JP3217864B2 - Graphite-containing composition for amorphous refractories and preparation method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composition for a carbon-containing amorphous refractory used for lining and repairing a vessel used in a process of iron making or steel making and a method for preparing the same.

[0002]

2. Description of the Related Art Graphite-containing refractories including graphite powder have favorable properties such as heat resistance and thermal shock resistance.
It is widely used in the fields of iron making and steel making because it is hardly wet by hot metal, molten steel, molten slag, etc., and has excellent corrosion resistance. And only, the preformed conventional graphite-containing monolithic refractory of baking or was fired, because it requires a lot of work and energy during the construction and manufacturing, even Tei excellent in performance, overall As you need a lot of cost and working time. On the other hand, as a general trend in refractories field, sometimes labor saving is a necessary condition for the business activities survival, Ru Tsutsua proportion increases of monolithic refractories.

Amorphous refractories are constructed by adding a dispersing medium such as water to a pre-mixed powder composition at the site, and are sprayed, vibrated, poured, and compacted. Will be constructed by. As the dispersion medium Ru can also use a good organic solvent wettability against the graphite particles, but the water in terms of working environment and cost have most preferred to use as a dispersing medium.

[0004] In the case of graphite-containing amorphous refractories, the graphite powder lacks hydrophilicity (similar to water dispersibility), so that water is used as a dispersion medium like many other amorphous refractories. Even if used, a molded article having a large bulk specific gravity cannot be obtained. Therefore, the obtained graphite-containing irregular shaped refractory is remarkably inferior in oxidation resistance, corrosion resistance, strength, etc. as compared with the regular refractory, and it is an obstacle to its practical use that a refractory having good durability cannot be obtained. I have.

The surface of graphite particles has only a small number of hydrophilic functional groups such as -OH and -COOH, and the surface has a hexagonal network structure of non-hydrophilic carbon atoms. And the small absolute value of the zeta (ζ) potential at the interface when water was used as the dispersion medium, which explains that the hydrophilicity of the graphite particles is small. As a means for avoiding the problem that the graphite particles have low hydrophilicity, that is, low dispersibility in water, a strong acid treatment method, a CVD method, a sol-gel method, a polymer coating method, etc. are being studied. However, satisfactory results have not been obtained by any of the methods.

[0006] In the strong acid treatment method, it concentrated sulfuric acid graphite powder, concentrated nitric acid, immersed in hydrofluoric acid, as possible out at room temperature to 100 ° C. is reacted with these acids the surfaces of the graphite particles hydrophilic. But,
In this method, the graphite particles expand due to the acid component penetrating into the graphite crystal layer to form an intercalation compound .
That the acid components remaining in the interior of the graphite particles after treatment,
And melts into water to be added as a dispersion medium by changing the pH value, problems such as also inhibits dispersion state is unstable
However, even when used as a raw material powder for an amorphous refractory, a molded product having a large bulk specific gravity cannot be obtained.

[0007] In the CVD method, the gas components such as SiO and B ₂ O ₃ is contacted with the surface of the graphite particle, for example, in 1000 ° C. Although Ru to produce a thin film such as SiC or B ₄ C on the surface, this time the surfaces of the graphite particles by the reaction because the <br/> oxidized, becomes more rough state of porosity, oxidation resistance of graphite particles have problems such as decreases. Another known method is a halide CVD method. However, as a method of treating a raw material powder of a refractory which is not considered to have a large added value because a raw material gas is expensive or an exhaust gas treatment is required. Not suitable.

[0008] In the sol-gel method, for example silicon alkoxides, hydrolyzed in aqueous alcohol such as aluminum alkoxide in the presence of an acid catalyst, the resulting sol solution was impregnated graphite powder, gelled dry, the graphite particles while depositing the SiO _2, Al ₂ O ₃ on the surface, poor wettability between the graphite particles and the sol solution, pores between the graphite particles and the coating layer is Ru is formed, a number part which is not covered with a covering layer due mainly lightnings such sufficient dispersibility can be obtained left and to water, be used for monolithic refractories, a large molded body bulk density is not obtained.

In the polymer coating method disclosed in Japanese Patent Publication No. 2-3666, etc., a graphite powder is impregnated with a solution of a phenol resin, a furan resin, a silicone resin or the like to coat the surface of the graphite particles with an organic resin. While you formed, lacks also wettability with the sol-gel method, the resin is Ri problem there that it becomes pyrolyzed porous compact of a good graphite-containing monolithic refractory of life can not be obtained during use.

A conventional attempt to solve the problem that graphite powder lacks hydrophilicity in graphite-containing amorphous refractories is described in, for example, Japanese Patent Publication No. 1-46473.
That is, graphite powder is mixed with a thermosetting resin or a thermoplastic resin, and is compacted into a pellet or a graphite powder obtained by crushing a compacted compact (hereinafter, a modified graphite powder is referred to as a graphite powder). ) Is used to improve the dispersibility in water.

