JP2013249241A - Unburned brick - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide unburned brick excellent in corrosion resistance and spalling resistance, even though the carbon content is remarkably reduced.SOLUTION: Hexamine is added as a hardening agent to 100 wt.% compounded composition comprising 5-15 wt.% alumina powder, 3-8 wt.% titania powder, 0.5-5 wt.% barium titanate and the balance of magnesia, and the composition is mixed with a phenol resin to be kneaded and formed, subsequently dried, and furthermore 3-8 wt.% zirconia powder or 3-8 wt.% zircon powder may be added to the composition.

Description

   The present invention relates to a refractory for lining used in a steel making furnace, a refining furnace, and the like.

  Conventionally, magnesia-chromium bricks having excellent corrosion resistance and spalling resistance have been used for refractories for lining used in various furnaces. Since magnesia-chromium bricks produce hexavalent chromium which is harmful to the human body and environmental health after use, so-called chromium-free bricks have been sought since early on.

  On the other hand, magnesia-carbon bricks containing 10% by weight or more of carbon are used in steelmaking converters and ladles. The magnesia-carbon brick, which contains a large amount of carbon, has the disadvantage that the brick structure becomes brittle due to oxidation and cannot withstand long-term use. In addition, the oxidation of carbon generates carbon dioxide and promotes global warming, and it is difficult to say that it is suitable for modern times. In addition, scaly graphite used in magnesia-carbon bricks has a tendency to increase its use amount, and there is an economic problem that the price rapidly rises due to the limited production country and production amount. In addition to these, when magnesia-carbon brick is used in an actual furnace, there is a problem of so-called carbon pickup in which carbon is dissolved into molten steel when the carbon content is high.

  Various refractories have been proposed from such a background.

  For example, in a chromium-free brick, a magnesia-calcia-aluminum titanate-based basic refractory (see Patent Document 1), a regular refractory in which aluminum titanate is added to spinel (see Patent Document 2), magnesia-alumina. -Titania bricks (see Patent Document 3) have been proposed.

  In addition, low-carbon magnesia-carbon bricks with low carbon content include low-carbon magnesia-carbon refractories for converter outlet sleeves to which pitch powder has been added (see Patent Document 4), tar and pitch. A magnesia carbon brick to which is added (see Patent Document 5) or a low carbonaceous carbon-containing refractory to which carbon black is added (see Patent Document 6) has been proposed.

Japanese Patent Laid-Open No. 9-20550 JP 11-147755 A JP 2001-253765 A Japanese Patent Laid-Open No. 8-259312 JP 2007-76980 A Japanese Patent Laid-Open No. 11-322405

  However, the above-mentioned chromium-free brick has the following problems.

  Magnesia and titania react at high temperatures to produce magnesium titanate, but this mineral is very dense and fragile, vulnerable to thermal expansion, low spalling resistance, long There is a disadvantage that it cannot withstand the use of the period.

  Moreover, it is necessary to synthesize aluminum titanate from titania and alumina, and there is a disadvantage that the cost is high for producing the clinker.

  Furthermore, since magnesia-alumina-titania brick has a large content of magnesia having a large expansion coefficient, it has a drawback that it is inferior in spalling resistance even though it is excellent in corrosion resistance.

  On the other hand, in magnesia-carbon bricks using tar and pitch, there is a problem that tar and pitch are carcinogenic substances and are harmful to the human body.

  In addition, since carbon black is very fine particles, there is a problem in that it is likely to be scattered around when producing a refractory and may affect the human body and the environment.

  Further, in the case of a low carbon magnesia-carbon brick, the spalling resistance is generally lowered due to the low carbon.

  Therefore, the present invention has been researched and developed to solve the above-mentioned problems, and provides a non-fired brick having excellent corrosion resistance and spalling resistance while significantly reducing the carbon content. For the purpose.

  In order to achieve the above object, the non-fired brick according to the present invention comprises 5 to 15 wt% alumina powder, 3 to 8 wt% titania powder, 0.5 to 5 wt% barium titanate, and the balance of magnesia as the balance. A curing agent is added to 100 wt%, kneaded and molded, and then dried.

  Thereby, after drying, magnesia-carbon brick has a higher porosity and maintains spalling resistance, and since there is much magnesia, the effect of improving corrosion resistance can be obtained. In addition, after being heated by use in an actual furnace, non-fired bricks that do not contain carbon change the structure of magnesia-titania-alumina to another structure, and have excellent spalling resistance and corrosion resistance. Become. In addition, since the non-fired brick is used, there is a secondary merit that the manufacturing cost can be kept low.

