle size is used, the object of the present invention cannot be achieved no matter how other conditions are modified.

The fired body obtained by the method of the present invention has a specific gravity of 0.4 without adversely affecting the crushing strength as an aggregate, water absorption resistance, etc.
Since it is possible to reliably obtain a high-grade material, it can be said to be suitable as a heat insulating material, a refractory material, or an extender thereof.

As a means of reducing the specific gravity of the fired product, it may be possible to raise the temperature of the pellet firing zone, but if it exceeds 1120 C, which is the preferred range in the method of the present invention (this temperature will fluctuate due to the oxygen W surrounding atmosphere). This is undesirable because it causes the pellet surface to melt and the pellets fuse together during firing in the rotary giln.Therefore, the residence time in the high temperature zone should be about 20 to 30 minutes, or less. It is preferable to do so.

The size of the fired pellets obtained by the method of the present invention is not particularly limited, but usually has a diameter of 5 to 2 Qmm.If the specific gravity is the same, the larger the diameter, the higher the crushing strength, and conversely, the water absorption rate decreases, but the average particle size It has a roughly spherical shape of about 7 mm, has a crushing strength of about 9 in 20, and a water absorption rate of 2 to 5% by weight.

Examples will be described below.

Example 1 Massive shale was crushed using a single toggle crusher, and then dried using a rotary kiln type dryer.
Next, it is subjected to secondary M crushing by applying an impeller breaker. The particle size was set to be less than eo mesh.

Next, to the shale powder was added 3% by weight of ferric oxide with a particle size of 15 μm or less and a grade 1 reagent, and a predetermined amount of silicon carbide with a particle size of 15 μm or less. Made of plate ironwork, diameter 2.5 nn% length 5.6 m1 ball size 50-75 mm % rotation speed 20 rpm Nine fine powder samples were taken.

The average particle size of the obtained V& powder sample was 8.5 μm (light transmission type granulometer).

The fine powder was then subjected to humidity control according to the usual procedure and granulated using a pan-type pelletizer to give an average particle size of about 5 mtn. After sufficiently drying the green pellets in a dryer, the green pellets were heated in a test kiln with an inner diameter of 50 (111%, length 4000 mm, slope 4.5%, rotation speed 3 rpm, and a propane burner as the heat source) at a temperature of 1050 to 1050. 1115C
, the same oxygen concentration is 8 to 9% by volume, the green pellet charging port temperature is 6357:, the same oxygen concentration is maintained at 12 to 13% by volume,
The residence time of the pellets in the firing zone is set to 15 minutes,
The pellets were fired for 30 minutes each with soog feed per minute. The average particle size of the fired pellets was measured after cooling, and other physical properties were determined using T-K5A1135.
Measured according to

- The crushing strength was determined by measuring the load value of 100 samples when they were crushed using a compression testing machine, and was expressed as the average value. The raw material shale composition shown in Table 1 was used. The results are shown in Table 2.

Table 1 (% by weight) Sin2A1203Fe203C! aOMgONa2O
+20 Tio269.78. 1,3JO4,94
1,501,394,370,50Mn0 BaO ignition loss Crystal water sao, 14 0.04 3. ]J 1
．． 75 0.37 0.52 Table 2 1 1115 0.1 0.73 24.8 1.57
．． 22 1/ 0.3 0.5524. ．． 0 2.8
7.23*10300.5 1.03 29.0 0.
8 7.04 1100 〃0.60 23.2 2.
5 7゜15 1115 1.0 0.4,5 22.
0 3.0 7.26 tt 2.0 0.41 21
．． 5 a, 8 7.1'I IIH) 2. ．． 5 0.
+8 22.5 8.6 7.0 Table Note: × is a reference value when the firing temperature is low.

As is clear from Table 2, all of the results are about 0, except for experimental sheet 3, which has a relatively low firing temperature, and experimental sheet 1, which has a small amount of silicon carbide added.
．． 6 or less 0. The specific gravity was on the + level and the physical properties were also satisfactory.

Example 2 A predetermined amount of an organic blowing agent as an additive and hematite (Fed
A predetermined amount (3% by weight) of 110 μm or less) was added thereto, and mixing, pulverization, granulation, and firing were carried out in the same manner as in Example 1 of Example 1.

The results are shown in Table 3.

Table 3 8 1110 1.0 Riku'n 0.1 0.68
25 1.3 7.29.1050 3.0 GM, O
O,50,65231,57,1101080L/1
．． 0 0.50 21 2.5 7.111 11.1
0 rr riff and n 1. Oo, 4・3 21
3.2 7.2 As can be seen from Table 3, Experiment No. 8 with a small amount of ferric oxide added and Experiment S9 with a low firing temperature have relatively high specific gravity, but the others have a specific gravity of more than 0.4. A product with low specific gravity and sufficient physical properties was obtained.

Example 3 The particle size of green pellets was about 7 mm, and the fired pellets were slowly cooled in a rotary gill to 1100 (A) and 200 c (B), then taken out indoors and rapidly cooled with water spray. A fired pellet was obtained in the same manner as in Example 1.

The results are shown in Table 4.

Table 4 A181115 0.5 0.4+155.09.1
10.2tt 19 tt 1.0 0.4552.1
9.810.8B 201120 1.2 0.4=2
33.220.510.1// 21 tt '1.5
0.4+ 35.019.110.4 The results in Table 4 showed that the water absorption was higher than in Table 2, but the crushing strength was sufficiently large and satisfactory.

Although the method of the present invention has been explained using only shale as the raw material, other similar materials such as perlite, right wing, whitebait, etc. can also be used as is.
It is possible to apply it.

1"11;j!l!person Patent Attorney Katsunari Donakamura 7.':)
! 1 proboscis 1. -v

Claims (1)

[Claims] (1) Average particle size of 20 μm in shale of 60 mesh or less
The following iron oxides and silicon carbide are divided into 2 to 10% by weight, 0.1 to 2.5% by weight, respectively, or iron oxides and lignin with an average particle size of 20 μm or less, polyvinyl alcohol, carboxymethyl cellulose, styrene butadiene type 2 to 10% by weight of one or more latexes
, 2% by weight or less, and then finely pulverized to an average particle size of 15 μm or less, humidity controlled, granulated, and fired. A method for producing lightweight aggregate, characterized by: