JPH0624813A - Heavy concrete - Google Patents

Abstract

(57) [Summary] [Object] The present invention provides an inexpensive and functional heavy-weight concrete using fine iron-based dust. [Structure] Pellets having a spherical equivalent diameter of 200 μm obtained by mixing 3 to 12% by weight of cement with iron-based dust having a spherical equivalent diameter of less than 50 μm and granulating the particles have a diameter of 20 μm or more. Heavy concrete made by mixing cement with a mixture of 70% or more of iron-based dust out of the total number of particles, and molding it into a structure. [Effects] According to the present invention, it becomes possible to inexpensively supply heavy concrete for wave-dissipating blocks, which uses a fine-grained dust that has not been conventionally used as a raw material and has little movement due to the impact of waves.
In addition, a large-scale effective utilization method of iron-based dust, which is a by-product from an iron manufacturing plant, has been established.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heavy concrete used for a wave-dissipating block, a radiation protection wall, etc., and provides an inexpensive and functional heavy concrete.

[0002]

2. Description of the Related Art Conventionally, as a wave-dissipating block known as Tetrapod (registered trademark) for preventing coastal disasters, generally, a structure formed by mixing sand, debris and cement has been used. This is because the raw materials such as sand, debris, and cement were inexpensive, easily available, mass-produced, and advantageous in manufacturing cost. On the other hand, in order to prevent the movement of the wave-dissipating block due to the impact of waves, the wave-dissipating block 1 has a size or volume larger than a certain size.
The weight per piece was set to a certain weight or more. Furthermore, as a measure to prevent movement of the wave-dissipating blocks, a method of installing the wave-dissipating blocks while stacking them has been adopted.

On the other hand, these measures for preventing movement of the wave-dissipating block have caused a great increase in cost. That is, it is necessary to increase the size of the wave-dissipating block, and it is necessary to manufacture a large number of the wave-dissipating blocks.
As a solution to this problem, a method of using iron ore having a high density as an alternative to sand and debris was devised (“Concrete and reinforced concrete construction method” Maruzen, 1st printing of 1966, 1st edition).
Page 10), manufactured experimentally. However, due to the high price of iron ore and the difficulty in converting it into concrete, it was not put into practical use.

In view of the above points, the present inventors have proposed an advantageous heavy-weight concrete using iron-based dust, which is a mixture of inexpensive metallic iron and iron oxide, in Japanese Patent Application No. 4-151173.
This is referred to as the previous invention). This is a heavy concrete that is shaped and structured by mixing cement with iron-based dust that is spherical and has a diameter of 20 μm or more in the iron-based dust of 70% or more of the total number of particles. .

[0005]

However, the heavy concrete proposed in the previous invention has a restriction condition in using raw materials, that is, it has a drawback that only specific iron-based dust can be used. Iron-based dust generated in the steelmaking process of an ironmaking plant is coarse-grained dust with a single particle size of 50 μm or more,
It is separated into fine particle dust of less than 50 μm, and the amount of these is 3 to 7 kg of coarse particle dust when producing 1 ton of iron.
(Average 5 kg), fine particle dust 12-30 kg (average 20 kg)
kg), and fine particles occupy about 80%. However, in the previous invention, since only 70% or more of iron-based dust having a spherical shape and a diameter of 20 μm or more out of the total number of particles can be used, most of fine-grain dust is not used as a raw material. . The present invention advantageously seeks to overcome this drawback.

[0006]

Means for Solving the Problems The present invention is to solve the above problems, and one of the inventions relates to a pellet which is an intermediate composition for producing heavy concrete and has a sphere-converted diameter of less than 50 μm. And its main constituent is FeO, Fe ₂ O ₃ , and metallic Fe 8
8 to 97% by weight and 3 to 12% by weight of cement are mixed,
It is a pellet characterized by being molded into a sphere-converted diameter of 200 μm or more. In addition, the main constituent here is Fe
It is also characterized in that a mixture of O, Fe ₂ O ₃ and metallic Fe is converter dust for steelmaking.

Another aspect of the present invention relates to heavy-weight concrete, in which cement is mixed with the above pellets, molding,
It is heavy concrete characterized by being made into a structure. In addition, the above pellet is more spherical and has a diameter of 2
The number of particles of 0 μm or more is 70% or more of the total number of particles, and the main constituents are FeO, Fe ₂ O ₃ , and metallic Fe.
It is a heavy-weight concrete characterized by being made into a structure by mixing a mixture consisting of and cement. In addition, the number of particles having a spherical shape and a diameter of 20 μm or more is 70% or more of the total number of particles, and a mixture of FeO, Fe ₂ O ₃ , and metallic Fe as the main constituents is a converter dust for steelmaking. It is also characterized by

[0008]

The present inventors, based on the idea that a dense and inexpensive substance should be used in place of sand and earth and stone in order to obtain a heavy concrete with low mobility, the steelmaking process of the steelmaking plant is changed. FeO and Fe ₂ O generated in the furnace
_3. I came up with the idea of utilizing iron-based dust, which is mainly composed of metallic Fe. Of these, the size of a single particle is 50
Coarse-grained dust of μm or more has a density of 5.9 to 6.2 g / cm ^3.
The particle shape is approximately 90% spherical. On the other hand, the fine particle dust with a single particle size of less than 50 μm has a density of 5.7.
It is about 6.1 g / cm ³ , and about 50% of the particle shape is spherical, and the rest is non-spherical.