  Here, in the unfired brick, 3 to 8 wt% of zirconia powder or zircon powder may be further added.

  Thereby, the effect of improving the spalling resistance can be obtained by the expansion and contraction of zirconia, and the effect of improving the corrosion resistance can be obtained because the melting point of zirconia is high.

  Moreover, a hardening agent is added to 5 wt% to 15 wt% of alumina powder, 3 to 8 wt% of zirconia powder or 3 to 8 wt% of zircon powder, 0.5 to 5 wt% of barium titanate, and 100 wt% of the blend composition containing magnesia as the balance. It is also possible to adopt a constitution characterized by drying after kneading and forming.

  As described above, even when the titania powder is replaced with zirconia powder or zircon powder, non-fired bricks having excellent spalling resistance and corrosion resistance can be realized.

  Further, carbon 1-8 wt%, alumina powder 5-15 wt%, barium titanate 0.5-5 wt%, zirconia powder 3-8 wt% or zircon powder 3-8 wt%, and the balance 100 wt% with magnesia as the balance It is good also as a structure characterized by adding a hardening | curing agent to, kneading | mixing and shaping | molding, and making it dry.

  As a result, the carbon contained therein is oxidized by use in an actual furnace, and the brick structure is changed, so that spalling resistance and corrosion resistance can be improved while being low carbon.

  As described above, according to the non-fired brick according to the present invention, it is possible to improve the spalling resistance and the corrosion resistance in two stages. That is, since the porosity is higher than that of magnesia-carbon brick at the time after drying as unfired brick, the spalling resistance is maintained, and the corrosion resistance is also improved because of the high magnesia content. The unfired brick after being heated by use in an actual furnace is further improved in spalling resistance and corrosion resistance by changing the structure such as magnesia-titania-alumina to another structure. Accordingly, non-fired bricks having excellent spalling resistance and corrosion resistance can be realized while significantly reducing the carbon content.

  The non-fired brick according to the present invention will be described in detail below.

  The unfired brick according to the first embodiment of the present invention is made of alumina powder 5 to 15 wt%, titania powder 3 to 8 wt%, barium titanate 0.5 to 5 wt%, and the balance is magnesia, and a curing agent is added. It is a non-fired brick which is produced by kneading and forming and then drying, and does not contain carbon.

  Magnesia, which is the main raw material, has a high melting point of about 2800 ° C. and is a highly basic substance and exhibits excellent corrosion resistance against slag. For this reason, the increase in the component ratio of magnesia leads to the improvement of the corrosion resistance of the brick. On the other hand, the thermal expansion coefficient of magnesia is as high as about 2.3% at 1500 ° C., for example, and there is a drawback that the brick structure is easily broken when the component ratio of magnesia is increased.

In this respect, in the present embodiment, by adding alumina powder, the thermal expansion coefficient of magnesia is reduced to about 2.0%, and the brick structure is hard to break. Further, when unfired brick is used in an actual furnace, the unfired brick is heated to about 1400 ° C. or more. When the unfired brick according to this embodiment to which alumina powder is added is heated to 1100 ° C. or higher, alumina and magnesia react to generate spinel (MgO + Al ₂ O ₃ → MgO · Al ₂ O ₃ ). . Due to the spinel generation, the expansion coefficient of spinel and magnesia is different, so that a microcrack is generated in the brick structure, the microcrack absorbs thermal stress, and the brick structure is difficult to break. If the alumina content is less than 5 wt%, the amount of spinel produced decreases, and it does not contribute to the improvement of spalling resistance. Moreover, if alumina is added in excess of 15 wt%, the amount of spinel generated is excessively increased, and microcracks due to spinel expansion increase, resulting in a decrease in corrosion resistance.

Titania reacts with calcia in the slag to produce perovskite (TiO ₂ + CaO → CaO · TiO ₂ ). Perovskite is a dense structure and is formed in the form of a film near the working surface of bricks, preventing other slag components and molten metal bricks from entering the structure, making it difficult for low melting point products to be formed, and providing corrosion resistance. improves. Further, at 1100 ° C. or higher, magnesium titanate produced by the reaction of magnesia and titania and spinel produce a solid solution, and elongated pores are formed. These pores absorb thermal stress and make unfired bricks difficult to break. If titania is less than 3 wt%, the amount of magnesium titanate produced is reduced, and the amount of elongated pores produced is also reduced. Therefore, improvement in spalling resistance cannot be expected. On the other hand, when titania is added in excess of 8 wt%, free magnesium titanate increases in addition to the solid solution of magnesium titanate and spinel. This released magnesium titanate is not preferable because it causes a decrease in spalling resistance.

