JP6024920B2 - Shaped refractory and method for manufacturing the same - Google Patents

Description

  The present invention relates to a shaped refractory having excellent slag corrosion resistance and a method for producing the same.

Firing refractories are an essential material for manufacturing facilities that handle high-temperature materials such as steel and cement. The composition is usually made of oxides such as SiO ₂ , Al ₂ O ₃ , MgO, CaO, ZrO ₂ , Cr ₂ O ₃ and TiO _2, and carbides such as SiC. The fired refractory is obtained by molding, drying, and firing a refractory raw material composition in a mold.

The fired refractory usually has about 5 to 25% by volume of open pores (pores) of 10 μm or more. The fired refractory that comes into contact with the high-temperature melt is required to have corrosion resistance, particularly slag corrosion resistance, and the selection and densification of the chemical composition are promoted. In particular, when slag corrosion resistance is required, magchrom (magnesia-chromia) or archro (alumina-chromia) refractories containing chromia (Cr ₂ O ₃ ) are often used, but chromia is expensive. Therefore, the application is limited.

  Regarding the magcro refractory, as described in Patent Document 1, the open pores are refined by adding an Fe-Cr alloy to the magcro refractory, and further 0.5 to 1.0 μm chromia powder is obtained. By impregnating with the dispersed liquid medium, 95% of the open pores are 5 μm or less, and the slag permeability is improved.

JP-A-9-52755

  However, since the refractory described in Patent Document 1 places importance on slag permeability and focuses on refining open pores, slag corrosion resistance is not considered and data is not disclosed. From the viewpoint of corrosion resistance, in order to increase the filling amount of chromia, it is preferable that the open pore diameter in the firing step is rather large. In other words, the refractory described in Patent Document 1 is judged to be inefficient in using chromia and insufficient in slag corrosion resistance. Further, in order to use a liquid medium in which chromia powder is dispersed, there is a case where it is necessary to take measures in order to satisfy environmental standards when discharging waste liquid and cleaning liquid.

  As described above, the actual situation is that there is no refractory that is sufficiently satisfactory from the viewpoints of corrosion resistance, economy, and environmental measures. In view of such circumstances, an object of the present invention is to provide a shaped refractory that is excellent in corrosion resistance and economy and a method for producing the same.

In order to solve the above-mentioned problems, the regular refractory according to the present invention comprises one or more oxide powders selected from the group consisting of zirconia, zircon, silica, and alumina in the pores of a regular fired refractory. In a center part that is 5 mm or more in the normal direction from the surface of the regular refractory, the pore size distribution curve of the pore volume in the regular refractory has a pore diameter of 5 μm or more. In addition to having the maximum peak, the aggregate of the oxide powder is formed in the pores of the fired refractory, so that the pore volume peak is also in the pore diameter range of 0.01 to 1.0 μm. It is characterized by that. The oxide powder is preferably not sintered with the fired refractory, and the fired refractory is preferably a magnesia-chromia fired refractory or an alumina-chromia fired refractory.

In addition, the method for producing the shaped refractory according to the present invention is as follows.
One or more oxidations selected from the group consisting of zirconia, zircon, silica, and alumina are formed into a regular fired refractory having a maximum peak at a pore diameter distribution curve of pore volume in the refractory of 10 μm or more. The slurry containing the product powder and the dispersing agent is mechanically stirred using beads as a stirring medium to break up the oxide aggregate particles in the slurry, and then impregnated and further dried, so that the normal direction from the surface of the shaped refractory In addition, in the central part 5 mm or more inside, the pore diameter distribution curve of the pore volume in the regular refractory has a maximum peak at a pore diameter of 5 μm or more, and also in a pore diameter range of 0.01 to 1.0 μm. It is characterized by having a peak.

The slurry containing the oxide powder and the dispersant was mechanically stirred using beads having a median particle size of 0.1 to 2 mm as a stirring medium to break up the aggregated particles of the oxide in the slurry, and then the fired refractory Preferably, the fired refractory is immersed in a slurry containing the oxide powder and the dispersant under reduced pressure, and then the slurry is pressurized and impregnated in the fired refractory.
Further, when the slurry containing the oxide powder and the dispersant is mechanically stirred to crush the oxide aggregate particles in the slurry and then impregnated in the fired refractory, the suspended particles in the slurry The median particle size is preferably less than 1 μm as measured by a laser diffraction / scattering method.