The amount of generation of these is approximately 3 to 7 kg of coarse dust (average 5 kg) and 12 to 30 kg of fine dust (average 20 kg) in the production of 1 ton of iron, and the ratio thereof is coarse dust 1: fine grain. It is dust 4. Assuming that iron production in Japan is 100 million tons / year, 50 (3
0-70) 10,000 tons / year, fine-grained dust 200 (120-
It is a large amount of 300) million tons / year. Moreover, since all the dusts have a high density and are by-products, they are inexpensive and are most suitable as a heavy concrete raw material.

The present inventors have examined the conditions for concrete conversion of these dusts in detail and have proposed them in the previous invention. The point is that in iron-based dust, cement is mixed with 70% or more of iron-based dust, which is spherical and has a diameter of 20 μm or more, out of the total number of particles, and is molded into a structure, The concrete strength and ease of manufacture were secured.

However, as described above, the amount of fine-grained dust, which accounts for about 80% of iron-based dust (coarse-grained dust + fine-grained dust), is limited due to its size and shape restrictions. That is, the fine dust cannot be used alone, and must be combined with the coarse dust. Moreover, the combined amount is up to 50% with respect to the coarse-grained dust. Therefore, about 75% of the total fine grain dust cannot be used.

As a means for solving this problem, a method of granulating fine-grain dust to make the shape spherical and a certain size or more was conceived. First, granulate and convert to a spherical diameter of 200 μm
The reason for making the above pellets will be described.

Fine-grained dust is as fine as less than 50 μm,
Since the particle shape is mixed spherical and non-spherical (amorphous), the strength of the molded product is as low as 20 kg / cm ² or less in the compressive strength even if the fine dust is molded by the normal compression molding method. The strength required for concrete cannot be obtained because the material is crushed during conversion. On the other hand, according to the method of the present invention, the sphere-forming material is coarsened while rolling by granulation, and the strength of the sphere-forming material (pellets) is increased by rolling, and the compression strength of the pellet is 50 kg / cm ² or more. In this case, a pellet having a sphere-converted diameter of 200 μm or more can stably secure a compressive strength of 50 kg / cm ² or more. Although the upper limit of the pellet diameter is not limited,
Generally, if it exceeds 5 cm, the compressive strength decreases, which is not preferable.

Next, the amount of cement mixed when granulating fine-grained dust will be described. The cement mixing amount is mixed to improve the strength of pellets obtained by granulation and improve the yield of pelletization. If the amount of cement mixed is less than 3% by weight based on the weight of fine dust + cement, the strength of the obtained pellets will be less than 50 kg / cm ^2, and many fine pellets less than 200 μm will be produced, which is not preferable. Even if the amount of cement mixed exceeds 12% by weight, further improvement in strength and yield cannot be expected. Therefore, the appropriate amount of cement mixed is 3 to 12% by weight of the weight of fine particles + cement. Therefore, the diameter in the pellet is 50
Fine iron-based dust of less than μm is 88 to 97% by weight.

The type of cement used for producing pellets is not particularly limited. Further, it is appropriate that the amount of water added during pellet production is 7 to 15% by weight based on the weight of dust and cement. This water content varies depending on the manufacturing method and is not particularly limited.

[0016] Heavy concrete is produced using the pellets produced as described above as a raw material, but the type of cement is not particularly limited, and the required amount for producing concrete is mixed with the pellets. Good. The proper mixing amount is 5 to 30 by weight with respect to the pellet.
% By weight. However, cement containing free lime is not preferable because it contacts with seawater and produces so-called scale.

Further, pellets and coarse iron-based dust and /
Alternatively, heavy concrete can be produced using a mixture of fine iron-based dust that is not pelletized as a raw material. In this case, the coarse iron-based dust and the fine iron-based dust that is not pelletized cannot secure the concrete strength and the ease of production unless the conditions specified in the above invention are satisfied. That is, it is spherical and its diameter is 20μ.
Iron-based dust having a particle number of m or more and 70% or more of the total number of particles must be used. So far, the compounding ratio of the fine iron-based dust that is not pelletized is not specified.

Sand and earth and stone may be mixed with the pellets to form concrete, but the amount per unit volume of the concrete is reduced, so the amount of the mixture should be kept within a small range. In addition, the amount of water added during kneading is 10 by weight based on the raw materials such as pellets and cement.
-25% is a proper range.

The use of the heavy concrete according to the present invention is not limited. That is, the present invention can be used for concrete requiring weight reduction, such as radiation shielding concrete.

