JP5276620B2 - Baking repair material - Google Patents

Description

  The present invention relates to a baking repair material including a refractory aggregate and an organic binder.

  In the following, one construction mode of the baking repair material will be described by taking the converter throwing repair method as an example without limiting meaning.

  As a repair method for a converter responsible for refining molten iron in the steelmaking process, a method is known in which a baking repair material packed in a burnable bag such as a vinyl bag or the like is thrown into a converter immediately after steelmaking.

  As the baking repair material, a fireproof aggregate composed of magnesia clinker or the like and an organic binder composed of pitch, resin or the like is added.

  The baking repair material thrown into the converter is once softened by the furnace heat and developed on the damaged part of the furnace wall, then the volatile matter in the organic binder is dissipated, and the carbon due to the fixed carbon in the organic binder. Solidify with bond formation.

  One of the characteristics required for a baking repair material is that the time required for solidification (hereinafter referred to as solidification time) is short. The shorter the hardening time of the baking repair material, the quicker the repair of the converter can be completed, which contributes to the improvement of the operation rate of the converter.

  Patent Document 1 proposes the application of Mg powder in order to shorten the solidification time of the baking repair material (see paragraph 0009 of Patent Document 1). Thereby, in addition to the heat received from the furnace inner surface, the combustion heat of Mg powder is generated from the inside of the construction body, so that the solidification time can be shortened.

  Patent Document 2 proposes application of Al powder to a baking repair material for the purpose of obtaining the same effect as Patent Document 1 (see paragraph 0041 of Patent Document 2). It is said that Al powder has a high calorific value due to oxidation and is effective in promoting solidification.

Japanese Patent Laid-Open No. 11-240771 Japanese Patent No. 3729495 Japanese Patent Laid-Open No. 5-117046

  The internal structure of the construction body made of the baking repair material tends to be more porous than the structure of the surface layer portion. Since this problem becomes serious particularly when the repairing material for baking is thickly constructed, even if the construction thickness is increased, it is difficult to obtain a repairing effect corresponding to the construction thickness.

  According to the present inventor, the main cause is that the combustion of the organic binder inside the construction body is delayed from the combustion of the organic binder in the surface layer portion, so that the volatile matter of the organic binder is confined inside the surface layer portion. It is thought that the solidification progresses.

  According to the proposals in Patent Documents 1 and 2, it seems that combustion from the inside of the construction body can be promoted by using metal powder such as Mg powder and Al powder. Since the oxygen necessary for this is not sufficiently present, heat generation from the inside cannot be obtained sufficiently.

  For this reason, depending on the techniques of Patent Documents 1 and 2, it is difficult to solve the problem of making the internal structure of the construction body porous, and there is still room for improvement in terms of shortening the solidification time.

  The objective of this invention is providing the baking repair material which can aim at shortening of solidification time and the internal structure of a construction body is hard to become porous.

  According to one aspect of the present invention, in a baked repair material including a refractory aggregate and an organic binder, the iron oxide powder and the metal powder have a mass ratio of iron oxide powder: metal powder of 9: 1 to 1: 9. Under such conditions, a baking repair material characterized by containing a total of 10% by mass or more of the outer coating with respect to the organic binder is provided.

  Based on the combined use of iron oxide powder and metal powder, it was found that the solidification time can be shortened and the internal structure of the construction body can be prevented from becoming porous. This is thought to be because iron oxide powder is reduced by metal powder and the metal powder burns, so that the dissipation of volatile matter from the inside of the construction body can be promoted and the residual volatile matter inside the construction body can be suppressed. It is done.

  In addition, since iron oxide also causes the carbon bond formed by the organic binder to oxidize and become brittle (see, for example, paragraph 0003 of Patent Document 3), there has been no example of applying this to a baking repair material. . However, when iron oxide powder and metal powder are used in combination, it has been found that this carbon bond weakening problem can be avoided.

It is a photograph which shows the cross section of the construction body which consists of a baking repair material.