  The fired refractory is preferably an alumina-chromia fired refractory. The fired refractory is preferably a magnesia-chromia fired refractory, and the slurry containing the oxide powder and the dispersant is mechanically stirred to break up the aggregated particles of the oxide in the slurry. The slurry when impregnating the fired refractory has a median particle size of 1 μm as measured by a laser diffraction / scattering method after the slurry is further adjusted to a pH of 8-9. It is preferable that it becomes less than.

According to the present invention, as a regular refractory, the pore diameter distribution curve of the pore volume in the refractory has a maximum peak at a pore diameter of 5 μm or more in a central portion 5 mm or more in the normal direction from the surface of the regular refractory. It is a regular refractory, and an aggregate of one or more oxide powders selected from the group consisting of zirconia, zircon, silica, and alumina is formed in the pores of the regular fired refractory. Since it has a second pore diameter peak at 0.01 to 1.0 μm, high slag corrosion resistance can be obtained at a low cost up to the center of the regular refractory.

In addition, as a method for producing a regular refractory, a regular baked refractory having a maximum peak in the pore diameter distribution curve of the pore volume in the refractory having a pore diameter of 10 μm or more is selected from the group consisting of zirconia, zircon, silica, and alumina. A slurry containing one or more selected oxide powders and a dispersing agent is impregnated after mechanically stirring the beads as a stirring medium to break up the agglomerated particles in the slurry. High slag corrosion resistance is obtained up to the center of the object.

(A) shows the influence of the presence or absence of impregnation of the zirconia powder-containing slurry based on the embodiment of the present invention on the pore size distribution of the pore volume in the shaped refractory, as the pore size distribution of the cumulative pore volume. FIG. 4B is a graph showing the influence of the presence or absence of impregnation of the slurry containing zirconia powder on the pore size distribution in the regular refractory according to the embodiment of the present invention; It is a relationship diagram shown by distribution. It is explanatory drawing which shows typically the pore structure of the impregnated refractory of the oxide powder containing slurry based on embodiment of this invention. It is a graph which compares and shows the erosion test result of the fixed form refractory based on embodiment of this invention, and the result when not performing a crushing process.

In one embodiment of the present invention, as a method for producing a regular refractory, the pore diameter distribution curve of the pore volume in the refractory has a maximum peak at a pore diameter of 10 μm or more, and the fired refractory has zirconia, zircon, silica, alumina. A slurry containing one or more oxide powders selected from the group consisting of the above and a dispersant is mechanically stirred to crush the aggregated particles in the slurry, and then impregnated. The regular refractory is a regular refractory having a maximum pore size peak with a pore diameter distribution curve of pore volume in the refractory of 5 μm or more, and is selected from the group consisting of zirconia, zircon, silica, and alumina. Alternatively, a slurry containing two or more kinds of oxide powder and a dispersing agent is mechanically stirred to pulverize the aggregated particles in the slurry, and then impregnated, so that the center inside the normal refractory is 10 mm or more in the normal direction. The pore diameter distribution curve of the pore volume in the shaped refractory has a second peak in the pore diameter range of 0.01 to 1.0 μm. Thereby, an aggregate of oxide powder can be efficiently formed in the pores of the refractory.
Here, the pore diameter distribution curve of the pore volume is a regular logarithm of the pore diameter obtained from the relationship between the pore diameter and the pore volume measured with a mercury porosimeter or the like, and is equally spaced (for example, 0.1 interval). FIG. 6 is a relationship diagram between a differential pore volume (vertical axis) corresponding to a section of pore diameters divided in this way and a representative diameter (horizontal axis) of the section of the pore diameter. (Hereinafter the same)

  In the embodiment of the present invention, the kind of oxide powder in the slurry impregnated in the fired refractory is one or more selected from the group consisting of zirconia, zircon, silica, and alumina. These oxide powders preferably have an average particle size (median particle size) of primary particles of 0.1 μm or more and 1 μm or less. If the average particle diameter exceeds 1 μm, it may not be possible to efficiently impregnate pores having an average diameter of 10 μm or more present in the fired brick, which is not preferable. On the other hand, normal oxide powder is produced by pulverizing particles of the same quality, but pulverization to an average particle size of 0.1 μm or less is very expensive and is not preferable because it does not meet the gist of the present invention. .

