JP2017065978A - Manufacturing method of carbon-containing brick refractory - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a carbon-containing brick refractory having enhanced spalling resistance without loosing a fibrous material even during decarbonization or dephosphorization refining of molten iron or the like.SOLUTION: There is provided a manufacturing method of a carbon-containing brick refractory by mixing a blend raw material containing at least one kind of AlOand MgO having particle size distribution of one with average particle diameter of 3 mm or more of 5 to 40 mass%, one with 1 to less than 3 mm of 10 to 45 mass%, one with 0.15 to less than 1 mm of 15 to 30 mass% and one with less than 0.15 mm of 5 to 45 mass%, a graphite raw material, a liquid binder consisting of an organic material of 2 to 5 mass% by outer percentage, at least two kinds of powder bodies of MgO, AlOand SiOwith average particle diameter of 1 μm or less with a mixer and then molding the same with using a press machine and further curing the same.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a method for producing a refractory for lining refractories for iron refining equipment used in high-temperature processes, particularly carbon-containing brick refractories using carbon as part of the raw material.

  MgO-C brick refractories have good corrosion resistance to steelmaking slag, and are excellent in thermal shock resistance compared to other fired bricks. For this reason, MgO-C brick refractories are used as lining refractories in the main equipment of today's steelmaking processes. However, since the MgO-C brick refractory contains carbon, the thermal conductivity is higher than that of the baked brick not containing carbon.

Starting with the Kyoto Protocol, which was voted in 1996, activities for reducing CO ₂ emissions on a global scale have been conducted for the global environment. Even in the steel industry, since a large amount of carbon is used, various efforts are being made to reduce CO ₂ , such as reduction of heat loss accompanying reduction in the ratio of reducing material in the blast furnace and effective use of heat. In the refractory field, in order to create a thermal margin, suppression of heat dissipation of the furnace body by reducing the thermal conductivity of the refractory is being studied.

  In order to suppress the heat dissipation of the furnace body, it is preferable that the brick refractory used in the furnace body has a low thermal conductivity. It is believed that the thermal conductivity of carbon-containing brick refractories such as MgO-C brick refractories depends on the carbon concentration. Therefore, low carbonization of MgO-C brick refractories can be expected to greatly contribute to the suppression of heat furnace body dissipation. In addition, by reducing the carbon of the brick refractory, it is expected to improve the quality of the steel slab, such as suppressing carbon pickup during refining.

  On the other hand, lowering the carbon of MgO-C brick refractories reduces the spalling resistance of brick refractories. It is believed that the spalling failure of MgO-C brick refractories used in the iron making process is caused by the occurrence of cracks due to repeated thermal loads applied to the refractories, and the development of the cracks.

  Therefore, when attention is paid to a technique for suppressing a decrease in the spalling resistance of a general brick refractory, Patent Document 1 discloses that 50 mass of carbon fiber (length: 0.13 to 50 mm, diameter: 5 μm or more) is used as a carbon source. A technique of adding to a refractory within a range of% or less and suppressing the progress of cracks with the carbon fiber is disclosed.

  In recent years, many carbon nanomaterials such as carbon black, carbon nanotube, carbon nanofiber, fullerene and graphene have been discovered. And the technique which added these carbon nanomaterials to the brick refractory, and suppressed the mechanical characteristic improvement of the brick refractory, especially the spalling resistance is also disclosed. For example, in Patent Document 2, a mesophase pitch and a thermosetting resin are added to a refractory material and thermally decomposed at a temperature of 1000 ° C. or lower to obtain carbon nanofibers (diameter: ˜500 nm, length: 100 μm). Techniques for producing bricks in refractories are disclosed. And the technique which improves the corrosion resistance and thermal shock resistance of a brick refractory by producing | generating carbon nanofiber in a brick refractory is disclosed.

  Patent Document 3 discloses a technique for improving the spalling resistance of a refractory by adding fullerenes to the refractory within a range of 5% by mass or less. The principle is that carbon nanofibers (CNF) are generated by reacting fullerenes with phenol resin as a binder by applying heat. The generated CNF plays a role of bridging against cracks, so that the spalling resistance of the refractory is improved.

In addition, some techniques for improving the mechanical properties of brick refractories by generating fibrous materials called whiskers in the refractories are also disclosed. Patent Document 4 discloses a refractory made of graphite materials such as anthracite, calcined coke, natural graphite or artificial graphite, a metal oxide such as Al ₂ O ₃ , metal silicon, and carbon black. The aim of this refractory is to increase the strength of brick refractories by generating silicon carbide whiskers.