However, although any of the treatment methods can improve the hydrophilicity of the graphite particles to some extent,
Coated on the surface of the graphite particle, or an organic resin incorporated into the graphite particle, most in use is thermally decomposed,
Porosity of the refractory is increased to be released as a gas,
Ru is an important characteristic oxidation resistance and corrosion resistance is damaged cracks in the refractory of this type.

Further, the above-mentioned publication describes that aluminum or silicon particles are coated with an organic resin at the same time as graphite particles. However, the surface of aluminum or silicon is also coated with an organic resin, and thus the surface is not necessarily hydrophilic. The hydrophilicity of the organic resin, which cannot be said to be good, controls the hydrophilicity of these powders.

As a recent technique, Japanese Patent Publication No. 3-2009 proposes a method for modifying the surface of solid particles. That is,
0.01 to 100 μm of the powder surface
Is a method proposed using a mechanical impact force the powder in the range of ~10μm Preferred methods that is fixed, how the powder to impact treatment is disclosed in a high speed air stream as a specific means. However, there is no suggestion in the specification that the surface treatment of graphite particles containing a large amount of flaky particles is possible by this treatment method, showing a peculiar property of cleavage in a flaky shape.

[0014]

SUMMARY OF THE INVENTION The object of the present invention is to
No disadvantages black lead quality powder of, to achieve hydrophilicity of excellent graphite powder, using this graphite powder monolithic refractories, large bulk density when construction, corrosion resistance It is an object of the present invention to provide a graphite-containing composition for an amorphous refractory capable of obtaining a molded article having excellent oxidation resistance.

[0015]

Graphite-containing monolithic refractory composition SUMMARY OF THE INVENTION The present invention is directed to a predominantly graphitic powder and refractory compound powder or Rana Ru composition, graphite powder, the surfaces of the graphite particles, the average particle diameter is smaller than the graphite particles, metallic oxide, metal carbide, metal nitride, a hydrophilic comprising one or more selected from the group consisting of metal borides and metal <br / > The particles are fixed, and the composition is characterized in that the composition contains 2 to 40% by weight of carbon powder in terms of carbon content.

In the present invention, the average particle size of the powder is integrated volume measured by a laser diffraction particle size distribution measuring apparatus refers to the particle size of the first portion of 2 minutes. In addition, small particles adhere to graphite particles without using adhesives that mediate bonding, especially when small particles are fixed to the surface of graphite particles.
Or refers to those referred to herein is in a state of being joined, then a refractory compound powder or mixed, a state of hard small particles peeled be mixed with the dispersion medium during the construction . Further, the weight% is based on the weight of the refractory, excluding the weight of the dispersing medium and the thermally decomposable organic additives.

Carbon content in graphite-containing composition for amorphous refractories
If the content of the graphite powder in terms of is less than 2% by weight, the formed refractory molded body is less likely to wet the slag,
Preferred features of good thermal shock resistance can not be exhibited, on
Serial content increases the porosity of more than the construction has been refractory molded body 40 wt%, oxidation resistance and corrosion resistance is small <br/> ing.

The refractory compound powder used in the graphite-containing amorphous refractory composition of the present invention is selected from the group consisting of metal oxides, metal carbides, metal nitrides, and metal borides.
Those comprising more than one species are preferred . Specific examples include magnesia, chromia, dolomite, spinel, alumina, zirconia, zircon, quartzite, pyroxene, chamotte and alum shale as metal oxides, silicon carbide as metal carbide, and metal nitride as metal nitride. Is silicon nitride,
Zirconium boride as the metal boride, there is boride titanium emissions, either even with heat resistance, those having a corrosion resistance in the conditions used is selected. In addition, as the refractory compound powder, those containing coarse and dense particles ( hereinafter, referred to as aggregate) are generally used in order to increase the bulk specific gravity of the refractory molded body and secure corrosion resistance.

In a preferred embodiment of the graphite-containing amorphous refractory composition of the present invention, the composition contains 4 to 25% by weight of a graphite powder in terms of carbon content. Converted to the amount of carbon in the composition
By making the content ratio of the graphite powder 4 to 25% by weight , a more durable graphite-containing amorphous refractory having a better balance of properties such as thermal shock resistance, oxidation resistance, and corrosion resistance can be obtained. Can be

[0020] In another preferred embodiment of the graphite-containing amorphous refractory composition of the present invention, the average particle size of the hydrophilic small particles is 40% or less of the average particle size of the graphite particles. By setting the average particle size of the small particles to 40% or less, more preferably 20% or less of the average particle size of the graphite particles, the surface energy of the small particles becomes larger, and the adhesion force of the graphite particles to the surface increases, The surface of the graphite particles can be more completely covered with a relatively small amount of small particles.

