JP2013253736A - Refractory for ferromanganese manufacturing furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reasonable and economical refractory for a ferromanganese manufacturing furnace, by preventing damage to the refractory due to slag containing much manganese oxide with strong erosion.SOLUTION: In a refractory for a ferromanganese manufacturing furnace, its main subject is alumina and carbon, and the content of alumina is 60-95 mass%, and the content of carbon is 5-40 mass%.

Description

  The present invention relates to a refractory for a ferromanganese manufacturing furnace.

Ferromanganese is manufactured by heating and melting manganese ore and coke in an electric furnace, reducing the manganese ore with coke, and adding iron ore and the like to adjust the iron content. By the way, generally 20-30% of manganese oxide is contained in the slag produced during the production of ferromanganese. In some cases, manganese oxide is reduced by collecting a reducing agent such as metallic silicon into the slag and recovered as manganese. Patent Documents 1 to 5 propose a low to medium carbon ferromanganese slag reduction method using a ladle.
For example, in US Pat. No. 6,057,049, oxidation blowing is applied to a molten manganese-based alloy in a vessel, the basic alloy being about 52% -70% manganese, about 15% -37% silicon and 3.5%. Manganese ore and coal are introduced into the molten metal during the oxidation blowing operation, and the introduction of oxygen causes stirring and combustion of the molten metal, during which the manganese content is higher than the base alloy And a ferromanganese alloy with a lower silicon content is made with a high manganese slag, to separate the ferromanganese alloy and the high manganese slag from each other and then react the new count base alloy with the slag The high manganese slag is separated from the new count molten base alloy in the vessel, followed by oxidation blowing, and at the same time manganese ore and coal are added to the molten master count alloy. Method for making a low to medium carbon ferromanganese alloy, wherein the obtaining is disclosed.
In Patent Document 2, molten manganese slag containing 10 to 40% Mn and Fe 1% or less and P 0.01% or less, reacting with the molten manganese slag containing Si 50% or more and P 0.05% or less. After charging the reaction vessel with a sufficient amount of iron alloy and iron making agent capable of producing low silicon ferromanganese with a Si content of 1.5% or less, the reaction vessel is allowed to perform a horizontal eccentric motion, and the charge is mixed and stirred. The manganese oxide of the molten manganese slag is reduced, and Mn is 90% or more, Si is 1.5% or less, C is 0.1% or less, and P is 0.05% or less. A manufacturing method is disclosed.
Furthermore, Patent Document 3 is characterized by receiving a melt of medium carbon ferromanganese slag having a basicity of 1.1 to 1.25 in a porous plug ladle, and adding and dissolving cold silicon manganese while stirring. A method for recovering Mn from medium carbon ferromanganese slag is disclosed.
Further, in Patent Document 4, molten slag containing manganese and iron alloy containing silicon are charged into a reaction vessel, and a stirring gas is supplied at 300 Nm / second or more from a nozzle installed in the charge. In addition, it is discharged into the charge at a rate of 0.2 Nl / min or more per kg of the charge, and the charge is stirred, and manganese-containing molten slag and silicon-containing alloy iron are reduced to contain manganese. A method for producing manganese-based alloy iron, characterized by producing alloy iron, is disclosed.
Further, in Patent Document 5, molten slag produced as a by-product during the production of ferromanganese is stored in a reaction vessel, and a reducing material containing alloy iron containing silicon and metallic aluminum is added to the molten slag and stirred. And the manufacturing method of manganese-type alloy iron from the byproduct slag characterized by reducing at least one part of the manganese oxide contained in the said molten slag is disclosed.

Japanese Patent Publication No.44-22734 Japanese Patent Publication No.57-36337 JP-A-61-157645 JP-A-3-49975 JP 2006-161079 A

  In the methods disclosed in Patent Documents 1 to 5, the ladle that receives the molten ferromanganese and the ladle for ferromanganese slag reduction recovery may actually be prepared separately. Many. Here, manganese oxide tends to react with silica, alumina, and magnesia, which are generally used as refractory aggregates that make up the ladle lining, and slag rich in manganese oxide makes refractory intense. Because of damage, it was difficult to extend the life of these ladles.