  Barium titanate has the effect of increasing the strength of unfired bricks by heating at 1300 ° C. or higher, and improving spalling resistance and corrosion resistance. This is because barium titanate produces a slight liquid phase by heating at 1300 ° C. or higher, which adheres around the magnesia particles and increases the bonding force between the magnesia particles, or barium titanate titanate And magnesia react to produce magnesium titanate to increase the strength.

  Here, the unfired brick of the present embodiment may further contain 3 to 8 wt% of zirconia or zircon powder, or may add 3 to 8 wt% of zirconia or zircon powder instead of titania powder.

  Unstabilized zirconia undergoes a phase transition from a monoclinic system to a tetragonal system by heating, and microcracks are generated by expansion and contraction in the process, thereby improving the spalling resistance. Moreover, since the melting point of zirconia is as high as 2950 ° C., the corrosion resistance is also improved. Note that when the amount of zirconia is less than 3 wt%, the amount of microcracks generated is insufficient and does not contribute to the improvement of the spalling resistance. Moreover, since zirconia is an expensive raw material, if it exceeds 8 wt%, the raw material cost which occupies for a manufacturing cost will become high, and is not desirable.

Zircon dissociates from about 1400 ° C. to zirconia and silica. Zirconia deviated from zircon has the same effect as above. On the other hand, silica separated from zircon reacts with magnesia to produce forsterite (SiO ₂ + 2MgO → 2MgO · SiO ₂ ). Since forsterite has a lower melting point than magnesia, it has the effect of improving the spalling resistance. If zircon is less than 3 wt%, the amount of microcracks generated is insufficient as in the case of zirconia, and does not contribute to the improvement of the spalling resistance. Further, if the zircon content exceeds 8 wt%, the silica content increases and the corrosion resistance is lowered. Therefore, the content is preferably 8 wt% or less.

  Next, the constituent materials of the unfired brick according to this embodiment will be described in detail.

  As for magnesia, either electrofused magnesia or sintered magnesia may be used. The purity is preferably 75 wt% or more, and the particle size is 5 mm or less.

  As the alumina, 1 mm or less of sintered alumina or calcined alumina can be used. The purity is desirably 98 wt% or more, and the particle size is desirably an average particle diameter of 50 μm or less.

  It is desirable to use titania having a purity of 90 wt% or more and a particle size of 30 μm or less in average particle size.

  Zirconia can be used if its purity is 98 wt% or more and 1 mm or less, but the particle size is desirably an average particle size of 50 μm or less.

  As zircon, zircon sand of 1 mm or less can be used, but it is preferable to use zircon powder having a zirconia content of 62 wt% or more and an average particle size of 50 μm or less.

  It is desirable to use barium titanate having a purity of 96 wt% or more and a particle size of 5 μm (including 90% or more of 20 μm or less).

  The non-fired brick of this embodiment is manufactured by adding hexamine as a curing agent to the above configuration, kneading and molding with a phenol resin, and drying. A drying temperature shall be 160-300 degreeC, and it is more preferable to set it as 180-250 degreeC. If the drying temperature is low, the curing agent hexamine is not sufficiently cured and the strength is lowered. Moreover, if the drying temperature is high, the components of the phenol resin are volatilized and the strength is lowered.

  Next, the non-fired brick according to the second embodiment of the present invention will be described.

  Non-fired bricks according to the second embodiment are carbon 1-8 wt%, alumina powder 5-15 wt%, barium titanate 0.5-5 wt%, zirconia powder 3-8 wt% or zircon powder 3-8 wt%, and The remainder is magnesia, hexamine is added as a curing agent, kneaded and molded with a phenol resin, and then dried to produce a low-carbon non-fired brick.

  Except for the point that it contains carbon and does not contain titania, it is the same as the first embodiment described above, so only the differences will be described.

  When the unfired brick of the second embodiment is used in an actual furnace, the contained carbon is oxidized. The structure after oxidation changes to a structure mainly composed of magnesia-zirconia-alumina. At this time, the zircon powder is dissociated into zirconia and silica upon receiving heat due to oxidation, and the spalling resistance and corrosion resistance are improved as in the first embodiment.