Specific examples of the small particles having hydrophilicity include silica, mullite, alumina, and metal oxide as the metal oxide.
Magnesia, spinel, chromia, zirconia, titania, boron oxide, zircon, alumina cement and clay, boron carbide and silicon carbide as metal carbide, silicon nitride and boron nitride as metal nitride, and boron as metal boride zirconium boride titanium emission are as metallic aluminum, silicon, titanium down, magnesium and alloys thereof are selected according to the application of the refractory.

The reason why the particle surfaces of these compounds have a hydrophilic, even particles that are not oxides, these
The surface of the particles is oxidized and polar,
Because it is easy to get wet with water.

In another preferred embodiment of the graphite-containing amorphous refractory composition of the present invention, the small particles having hydrophilicity are at least one selected from alumina, silica, silicon carbide, silicon and aluminum. Alumina, silica and silicon carbide has a heat resistance at a relatively easily available, along with small particles of silicon and aluminum and silicon carbide imparts hydrophilicity to the graphite particles, the preferred functions of preventing oxidation of graphite Demonstrate at the same time.

As the small particles, when the amorphous refractory is made into, for example, a spraying clay, a casting clay, or a compacting clay, the dispersion medium is water (including conditions such as pH) .
In some cases, it is preferable that the absolute value of the zeta potential is large, the dispersibility is good, and the water content can be reduced . Furthermore, small particles that impart properties such as heat resistance, thermal shock resistance, thermal conductivity, electrical conductivity, and an antioxidant function of graphite particles may be selected according to the use of the final product.

[0025] From the viewpoint of favorable properties than the hydrophilic graphite particles are applied some examples of small particles having a hydrophilic have most preferred powder of silicon carbide. Alumina and silica have better a easy powder available as small particles heat resistance mower RiYoshimi having hydrophilic.

Examples of the hydrophilic small particles to impart antioxidant function in the graphite particles, silicon, aluminum or may consist of silicon carbide, oxidized to the hydrophilic small particles breathability Ru reduce the sintered body as it is made of silicon or silicon carbide, silica or silicate as a hydrophilic small particles having a property of Ru to improve oxidation resistance to cover and surface of the refractory by forming a glass phase melt at high temperatures What
Shall, and the like, respectively.

[0027] In another preferred embodiment of the graphite-containing amorphous refractory composition of the present invention, the refractory compound powder is magnesia or alumina. Conventionally, refractory compound powders, which are often used in iron and steelmaking processes as refractory compound powders for graphite-containing refractories, are easily available and have excellent heat resistance, and are suitable for molten steel, hot metal and slag. Magnesia and alumina with excellent corrosion resistance. Magnesia and alumina, especially powders obtained by electromelting , when used as a refractory compound powder of the graphite-containing amorphous refractory composition of the present invention, have excellent durability in ironmaking and steelmaking applications. particularly not preferred because refractory molded article is obtained.

Examples of the graphite particles that can be used in the graphite-containing amorphous refractory composition of the present invention include artificial graphite such as flaky natural graphite, soil natural graphite and electrode scrap, pitch coke and carbon black heat-treated at a high temperature, and the like. or mixtures thereof. Of these, flaky natural graphite is particularly preferred graphite particles excellent in oxidation resistance and corrosion resistance.

The average particle size of the graphite particles is 0.1 μm
Available from to those coarse 1mm greater, but preferably the average particle size to use in the range from 1μm to 1mm.

When the average particle size of the graphite particles is 1 μm or more , favorable characteristics such as corrosion resistance and oxidation resistance inherent to graphite are exhibited, and when the average particle size is 1 mm or less, the impact of small particles having hydrophilicity is reduced. It is easy to adhere to the graphite particle surface by the treatment, and a stable coating of hydrophilic small particles is easily formed on the surface of the graphite particle.

The method for preparing the graphite-containing amorphous refractory composition of the present invention is characterized in that the graphite powder is 70 to 97% by weight , the average particle size is 40% or less of the graphite particles of the graphite powder , Consisting of at least one selected from the group consisting of materials, metal carbides, metal nitrides, metal borides, and metals , having hydrophilicity
That a mixed powder of powder 3-30 wt% consisting of small particles,
By impact treatment in a high-speed air flow, the hydrophilic small particles are fixed to the surface of the graphite particles to obtain a graphite powder, and the refractory compound powder is added to the graphite powder and mixed. It is characterized in that the amount of the graphite powder is 2 to 40% by weight in terms of the amount of carbon.

The preferred proportion of small particles of hydrophilic to be adhered to the surface of the black lead particles is also affected by the ratio of the average particle sizes of the graphite particles small child <br/>, graphite particles It requires sufficient proportions to substantially completely cover the surface of the. If the <br/> example, place the flat Hitoshitsubu diameter using the following small particles 10μm
If the purpose is to give the surface of graphite particles dispersibility in water
Therefore, it is preferable to set the content ratio of the small particles to 3% by weight or more.
New

However, since the small particles are not a constituent of the refractory whose main characteristic is corrosion resistance in many cases, the mixing ratio is usually 30% by weight or less, preferably 20% by weight, based on the total amount of the graphite particles. The following is assumed.

