JPH1143716A - Tuyere brick in vessel for molten metal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tuyere brick lowering slag wetting, metal sticking, poros ity and giving high strength by applying a hydrostatic pressure forming to a material which consists essentially of MgO base aggregate, specific quantities of carbonaceous material, metal and Al2 O3 are added to and uses thermosetting resin and kneaded. SOLUTION: A raw material for tuyere brick consists essentially of MgO base aggregate and adds 0.3-15.0 wt.% carbonaceous material, 0.2-5.0% metal or alloy powder composed of one or more kinds among Al, Mg, Ca and Si and 0.1-30% Al2 O3 to this aggregate. The thermosetting resin is added as binder to this raw material and kneaded and formed by using a hydrostatic pressure. As the MgO base aggregate, sintered magnesia or electromelted magnesia, etc., having >=98% MgO is used and this grain size is desirable to be about 1-5 mm. As the carbonaceous material, natural graphite, artificial graphite, pitch power, amorphous carbon, carbon coke, etc., can be used. As the thermosetting resin, a material blending one or more kinds among phenol resin, urea resin, epoxy resin and urethane resin, can be used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a ladle, a ladle for various refining, a nozzle brick disposed at the bottom of a container for molten metal such as a tundish, and a well brick for receiving a porous brick for gas injection. That is, it relates to tuyere brick.

[0002]

2. Description of the Related Art Conventionally, a nozzle brick of a container for molten metal has
And a well brick for gas blowing porous brick, ie, a tuyere brick, for example, as shown in FIGS. 3A and 3B, a nozzle brick for discharging molten metal to a central portion of a square brick 4 or a nozzle brick. A frusto-conical hole 5 for mounting a porous brick for blowing an inert gas for stirring the molten metal in the pot is formed.

[0003] Such tuyere bricks are conventionally formed integrally by hydraulic pressure or friction press because of their large shape. The size is, for example, 200 mm to 50 mm.
It has a rectangular shape of 0 mm and a height of about 150 mm to 500 mm.

The material of the tuyere brick for molten metal is zircon or alumina fired brick or Al ₂ O _3.
-C quality precast products are used. But,
Since these tuyere bricks are large in shape, fired products obtained by press molding have high porosity, and because of their low bulk specific gravity and low physical properties, they have large erosion loss due to molten metal and short life. .

Further, since the precast products Al ₂ O ₃ -C electrolyte is cast molded product using alumina cement, the porosity becomes high, slag infiltrate easily like spalling occurs problems was there.

[0006] Therefore, since the service life of each of the tuyere bricks is short, the side wall brick of the container for molten metal is shorter than the life of the brick, and as a result, the side wall brick as the container for molten metal has a refractory lining such as a brick. It reduces the life of the material, increases the basic unit of refractory lining, and raises the cost of producing steel. Accordingly, there is an increasing demand for a longer life of tuyere bricks.

Specifically, when a nozzle brick or a porous brick for gas injection is mounted on the tuyere brick, the nozzle brick or the tuyere brick is fitted and mounted in the truncated conical hole using a refractory mortar or the like. The nozzle brick or the porous brick for gas injection usually has a life of about one charge, and is therefore frequently replaced.

For this reason, it is necessary to remove deposits such as ingots on the surface on which nozzle bricks or porous bricks for gas injection (hereinafter referred to as nozzle bricks) and tuyere bricks are fitted and mounted. For this reason, tuyere bricks are exposed to severe environmental conditions such as erosion due to oxygen cleaning, mechanical shock due to desorption, and abrasion due to molten metal flow.

Further, nozzle bricks and the like are required to have erosion resistance to slag existing in a container for molten metal. Further, the conventional tuyere brick has a large size, so that the production period is long and there is also a problem that deformation, distortion, and cracks are frequently generated during firing.

[0010] In terms of quality, tuyere bricks are large in shape and have a low degree of material filling due to large irregularities, and the quality varies widely. In particular Al ₂ O ₃ -C quality precast products, in casting article of alumina cement bond, there are variations in the degree of filling to contain the carbon material, strength there is weak and many other problems, their resolution is desired I was

Therefore, in Japanese Utility Model Publication No. 61-45964, tuyere bricks are divided into upper tuyere bricks and lower tuyere bricks to disperse thermal stress during use and prevent cracks. However, such a two-stage structure is inconvenient at the time of brick construction.

[0012]

Therefore, in the present invention, there is little slag infiltration into tuyere bricks, little adhesion of ingots, etc., good filling of tuyere bricks with raw materials, and low porosity. Another object of the present invention is to provide a tuyere brick having a high strength, a long life, and a good production yield.

[0013]

Means for Solving the Problems The inventors of the present invention have conducted various studies in order to solve the above-mentioned problems, and as a result, have replaced the conventional method of forming tuyere bricks containing a carbon material with an isostatic pressing method. The inventors obtained the finding that the degree of filling of the brick can be increased by application, the density can be increased, and defects such as lamination and crack generation can be eliminated, and the following invention has been accomplished.