In Patent Document 5, a pitch and an Al alloy are reacted at a high temperature to produce whiskers such as AlN and Al ₄ C _3, and pitch or carbon black containing Al or an Al alloy in an ASC castable (saddle material) Discloses a refractory to which 0.01 to 7 mass% is added.

  Both of these technologies allow for the presence of fibrous materials in the structure of refractory bricks, and the bridging effect of the fibrous materials prevents the development of cracks in the refractory bricks caused by mechanical loads. It is a targeted technology. Note that these technologies can be applied not only to brick refractories but also to brick refractories with a relatively high carbon content, further increasing the strength of brick refractories or further improving spalling resistance. realizable.

JP-A-62-9553 JP-A-2005-139062 JP 2006-8504 A Japanese Patent No. 5539201 JP 2003-73175 A

  However, in the case of MgO-C brick to which such a fibrous material is applied is refractory, the material of the fibrous material is non-oxide, so that it disappears during use. For this reason, the effect of suppressing crack propagation due to bridging of the fibrous material is also lost. Decarburization and dephosphorization of molten iron and the like are performed by supplying oxygen-containing substances into molten iron and oxidizing carbon and phosphorus. For this reason, the oxygen-containing substance and the brick refractory are in direct contact with each other during decarburization and dephosphorization, and it is difficult to prevent the disappearance of oxidation.

  Moreover, regarding the steelmaking refining vessel, when the refining process is a batch type, it becomes an empty furnace that does not hold hot metal after the process. At this time, a large amount of air comes into contact with the workpiece refractory in the furnace, and even in this case, it is difficult to prevent oxidation loss. From these viewpoints, in the above technique, Patent Document 1, Patent Document 2 and Patent Document 3 are carbonaceous materials, and Patent Document 4 and Patent Document 5 are carbides and nitrides, both of which are fibers in brick refractory during oxidation refining. There is a high possibility that the solid material will disappear. Moreover, in patent document 3, the substance to add is a comparatively expensive fullerene, and causes the increase in the manufacturing cost of a brick refractory. Furthermore, when adding a fiber substance like patent document 1, the denseness of a brick refractory is impaired by the added fiber substance, and conversely, it may become difficult to mold a brick refractory. Also, this method causes an increase in the manufacturing cost of brick refractories. Therefore, the object of the present invention is to solve such problems of the prior art, and to improve the spalling resistance in which fibrous materials are not lost even during decarburization and dephosphorization of molten iron, etc. It is in providing the manufacturing method of.

The features of the present invention for solving such problems are as follows.
(1) The average particle size is 5 to 40% by mass of 3 mm or more, 10 to 45% by mass of 1 to 3 mm, 15 to 30% by mass of 0.15 to less than 1 mm, and 5 to 45% by mass of less than 0.15 mm. At least one of Al ₂ O ₃ and MgO having a particle size distribution of, a graphite raw material, a liquid binder composed of an organic substance of 2 to 5% by mass as an outer shell, and MgO having an average particle size of 1 μm or less, A carbon-containing brick refractory characterized by mixing a raw material containing at least two kinds of powders of Al ₂ O ₃ and SiO ₂ with a kneader, molding with a press machine, and further curing. Manufacturing method.
(2) When two kinds of powders of MgO, Al ₂ O ₃ and SiO _{2 having} an average particle diameter of 1 μm or less are MgO + Al ₂ O ₃ , the blending amount of MgO is 5 to 40% by mass,
When the powder is MgO + SiO ₂ , the amount of SiO ₂ is 40-60% by mass,
When the powder is SiO ₂ + Al ₂ O ₃ , the blending amount of Al ₂ O ₃ is 60 to 80% by mass, The method for producing a carbon-containing brick refractory according to (1), .
(3) The method for producing a carbon-containing brick refractory according to (1) or (2), further comprising firing after the curing.
(4) The method for producing a carbon-containing brick refractory according to any one of (1) to (3), wherein an iron-containing material is further added to the blended raw material.
(5) The addition amount of the iron-containing material is 0.02% by mass or more and 0.3% by mass or less with respect to the blended raw material. The carbon-containing brick refractory according to (4), Production method.
(6) The total mass of at least two kinds of powders of MgO, Al ₂ O ₃ and SiO _{2 having} an average particle diameter of 1 μm or less, and the iron-containing material is 0.5 mass relative to the blended raw material. % Or more and 4 mass% or less, The method for producing a refractory material containing carbon according to (4) or (5).

  The carbon-containing brick refractory manufactured by the manufacturing method according to the present invention generates a fibrous material composed of an oxide. Fibrous materials composed of oxides are not oxidized and lost even during decarburization or dephosphorization of molten iron. For this reason, even if a carbon-containing brick refractory is used for decarburization or dephosphorization of molten iron or the like, the high spalling resistance of the brick refractory is maintained. Thus, by carrying out the present invention, a carbon-containing brick refractory that can maintain high spalling resistance even when the brick refractory is used for decarburization or dephosphorization can be produced.