[0034] or an average particle size of the small particles is larger than the average particle size of the graphite particles, if it is equal to the number of small particles is reduced with a hydrophilic to be adhered to the surface of the graphite particle,
Except that the strength of fixation of small particles is reduced, then liver and is construction as a monolithic refractory, resulting construction body has a larger porosity, since only be obtained inferior in performance as a refractory undesirable.

The graphite powder of the present invention, a powder mixture of powder and graphite powder of small particles having a low hydrophilic average particle diameter than the graphite particles, conventionally known dry mechanical pulverizer In particular, efficient treatment is performed by applying a shock in a high-speed airflow or performing a process of causing both particles to collide with each other using a shock treatment device described in Japanese Patent Publication No. 3-2009. , and conveniently obtained, et al.
Re that. Furthermore, if the mixed powder in which the hydrophilic small particles are weakly adhered to the surface of the graphite particles in advance is put into the impact treatment device, the small particles are more efficiently fixed to the graphite particle surface.

[0036] When the small particles by electrostatic can not adhere to the surface of the graphite particles, wet the surface of the black lead particles by spraying, water (which may be a small amount of surfactant or coupling agent) There is also a method of mixing afterwards.

In most combinations with small particles having hydrophilicity, graphite particles have a lower hardness than small particles, so that the impact-treated small particles are partially immersed in the surface of the graphite particles. done tightly is sticking to the particle surface, easily attached to the parent aqueous small graphite particles hydrophilic
Kill with pressurized.

Hereinafter, a specific example of the processing using the impact processing apparatus will be described. First, mixed by introducing the predetermined proportion powder of graphite powder and a hydrophilic small particles into a mixer equipped with a stirring blade, preferably small particles adhere due to static electricity around the graphite particles, It is a mixed powder that is evenly dispersed. Next, the mixed powder is put into a device for impact treatment in a high-speed air stream, and mechanical action such as impact, compression, friction, and shear is repeatedly applied to the particles of the mixed powder. While adjusting the meantime graphite particles is crushed RENA unusually magnitude of an impact Ru small particles are adhered to the surface of the graphite particle.

[0039] The impact treatment, together with the graphite particles is close to spherical or ellipsoidal shape mellow, fixed in a state of being sunk hydrophilic small particles a portion on the surface of the graphite particles, coated graphite particles by small particles It will be in the state that was done . The shape of the black lead particles, scaly or needle-like aspect ratio as large as more of (long diameter / short diameter refers to the ratio of) towards those small cubes and aspect ratio as spherical graphite Particles are hardly crushed and small particles are easily fixed.

[0040] Accordingly, or to reduce the aspect ratio previously subjected to mechanical impact treatment in the graphite particles, it is not preferable to choose a small graphite particles aspect ratio. However, according to the method of performing the impact process with a high speed air stream, it acts to reduce the aspect ratio of black lead pellets child proceeds simultaneously, even more cracks or unevenness on the surface of the graphite particles, small particles this part The density of the particles is increased by being entrapped and fixed, and a molded article of an amorphous refractory having a large bulk specific gravity is obtained.
You.

[0041] In hydrophilized graphitic powder has good filling property as this, water can also reduce the porosity in the case of performing the construction without a dispersion medium, a large monolithic refractories bulk density molded body Ru obtained.

The surface hydrophilic graphite powder small particles are fixed in the grain child is when admixed with water as a dispersion medium, an absolute value is large zeta potential at the interface, dispersibility in water it is good, other refractory compound powder and a relatively small amount of water mixed with good fluidity clay, or Ru possible to obtain a good clay filling property. Construction using this clay
By doing so, a molded article of an amorphous refractory having a small porosity, a large bulk specific gravity, and excellent in oxidation resistance and corrosion resistance can be obtained.

The thus obtained graphite-containing monolithic refractory composition having good dispersibility graphite powder is blended with water, by construction as a monolithic refractory, bulk density-free conventional graphite greater than monolithic refractories, Ru obtained close to black lead containing monolithic refractory. Even further if the bulk density is slightly smaller than the graphite-containing monolithic refractory, than there is no joint fit easily eroded as monolithic refractories to monolithic refractories, overall oxidation resistance, corrosion resistance, etc. Thus, a graphite-containing amorphous refractory comparable to a graphite-containing regular refractory in terms of the above characteristics can be obtained.

[0044] At the same time two or more small particles to the surface of the black lead particles, or the case where Ru is adhered to overlap, it is possible to each of the small particles play a different function other than hydrophilic. In addition, different small particles are fixed to the surface of graphite particles
If Ru is is, having a hydrophilic small particles that is fixed to the last
That as the Ru graphite powder having a hydrophilic property can be obtained if.