  A slurry in which these oxide powders are dispersed under predetermined conditions is impregnated into a fired refractory and then dried, and a pore diameter distribution curve of pore volume is 0.01 on the pore inner wall of the fired refractory. An aggregate of the oxide powder having a peak in a pore diameter range of ˜1.0 μm is formed. This aggregate of oxide powder is used as a network former of the oxide in the molten slag by the interaction with the molten slag that penetrates into the pores of the refractory as the refractory is eroded by the slag, or as a molten It acts as solid particles dispersed in the slag and has the effect of increasing the slag viscosity. As a result, it has the effect of suppressing slag erosion by suppressing the penetration of slag into the pores. When the peak of the pore volume distribution of the pore volume due to the aggregate of oxide powders formed in the refractory exceeds 1.0 μm, the interfacial area per unit volume of the intruded molten slag decreases, and the molten slag Since the interaction of slag is limited, the effect of reducing slag erosion cannot be sufficiently obtained. On the other hand, if the pore size distribution peak is less than 0.01 μm, the surface energy is high, so that it is difficult to stably maintain the pore structure during use at high temperatures. Since the pore volume corresponding to is sometimes significantly reduced, it is not effective.

  These oxide powders are preferably present in the pores of the fired refractory in a state where they are not sintered with the fired refractory. Impregnating a slurry in which oxide powder is dispersed under predetermined conditions, drying, and forming a shaped refractory product without further firing, not only simplifies the manufacturing process and reduces costs, but also 0.01 to A pore structure with a pore volume peak even within a pore diameter range of 1.0 μm is maintained until the slag infiltrates during use of the refractory, so that molten slag that penetrates into the pores of the refractory It is suitable for obtaining the effect of reducing slag erosion by the interaction with. When the oxide powder-containing slurry is impregnated and baked at a high temperature after drying, the pore volume in the pore diameter range of 0.01 to 1.0 μm is obtained due to sintering of the original baked refractory and the oxide powder. In some cases, the desired effect may not be obtained.

The kind of the fired refractory that can be used in the embodiment of the present invention is not particularly limited, and is an oxide such as SiO ₂ , A 1 ₂ O ₃ , MgO, CaO, ZrO ₂ , Cr ₂ O ₃ , TiO ₂ , and SiC. Fired refractories made of pure substances such as carbides, compounds or mixtures thereof can be used, but alumina-chromia fired refractories and magnesia-chromia fired refractories are highly resistant to slags of a wide range of compositions. A chromia-containing fired refractory is particularly preferred. In these chromia-containing fired refractories, the dissolution rate of the mineral particles themselves constituting the refractory into the slag is low, and it is considered that the wear of the refractory proceeds mainly by the following two mechanisms. That is, the bonded portion between the mineral particles, which has a relatively low melting point composition, is eroded by the pores of the fired refractory, that is, the molten slag that has entered between the mineral particles, and the mineral particles are in the molten slag. It is important for refractory wear that the wear of the refractory progresses as if it falls off or that the molten slag component penetrates into the fired refractory through the pores and promotes peeling by structural spalling. This is a major factor. Therefore, by applying the embodiment of the present invention to these chromia-containing fired refractories and suppressing the intrusion of slag into the pores, it becomes possible to particularly effectively reduce refractory wear.

In addition, the composition conditions of the slag to which the regular refractory according to the embodiment of the present invention is applied are not particularly limited, and steel, non-ferrous metal, cement, dust melting treatment, etc. that handle slag of a wide range of composition conditions It is applicable to various high temperature processes. When the corrosion resistance to low basicity slags such as basicity (mass% CaO / mass% SiO ₂ ) is 1.0 or less is a problem, the application of the regular refractory according to the embodiment of the present invention is particularly effective. Corrosion resistance can be improved because the viscosity of the molten slag that has penetrated into the pores can be significantly increased, and slag penetration into the pores or mass transfer through the penetrated slag can be significantly suppressed.

  As the oxide powder that can be used for impregnation, for example, a commercially available powder having a maximum particle size of about 0.1 to 1.0 μm and a purity of 98% or more is used. In order to efficiently impregnate this oxide powder-containing slurry, it is preferable to have a pore size that is at least one digit larger, so that the fired refractory impregnated with the oxide powder-containing slurry has a pore volume pore size distribution curve. It shall have a maximum peak at a pore diameter of 10 μm or more. In a regular refractory that has been impregnated with an oxide powder-containing slurry and dried, the maximum peak of the pore volume distribution curve of the pore volume shifts to a smaller pore diameter side than that of the fired refractory used as the material. However, it has a maximum peak at a pore diameter of 5 μm or more.