Patent Documents 1 to 5 disclose slag basicity at the time of producing low to medium carbon ferromanganese. Referring to the phase diagram of the CaO—SiO ₂ —Al ₂ O ₃ system, alumina has a high solubility in the slag of the composition, and produces a liquid phase in a wide composition range at a high temperature of 1700 ° C. or higher. On the other hand, referring to the phase diagram of the CaO—SiO ₂ —MgO system, magnesia has a low solubility with respect to the slag, and the composition range in which a liquid phase is generated even at a high temperature of 1700 ° C. or higher is slight. For this reason, as a refractory for the ladle for manganese recovery, a magnesia-based refractory has been conventionally used as disclosed in Patent Documents 1 and 3.

  Further, it is generally known that carbon is difficult to wet with slag composed of oxides and greatly improves the thermal conductivity of the refractory, so that the durability of the brick is improved by the cooling effect of the brick. For these reasons, MgO-C refractories have been used recently in producing ferromanganese. However, damage to the refractory was great, and it could not be said that sufficient durability was obtained, and improvement was required.

  Accordingly, an object of the present invention is to provide a rational and economical refractory for a ferromanganese manufacturing furnace by suppressing damage to the refractory by slag containing a large amount of manganese oxide having strong erosion power.

  That is, the present invention is a ferromanganese refractory for a ferromanganese manufacturing furnace, characterized by comprising mainly alumina and carbon, having an alumina content of 60 to 95% by mass and a carbon content of 5 to 40% by mass.

  In addition, the refractory for a ferromanganese manufacturing furnace of the present invention is characterized by containing silicon carbide in an amount of 20% by mass or less.

  Furthermore, the refractory for a ferromanganese manufacturing furnace of the present invention is characterized by containing periclase in an amount of 35% by mass or less.

  In addition, the present invention is characterized in that the refractory for a ferromanganese manufacturing furnace of the present invention is used in a ladle whose viscosity of an object to be processed is 0.5 poise or more.

  The refractory for a ferromanganese production furnace of the present invention can increase the viscosity of the refractory-slag interface, thereby providing excellent durability and greatly improving the damage rate.

The state of the vertical crack at the time of the actual furnace use of the refractory which consists of alumina content 63 mass%, carbon content 21 mass%, silicon carbide content 6 mass%, and other inevitable impurities is shown.

ここで、Ｃは、スラグ中の特定の耐火物成分の濃度、ｘは、耐火物壁面からの距離、Ｄは、拡散係数であり、Ｃ_ｅは、特定の耐火物成分のスラグへの飽和濃度、Ｃ_０は、スラグ中の特定の成分の濃度，δは、境膜厚さである。 The present inventors have made various studies in order to obtain a refractory having excellent corrosion resistance against slag generated during ferromanganese production. The mass transfer rate J when the refractory is dissolved in the slag is expressed by the following equation (1) (Fick's law):

Here, C is the concentration of a particular refractory components in the slag, x is the distance from the refractory walls, D is a diffusion coefficient, C _e is the saturation concentration of the slag of the particular refractory component , C ₀ is the concentration of a specific component in the slag, and δ is the film thickness.

In order to suppress the melting loss of the refractory from this equation, in other words, to reduce the mass transfer rate (J), the solubility of the refractory constituting particles must be decreased, that is, (C _e −C ₀ ) must be decreased. Presumed to be effective, the common response in the conventional refractory industry was based on this. In ladles that receive molten ferromanganese and ladles used to recover manganese from ferromanganese slag, improvements have been made with the main focus on lowering the solubility of refractory constituent particles as described above. And have achieved certain results. This is the result of using magnesia refractories. However, this approach is technically limited in order to further increase the durability.