The graphite-containing amorphous refractory composition according to the present invention contains lactic acid, phosphate, silicate, borate, lactate, clay, alumina cement, siligasol, etc. as a binder.
In the range of 1 to 5 wt%, and the phosphate as a dispersing agent, silicate, a sulfonate other surfactants can Rukoto be contained respectively in the range of 0.01 to 1 wt%.

Thus, the hydrophilic small particles are adhered to the surface.
The graphite powder and the refractory compound powder composition and binder were added and mixed consisting of graphite particles were, by kneading a mixture or by adding a dispersing agent and water, even with a small addition to water volume An amorphous refractory containing graphite, such as a cast material, a ramming material, a stamp material, and a spray material, which can be applied , that is, has a large bulk specific gravity, is obtained.

The graphite-containing shaped refractory formed by on-site application of the composition of the present invention, when used as a lining material for containers used for iron making or steel making, requires less manpower for construction. finished, conventional oxidation resistance as compared with the black lead containing castable refractory, such as excellent corrosion resistance, poor corrosion resistance joints as monolithic refractories by the absence, superior overall graphite-containing monolithic refractory Has a cost performance ratio
You.

[0048]

EXAMPLES The following is a description of the graphite-containing monolithic refractory composition of the present invention examples specifically, the present invention is limited constant of Lena had by these examples. In the following example, an impact treatment device (model name: NHS-3) manufactured by Nara Machinery Co., Ltd. is used as a device for impact-treating a mixed powder of graphite powder and powder composed of hydrophilic small particles in a high-speed airflow. Was.

The main part of this device has the structure shown in a sectional view in FIGS. 1 and 2, wherein FIG. 1 is a front sectional view and FIG. 2 is a side sectional view thereof. 1 and 2,
1 is a casing, 2 is a front wall, 3 is a rear wall, 4 is a rotating plate, 5 is a blade, 6 is a rotating shaft, 7 is a shock chamber, 8 is a shock wall, 9 is a powder outlet valve, and 10 is powder circulation. A circuit tube, 11 is a raw material powder introduction valve, and 12 is a hopper.

In this apparatus, a mixed powder composed of graphite particles and small particles put in the hopper 12 is supplied to the raw material inlet valve 1.
1 is opened and introduced into the shock chamber 7 formed of a ring-shaped space. In the shock chamber 7, a rotating plate 4 fixed to a rotating shaft 6 driven by an electric motor (not shown);
And rotates at high speed.

The rotational energy of the blade 5 is supplied to the impact chamber 7
Is converted into high-speed airflow energy inside the impact chamber 7
The airflow circulates the powder in the closed flow path of the powder circulating circuit tube 10 attached in the direction indicated by the arrow.

The graphite particles and the hydrophilic small particles of the mixed powder collide with each other, and circulate under the impact force of the blade 5 rotating at high speed, so that the compressive force and the frictional force are reduced. Repeatedly receives mechanical action such as force and shear force.

[0053] As a result, the black lead particles gradually 0.00 the corner, a small spherical aspect ratio or simultaneously approach the ellipsoidal shape of the particle shape, the surface of the graphite particle is fixed hydrophilic small particles, and The coating imparts hydrophilicity to the graphite particles.

[0054] Rotation speed of the time the blade 5, the black lead particles is adjusted to the speed had Lena crushed. After the impact treatment for a predetermined time, the graphite powder composed of graphite particles whose surface is coated with hydrophilic small particles is taken out by opening the powder outlet valve 9.

Test Example As a graphite powder, the carbon content was 98% by weight and the particle size was 150 μm.
m and an average particle size of about 51 μm, and artificial graphite powder having a carbon content of 99% by weight and a particle size of 150 μm or less and an average particle size of about 32 μm. absolute value is much large zeta potential compared with graphite powder as a powder consisting of particles, alumina is excellent in dispersibility in water (average particle size of about 0.6 .mu.m), silica (average particle diameter 0.
2 [mu] m), silicon carbide (average particle size of about 5.4 [mu] m), the respective powders of aluminum (average particle size of about 12 [mu] m) alone or in combination using Table 1, Table 2, in combination with conditions shown in Table 3 The graphite powder was subjected to a hydrophilic treatment to obtain a graphite powder having hydrophilicity.

That is, the mixed powders of each combination were put into the above-described high-speed airflow impact treatment apparatus, and the impact treatment was performed. The temperature of the powder during this impact treatment is at most 1
The temperature is about 50 ° C., and the graphite particles and small particles do not undergo a chemical change. Peripheral speed of the rotating plate 4 at a high speed air stream impact treatment apparatus, Ru <br/> can be adjusted in the range of 10 to 150 m / sec, in the case of black lead particles subjected to tests, so that fracture seldom occur It has been found that it is appropriate to perform the impact treatment at a peripheral speed of 100 m / sec or less. During this time, there is no problem even if the small particles are crushed to some extent.