It shows an SEM photograph of MgAl ₂ O ₄ system whiskers. It shows an SEM photograph of the MgO-SiO ₂ system whiskers. Al ₂ O ₃ shows an SEM photograph of -SiO ₂ system whiskers. Shows an SEM photograph of MgAl ₂ O ₄ based whisker was generated by the addition of iron powder. It is a figure explaining the crack generation | occurrence | production of a brick refractory by a whisker, and a crack growth inhibitory function.

In order to improve the strength and spalling resistance of brick refractory by resisting cracking growth by bridging and withstanding oxidizing atmosphere or smelting, it is an oxide-based fibrous material that is stable at high temperatures. The generation of whiskers is desired. Examples of oxide-based whiskers include spinel (MgAl ₂ O ₄ ) whiskers, magnesium silicate (Mg ₂ SiO ₄ , MgSiO ₃ ) whiskers, mullite (3Al ₂ O ₃ .2SiO ₂ ) whiskers, and the like. As a result of studying whether oxide-based whiskers can be synthesized by heating, the inventors have clarified that oxide-based whiskers are generated by a synthesis reaction between fine particles having a particle diameter of 1 μm or less. The bridging will be described later.

First, generation of these oxide-based whiskers will be described. The production of oxide whiskers was examined by the following procedure. A group of MgO, Al ₂ O ₃ and SiO ₂ particles having a particle size of 1 μm or less were mixed at a ratio of stoichiometric composition of MgAl ₂ O ₄ , Mg ₂ SiO ₄ , MgSiO _3, 3Al ₂ O ₃ .2SiO ₂ . Further, a powder obtained by mixing them and powdered carbon black was compacted and fired at 1400 ° C. for 3 hours in a reducing atmosphere. When the fired body after firing was observed using an SEM, MgAl ₂ O ₄ -based, MgO—SiO ₂ -based, and Al ₂ O ₃ —SiO ₂ -based whiskers were confirmed. Note that MgO, Al ₂ O ₃ , and SiO ₂ having a particle size of 1 μm or less refer to powders that have passed through a mesh having an opening of 1 μm, and are hereinafter referred to as “fine particles”.

FIG. 1 shows an SEM photograph of MgAl ₂ O ₄ based whiskers. FIG. 2 shows an SEM photograph of MgSiO ₃ whisker. FIG. 3 shows a SEM photograph of Al ₂ O ₃ —SiO ₂ whisker.

Further, in the MgAl ₂ O ₄ system, 1 g of iron powder having a particle size of 200 μm or less is added to 8 g of MgO and Al ₂ O ₃ and compacted, and fired at 1400 ° C. for 3 hours in a reducing atmosphere. did. The iron powder having a particle size of 200 μm or less means iron powder that has passed through a mesh having an opening of 200 μm.

FIG. 4 shows a SEM photograph of MgAl ₂ O ₄ whisker produced by adding iron powder. By adding iron powder, as shown in FIG. 4, many fine fibrous whiskers were observed as compared with FIG. From this, it is thought that iron powder functioned as a catalyst and produced many fine MgAl ₂ O ₄ type whiskers. Incidentally, with reference to FIG. 4, although fine fibrous whisker of MgAl ₂ O ₄ system is an example that can be generated by adding iron powder, even MgSiO ₃ or _Al 2 _O 3 -SiO ₂ -based whiskers, A fine fibrous whisker can be generated by adding 1 g of iron powder having a particle size of 200 μm or less to 8 g of the total amount of blended raw materials.

The composition of the whiskers shown in FIGS. 1, 2, 3 and 4 was analyzed using SEM-EDS. Similarly, the crystal structure of these whiskers was analyzed using TEM. As a result, whiskers shown in Figure 1, 2 and 3, respectively MgAl ₂ O ₄ whiskers, MgSiO ₃ whiskers, mullite _{(3Al 2 O 3 · 2SiO 2} ) in at near _Al 2 _O 3 -SiO ₂ -based whiskers I found out. Further, the fine whiskers shown in Figure 4, was found to be MgAl ₂ O ₄ whiskers.

  Next, a whisker generation mechanism will be described. MgO particles and carbon black react as shown in chemical reaction formula (1) below to generate Mg gas.

  MgO (s) + C (s) = Mg (g) + CO (g) ·· Chemical reaction formula (1)

  Or, first, carbon and oxygen in the atmosphere react as shown in chemical reaction formula (2) below to generate CO. Next, the generated CO gas reacts with the MgO particles as shown in the chemical reaction formula (3) shown below to generate Mg gas.