One or more oxide powders selected from the group consisting of zirconia, zircon, silica, and alumina are dispersed in water or ethanol and used for impregnation. Water is the cheapest available and easy to handle. In addition, ethanol has a low surface tension and is excellent in dispersibility and impregnation of oxide powder. The oxide powder is dispersed in water or ethanol at a rate of 3 to 40% by volume to form a slurry.
It should be noted here that the oxide powder is dispersed in the slurry to the primary particles of the powder. The oxide powder particles in the slurry are suspended in an agglomerated state by simply adding the oxide powder into the liquid medium and stirring to such an extent that precipitation does not occur as is normally done. Even when an oxide powder having a particle diameter of 0.2 μm is used, the average particle diameter of the suspended particles in the slurry is 2 μm or more when measured by a laser diffraction / scattering method. When such a slurry is impregnated in the fired refractory, the narrowed portion in the middle of the pores is clogged with the aggregated particles of the oxide powder, and it becomes difficult to reach the oxide particles to the inside. For this reason, the impregnation of the slurry into the fired brick is limited to the vicinity of the brick surface, and although the oxide particles reach the vicinity of the brick surface, only the liquid component reaches the inside of the brick.

  Therefore, in order to facilitate the supply of one or more oxide powders selected from the group consisting of zirconia, zircon, silica, and alumina into the refractory, the oxide powder has a group having an affinity. It is necessary to use a dispersant to promote the dispersion of the primary particles of the oxide powder in the slurry. By using an appropriate dispersant, it is effective to facilitate the pulverization of the aggregated particles of the oxide powder and to maintain the primary particles dispersed in the slurry. Dispersing agent which is a sodium salt or ammonium salt of a polymer having surface activity such as naphthalene sulfonic acid formalin condensate has an effect of suppressing aggregation by adsorbing to oxide particles of zirconia, zircon, silica and alumina. Are preferably used.

Further, by mechanically stirring using a bead mill, the aggregated particles of the oxide powder in the slurry can be crushed and a state where the primary particles of the oxide powder are dispersed can be realized.
At this time, the energy input speed of mechanical stirring is preferably 0.2 W / L or more per slurry volume, more preferably 1 W / L or more, and the energy input density is 2 kJ / mass per oxide powder mass. Crushing suitably proceeds by setting it to kg or more, more desirably 10 kJ / kg or more. Here, the energy input speed is obtained from the difference between the power consumption at the time of the crushing process and the power consumption corresponding to the friction loss at the time of idling without using a stirring medium such as slurry and beads.

In the bead mill, it is preferable to use ceramic beads having an average particle diameter of about 0.1 to 2 mm as a medium. The bead mill can be continuous by providing a container for storing beads and slurry, a rotor for stirring the beads, and the like, and providing a slurry inlet and outlet for the container. Also, a pot mill or the like that stirs beads and slurry by putting beads and slurry into the pot and vibrating or rotating the pot can be used.

  By mechanically stirring the slurry containing the oxide powder and the dispersant as described above and pulverizing the aggregated particles in the slurry, the median particle size of the suspended particles in the slurry when impregnated in the fired refractory, It is preferable that the measured value by laser diffraction / scattering method is less than 1 μm. By impregnating a slurry containing such an oxide powder and a dispersant into a fired refractory having a maximum peak in a pore diameter distribution curve of a pore volume of 10 μm or more, a normal line is formed from the surface of the shaped refractory. It is possible to improve the corrosion resistance by impregnating the slurry up to the inner part 5 mm or more in the direction to form an aggregate of oxide particles inside the pores of the fired refractory.

The slurry can be impregnated into the fired refractory in vacuum or under pressure.
That is, for example, after putting the baked refractory into a container in the hermetic chamber, the air in the hermetic chamber is deaerated with a vacuum pump to make the inside of the pores of the baked refractory in the container substantially vacuum, and then in an airtight state. The slurry is poured into the container, the slurry is pressurized and impregnated by the static pressure of the slurry itself without being obstructed by the air in the pores of the fired refractory in the container, and then the air is returned to the airtight chamber. The slurry is further impregnated under pressure at atmospheric pressure. Note that the air in the hermetic chamber may be further pressurized, and in this way, the slurry is further pressurized, so that impregnation of the slurry can be promoted.
The fired refractory impregnated with the slurry is taken out from the slurry, evaporated to dry the liquid medium, and one or two kinds selected from the group consisting of zirconia, zircon, silica, and alumina in the pores of the fired refractory. A regular refractory in which an aggregate of the above oxide particles is formed is obtained.

  The slurry after use can be used repeatedly by replenishing the amount impregnated with the fired refractory, but if used over a long period of time, the oxide particles may gradually aggregate and become difficult to impregnate. When the particle size distribution of the suspended particles is confirmed, and the ratio of aggregated particles having a particle size of 2 μm or more increases, it is desirable to replace the slurry with a newly prepared slurry. At this time, as the newly adjusted slurry, a slurry obtained by reusing the degraded slurry, adjusting the components such as pH and the concentration of the dispersant, and then performing the pulverization treatment again may be used.