  For fireproof aggregates, for example, magnesia raw materials such as magnesia clinker, dolomite raw materials such as dolomite clinker, calcia raw materials such as calcia clinker, spinel raw materials such as spinel clinker, alumina raw materials, and these are used as raw materials. One or more kinds selected from pulverized used refractories can be appropriately selected and used according to the material of the surface to be repaired. Refractory aggregates are less likely to be reduced than iron oxide powder. In the present specification, iron oxide powder and metal powder are excluded from the concept of refractory aggregate.

  In order to form a dense packing structure, the refractory aggregate is measured using a sieve specified in JIS-Z8801, for example, coarse particles having a particle size of 1 mm or more: 35 to 45 mass%, particle size of 75 μm or more and less than 1 mm The particle size is composed of 20 to 30% by mass of fine particles and fine particles having a particle size of less than 75 μm: 15 to 30% by mass.

  The organic binder is a substance that forms a carbon bond with heat. For example, bitumen, resin, or a combination of both can be used. Examples of the bitumen include pitch, tar, and asphalt, and examples of the resin include carbon resins such as a phenol resin, a furan resin, and an epoxy resin.

  The addition amount of the organic binder can be appropriately selected by those skilled in the art depending on the construction conditions. For example, the mass ratio of organic binder / refractory aggregate can be 10/90 to 40/60. By setting it to 10/90 or more, the effect of improving the strength and adhesiveness due to the formation of the carbon bond is particularly remarkable, and by suppressing it to 40/60 or less, the denseness of the structure of the construction body can be increased.

  A wetting agent may be used in combination with an organic binder. The wetting agent has an effect of improving the fluidity and filling property of the baking repair material. The wetting agent is selected from polyhydric alcohols such as ethylene glycol, kerosene, anthracene oil, light oil, heavy oil, creosote oil, wax oil, paraffin, p-alkylphenols, lactams, bisphenol, diphenyl, diphenylamine and the like 1 Seeds can be used. When a wetting agent is used, the amount added is preferably 100% by mass or less, more preferably 60% by mass or less, based on the outer coating with respect to the organic binder.

  The metal powder is selected from an element that easily reduces iron oxide powder, that is, an element that has a lower ionization tendency than Fe, specifically, for example, Al, Mg, Ca, and an alloy containing at least one of them. One or more can be used. Examples of the alloy include Al—Mg, Ca—Si, Al—Si, Al—Si—Mg, and Al—Si—Mg—Ca. The metal powder may be one in which a film for preventing ignition in the atmosphere is formed on each particle constituting the metal powder.

The iron oxide powder is preferably a chemical component value in which FeO, Fe ₂ O ₃ , Fe ₃ O ₄ , or a combination thereof occupies 90% by mass or more. Among these, a powder made of trivalent Fe ₂ O ₃ whose raw material is inexpensive and stable is preferable.

  The iron oxide powder serves as a supply source of oxygen necessary for the combustion of the metal powder, thereby promoting the combustion from the inside of the construction body together with the metal powder. For this reason, the residual amount of the volatile matter inside a construction body can be reduced, and even if it is a case where a construction body is formed thickly, it becomes difficult to roughen the internal structure of a construction body. Since the solidification of the construction body is promoted by the combustion, the solidification time can be shortened.

  In order to make this effect remarkable, it is preferable that the particle sizes of the metal powder and the iron oxide powder are smaller. Specifically, the particle sizes of the metal powder and iron oxide powder are preferably 0.5 mm or less, more preferably 75 μm or less, as measured using a sieve specified in JIS-Z8801.

  It is necessary to mix the iron oxide powder and the metal powder under the condition that the mass ratio of iron oxide powder: metal powder is 9: 1 to 1: 9. If the mass ratio of iron oxide powder / metal powder is less than 1/9, the ratio of the metal powder is too high, and the problem of insufficient oxygen necessary for the combustion of the metal powder tends to occur. When the mass ratio of iron oxide powder / metal powder exceeds 9, the ratio of iron oxide powder is too high, and the problem of weakening the carbon bond formed by the organic binder tends to occur.