C (s) + 1 / 2O ₂ (g) = CO (g) —chemical reaction formula (2)

MgO (s) + CO (g) = Mg (g) + CO ₂ (g) ·· chemical reaction formula (3)

In the MgAl ₂ O ₄ system, the Mg gas generated in the chemical reaction formula (1) or (3) reduces Al ₂ O ₃ as in the chemical reaction formula (4) to generate Al gas.

3Mg (g) + Al ₂ O ₃ (s) = 3MgO (s) + 2Al (g) ·· chemical reaction formula (4)

The generated Al gas reacts with Mg gas and CO gas as shown in chemical reaction formula (5) to generate spinel (MgAl ₂ O ₄ ) whiskers.

Mg (g) + 2Al (g) + 4CO (g) = MgAl ₂ O ₄ (s) + 4C (s) ·· chemical reaction formula (5)

Alternatively, MgAl ₂ O ₄ whiskers are generated by reacting with Mg gas, Al ₂ O ₃ , and CO gas as shown in chemical reaction formula (6).

Mg (g) + Al ₂ O ₃ (s) + CO (g) = MgAl ₂ O ₄ (s) + C (s) ·· chemical reaction formula (6)

Alternatively, MgAl ₂ O ₄ whiskers are generated by reacting with Mg gas, Al ₂ O ₃ , and CO ₂ gas as shown in chemical reaction formula (7).

Mg (g) + Al ₂ O ₃ (s) + CO ₂ (g) = MgAl ₂ O ₄ (s) + CO (s) ·· chemical reaction formula (7)

In the MgO—SiO ₂ system, magnesium silicate (Mg) is produced by Mg gas generated by the chemical reaction formula (1), CO ₂ gas generated by the chemical reaction formula (3), and SiO gas generated by the chemical reaction formula (8). ₂ SiO ₄ , MgSiO ₃ ) whiskers are considered to be formed.

SiO ₂ (s) + C (s) = SiO (g) + CO (s) ·· chemical reaction formula (8)

That is, SiO gas reacts with Mg gas and CO ₂ gas as shown in chemical reaction formula (9) to produce MgSiO ₃ whiskers.

Mg (g) + SiO (g) + 2CO ₂ (g) = MgSiO ₃ + 2CO (g) ·· chemical reaction formula (9)

Alternatively, SiO gas reacts with Mg gas and CO ₂ gas as shown in chemical reaction formula (10) to produce Mg ₂ SiO ₄ whiskers.

2Mg (g) + SiO (g) + 3CO ₂ (g) = Mg ₂ SiO ₄ + 3CO (g) ·· chemical reaction formula (10)

In the Al ₂ O ₃ —SiO ₂ system, the SiO gas generated by the chemical reaction formula (8) reacts with Al ₂ O ₃ to produce mullite (3Al ₂ O ₃ · 2SiO ₂ ) whiskers or Al close to the composition. _It is considered that ₂ O ₃ —SiO ₂ type whiskers are formed. That is, SiO gas reacts with Al ₂ O ₃ and CO ₂ gas as shown in the chemical reaction formula (11) to produce Al ₂ O ₃ —SiO ₂ whiskers.

3Al ₂ O ₃ (s) + 2SiO (g) + 2CO ₂ (g) = 3Al ₂ O ₃ .2SiO ₂ + 2CO (g) .. chemical reaction formula (11)

In addition, iron is present as a simple metal or in the form of iron oxide by reacting with CO _2, and it is considered that they act as a catalyst. It has been reported in various fields that Group VIII elements such as iron, nickel and cobalt generally have a catalytic action, and in the presence of these elements, nanomaterials such as carbon nanotubes are likely to grow.

The addition amount of the iron-containing material is preferably 0.02% by mass or more and 0.3% by mass or less in terms of metallic iron in the entire blended raw material (excluding the liquid binder) constituting the brick refractory. The addition amount of the iron-containing material less than 0.02% by mass is less effective as an iron catalyst for at least two kinds of powders of MgO, Al ₂ O ₃ and SiO ₂ having an average particle diameter of 1 μm or less. Therefore, it is not preferable. On the other hand, an addition amount of iron-containing material of more than 0.3% by mass is not preferable because the iron content in the brick refractory matrix increases excessively and adversely affects the corrosion resistance. The iron-containing material to be added is preferably metal iron powder (atomized powder or the like), but may be iron oxide or an iron compound (organic compound such as ferrocene or iron carbonate). Good.