  Therefore, even if the solubility increases somewhat, the mass transfer rate (J) can be reduced if the film thickness (δ) can be increased by increasing the viscosity of the refractory-slag interface. I thought. As a result of extensive studies from this point of view, by using mainly alumina and carbon, the slag viscosity at the refractory-slag interface can be increased and the film thickness (δ) can be increased. It has been found that the MgO-C brick that has been used has better corrosion resistance.

  On the other hand, there was a concern that the increase in slag viscosity could reduce the refining efficiency, but as a result of the trial of the actual machine, it was found that it was within the range where there was no problem. The present invention has been made based on such findings.

  That is, the refractory for a ferromanganese manufacturing furnace of the present invention is mainly characterized by alumina and carbon, the alumina content is 60 to 95% by mass, and the carbon content is 5 to 40% by mass.

  Since the refractory for a ferromanganese manufacturing furnace of the present invention contains alumina as a main component, the viscosity of the slag at the refractory-slag interface can be increased, thereby improving the corrosion resistance. In the refractory for a ferromanganese manufacturing furnace of the present invention, the content of alumina is preferably 60% by mass or more. If it is less than this, the slag viscosity at the refractory-slag interface will not increase, and the corrosion resistance cannot be improved. More preferably, it is 70 mass% or more. On the other hand, if the content of alumina exceeds 95% by mass, cracking and peeling due to oversintering become prominent and the durability decreases, which is not preferable. More preferably, it is 93 mass% or less.

On the other hand, the solubility with respect to the slag of the refractory for a ferromanganese manufacturing furnace increases by making alumina a main component. In a general ladle, an increase in the solubility of refractories in slag causes a decrease in corrosion resistance. However, when a ferromanganese furnace refractory is used as a lining material for a ladle for recovering manganese, for example, Rising is not a big problem. The reason for this is not necessarily clear:
That is, the largest cause is the viscosity of the ladle contents. For example, in the case of a general steelmaking ladle, the viscosity of the molten steel as the contents is several centipoise. In the case of a ladle for molten steel, the slag is not only floating on the ladle surface but also finely suspended in the molten steel. Suspended slag adheres to the refractory surface of the steel bath and reacts with the refractory to cause erosion. At this time, when the content of the ladle is small, such as molten steel, when the ladle content is greatly agitated, the slag adhering to the surface of the refractory is easily peeled off from the interface by the flow of the molten steel. The length (δ) becomes smaller. For this reason, even if the viscosity of the slag increases due to dissolution of alumina, it does not have a significant effect. In the slag line portion, although the slag viscosity is high, the slag is vigorously stirred by the flow of the molten steel, so that the boundary film thickness δ is kept small in this case as well. Therefore, even in this part, even if the viscosity of the slag increases due to the dissolution of alumina, there is no significant effect.

  On the other hand, when the refractory for the ferromanganese manufacturing furnace is used as the lining material for the ladle for manganese recovery, the ladle for manganese recovery treats slag, and the ladle contents, that is, the viscosity of the slag is several The poise is 2 orders of magnitude larger than the molten steel. In order to increase the speed of the reduction reaction, methods such as those disclosed in Patent Documents 1 to 5 are applied. However, since the slag viscosity is high, it is not as stirred as the molten steel in the molten steel ladle. For this reason, the film thickness (δ) increases. At this time, it is considered that when the alumina melts between the refractory and the slag and the slag viscosity increases, the boundary film thickness (δ) further increases and the corrosion resistance improves.

  In other words, the method of reducing the dissolution rate, that is, improving the corrosion resistance by always increasing the boundary film thickness (δ) due to the increase in slag viscosity while allowing the increase in solubility can always be established. It is not a technique. This method can be established only when the viscosity of the workpiece in the ferromanganese manufacturing furnace is high. Therefore, the viscosity of the object to be processed is preferably 0.5 poise or more. When smaller than this, the improvement effect of the corrosion resistance of the refractory for a ferromanganese manufacturing furnace of the present invention may not be exhibited. More preferably, it is in the range of 2 to 30 poise. If the viscosity of the workpiece exceeds 30 poise, the viscosity becomes too high, and the contents of the ladle cannot be sufficiently stirred, which is not preferable because the operation may be hindered.