  When corrosion resistance is required only on the surface of the refractory, it is economical to impregnate the slurry only on the surface, but generally it is required to improve the corrosion resistance up to the center of the regular refractory, It is necessary to impregnate the slurry to the center of the regular refractory. When the crushing treatment by mechanical stirring as described above is not performed, the median particle size of the suspended particles in the slurry is determined by the laser diffraction / scattering method even if oxide particles having a primary particle size of less than 1 μm are used. Even if the slurry is impregnated with a fired refractory having a maximum peak in the pore diameter distribution curve of the pore volume of 10 μm or more, only the surface layer portion of less than 5 mm from the surface is measured. The oxide particles in the slurry did not reach, and it was difficult to improve the corrosion resistance to the inside.

  When impregnating a fired refractory with a slurry containing an oxide powder and a dispersant, depending on the conditions such as the type of the dispersant, the oxide powder, and the fired refractory, the distance from which the oxide particles penetrate from the surface of the refractory Please note that there may be some variation. This is considered to be caused by the influence of components eluted from the fired refractory into the slurry, or the concentration of the components in the slurry solution adsorbed on the fired refractory. Even if there is no significant change in the composition of the solution in the entire slurry, the surface area of the refractory is very large relative to the amount of solution in the slurry that has entered the pores, so a relatively short impregnation time Even so, the components of the solution in the pores may change significantly. Even in such a case, in order to keep the dispersion state of the oxide particles in the slurry in a state suitable for impregnation, it is confirmed that the suspended particle size in the slurry under the expected solution conditions is appropriate. In addition, it is desirable to select a dispersant.

  Specifically, in the case of a magnesia-chromia fired refractory, a slurry containing oxide powder and a dispersant is mechanically stirred to break up aggregated particles in the slurry, and then the aqueous solution of sodium hydroxide is added to the slurry. Is added to adjust the pH to the range of 8-9, and then a dispersant is selected so that the median particle size of the suspended particles in the slurry is less than 1 μm as measured by the laser diffraction / scattering method. Is preferred. Examples of such a dispersant include, but are not limited to, a sodium salt of a polymer having surface activity such as a polycarboxylic acid type polymer system or a β-naphthalenesulfonic acid formalin condensate system. Any dispersant that satisfies the conditions can be suitably used.

  For example, when an acidic polymer-based dispersant described later is used, the pH of the initial slurry is in the range of 5-6, and when the magnesia-chromia-based fired refractory is repeatedly impregnated, the pH gradually rises to 7-7. The range is 8. Further, in the pores of the magnesia-chromia-based fired refractory, it is considered that the pH is in the range of pH 9 to 10, which is an equilibrium elution value by a shaking test using a ground product of the refractory.

  In the example of the slurry obtained by pulverizing a 30% by mass aqueous solution slurry of zirconia for refractories having a nominal average particle size of 0.2 μm using this dispersant, the median particle size of the initial suspended particles is 0.21 μm. In the slurry in which the aqueous solution of sodium hydroxide was added to the slurry and mixed to adjust the pH to 8-9, the median particle size of the suspended particles increased to about 0.5 μm.

  In the case of using this dispersant, the fixed form refractory of this embodiment prepared by impregnating the initial slurry of pH 5-6 and the fixed form of this embodiment prepared by impregnating the slurry repeatedly used of pH 7-8. In both refractories, good corrosion resistance could be obtained up to the central part, but in the case of a dispersant in which the median particle size of the suspended particles agglomerates to 2 μm or more due to the increase in pH, the oxide particles reach the central part of the regular refractory. In some cases, it is difficult to achieve high corrosion resistance.

  When impregnated with an oxide powder-containing slurry and then dried, the porosity of the refractory is reduced by about 1 to 10% from the fired refractory used for the material, and the oxide concentration in the refractory is the original fired refractory. It increases about 1-15 mass% from the value of a thing. Moreover, it becomes to have a 2nd pore diameter peak in 0.01-1.0 micrometer by impregnating an oxide powder containing slurry. As shown in FIG. 2, this peak is because the impregnated oxide powder forms a packed layer (impregnated material layer) on the inner walls of the pores of the fired refractory, and the oxide of this packed layer (impregnated material layer) It is presumed that micropores corresponding to the gaps between the powders have been detected.