  For example, when iron oxide is added, the iron oxide is reduced by the CO gas generated in the chemical reaction formula (1) under a high temperature condition to produce metallic iron. The metallic iron becomes very fine grain iron and can be a preferable catalyst for whisker production.

In addition, the total mass of at least two kinds of powders of MgO, Al ₂ O ₃ , SiO ₂ having an average particle diameter of 1 μm or less, and the iron-containing material to be added is based on the blended raw materials constituting the brick refractory. It is preferable that they are 0.5 mass% or more and 4 mass% or less. A total mass of less than 0.5% by mass is not preferred because the amount of whisker produced by the fine compound is reduced and the mechanical properties of the refractory are not improved. Further, a total mass of more than 4% by mass is not preferable because the fine powder region in the brick refractory matrix becomes excessive and molding becomes difficult. Further, a total mass of more than 4% by mass is not preferable because the porosity of the brick refractory is increased, and the strength and corrosion resistance of the brick refractory are reduced. Further, three kinds of powders of MgO, Al ₂ O ₃ and SiO ₂ may be added, and in this case, plural kinds of whiskers are generated. When the particle size of at least two kinds of powders among MgO, Al ₂ O ₃ , and SiO ₂ becomes small, the surface area of the powder becomes large. _{Accordingly, MgO, Al 2 O 3,} SiO 2 improved reactivity between the particles and the carbon black, whiskers are produced. Therefore, the average particle diameter of MgO, Al ₂ O ₃ and SiO ₂ was set to 1 μm or less. The average particle size is an arithmetic average particle size, and is calculated by measuring the particle size distribution of each particle and calculating “each particle size × ratio”.

The preferred blending ratio of MgO: Al ₂ O ₃ , MgO: SiO ₂ , Al ₂ O ₃ : SiO ₂ is such that the MgO blending amount is 5 to 40% by mass when producing MgAl ₂ O ₄ -based whiskers. Is preferred. Further, in the case of producing the MgO + SiO ₂ based whisker, it is preferable that the SiO ₂ amount to 40 to 60 mass%. _Further, in the case of producing a SiO 2 + _Al 2 _{O 3} based whisker, it is desirable that the _Al 2 _{O 3} amount in the 60 to 80 mass%. These blending amounts are derived from the stoichiometric relationship of the chemical reaction formula in which each whisker is generated.

MgAl ₂ O ₄ whiskers, MgSiO ₃ , Mg ₂ SiO ₄ whiskers and Al ₂ O ₃ —SiO ₂ whiskers are also generated in refractories such as various carbon-containing bricks such as MgO—C and Al ₂ O ₃ —C. These whiskers bridge the brick in the refractory and prevent the development of cracks in the brick refractory.

  FIG. 5 is a diagram for explaining the function of suppressing crack propagation of a brick refractory by a whisker. In FIG. 5, the brick refractory 10 is a brick refractory produced by the whisker 12. The brick refractory 10 has a crack 14, and the crack 14 is about to progress in the direction indicated by the arrow 16.

  As shown in FIG. 5, the whisker 12 that has been generated slightly backward from the tip of the crack 14 mechanically suppresses the opening of the crack 14 generated in the brick refractory 10 by bridging. Thereby, the progress of the crack 14 is suppressed by the whisker 12. Thus, it is called bridging that the whisker 12 generated in the brick refractory 10 suppresses the progress of the crack 14. In addition, the whisker 12 also suppresses the generation of the crack 14 by bridging described above in a state where the crack 14 is not generated in the brick refractory 10.

It is generally known that the whisker 12 is a single crystal and has high strength. All of the whiskers 12 generated this time have high strength. Therefore, since the whisker 12 does not break in the middle, it can suppress that the crack 14 generate | occur | produces in the brick refractory 10. Further, the whisker 12 can suppress the progress of the crack 14 even if the crack 14 is generated in the brick refractory 10. Thereby, the intensity | strength improvement of the brick refractory 10 which produced the whisker 12, and the improvement of spalling resistance are realizable. Note that the brick refractory 10 is not limited to various carbon-containing bricks such as MgO—C and Al ₂ O ₃ —C, and may be a brick refractory to which SiC is added.

Next, the manufacturing method of the carbon-containing brick refractory which has the whisker mentioned above is demonstrated. As a raw material for brick refractory, the average particle size is 5 to 40% by mass of 3 mm or more, 10 to 45% by mass of 1 to 3 mm, 15 to 30% by mass of 0.15 to less than 1 mm, and less than 0.15 mm. At least _{two of} Al ₂ O ₃ and MgO having a particle size distribution of 5 to 45% by mass, a graphite raw material, and MgO, Al ₂ O ₃ and SiO ₂ having an average particle size of 1 μm or less Fine particles, a liquid binder, and a curing agent were used. The particle size distribution in at least one compound of Al ₂ O ₃ and MgO as the brick refractory raw material is a particle size distribution derived from the formula of Andreasen. By satisfying the particle size distribution, a dense brick having a high packing density of the material can be made a refractory.