  The alumina raw material used in the refractory for the ferromanganese manufacturing furnace of the present invention includes commercially available fused alumina such as white fused alumina and brown fused alumina, sintered alumina, calcined alumina, and calcined bauxite. Or natural alumina such as calcined clay shale can be used, and one or more selected from these can be used. Inevitable impurities derived from these components are allowed.

  By containing carbon, the refractory for a ferromanganese manufacturing furnace of the present invention can impart resistance to wetting of slag to the refractory, suppress slag infiltration, and suppress spalling. The carbon content is preferably 5% by mass or more. When the carbon content is less than 5% by mass, slag infiltration into the refractory cannot be suppressed, and peeling due to slag infiltration may occur frequently, resulting in a short life. As the carbon content increases, the refractory becomes higher in thermal conductivity, so that the refractory contributes to the improvement of the viscosity of the slag near the refractory-slag boundary due to the cooling effect, and can further increase the durability. . However, if the carbon content exceeds 40% by mass, the cooling effect becomes excessive, and the molten metal temperature is lowered, which may hinder the operation. Therefore, the carbon content is preferably 5 to 40% by mass, more preferably 7 to 30% by mass.

  As the carbon source, in addition to scaly graphite generally used for refractories, various materials such as spherical graphite, artificial graphite, powder pitch, and carbon black can be used, and one or more kinds can be used. it can.

  The refractory for a ferromanganese manufacturing furnace of the present invention may further contain silicon carbide in an amount of 20% by mass or less. Silicon carbide works effectively as an antioxidant for carbon. Moreover, since silicon carbide has a high thermal conductivity, it can provide a cooling effect in the same manner as carbon. However, if the content of silicon carbide exceeds 20% by mass, the corrosion resistance of the refractory is lowered and the durability becomes low, which is not preferable. Therefore, when the refractory for a ferromanganese manufacturing furnace of the present invention contains silicon carbide, the content of silicon carbide is preferably 20% by mass or less, more preferably 15% by mass or less. Silicon carbide is mainly composed of silicon carbide such as generated powder after polishing any material using silicon carbide-based abrasives and silicon carbide-based abrasives in addition to commercially available silicon carbide raw materials of various purity levels. Anything can be used.

Although the refractory for a ferromanganese manufacturing furnace of the present invention is mainly composed of alumina and carbon as described above, a longitudinal crack accompanying cooling is rarely observed. FIG. 1 is a photograph showing the state of vertical cracks when a refractory consisting of alumina content 63 mass%, carbon content 21 mass%, silicon carbide content 6 mass%, and other inevitable impurities is used in an actual furnace. This is considered to be due to a lack of residual expansibility of the refractory. As a countermeasure against the longitudinal crack, the refractory for a ferromanganese manufacturing furnace of the present invention can further contain periclase (MgO) in order to impart residual expansion to the refractory. Periclase is a magnesia (MgO) crystal that reacts with alumina (Al ₂ O ₃ ) at a high temperature to produce spinel (MgAl ₂ O ₄ ), which causes volume expansion, giving the refractory a residual expansion property. can do. When the periclase content is increased, the residual expansibility also increases. However, if the periclase content exceeds 35% by mass, separation occurs due to the tissue gap between the working surface and the back surface due to the spinel formation reaction between alumina and periclase near the working surface. This is not preferable because Therefore, in the refractory for a ferromanganese manufacturing furnace of the present invention, the content of periclase is desirably 35% by mass or less, more preferably 30% by mass or less.

  Further, the content of periclase in a magnesia-containing raw material or a refractory containing the same can be estimated from chemical analysis, and can be quantified from X-ray diffraction analysis. For example, the high-purity magnesia raw material consists of periclase. When some inevitable impurities are included, since the inevitable impurities and magnesia form a compound, the periclase content can be quantified with a certain degree of accuracy from the amount. On the other hand, by using a powder X-ray diffraction method, periclase as a mineral composition can be quantified.