  It is presumed that the oxide-filled layer formed on the inner walls of the pores of the fired refractory has an effect of efficiently suppressing slag erosion. It is preferable that the pore volume (measured with a mercury porosimeter) between 0.01 and 1.0 μm in pore diameter is 1 ml / kg or more, more desirably 3 ml / kg or more, thereby effectively improving the corrosion resistance. Can be improved. The upper limit of the pore volume between the pore diameters of 0.01 to 1.0 μm is not particularly required, and may be 10 ml / kg or more when a normal fired refractory is used. The method of impregnating a slurry containing one or more oxide powders selected from the group consisting of zirconia, zircon, silica, and alumina is simply an oxide that improves corrosion resistance such as chromia in the raw material of the fired refractory Compared to baking with increasing the amount of added, the effect of improving corrosion resistance is large, and the cost performance is excellent.

  The pores in the baked refractory correspond to the gaps between the high melting point mineral particles, and the erosion of the baked refractory with molten slag causes the molten slag to enter the gaps, so that the bonding points between the mineral particles have a low melting point. And the erosion progresses as the mineral particles fall out into the molten slag. On the other hand, in the regular refractory according to the embodiment of the present invention, one or two kinds selected from the group consisting of zirconia, zircon, silica, and alumina in the pores of the baked refractory, that is, the gaps between the mineral particles. Since the aggregate of the above oxide particles is formed so as to have 0.01 to 1.0 μm pores, the molten slag that has entered the pores is quickly brought into contact with the oxide particles and the high-viscosity compound melt. Since the joints between the mineral particles of the fired refractory are effectively protected, the rate at which the erosion progresses as the mineral particles fall off is small, and the erosion rate is greatly reduced. can do.

  Furthermore, one kind selected from the group consisting of zirconia, zircon, silica, and alumina so as to have a pore of 0.01 to 1.0 μm in the central part 5 mm or more in the normal direction from the surface of the shaped refractory or Since an aggregate of two or more kinds of oxide particles is formed, the above-described effect of reducing the erosion rate can be maintained even when the erosion progresses to the center of the regular refractory.

Using a direct bond magcro brick (10% by mass CrO ₃ —MgO; porosity 21.0%), a regular refractory according to an embodiment of the present invention impregnated with various oxide powder-containing slurries was prepared, The performance was compared with a comparative direct bond magcro brick that was not impregnated. The direct bond magcro brick used is based on a normal manufacturing method, and as shown in FIG. 1 to be described later, the pore diameter distribution curve of the pore volume has the maximum peak at a pore diameter of 12.6 μm.

Examples of the oxide powder include zirconia for refractories having a nominal average particle size (median particle size, D ₅₀ , the same applies hereinafter) (Example 1), zircon for refractories having a nominal average particle size of 0.55 μm (Example) 2) Silica for refractory having an average particle size of 0.15 μm (Example 3) and alumina for refractory having an average particle size of 0.5 μm (Example 4) were prepared, and 7. A bead mill using zirconia beads having a diameter of 1 mm, which is added to pure water (ion-exchanged water) together with 5% by mass of an acidic polymer dispersant to form an aqueous slurry having a mass ratio of oxide powder to slurry mass of 30% by mass. Then, 10 L of the slurry was crushed at an energy input rate of 1.5 W / L for 2 hours, and then used for impregnation of the refractory.

  As the dispersant, a polymer copolymer having a functional group having affinity for oxide particles was used. A 80 mm thick rectangular direct bond magcro brick was used, the side surfaces other than the thickness direction were sealed, and the slurry was prevented from entering from the side surfaces, and then impregnation was performed in a vacuum vessel. After depressurizing the inside of the vacuum vessel containing the brick sample to 1 kPa or less, the slurry after the above pulverization treatment was poured into the vacuum vessel so that the brick sample was immersed in the slurry. After that, the atmosphere is introduced into the decompression vessel, the slurry is pressurized at atmospheric pressure, held for 1 hour and impregnated, and then the brick impregnated with the slurry is taken out and dried at 110 ° C. to test a fixed refractory sample. It was.