The present invention is characterized in that the tuyere brick provided at the bottom of the molten metal container is formed into a cylindrical shape or a truncated conical shape using a hydrostatic press (CIP). Tuyere brick of container for molten metal.

The tuyere brick is formed into a cylindrical shape or a truncated conical shape using a hydrostatic press (CIP) capable of compressing the tuyere brick in a three-dimensional direction, so that the filling degree of the tuyere brick is uniformly increased in the three-dimensional direction. By increasing the density and making the shape cylindrical or truncated cone, the thermal stress generated during use can be evenly dispersed in the brick, so that the life of the tuyere brick can be improved. it can.

The tuyere brick is mainly composed of an MgO aggregate, 0.3-15.0% by weight of carbon material, Al, Mg, C
a, and 0.2 to 5.0% by weight of a metal or alloy powder composed of one or more of Si, Al ₂ O ₃ 0.1
A tuyere brick for a container for molten metal, which is formed by kneading a raw material consisting of -30% by weight with a thermosetting resin added as a binder and kneading the mixture.

Since MgO aggregate has high thermal shock resistance, it is most suitable as a main component of tuyere brick.
~ 15.0% by weight, 1 of Al, Mg, Ca, and Si
Powder of metal or alloy consisting of two or more species 0.2
5.0%, the raw material made of Al ₂ O ₃ 0.1 to 30 wt%, and in addition a thermosetting resin by kneading, molded using isostatic pressing (CIP) as binder The tuyere brick has a particularly long life.

Specifically, sintered magnesia of 98% or more of MgO and fused magnesia of 98% or more of MgO can be used. The particle size is desirably about 1 to 5 mm.

The carbon material is blended in order to increase the slag infiltration resistance to the brick. As the carbon material, natural graphite, artificial graphite, pitch powder, amorphous carbon, carbon coke, and the like can be used. If the carbon material content is less than 0.5% by weight, the effect of slag infiltration, which is the effect thereof, is insufficient, and the spalling resistance also deteriorates.

On the other hand, if it exceeds 15% by weight, the degree of filling of the raw material decreases, the strength decreases, and, for example, the wear resistance due to molten steel and slag also decreases.
It is desirable that When graphite is used as the carbon material, the particle size is desirably about 0.043 to 0.2 mm.

When the metal powder is added, A
It reacts with l ₂ O ₃ , MgO, etc., and has a great effect of preventing oxidation of carbon material and improving strength. Al, M as metal powder
Powders of metals or alloys of one or more of g, Ca, and Si are desirable. This is because these metal powders react with Al ₂ O ₃ , MgO or the like in the matrix to form oxides, promote the bonding of the raw materials, and improve the strength.

If the amount of the metal powder is less than 0.2% by weight, the effect is not recognized. If the amount exceeds 5.0% by weight, abrasion due to the molten metal flow is promoted by softening and melting of the metal. Therefore, the amount of the metal powder added is from 0.2% by weight to 5.0% by weight.
And The particle size of the metal powder is desirably about 0.043 to 0.2 mm.

Al ₂ O ₃ is suitably added in an amount of 0.1 to 30% by weight in order to increase the thermal shock resistance of the raw material and to suppress excessive residual expansion. Desirable particle size of Al ₂ O ₃ is 0.15
It is about 0 to 3 mm.

Since the tuyere of the present invention is used as an unfired brick, a thermosetting resin is blended as a binder. As the thermosetting resin, a phenol resin, a urea resin, an epoxy resin, and a resin in which one or more kinds of urethane resins are blended can be used. This is because phenol resins, urea resins, epoxy resins, and urethane resins are relatively easily and inexpensively available resins and are convenient for producing tuyere bricks. When tuyere bricks are used for ladles, these resins have the effect of hardening the refractory material and improving the strength of the bricks.

The molten metal container may be a ladle for molten metal,
A tuyere brick for a container for molten metal, which is either a ladle for refining or a tundish.

The ladle, refining ladle and tundish for molten metal use nozzle bricks or porous bricks for gas injection. However, the nozzles and the like of the present invention have a long life so that these bricks are used. Can be used effectively.

(Operation) The hydraulic or friction press, which is a conventional molding method, is a uniaxial press method, so that the raw material filling property is poor. Therefore, in the present invention, the tuyere brick provided at the bottom of the molten metal container is formed into a cylindrical shape or a truncated cone shape by using a hydrostatic press (CIP) capable of compressing the tuyere brick in a three-dimensional direction. Forming one body using a hydrostatic press (CIP) results in a dense body having a uniform filling degree in the three-dimensional direction and significantly improved strength.

Further, by making the tuyere shape cylindrical or truncated cone shape, the filling degree of the tuyere brick is increased,
Density can be increased. Furthermore, by making the shape cylindrical or frusto-conical, the thermal stress generated during use can be uniformly dispersed in the brick, so that the occurrence of cracks during use can be reduced.