  As the raw material for periclase, commercially available electrofused magnesia, sintered magnesia, seawater magnesia, dead-burned magnesia, and the like can be used. In addition, magnesia bricks after use can be used as long as they are mainly magnesia. Although there is no restriction | limiting in particular about the particle size of magnesia, when it adds by the particle size exceeding 1 mm, expansion | swelling behavior will be loose and it will expand | swell continuously. When added as a fine powder of 1 mm or less, the reaction between magnesia and alumina tends to proceed and a large residual expansion is obtained.

  Furthermore, for the refractory for the ferromanganese manufacturing furnace of the present invention, metal silicon, metal aluminum, metal magnesium, aluminum-magnesium alloy, iron powder, etc. are used as metal powder for preventing carbon oxidation and imparting strength of the refractory. It is possible, and one or more of these can be selected and blended. The amount of these metal powders is 0.2 to 5% by mass on the outer shell, preferably 0.5 to 3% by weight on the outer shell. If the amount of the metal powder is less than 0.2% by mass, it is not preferable because the effect is not exhibited. If the amount is more than 5% by mass, the amount of expansion due to oxidation of the metal powder in use is large. Since it becomes too much, it is not preferable.

  There are various binders used in the refractory for the ferromanganese manufacturing furnace of the present invention, and basically there are no particular limitations including organic and inorganic types. The amount of the binder is 0.5 to 6% by mass on the outer shell, preferably 1.5 to 4% by weight on the outer shell. If the amount of the binder is less than 0.5% by mass, it is not preferable because the effect is not exhibited, and if it exceeds 6% by mass, the porosity after heating is not preferable. .

  In addition, as described above, organic binders such as phenol resin, pulp waste liquid, molasses, epoxy resin, and liquid dextrin may be thermally decomposed when heated in a non-reducing atmosphere, and some of them may remain as carbon. This carbon is preferable because it has good dispersibility and can contribute to improvement of refractory characteristics. However, the amount of residual carbon may not be specified because it varies depending on the use conditions, and is not included in the above-described carbon content.

As the inorganic binder, alumina cement, bitter (MgCl ₂ ), alkali metal silicate such as sodium silicate and potassium silicate, sodium aluminate and the like can be used.

  The refractory for a ferromanganese production furnace of the present invention is mainly composed of alumina and carbon as described above, and has the silicon carbide content and / or the periclase content. In the refractory for a ferromanganese manufacturing furnace of the present invention, if the alumina content, carbon content, silicon carbide content and periclase content are within the above ranges, other refractory oxides such as silica, magnesia, calcia In addition, one or more compounds containing zirconia, chromia, or the like, or a compound of these and alumina, or one or more of a solid solution may be used. Inevitable impurities derived from these components are acceptable.

  The refractory for a ferromanganese production furnace of the present invention can be used as a brick in a ferromanganese production furnace. The method for producing the brick is not particularly limited. For example, the above raw materials are mixed or kneaded with a mixer or a kneader, all at once or divided. In general, kneading, which is a pre-processing step of brick press molding, includes a roller type SWP, a Simpson mixer, a blade type high speed mixer, a pressure type high speed mixer, a Henschel mixer, or a pressure kneader. A kneading machine called a roller type MKP, a wet pan, a Conner mixer, a blade type Eirich mixer, a vortex mixer or the like can be used. Moreover, pressurization or pressure reduction, a temperature control device (heating, cooling or heat retention) or the like can be installed in these kneaders and mixers. The mixing or kneading time varies depending on the type of raw material, the blending amount, the type of binder, the temperature of the kneaded product, the type and size of the mixer or kneader, but is usually in the range of several minutes to several hours.