[0057] shock treatment is better to such a strong shock force as graphite particles are slightly crushed there is attachment to graphite particles <br/> small particles having a hydrophilic becomes good. In the following test, the rotation speed of the rotating shaft 6 was adjusted so that the peripheral speed was 60 m / sec so that the crushing of the graphite particles did not occur remarkably and the small particles were effectively fixed. About 1kg at a time
Was subjected to impact treatment.

The average particle diameter of the powder was measured by a laser diffraction particle size distribution analyzer (Microtrac, Model 799).
The particle size distribution was measured according to 7), and the particle size at a point where the integrated volume was half was obtained. In addition, the time of the shock treatment can be changed in a range of 1 to 20 minutes,
Three minutes was set as a condition under which a sufficient processing effect was obtained even in a short time.

Tables 1, 2 and 3 show the types of small particles having hydrophilicity combined to obtain hydrophilic graphite powder, and the results of measuring the zeta potential of the impact-treated graphite powder, respectively. The results are summarized in Table 3. Example 18,
19, 20, and 23 are comparative examples.

Using the thus obtained hydrophilic graphite powder, a graphite-containing amorphous refractory composition obtained by combining electrofused magnesia powder and electrofused alumina powder as a refractory compound powder. I mixed. These compositions were evaluated by the following methods, and the results are summarized in Tables 4, 5, and 6.

A. Zeta potential 10 parts by weight of a 0.01 molar KCl aqueous solution was added to 1 part by weight of the graphite powder subjected to the impact treatment or another graphite powder and mixed to obtain a slurry. After degassing the slurry for 30 minutes under reduced pressure, a 0.01 N aqueous KOH solution was added to adjust the pH.
Was adjusted to 11 and the zeta potential was measured at 25 ° C. by a colloid oscillating potential method. The zeta potential that they have excellent dispersibility in water as the larger absolute value.

B. Clay liquidity magnesia (Example 1-20) impact treatment with a hydrophilic graphite powder small particles are adhered to the surface with a graphite powder or graphite powder as a comparative example
6 to 22 parts by weight, maximum particle size 20 mm, minimum particle size 40
86 parts by weight of fused magnesia powder of 4 μm, 4 parts by weight of alumina fine powder (average particle size of about 0.6 μm), 4 parts by weight of silica fine powder (average particle size of about 0.2 μm), metal silicon powder (particle size) 3 parts by weight of 149 μm or less), 1.5 parts by weight of lactic acid as a binder, 0.1 parts by weight of sodium β-naphthalenesulfonate as a surfactant, and 8 to 12 parts by weight of distilled water. The mixture was put into a mixer and mixed for 1 minute to obtain a clay having thixotropic properties.

Alumina (Examples 21 to 23) Similarly, 6 parts by weight of graphite powder, 72 parts by weight of fused alumina powder having a maximum particle size of 5 mm and a minimum particle size of 40 μm as a refractory compound powder, Alumina fine powder (average particle size of about 2.
3 μm), 7 parts by weight of silica fine powder (average particle size 0.2 μm)
m) of 4 parts by weight and silicon carbide powder having a particle size of 74 μm or less
3 parts by weight of metal silicon powder having a particle size of 149 μm or less, 5 parts by weight of alumina cement as a binder, 0.1 part by weight of sodium tripolyphosphate as a dispersant, and 6.3 to 8.3 parts by weight of distilled water. The mixture was put into a universal mixer and mixed for 1 minute to obtain a thixotropic clay.

The kneaded material is made 100 mm in inner diameter and 50 m in height.
m is filled in the mold, and the clay with the mold removed is subjected to a vibration of 3G strength for 10 seconds in the vertical direction to soften and deform the clay, and measure the maximum spread length of the clay to flow. It was an index of sex. However, among these kneaded clays, the kneaded clay having insufficient fluidity to be poured has a relatively large amount of distilled water added thereto, and therefore, it is necessary to consider this point in the comparison of the fluidity.

C. Bulk specific gravity 50 mm × 50 mm ×
Each of the test pieces was removed from the mold after being molded by vibration casting in a mold having an inner dimension of 50 mm, and left to stand at room temperature for 24 hours, and then dried at 110 ° C. for 24 hours. It measured and calculated bulk specific gravity.

[0066]

[Table 1]

[0067]

[Table 2]

[0068]

[Table 3]

[0069]

[Table 4]

[0070]

[Table 5]

[0071]

[Table 6]

D. Oxidation resistance Magnesia refractories (Examples 1 to 20, 24) Each of the 50 mm × 50 mm × 50 mm test pieces whose bulk specific gravity was examined was heated and held in the air at 1500 ° C. for 2 hours.
After cooling, it was cut at the central part, the depth of the decarburized layer in the cross section was measured, and it was used as an index of its oxidation resistance. Further, as another comparative example, a similar test was conducted on a magnesia-graphitic non-fired regular brick having a bulk specific gravity of 2.9 containing 15% by weight of flaky graphite (Example 24), and the depth of the decarburized layer was 4.6 mm. Met.