In addition, as Al ₂ O ₃ and MgO as a blending raw material of the brick refractory, any of electrofused products, sintered products, and natural materials (including seawater MgO) may be used. As the graphite raw material, any of scale-like graphite, carbon black, and thin graphite may be used regardless of the particle size. Further, the addition amount of the graphite raw material is preferably 1% by mass or more and 50% by mass or less with respect to the blended raw material of the brick refractory. In addition, it is more preferable that the addition amount of the graphite raw material is 1% by mass or more and 10% by mass or less because a brick having low thermal conductivity and high spalling resistance can be formed as a refractory.

  The liquid binder is generally a liquid resin made of an organic material that is cured by a curing agent when a carbon-containing brick refractory is prepared. The addition amount of the liquid binder was set to be 2.0% by mass or more and 5.0% by mass or less, based on the blended raw material of the brick refractory. If the added amount of the binder is less than 2.0% by mass, the brick refractory cannot be molded. If the added amount is more than 5.0% by mass, the binder protrudes from the mold during molding and sufficient molding cannot be performed. The curing agent may be any substance that cures the liquid binder, and the addition amount is preferably 1/10 of the binder addition amount. Here, the outer cover indicates a ratio in which the total mass of other compounding raw materials excluding the liquid binder is 100. The curing agent may not be added depending on the type of the binder.

  Brick refractories containing raw materials that produce whiskers are used in refining equipment for iron making used in high-temperature processes. For example, when the brick is used as a refractory lining for a converter used for decarburization and refining of molten iron, a hot brick equivalent to the molten steel temperature at the time of steel removal from the hot metal temperature at the start of decarburization refining becomes a refractory. Is granted. The heat can be used to produce whiskers in the brick refractory. Therefore, the carbon-containing brick refractory manufacturing method may be substantially the same as the conventional process. That is, a brick refractory can be manufactured by kneading the raw materials without kneading them in a high-temperature environment after kneading them with a kneader. Here, the curing refers to a treatment in which the binder and the curing agent are reacted and cured by heating to about 120 to 300 ° C. and supplying thermal energy to the binder made of an organic material. Note that the curing may be performed in an inert atmosphere or in an air atmosphere.

  Brick refractories hardened by curing are repeatedly decarburized by being used in steelmaking refining equipment. For example, the heat of molten iron exceeding 1400 ° C during decarburization refining is applied. It is done. By applying the heat exceeding 1400 ° C., the brick refractory is fired, and the whisker can be generated in the brick refractory. Thereby, the brick refractory becomes a brick refractory having high spalling resistance. In addition, a separate firing step may be provided, and the carbon-containing brick refractory after the curing is performed may be fired at a temperature of 1300 ° C. to 1400 ° C. for 3 hours to generate whiskers in the brick refractory in advance.

  An MgO—C brick refractory was produced using a fused MgO aggregate having a maximum particle size of 5 mm, MgO fine powder of 1 mm or less, and phosphorous graphite. The carbon concentration in the brick refractory was 20.0% by mass. Table 1 shows the composition of the reference MgO-C brick refractory. The particles of this brick refractory having a size of 0.15 mm or less were replaced with fine particles having an average particle size of 1 μm or less.

Table 2 shows a list of inventive examples and comparative examples. Invention Example 1 prepares fine particles in which MgO having a particle size of 0.15 μm and Al ₂ O ₃ having a particle size of 0.3 μm are mixed at a compounding ratio of MgO: Al ₂ O ₃ = 30: 70. Fine particles in an amount of 4% by mass with respect to the amount of raw material were replaced with particles of brick refractory of 0.15 mm or less. No added metal element was added.

Invention Example 2 prepares fine particles obtained by mixing MgO having a particle size of 0.5 μm and SiO ₂ having a particle size of 0.6 μm at a compounding ratio of MgO: SiO ₂ = 50: 50. The amount of fine particles of 2% by mass was replaced with 0.15 mm or less particles of brick refractory. No added metal element was added.

Invention Example 3, _Al 2 _{O 3} and 0.1 [mu] m SiO ₂ of a particle size of _{0.1μm Al 2 O 3: SiO 2} = 65: Prepare 35 mixed fine particles in compounding ratio of the brick refractory The fine particles in an amount of 2% by mass with respect to the blended raw material amount were replaced with particles of 0.15 mm or less of brick refractory. No added metal element was added.