  About the obtained fixed refractory sample for test and the comparative direct bond magcro brick which is not impregnated (Comparative Example 1), the corrosion resistance and the pore size distribution of the pore volume were examined in the following manner. A sample refractory sample for testing was cut into two trapezoidal pillars in each example, and the surface including the bottom of the shorter trapezoidal cross section (upper bottom surface) was not subjected to sealing treatment during impregnation. A test vessel with a 10-sided prism with a horizontal axis was prepared by combining with a sample for comparison so that the thickness was parallel to the sample surface and the upper bottom surface was inward. The slag erosion test was conducted by putting slag into the inside of the test vessel from the opening provided in the end wall of the test vessel of the 10-prism column, rotating the test vessel around its axis, and controlling the test temperature by burner heating. (Rotary slug method). Slag basicity is 0.7, slag is replaced every hour, eroded at 1750 ° C for 4 hours, after cooling, the test refractory is cut, the average erosion depth is measured, and the impregnation is not performed Comparison was made with an erosion index where the erosion depth of Example 1 was 100.

The pore size distribution of the pore volume was measured with a mercury porosimeter by cutting out a measurement sample for a mercury porosimeter from the center of about 40 mm from the surface of the prepared test refractory sample and comparative brick sample.
For each example, evaluation results of corrosion resistance and pore size distribution of pore volume (pore diameter showing maximum peak, pore diameter showing second peak, pore volume in 0.01 to 1 μm pore diameter range) and increase in impregnation mass Table 1 shows the rate (impregnation per mass of fired brick before impregnation, mass increase rate after drying (mass%)).

As is clear from Table 1, the refractories of Examples 1 to 4 exhibit excellent slag corrosion resistance when any oxide powder is used. Examples of pore diameter distribution of pore volume (Example 1 and Comparative Example 1) are shown in FIGS. Here, FIG. 1 (a) shows the pore size distribution of the pore volume at the center of the shaped refractory with and without impregnation of the slurry containing zirconia powder based on this embodiment (Example 1) and without (Comparative Example 1). Of the cumulative pore volume (cumulative from the largest pore to the predetermined pore size) is shown in FIG. 1B, and FIG. 1B shows the impregnation of the slurry containing zirconia powder according to the present embodiment ( Example 1) and absence (Comparative Example 1) affect the pore size distribution of the pore volume in the central part of the regular refractory in terms of the logarithmic differential pore volume (pore volume in the range of pore diameter interval d to d + Δd ( mL / kg) is represented by a pore size distribution of Log ₁₀ (value obtained by dividing by (d + Δd) / d).

  With impregnation of the zirconia powder-containing slurry (Example 1), a second pore diameter peak exists at 0.01 to 1.0 μm. In addition, the impregnation of the zirconia powder-containing slurry decreases the pore volume of the fired refractory having a thickness of 10 μm or more and shifts the pore diameter showing the maximum peak to the small pore diameter side, but has a maximum peak at a pore diameter of 5 μm or more. It can be confirmed that the pore volume of 0.01 to 1.0 μm corresponding to the aggregate of zirconia particles in the impregnated slurry increased. FIG. 2 shows a model of the pore structure of the regular refractory according to the embodiment of the present invention recognized from micro observation of the pore. In Examples 2 to 4 using powders of other oxide species, the pore volume distribution of pore volume had the same tendency.

  In the regular refractory according to the embodiment of the present invention, a slurry containing at least one oxide powder selected from the group consisting of zirconia, zircon, silica, and alumina in pores having an average diameter of about 10 to 20 μm in the fired refractory. Since the aggregate of the oxide powder particles was formed as a packed layer so as to cover the inner walls of the pores in the baked refractory by drying after impregnating It is presumed that the joint portion was effectively protected and the slag erosion was effectively suppressed.

  In the same manner as in Example 1, a 30 mass% aqueous solution slurry of zirconia for refractory having a nominal average particle size of 0.2 μm was prepared by stirring to such an extent that precipitation was not caused by a stirring device without adding a dispersant ( For Comparative Example 2), the particle size distribution of the suspended particles in the slurry was measured by the laser diffraction / scattering method and compared with the slurry used in Example 1.

In Comparative Example 2 where the crushing treatment was not performed, the median particle size of the suspended particles in the slurry was 2.2 μm even though a powder having a nominal average particle size of 0.2 μm was used, and the zirconia powder aggregated. I understand that
On the other hand, the median particle size of the slurry obtained by adding 7.5% by mass of the above acidic polymer-based dispersant to the zirconia powder and crushing for 2 hours with a bead mill using zirconia beads having a diameter of 1 mm was 0.21 μm. It can be seen that the powder was crushed to the primary particle level. When this acidic polymer-based dispersant was used, the initial slurry had a pH of about 5 to 6, but a 0.1 N sodium hydroxide aqueous solution was added to the slurry and mixed to adjust the pH to 8. In the slurry adjusted to ˜9, the median particle diameter of the suspended particles by the laser diffraction / scattering method was about 0.5 μm.