[0020]

【Example】

Example (Invention) Portland cement was mixed with fine grain dust in an amount of 5 to 8% by weight based on the weight of fine grain dust and cement, and 1 was added to this mixture.
Pellets were produced with a Sara-type granulator having a diameter of 2.8 m while adding 5% by weight of water. Sphere equivalent diameter 200μ
Pellets of m or more are 9% of all the pellets produced by weight ratio.
It was 5%. Further, the compressive strength of all pellets having a spherical equivalent diameter of 200 μm or more was 50 kg / cm ² .

To the pellets, 25% by weight of Portland cement and 20% by weight of water were added and kneaded to form a slurry, and 10 × 10 × 40 cm strength measuring concrete pieces and a volume of 2 m ³ of triangular pyramidal type were erased. Wave blocks were manufactured. As a result of measuring the compressive strength of the concrete pieces for strength measurement, all the concrete pieces were 415 to 450 kg /
It was a high level of cm ² . In addition, the weight of the wave-dissipating block is 2.6 to 3.3 ton / m ^3, which is about twice as high as that of the wave-dissipating block made from ordinary sand and debris, which is effective in preventing movement of the wave-dissipating block due to wave impact. It turned out to be the target. Further, a weight concrete composed of 50% by weight of the pellets and 50% by weight of iron-based dust defined in the above invention was produced, and the same favorable results as above were obtained.

Comparative Example Portland cement was added to fine-grained dust as fine-grained dust +
Pellets were produced by a Sara-type granulator having a diameter of 2.8 m while mixing 2% by weight of the cement weight and adding 15% by weight of water to the mixture. The pellets having a sphere-converted diameter of 200 μm or more were 70% of all the pellets produced in a weight ratio, which was lower than that in the previous example. In addition, 200μ equivalent diameter
The compression strength of pellets of m or more is 15 to 25 kg / cm ²
And less than 1/2 of the example.

To the pellets, 25% by weight of Portland cement and 20% by weight of water were added and kneaded to form a slurry, and 10 × 10 × 40 cm strength measuring concrete pieces and a volume of 2 m ³ of triangular pyramidal type. Wave blocks were manufactured. As a result, the weight of the wave breaking block is 2.6 to 3.2.
It was a satisfactory value of ton / m ³ , but the compressive strength of the concrete pieces for strength measurement was 2 for all concrete pieces.
It remained at an extremely low level of 15 to 265 kg / cm ² .

Further, Portland cement is mixed with fine grain dust by 15% by weight of fine grain dust + cement weight,
After that, the same operation as that of the example was performed, but the obtained result was at the same level as that of the example.

Further, without pelletizing the fine-grain dust, 25% by weight of Portland cement and 2 parts of water were added to the fine-grain dust.
After adding 0% by weight and kneading to form a slurry, 10 × 10 ×
Concrete piece for strength measurement of 40 cm, and volume of 2 m
³ of triangular pyramid type wave dissipating block was produced. As a result, the weight of the wave breaking block was 2.5 to 3.2 ton / m ³ , which was a satisfactory value, but the compressive strength of the concrete pieces for strength measurement was 105 to 160 kg / c for all concrete pieces.
It remained at a very low level of m ² . In addition, the surface of the wave-dissipating block was cracked, which was not desirable.

[0026]

INDUSTRIAL APPLICABILITY As described above in detail, according to the present invention, a functional and inexpensive heavy-weight concrete made of fine-grained dust, which cannot be used conventionally, among the iron-based dust generated in the steelmaking process of the ironmaking plant. It has become possible to provide. According to the method of the present invention, it is possible to reduce the movement of the concrete due to the impact of the wave of the heavy concrete used for the disaster prevention wave-dissipating block on the coast, and to significantly reduce the manufacturing cost thereof. Furthermore, a method for effectively utilizing a large amount of iron-based dust, which is a by-product from an iron manufacturing plant, has been established, which is extremely beneficial to Japanese industry.

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Claims (5)

[Claims] 1. A sphere-converted diameter having a sphere-converted diameter of less than 50 μm, and a mixture of 88 to 97% by weight of a mixture whose main constituents are FeO, Fe ₂ O ₃ and metallic Fe, and 3 to 12% by weight of cement. A pellet characterized by being molded to 200 μm or more. 2. The pellet according to claim 1, wherein a mixture of FeO, Fe ₂ O ₃ and metallic Fe as main constituents is steelmaking converter dust. 3. Heavy concrete, characterized in that the pellet according to claim 1 or 2 is mixed with cement, molded and structured. 4. A mixture having a spherical shape and a number of particles having a diameter of 20 μm or more is 70% or more of the total number of particles, the main constituent of which is FeO, Fe ₂ O ₃ and metallic Fe, and cement. 3. A heavy concrete obtained by mixing the pellets according to claim 1 or 2 and molding and forming the pellets. 5. A steel-made rolling mixture containing spherical particles having a diameter of 20 μm or more and 70% or more of the total number of particles and having FeO, Fe ₂ O ₃ and metallic Fe as main constituents. The heavy concrete according to claim 4, which is furnace dust.