Invention Example 4 prepares fine particles in which MgO having a particle size of 0.05 μm and Al ₂ O ₃ having a particle size of 0.03 μm are mixed at a compounding ratio of MgO: Al ₂ O ₃ = 35: 65, and is a raw material for brick refractory The amount of fine particles of 2% by mass with respect to the amount was replaced with particles of 0.15 mm or less of brick refractory. As the additive metal element, iron powder having a particle size of 100 μm was added in an amount of 0.2% by mass with respect to the amount of the raw material for the brick refractory.

  On the other hand, in the comparative example 1, it mixed as the mixing | blending shown in Table 1, and nothing was added as an additional metal element. Comparative Example 2 was also mixed according to the formulation shown in Table 1, but Al powder was added as an additive metal element in an amount of 3.0% by mass with respect to the amount of blended refractory material. In the comparative example 3, it mixed as the mixing | blending shown in Table 1, and Si powder of the quantity used as 3.0 mass% with respect to the mixing | blending raw material quantity of a brick refractory was added as an additional metal element.

Comparative Example 4 prepared particles in which MgO having a particle diameter of 1.5 μm and 3.0 μm of SiO ₂ were mixed at a mixing ratio of MgO: SiO ₂ = 30: 70. Particles in an amount of mass% were replaced with particles of 0.15 mm or less of brick refractory. No added metal element was added.

Comparative Example 5 prepared particles in which MgO having a particle size of 5.0 μm and SiO ₂ having a particle size of 6.0 μm were mixed at a compounding ratio of MgO: SiO ₂ = 50: 50. Particles in an amount of mass% were replaced with particles of 0.15 mm or less of brick refractory. No added metal element was added.

Comparative Example 6 prepared particles in which Al ₂ O ₃ having a particle diameter of 1.2 μm and SiO ₂ having a diameter of 1.5 μm were mixed at a mixing ratio of Al ₂ O ₃ : SiO ₂ = 50: 50, and the mixture of brick refractory The amount of particles of 2% by mass with respect to the amount of raw material was replaced with particles of 0.15 mm or less of brick refractory. No added metal element was added.

Comparative Example 7 prepared particles in which MgO having a particle size of 5.0 μm and Al ₂ O ₃ having a particle size of 3.0 μm were mixed at a mixing ratio of MgO: Al ₂ O ₃ = 50: 50, and the amount of the raw material for the brick refractory 2% by mass of the particles were replaced with 0.15 mm or less particles of brick refractory. As the additive metal element, iron powder having a particle size of 100 μm was added in an amount of 0.2% by mass with respect to the amount of the raw material for the brick refractory.

  After blending the raw materials in both the inventive example and the comparative example, phenol resin is used as the liquid binder, and the liquid binder in an amount of 3% by mass is mixed with the brick refractory raw material, and kneaded by a kneader. went. Thereafter, molding was performed using a friction press. The molded product was held at 230 ° C. for 24 hours and cured, and then fired by holding at 1350 ° C. in a reducing atmosphere for 3 hours to obtain a sample for evaluation. In the evaluation, bending strength σ (MPa) and elastic modulus (dynamic elastic modulus) E were measured as mechanical properties, and a thermal shock fracture resistance coefficient R was derived according to the following mathematical formula (1). It can be said that the larger the value of the thermal shock fracture resistance coefficient R, the harder it is to break.

  R = σ / E .. Formula (1)

  Next, the spalling test of the MgO-C brick refractory was performed. A brick refractory sample was placed in an electric furnace heated to 1400 ° C., heated for a predetermined time, and then rapidly cooled by being immersed in running water maintained at 20 ° C. This operation was repeated 1 to 10 times per sample. The in-furnace holding time and quenching time are both 15 minutes. The surface of the brick refractory after heating and quenching 10 times was visually observed to compare the presence or absence of cracks on the brick surface after the spalling test.

  Furthermore, in order to evaluate the corrosion resistance of the brick refractory to the slag, a erosion test was conducted. A hole having a diameter of 30 mm and a depth of 20 mm was made in a brick refractory, and a slag having a composition shown in Table 3 was charged therein, and held at 1500 ° C. for 3 hours in a nitrogen atmosphere. After cooling, the sample was divided into two and the amount of erosion loss was measured. Then, the melting rate was calculated by dividing the measured amount of melting by the holding time.

  Table 4 shows the results of bending strength, elastic modulus, thermal shock fracture resistance coefficient R, the presence or absence of cracks on the brick refractory surface after the spalling test, and the melting rate in each sample. The “very fine crack” as a result of the presence or absence of cracks on the brick refractory surface after the spalling test is a crack having a length of 20 mm or less and a width and depth of less than 0.1 mm. The “fine crack” in the result is a crack having a length of 20 mm or less and a width and a depth of 0.1 mm or more, and the “large crack” is a crack having a length of 20 mm or more. .