  The resulting kneaded product is molded by a press called a hydraulic press or toggle press, which is a hydrostatic press, such as a friction press that is an impact pressure press, a screw press or a hydro screw press, or a molding machine called a CIP. can do. These molding machines can be provided with a vacuum deaeration device, a temperature control device (heating, cooling or heat retention) and the like. The molding pressure and number of tightening by the press molding machine vary depending on the size of the brick to be molded, the type of raw material, the blending amount, the type of binder, the temperature of the kneading clay, the type and size of the molding machine, etc. The pressure is usually 0.2t to 3.0t, and the number of fastenings can be molded from 1 to several tens of times.

  The molded brick can be heated at 500 ° C. or lower in order to prevent explosion due to volatile emission during use. In this heating, a hot air circulation type drying heating furnace or the like can be used. When heating at a temperature exceeding 500 ° C. is required, an electric heating type, gas heating type, oil heating type batch type single kiln, etc. For example, a shuttle kiln, a carbell kiln, or a continuous tunnel kiln is optimal. Of course, any type of heating furnace can be used as long as the temperature is sufficiently adjustable and uniform heating is possible.

  The refractory for the ferromanganese production furnace of the present invention is intended to improve durability in a ladle for ferromanganese slag reduction recovery, but a ladle that receives molten ferromanganese, an electric furnace furnace body and ladle, It can be used effectively in various ferromanganese production furnaces and equipment such as a steel outlet, and exhibits excellent corrosion resistance compared to conventional MgO-C bricks. Therefore, it can be widely applied as a refractory for various ferromanganese production furnaces, and in particular, a ladle that receives molten ferromanganese has a relatively high application effect and is preferably applied.

Hereinafter, the refractory for a ferromanganese manufacturing furnace of the present invention will be further described with reference to examples.
Examples A composition was prepared by combining various raw materials and binders at the blending ratios shown in Table 1 below, kneaded, and then molded at a molding pressure of 1.5 ton / cm ² using a friction press. The obtained molded product was heated in a hot air circulation heating furnace at 250 ° C. for 24 hours to obtain a refractory for a ferromanganese manufacturing furnace of the present invention.
Further, various raw materials and binders were combined at the blending ratios shown in Table 2 to prepare a blend, and a comparative refractory was obtained in the same manner as the present invention.

  Tables 1 and 2 also show various characteristics of the refractories of the present invention and comparative products. In the table, the purity of electrofused white alumina is 99.6% by mass, the purity of electrofused magnesia is 97.2% by mass, and the purity of silicon carbide is 92.5% by mass, The carbon purity of the scaly graphite was 95.8% by mass.

In addition, the “erosion test” was performed by a rotating drum erosion test method in which slag flows and the influence of slag viscosity can be easily evaluated. The test was conducted by raising the temperature to 1700 ° C., holding 1700 ° C. for 5 hours, and replacing the slag every hour. The slag was taken from a ferromanganese recovery furnace to match the conditions with the actual furnace.
The “damage rate index” is an index in which the damage rate of the MgO—C refractory of comparative product 1 conventionally used in a ferromanganese manufacturing furnace is 100, and the lower the value, the slower the damage rate, the better It is.
“Slag wetting” is an evaluation of the infiltration of slag into the specimen, and “◎” indicates that no infiltration was seen. ○, △, and x were evaluated, and those with x were markedly infiltrated and unacceptable.
“Presence / absence of peeling” is an evaluation of peeling of the working surface of the specimen, and “A” indicates that no peeling was observed. O, Δ, and x were evaluated. Thick delamination occurred repeatedly in the case of x, and it is considered to cause a problem in durability when actually used.
The “residual expansion rate (%)” is obtained by cutting each specimen with a dry cutter, creating a 30 × 30 × 150 mm residual expansion coefficient measurement sample, and embedding it in a breeze. The temperature is raised to 1500 ° C. under the condition of 5 ° C./minute using, and then baked for 3 hours, then cooled to room temperature, the sample is taken out, and the dimensional change rate is obtained on the basis of the dimensions before firing. The residual expansion rate (%) is an index for preventing longitudinal cracks caused by insufficient residual expansibility of the refractory.