  A fixed-form refractory sample (Comparative Example 2 (no pulverization) and Example) prepared by impregnating direct bond magcro bricks with the two types of slurries evaluated for the particle size distribution of the suspended particles. 1 (with crushing)) was evaluated for corrosion resistance at the center in the thickness direction perpendicular to the surface that was not sealed during impregnation. Cut the upper bottom surface of the trapezoidal column sample so that it matches the thickness center surface of the standard refractory sample or the surface that has not been sealed during impregnation, and assemble it into a 10-sided column test container with the upper bottom surface facing inward. The erosion test was performed by the same rotary slag method as described above.

The comparison was made in FIG. 3 with an erosion index where the erosion depth was 100 when the thickness center plane of the brick sample of Comparative Example 1 that was not impregnated was taken as the erosion face. In Comparative Example 2 using the slurry that has not been crushed, the zirconia powder-containing slurry cannot penetrate into the center of the brick, so the corrosion resistance inside the brick cannot be improved (the amount of erosion is comparable to the case without slurry impregnation). .
On the other hand, in the case of Example 1 using the slurry subjected to the pulverization treatment, although the corrosion resistance of the brick surface at the time of impregnation is slightly inferior, the erosion amount at the center of the brick at the time of impregnation is reduced by about 40% compared to the case without slurry impregnation. It was also confirmed that the corrosion resistance of the brick center could be improved.

  As mentioned above, although embodiment of this invention was described based on the Example, this invention is not limited to the above-mentioned Example, It can change suitably within the description range of a claim.

  Thus, according to the fired refractory of the present invention and the manufacturing method thereof, high slag corrosion resistance can be achieved at low cost.

Claims (10)

A fixed-form refractory in which one or more oxide powders selected from the group consisting of zirconia, zircon, silica, and alumina are present in the pores of the regular fired refractory,
In the central part 5 mm or more in the normal direction from the surface of the fixed refractory,
The pore diameter distribution curve of the pore volume in the regular refractory has a maximum peak at a pore diameter of 5 μm or more, and the aggregate of the oxide powder is formed in the pores of the fired refractory. A regular refractory having a pore volume peak in a pore diameter range of 0.01 to 1.0 μm.   The shaped refractory according to claim 1, wherein the oxide powder is not sintered with the fired refractory.   The shaped refractory according to claim 1 or 2, wherein the fired refractory is a magnesia-chromia fired refractory or an alumina-chromia fired refractory. One or more oxidations selected from the group consisting of zirconia, zircon, silica, and alumina are formed into a regular fired refractory having a maximum peak at a pore diameter distribution curve of pore volume in the refractory of 10 μm or more. The slurry containing the product powder and the dispersing agent is mechanically stirred using beads as a stirring medium to break up the oxide aggregate particles in the slurry, and then impregnated and further dried, so that the normal direction from the surface of the shaped refractory In addition, in the central part 5 mm or more inside, the pore diameter distribution curve of the pore volume in the regular refractory has a maximum peak at a pore diameter of 5 μm or more, and also in a pore diameter range of 0.01 to 1.0 μm. A method for producing a shaped refractory characterized by having a peak.   The slurry containing the oxide powder and the dispersant is mechanically stirred using beads having a median particle size of 0.1 to 2 mm as a stirring medium, and the aggregated particles of the oxide in the slurry are crushed. The method for producing a regular refractory according to claim 4, wherein impregnation is performed.   6. The fired refractory is immersed in a slurry containing the oxide powder and a dispersing agent under reduced pressure, and then the slurry is pressurized and impregnated in the fired refractory. Manufacturing method for regular refractories.   When the slurry containing the oxide powder and the dispersant is mechanically stirred to crush the aggregated particles of the oxide in the slurry and then impregnated in the fired refractory, the median particles of the suspended particles in the slurry 7. The method for producing a regular refractory according to claim 4, wherein the diameter is less than 1 μm as measured by a laser diffraction / scattering method.   The method for producing a regular refractory according to one of claims 4 to 7, wherein the fired refractory is an alumina-chromia fired refractory.   The method for producing a regular refractory according to one of claims 4 to 7, wherein the fired refractory is a magnesia-chromia fired refractory.   When the slurry containing the oxide powder and the dispersant is mechanically stirred to crush the aggregated particles of the oxide in the slurry and then impregnated into the fired refractory, the slurry further has a pH of 8 10. The median particle diameter of suspended particles in the slurry after being adjusted to a range of ˜9 is less than 1 μm as measured by a laser diffraction / scattering method. A method for producing the shaped refractory as described in 1.

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