[0029]

Next, the present invention will be described with reference to examples. Table 1
1% by weight of metal Al and 3.0% by weight of a phenolic resin as a binder were added to the raw material composition shown in FIG. 1 and kneaded. Using these raw materials, a porous brick receiver as shown in FIGS. 1A and 1B was used. A tuyere brick was made. The tuyere brick has an outer diameter (D1) of 320 mm.
m, height (H1) 210 mm, inner hole is upper part (D1
(U)) is 143 mmφ, and the lower part (D1 (d)) is 187 mmφ.
mmφ. The tuyere brick was formed using a hydrostatic press at a pressure of 1 t / cm ² .

Further, as another embodiment, a tuyere brick for a ladle made of molten steel as shown in FIG. 2 was produced. The dimensions are 365 mm in outer diameter (D2), 300 mm in height (H2), and 159 mm in inner hole (D2 (u)) and lower part (D2
(D)) is 220 mmφ. The other points are the same as above.

As a comparative example, FIG.
Outer diameter (L3) 420mm, height 387m as shown in B
m is formed using a 500 ton friction press, followed by a curing treatment (250 ° C.).
× 10 hours) to obtain tuyere bricks. Table 1 shows the chemical components and physical properties of the inventive products No. 1 to No. 3 and Comparative Examples No. 4 to No. 6.

The wear test was performed by a rotating drum method.
In this method, the cross section of the tuyere bricks of the present invention and the comparative example is trapezoidal (upper side 50 mm, lower side 90 mm, height 60 m).
m, 115 mm in length), a plurality of samples were stuck on the inside of the drum, and the molten slag (component composition was
CaO 45% by weight, SiO ₂ 30% by weight, Al ₂ O ₃ 10
(Weight%, Fe ₂ O ₃ 15% by weight), the drum is rotated with its axis horizontal, and its wear state is measured. The product of the present invention No. 1 was set to 100, and the degree of wear of the product of the present invention was measured.

The slag erosion index is determined by preparing a sample from the above-mentioned product of the present invention and the tuyere brick of the comparative example, lining the inner wall of a small induction furnace, and immersing molten steel and slag (the composition of the component is (Same as molten slag) was charged and the state of erosion was measured. Also in this case, the degree of erosion of the product No. 1 of the present invention was 10
It was set to 0, and the state of erosion of the product of the present invention was measured.

The number of occurrences of cracks was determined by cutting the sample after the test in the above-mentioned rotary drum method, measuring the length of the crack in the cross section, and indicating the length as 10 mm.

As is clear from the results shown in Table 1, the tubular tuyere brick of the product of the present invention obtained by isostatic pressing has low porosity as physical properties, high bulk specific gravity, abrasion test, and slag erosion. The index is also greatly improved compared to the conventional product.

From Table 1, it can be seen that the product of the present invention was excellent in any of the number of cracks, the wear index and the slag erosion index. Table 2 shows the tuyere bricks described above at 50 tons and 300 tons.
The result of having investigated the number of times (the number of heats) which can be used for a ton ladle is shown. The product of the present invention had less slag infiltration, less adhesion of ingots and the like than the conventional product, no cracks and cracks, and a high spall resistance, and had about twice the life.

[Table 1]

[Table 2]

[0037]

As described above, the tuyere brick according to the present invention is formed into a cylindrical shape or a truncated conical shape by a hydrostatic press, and further, since the main component is made of MgO-based aggregate, the molten metal is formed. Contact heating and cooling many times,
Its life is more than twice as long as the conventional tuyere brick,
As a result, the life of various ladles can be greatly extended, and the effect is remarkable. Needless to say, the above brick can be used not only as tuyere brick but also as other bricks subjected to heating and cooling many times.

[Brief description of the drawings]

FIG. 1 is a plan view showing one embodiment of a tuyere brick according to the present invention.

FIG. 1B is a longitudinal sectional view showing one embodiment of the tuyere brick of the present invention.

FIG. 2 is a longitudinal sectional view showing another embodiment of the tuyere brick of the present invention.

FIG. 3A is a plan view showing the shape of a conventional tuyere brick.

FIG. 3 is a vertical sectional view showing the shape of a conventional tuyere brick.

[Description of Signs] 1 Molded product by hydrostatic press (CIP) 2 Hole for mounting porous brick 3 Precast material 4 Square shaped molded product by friction press 5 Hole for mounting porous brick

Claims (3)

[Claims] 1. A tuyere brick provided at the bottom of a molten metal container, wherein the tuyere brick is formed into a cylindrical shape or a truncated conical shape by using a hydrostatic press, and is mainly made of MgO aggregate. As a component, carbon material 0.3 to 15.0% by weight, A
l, Mg, Ca, and one or of two or more metals or powder 0.2 to 5.0% by weight of these alloys Si, a raw material consisting of Al ₂ O ₃ 0.1 to 30 wt%, A tuyere brick for a container for molten metal, which is formed by adding a thermosetting resin as a binder and kneading the mixture. 2. The thermosetting resin is a phenol resin,
One of urea resin, epoxy resin, and urethane resin,
A tuyere brick for a container for molten metal according to claim 1, wherein two or more kinds are blended. 3. The tuyere of a molten metal container according to claim 1, wherein the molten metal container is one of a molten metal ladle, a refining ladle, and a tundish. Brick.