  It is necessary that the iron oxide powder and the metal powder be blended in a total amount of 10% by mass or more with respect to the organic binder. If the total amount of both is less than 10% by weight with respect to the organic binder, the probability that the metal powder and the iron oxide powder come into contact with each other in the construction body becomes small, and the amount of heat generated by the combustion of the metal powder becomes insufficient. The effect of promoting combustion of volatile matter from the inside of the construction body is difficult to obtain.

  In addition, the upper limit of the total amount of iron oxide powder and metal powder is not particularly limited. The larger the total amount of both, the shorter the solidification time and the better the internal structure. However, if the total amount of the two is too large, the proportion of the refractory aggregate and the organic binder that should be the main materials decreases accordingly, so that the corrosion resistance tends to decrease. It will be apparent to those skilled in the art that the total amount of both is naturally limited in order to ensure common sense characteristics as a baking repair material.

  For example, by suppressing the total blending amount of the metal powder and the iron oxide powder to 90% by mass or less by external coating with respect to the organic binder, the effect of improving the corrosion resistance can be obtained in combination with the effect of densification of the internal structure described above. .

  The construction method of this baking repair material is not specifically limited. Typically, it is put into a site to be repaired in a state where it is contained in a burnout bag such as a flexible container bag or a vinyl bag. In addition, by subjecting the baking repair material to pressure forming in a block shape or a lump shape in advance, it is possible to put the material into the repair target region without using a burnable bag. Moreover, this baking repair material can also air-transport the inside of piping, and can spray it on the repair object site | part.

  The use of this baking repair material is not particularly limited. This baking repair material can be widely used for hot repair of converters, electric furnaces, molten steel pans, hot metal ladle, degassing furnaces, electric furnaces, tapping and other molten metal containers. In the present specification, hot refers to a state in which the inner surface of the molten metal container is 400 ° C. or higher.

  This baking repair material is particularly significant when thickly constructed. Even in the case of thick construction, the solidification time can be shortened and the internal structure of the construction body can be prevented from becoming porous. For example, relatively deep, for example, a depth of 30 mm or more, such as around the steel outlet sleeve or bottom tuyeres of the converter, around the nozzle hole of the ladle, or an abnormally melted spot on the inner surface of the molten metal container. Is suitable for repairing a recess having a depth of 50 mm or more. However, it goes without saying that this baking repair material can be preferably used even when it is constructed to a thickness of about 10 mm.

  Tables 1 to 3 show examples of the baking repair material and comparative examples.

  In Tables 1 to 3, the refractory aggregate used was a magnesia clinker whose particle size was adjusted so as to consist of coarse particles: 45% by mass, medium particles: 25% by mass, and fine particles: 30% by mass. As the organic binder, a combination of phenol resin and pitch at a mass ratio of 1: 3 was used. As the iron oxide powder, a bengara made of trivalent iron oxide and having a particle size of 75 μm or less was used. As the metal powder, one having a particle size of 75 μm or less was used.

  Early solidification was evaluated in the following manner. A brick in which a cylindrical concave portion is cut is prepared, and this is heated to 1000 ° C., and the concave portion is filled with a baking repair material. After filling, every 3 minutes, a round bar having a weight of 160 g and an outer diameter of 2.5 mm is allowed to penetrate the construction body in the recess by its own weight, and solidification is completed when the penetration depth becomes zero. The time from filling to completion of solidification was defined as the solidification time, and relative evaluation was performed in four stages of ◎, ○, Δ, and × depending on the shortness of the solidification time.

  The internal organization was evaluated in the following manner. A portion including the central portion in the thickness direction is cut out from the construction body that has been solidified as described above, and its apparent porosity is measured. Relative evaluation was performed in four stages of ◎, ○, Δ, and × depending on the apparent porosity.

  Corrosion resistance was evaluated in the following manner. A plate-shaped refractory placed horizontally is heated to 1000 ° C., and a baking repair material is applied to its surface to a thickness of about 50 mm. After confirming the solidification of the baking repair material as described above, the plate-shaped refractory is set up vertically, and the construction of the baking repair material is combined with the converter slag and steel pieces in a mass ratio of 1: 1. Spray the ingredients. The conditions such as the supply amount of the erosion material and the spraying time were the same, and relative evaluation was performed in four stages of ◎, ○, Δ, and × depending on the depth to which the construction body was removed by spraying.