  As shown in Table 1, the damage rate of the product of the present invention was better than that of the comparative product 1. In addition, infiltration and peeling were not observed at all or were slight, and there was no particular problem. Furthermore, it turns out that this invention products 9-12 which mix | blended electrofused magnesia can obtain favorable residual expansibility.

Comparative product 1 is a MgO-C refractory conventionally used in a ferromanganese manufacturing furnace.
Comparative product 2 is a blend of 55% by weight of fused white alumina and 45% by weight of scaly graphite. Comparative product 3 is a blend of 50% by weight of fused white alumina and 50% by weight of scaly graphite. is there. These had a low damage rate and no delamination.
Comparative product 4 is composed of 3% by weight of scaly graphite, and comparative product 5 is composed of 1% by weight of scaly graphite, both of which have large slag infiltration and are overfired by heat reception during the test. As a result of the crystallization, repeated delamination was severely damaged.
Comparative product 6 was a mixture of 25% by mass of silicon carbide, but the corrosion resistance was reduced because the amount of silicon carbide was excessive.
Comparative product 7 contains 37% by mass of magnesia, but the residual expansion rate exceeds 2%, which is excessive. In addition, slag infiltration was remarkable, and due to these effects, peeling during operation was very remarkable and the life was short.

Table 3 shows the results of applying the inventive products 1, 2, 6, 9, and 12 and the comparative products 1, 2 and 3 to the ferromanganese recovery furnace and the ladle slag line for steelmaking. In the ferromanganese recovery furnace, the slag composition is SiO ₂ : 34.0 mass%, MnO: 21.0 mass%, CaO: 40.0 mass%, MgO: 5.0 mass%, basicity CaO / SiO ₂ = The slag viscosity at 1500 ° C. was 3.2 poise.
Moreover, ordinary steel was processed in the ladle for steel making, and the viscosity of the molten steel at 1600 ° C. was 6 centipoise.
“Damage rate” is shown as an index when the damage rate of Comparative Product 1 is 100.
In addition, the "melt temperature change" at the time of the test was also investigated, and ◎ indicates that there was no problem at all. For the specimens in which the change in the melt temperature was observed, ○, Δ, × In the case of x, the temperature drop of the molten metal becomes excessive, which causes operational problems.

In the use in the ferromanganese recovery furnace, all of the products of the present invention had a damage rate smaller than that of the comparative product 1, and the damage was minor. Moreover, it was the range which does not have a problem also about the fall of the molten metal temperature during operation.
Comparative products 2 and 3 were less damaged than the products of the present invention, and the damage was minor, but the temperature of the molten metal during use was significantly reduced, which hindered operation.
On the other hand, when the product of the present invention is used for a steel ladle, unlike the case of using it in a ferromanganese recovery furnace, the product of the present invention has a higher damage rate than the comparative product 1 and the damage is large, and it has sufficient durability Was not obtained. This is probably because the viscosity of the molten steel is small as described above.
Thus, since the viscosity of the object to be processed is relatively high like ferromanganese slag and the effect of improving the viscosity by dissolving alumina is large, the product of the present invention has improved corrosion resistance and has obtained good results. Conceivable.

Claims (4)

  A ferromanganese refractory for a ferromanganese manufacturing furnace, comprising mainly alumina and carbon, having an alumina content of 60 to 95% by mass and a carbon content of 5 to 40% by mass.   Furthermore, the refractory for a ferromanganese manufacturing furnace of Claim 1 which contains silicon carbide in the quantity of 20 mass% or less.   Furthermore, the refractory for a ferromanganese manufacturing furnace of Claim 1 or 2 which contains periclase in the quantity of 35 mass% or less.   The refractory for a ferromanganese manufacturing furnace according to any one of claims 1 to 3, wherein the refractory is used in a ladle having a viscosity of 0.5 poise or more.

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