Alumina-based refractories (Examples 21 to 23, 25) Each test piece whose bulk specific gravity was examined in the same manner was heated and maintained at 1450 ° C. for 5 hours in air, cut at the center after cooling, and cut in a cross section. The depth of the decarburized layer was measured and used as an index of its oxidation resistance. Further, as another comparative example, a similar test was performed on an alumina-graphite unfired shaped brick having a bulk specific gravity of 2.9 (Example 25) containing 10% by weight of flaky graphite and 5% by weight of silicon carbide. Was 6.7 mm in depth.

E. Corrosion magnesia-based refractory Ri by the (Example 1～20,24) casting, cross made from black lead-containing monolithic refractory
Is an isosceles trapezoid (upper side: 45 mm, lower side: 95 mm, other 2
Six (50 mm) side columnar (height: 160 mm) test pieces were prepared, and as a comparative example, the magnesia-graphite non-fired shaped brick (Example 24) was cut into the same size as 6 pieces.
Created. The six test pieces are combined to form a column having a hexagonal hole (inner diameter of about 7.8 cm) in the center. This prism is held in a horizontal state, and is held at a predetermined temperature while rotating at 20 rpm, and the slag and A rotating erosion test was performed by continuously adding additional carbon steel slabs inside the hexagonal holes to compare the corrosion resistance of the refractories.

That is, a combination of six test pieces in a columnar shape was fixed in a rotary erosion test furnace, and an erosion agent obtained by combining a carbon steel piece and slag at a weight ratio of 1: 1 was inserted into the center hole of the test piece. First put 0.6 kg, while maintaining the furnace temperature to 1650 ° C., with added in 0.3kg additional erosion agent every 30 minutes, was subjected to rotary corrosion test of 5 hours while extracting the same amount of erosion agent . Each test piece taken out after cooling was cut in the longitudinal direction at the center, and the erosion rate was determined from the amount of erosion of the most deeply eroded portion, which was used as an index of corrosion resistance.

In this test, the erosion rate of the magnesia-graphitic non-fired shaped brick (Example 24) was 5.8 mm / hour. The chemical composition of the slag used for this test in weight%, CaO: 40%, CaF 2: 20%, SiO 2:
10% and Al ₂ O ₃ : 30%.

Alumina-based refractories (Examples 21 to 23 and 25) Alumina-graphite irregular-shaped refractories have a cross section of an isosceles trapezoid.
(Top side: 50mm, bottom side: 83mm, the other of the two sides: 40m
m), eight column-shaped (height: 120 mm) test pieces were cast to prepare eight test pieces . The alumina graphite unfired monolithic refractory specimens cut the same shape as the ratio Comparative Examples in further (Example 2
8 ) were prepared . A combination of eight test pieces is fixed with mortar at a position to be a molten metal surface in a crucible of an induction furnace so as to form an octagonal hole (inner diameter of about 8.7 cm) in the center,
A total of about 50 kg of an erosion agent in which pig iron and slag were combined at a ratio of 1: 1 was put into the crucible, induction-heated at 1500 ° C. for 5 hours, held in a molten state, and after cooling, a test piece was taken out.
Each test piece was cut in the longitudinal direction, and the erosion rate was examined from the maximum erosion depth, which was used as an index of corrosion resistance .

In this test, the erosion rate of the non-fired alumina-graphite shaped refractory (Example 25) was 3.4 mm / hour. The chemical components of the slag used in this test are in weight%, CaO : 50%, CaF ₂ : 25%, SiO ₂ :
10% and FeO : 15%.

From the above test results, it can be seen that the graphite powder in which hydrophilic small particles are fixed on the surface of graphite particles can be used even when one kind of hydrophilic small particles is fixed on the surface of graphite particles. , when the small particles having two or more hydrophilic was fixed to the surface of the graphite particles also surface treatment is not performed, or
Other than conventional graphite powders front surface processing has been performed, the absolute value of the zeta potential is large, it has been revealed to have excellent dispersibility in water.

As is apparent from the test results of Example 20, S
Graphite powder obtained by CVD coating of iC in SiO gas has a large absolute value of zeta potential and excellent dispersibility, but has a large porosity when used as a refractory, and has poor performance including corrosion resistance. I understood that. This is by the surface of the graphite particle has a large rough state of pores, because the bulk density is small.

[0081] In the castable refractory by monolithic refractories composition of the present invention obtained by using the graphite powder having a hydrophilic when used with water as a dispersion medium, less amount of water added is Also, the fluidity of the clay is good, and the molded article of the irregular-shaped refractory obtained by molding this clay has a large bulk specific gravity and is excellent in corrosion resistance and oxidation resistance.