  Inventive Examples 1 to 3 in which fine particles having an average particle diameter of 1 μm or less are added in the range of 0.05 to 4% by mass have increased strength and elastic modulus as compared with Comparative Example 1, and Comparative Examples 1 to 3 Compared to the above, the thermal shock fracture resistance coefficient R value was improved. Furthermore, Invention Example 4 to which 0.2% by mass of iron powder was added had the largest thermal shock fracture resistance coefficient R value.

When comparing the results of the spalling test, no cracks were observed on the surface of the brick refractory in the inventive examples 1 to 4, but the fine cracks in the comparative example 1 and the relatively large cracks in the comparative examples 2 and 3 Brick was observed on the surface of the refractory. This has the same tendency as the thermal shock fracture resistance coefficient R value of the inventive example being larger than that of the comparative example. Further, Comparative Examples 4 to 7 to which fine MgO, Al ₂ O ₃ , and SiO ₂ particles having a particle diameter of 1 μm or more were added had a thermal shock fracture resistance coefficient R larger than that of Comparative Examples 1 to 3. It is smaller than Invention Examples 1-4. Moreover, the big difference was not looked at by the melting rate in the invention examples 1-4 and the comparative examples 1-6. That is, the corrosion resistance to the slag was the same in both the invention example and the comparative example.

  Thus, the thermal shock destruction resistance coefficient R of the brick refractory became high in invention examples 1-4 rather than any of comparative examples 1-6. As described above, the larger the thermal shock fracture resistance coefficient R value, the harder the material to break. Therefore, it can be said that Invention Examples 1-4 are refractory materials which are hard to break compared with Comparative Examples 1-6. Similar results were obtained in the spalling test. That is, in Comparative Examples 1 to 6, the occurrence of cracks was confirmed by the spalling test, whereas in Invention Examples 1 to 4, the occurrence of cracks was not confirmed. From these results, it was clarified that the whisker, which is a fibrous material produced in Invention Examples 1 to 4, does not disappear due to oxidation even after the 1400 ° C. spalling test. As a result, the carbon-containing brick refractory produced by the practice of the present invention maintains the high spalling resistance of the brick refractory without causing the fibrous material to disappear even during decarburization and dephosphorization of molten iron and the like. It became clear that we could do it.

  It can be used as a method for producing a refractory for lining refractories for refining equipment for iron making used in high temperature processes, particularly for bricks using carbon as a part of raw materials.

10 Brick refractory 12 Whisker 14 Crack 16 Arrow

Claims (6)

The average particle size is 5 to 40% by mass of 3 mm or more, 10 to 45% by mass of 1 to 3 mm, 15 to 30% by mass of 0.15 to less than 1 mm, and 5 to 45% by mass of less than 0.15 mm. and at least one _Al 2 _{O 3} and MgO having a graphite material, a binder liquid composed of 2 to 5% by weight of organic substances in outer percentage, MgO average particle diameter of 1μm or less, _Al 2 O _{3. A} method for producing a carbon-containing brick refractory, comprising mixing a raw material containing at least two kinds of powders of SiO ₂ with a kneader, molding using a press machine, and further curing the mixture. . When the two kinds of powders of MgO, Al ₂ O ₃ and SiO _{2 having} an average particle diameter of 1 μm or less are MgO + Al ₂ O ₃ , the blending amount of MgO is 5 to 40% by mass,
When the powder is MgO + SiO ₂ , the amount of SiO ₂ is 40-60% by mass,
When the powder is a _SiO 2 + _Al 2 _{O 3} The manufacturing method of a carbon-containing bricks refractory according to claim 1, characterized in that 60 to 80 wt% of the amount of _Al 2 _{O 3} .   The method for producing a refractory material containing carbon according to claim 1 or 2, further comprising firing after the curing.   The method for producing a carbon-containing brick refractory according to any one of claims 1 to 3, wherein an iron-containing material is further added to the blended raw material.   The method for producing a carbon-containing brick refractory according to claim 4, wherein the iron-containing material is added in an amount of 0.02% by mass to 0.3% by mass with respect to the blended raw material. The total mass of at least two kinds of powders of MgO, Al ₂ O ₃ and SiO _{2 having} an average particle diameter of 1 μm or less, and the iron-containing material is 0.5% by mass or more and 4% by mass. The method for producing a carbon-containing brick refractory according to claim 4 or 5, wherein the content is not more than mass%.