  Example A is a comparative example that does not contain iron oxide powder, and the combustion of Al powder does not proceed properly, and is particularly inferior in terms of early solidification.

  Example K is a comparative example that does not contain metal powder, and is inferior in terms of early solidification properties, and is also relatively inferior in terms of the density of the internal structure, probably because iron oxide powder has oxidized carbon bonds.

  Examples B to J are examples including both iron oxide powder and Al powder, and when the mass ratio of iron oxide powder: Al powder is 9: 1 to 1: 9, than Comparative Examples A and K. Excellent results have been obtained. From the results in Table 1, it can be said that the mass ratio of iron oxide powder: metal powder is preferably 2: 8 to 8: 2, and more preferably 3: 7 to 7: 3.

  In addition, from the result of Table 1, the optimal mass ratio of iron oxide powder and Al powder is estimated to be 5: 5. This value is different from the theoretical value (Al powder: iron oxide powder = 1: 2) in which both cause thermite reaction without excess or deficiency, but as the mass ratio of both approaches 5: 5, both react in the structure. Since the probability increases, it is considered that the effect of improving the early solidification property and the internal structure is remarkable.

  Fig.1 (a) shows the cross section of the construction body which consists of a baking repair material of Example F of Table 1. It can be seen that the organization is dense.

  FIG.1 (b) shows the cross section of the construction body which consists of a baking repair material of the comparative example A of Table 1. FIG. Since the comparative example A does not contain iron oxide powder, the structure is slightly rough compared to FIG.

  FIG.1 (c) shows the cross section of the construction body which consists of a baking repair material of the comparative example K of Table 1. FIG. Since the comparative example K does not contain metal powder, it is because the iron oxide powder has oxidized the carbon bond, or the structure is rough compared to FIGS. 1 (a) and 1 (b).

  In Table 2, Examples L to S used 20% by weight of organic binder, Examples T to V used 40% by weight of organic binder, and Examples W and X used 10% by weight of organic binder.

  In all the examples in Table 2, the mass ratio of iron oxide powder: metal powder is 5: 5, but Examples L and T are comparative examples in which the total amount of both was too small and no improvement effect was observed. , Examples M to S, and U to X are examples in which the total amount of both is sufficient to express the improvement effect.

  As shown in Examples M and U, the total amount of iron oxide powder and metal powder necessary for the improvement effect depends on the content of the organic binder. In other words, the larger the amount of organic binder used, the more volatile components need to be dissipated, so that more iron oxide powder and metal powder are required.

  Therefore, it is appropriate that the total amount of iron oxide powder and metal powder is defined by the outer coating on the organic binder. From the results of Examples M, U, and W, the total amount of both needs to be 10% by mass or more of the outer coating with respect to the organic binder. As examples N to S, V, and X show, the greater the total amount of both, the higher the improvement effect with respect to the early solidification and the denseness of the internal structure. 20 mass% or more is preferable and 30 mass% or more is more preferable.

  However, as shown in Examples R and S, when the total amount of both is too large, the corrosion resistance tends to be reduced. This is mainly due to a decrease in the proportion of the refractory aggregate in the baking repair material. Therefore, the total amount of both is preferably 80% by mass or less, more preferably 70% by mass or less, based on the organic binder.

  In Table 3, Example Y is an example using Mg powder as metal powder, Example Z is an example using Al-Mg alloy powder as metal powder, and Example AA is Al-Si alloy powder as metal powder. The used example, Example AB, is an example using Ca-Si alloy powder as the metal powder. From the results in Table 3, it is considered that it is particularly preferable to use Mg powder and / or Ca—Si alloy powder as the metal powder.

  As mentioned above, although demonstrated along the Example, this invention is not limited to this. For example, it will be apparent to those skilled in the art that various combinations and improvements are possible.

Claims (1)

  In a baking repair material including a refractory aggregate and an organic binder, the iron oxide powder and the metal powder are externally applied to the organic binder under the condition that the mass ratio of iron oxide powder: metal powder is 9: 1 to 1: 9. A baking repair material characterized by containing a total of 10% or more by hook.