A comparison between the graphite-containing shaped refractory which is widely used in the field of iron and steelmaking and has a reputation for performance and the graphite-containing shaped refractory according to the present invention shows that the corrosion resistance and the oxidation resistance are high. However, irregular refractories are advantageous because there is no joint having poor corrosion resistance. Thus,
Graphite-containing monolithic refractory having at least manufacturing processes and The required manpower and energy cost performance ratio only excellent markedly Herase that content consumption at the construction is obtained.

[0083]

The graphite powder used in the composition for a carbon-containing amorphous refractory of the present invention has a large absolute value of zeta potential in water and has no surface treatment.
Compared with the surface-treated graphitic powder in another way, show easy to use water as a dispersion medium is divided dispersion medium der Rutoki, excellent dispersibility.

[0084] Thus, even without the use of organic solvents the working environment is a problem as a dispersion medium, yo Rikasa specific gravity excellent large corrosion resistance, further provides an excellent graphite-containing monolithic refractory in oxidation resistance kill at.

[0085] Also, by selecting the material of the small particles of hydrophilic Ru is adhered to the surface of the graphite particles, or by Rukoto by fixing two or more kinds of hydrophilic small particles, also preferred characteristics other than the hydrophilic graphite powder obtained having both, wear whereby graphite-containing monolithic refractory material excellent in such as oxidation resistance <br/> provide.

[0086] By mixing the powder with the powder of the small particles having a graphite powder and a hydrophilic bombardment process, conveniently a graphite powder having excellent dispersibility in water can be obtained efficiently, also the particle shape of the graphite particles and the like large scaly or needle-like aspect ratio, the process close to ellipsoidal shape spherical or by reducing the aspect ratio, the hydrophilicity of the small particles sticking to the surface of the graphite particle Since the processing is performed at the same time,
When used as a graphite-containing amorphous refractory, a molded product having a good filling property and a large bulk specific gravity can be obtained.

[0087] Thus, if the conventional water used in the dispersion medium
Has a bulk molded body can not be obtained in large refractory specific gravity, graphite-containing monolithic refractory which has not been used much in the field of oxidation resistance and corrosion resistance to molten iron and steelmaking made because of insufficient, the present invention By using graphite-containing amorphous refractory composition,
It can be formed into a molded article of an amorphous refractory having a large bulk specific gravity, and the oxidation resistance and the corrosion resistance are greatly improved. Therefore, labor saving is a unique feature in monolithic refractories, also can with advantage in the graphite-containing refractory to the effects of energy saving, utility value on that industry is great.

[Brief description of the drawings]

Front sectional view showing an example of a device used to hydrophilic treatment the graphite powder used in the carbon-containing monolithic refractory composition of the present invention; FIG

FIG. 2 is a side sectional view of FIG. 1;

[Explanation of symbols]

 1: casing 2: front wall 3: rear wall 4: rotating plate 5: blade 6: rotating shaft 7: shock chamber 8: shock wall 9: powder outlet valve 10: powder circulation circuit tube 11: raw material powder introduction valve 12: Hopper

Claims (5)

(57) [Claims] Claims: 1. A method according to claim 1, comprising mainly a graphite powder and a refractory compound powder.
A Rana Ru composition, the group graphite powder, comprising the surface of the graphite particles, the average particle diameter is smaller than the graphite particles, metal oxides, metal carbides, metal nitrides, metal borides and metal
Are those small particles having a hydrophilic comprising one or more selected from is pinned, and characterized in that graphite powder is contained 2 to 40% by weight in terms of carbon content in the composition A graphite-containing amorphous refractory composition. 2. A graphite-containing monolithic refractory composition according to claim 1, wherein an average particle diameter of the small particles is 40% or less of the average particle diameter of the graphite particles with a parent aqueous. 3. A group small particles having a parent aqueous is alumina, silica, silicon carbide, silicon and aluminum
According to claim 1 or 2 comprising one or more selected from
A graphite-containing amorphous refractory composition. 4. The resistance to fire compound powder comprises magnesia or alumina claims 1, 2 or graphite-containing monolithic refractory composition according to 3. 5. A graphite powder 70 to 97 wt%, I mean particle size of less than 40% der graphite particles of the graphite powder, metal oxides, metal carbides, metal nitrides, metal borides and metal Or
Consisting of one or more selected from the group consisting of
That a mixed powder of powder 3-30 wt% consisting of small particles,
By impact treatment in a high-speed air flow, the hydrophilic small particles are fixed to the surface of the graphite particles to form a graphite powder, and the refractory compound powder is added to the graphite powder and mixed. A method for preparing a graphite-containing amorphous refractory composition, wherein the amount of the graphite powder is 2 to 40% by weight in terms of carbon amount.