  As the carbon used here, general carbon such as scaly graphite, pitch, earthy graphite, and carbon black can be used, but scaly graphite is most desirable.

  In general magnesia-carbon bricks, metal aluminum or metal silicon may be added as a carbon antioxidant. In the non-fired brick of the second embodiment, the performance is improved by positively oxidizing the carbon and changing the brick structure to another structure. There is no need.

  Next, the non-fired brick according to the present invention will be described in more detail with reference to examples and comparative examples. The following examples and comparative examples show the influence of the amount of each constituent material added on the brick properties.

  The raw materials were prepared in the proportions shown in the following tables, 0.5 wt% of hexamine was added, about 2.5 wt% of novolac type phenol resin was added, kneaded for 15 minutes in a small fret mill, and a 150 ton friction press. And pressure-molded into a parallel shape (230 × 115 × 65 mm). The molded body was left to stand for about 1 day and then dried at 180 ° C. for 24 days. The dried body was cut into a predetermined size, a test with the following items as evaluation items was performed on the examples and comparative examples, and the characteristics were investigated.

As an evaluation item,
(1) Based on the JIS standard, the apparent specific gravity, the apparent porosity, and the bulk specific gravity of the test piece after drying and the test piece after oxidation for 24 hours at 1400 ° C. were measured.
(2) The test piece was cut into 50 × 50 × 50 mm, and the compression strength was measured with an Amsler compression tester.
(3) In the spalling resistance test, a test piece having a size of 40 × 80 × 20 mm was quickly put in an electric furnace maintained at a temperature of 1200 ° C., heated for 15 minutes, then taken out and cooled in water. This operation was performed as one cycle and repeated 10 cycles, and the evaluation was performed in terms of how many cycles the cracks occurred in the test piece and how many cycles the peeling occurred in the test piece. This test was also performed on the test piece after drying and the test piece after oxidation for 24 hours.
(4) Corrosion resistance was evaluated using a rotary erosion tester. The erosion material of steel: slag (basicity 3.0) = 6: 4 was thrown in and this was replaced every 30 minutes for a total of 10 times, and the total erosion time was 5 hours. The results are expressed as an index (melting index), where the melting amount of magnesia-carbon brick containing 13 wt% carbon is taken as 100. In this test, the smaller the erosion index, the smaller the amount of erosion, that is, the better the corrosion resistance. This test was also performed on the test piece after drying and the test piece after oxidation for 24 hours.

  Table 1 shows the influence of the amount of titania powder added on the brick properties. Note that MC13 in the table means magnesia-carbon brick containing 13 wt% of carbon (scale-like graphite), and the melting index in each table is based on the amount of MC13 as 100. In Table 2 and later, only items relating to spalling resistance and corrosion resistance are displayed for MC13.

  Comparative Example 1 with a small addition amount of titania and Comparative Example 2 with a large addition amount exceed MC13 in spalling resistance, but there is no significant difference in terms of the melting index. On the other hand, Examples 1-3 are superior not only to MC13 but also Comparative Examples 1 and 2 in spalling resistance and corrosion resistance.

  In addition, when the brick is 1 mm or more in the form of sparse grains, 1 mm or less in the middle grains, and 74 μm or less in fine grains, these addition ratios are generally about 40%, about 30%, and about 30%, respectively. When the thickness is 5 mm or less, about 13 wt% of the fine particles of 74 μm or less are included. In Comparative Example 1, since the addition amount of the fine powder is small, the filling property is poor and the porosity is high. On the other hand, in Comparative Example 2, since fine powder increases, small pores increase. Further, since molding cracks are likely to occur, molding is required at a low pressure, resulting in high efficiency.

  The reason why the melting index of Comparative Example 1 is not good is thought to be that the amount of titania powder added is small and the amount of reaction with lime in the slag is small. In other words, the density of the brick near the working surface is reduced, and as a result, other slag components penetrated into the brick and a low melting point material of alumina-silica-magnesia system was generated, resulting in a large melting index. It is thought that it became. The reason why the melting index of Comparative Example 2 is not good is that the porosity is increased by low pressure molding.

  In Comparative Example 2, the spalling resistance tends to decrease. This is because when titania powder is present in excess, magnesium titanate is produced by reaction with magnesia, but magnesium titanate is inherently inferior in spalling resistance and is affected by this.

  In addition, the melt | fever loss index | exponent of Examples 1-3 is small, ie, it is attributed also to the intensity | strength being high besides chemical components, such as titania, that it is excellent in corrosion resistance. This is because when the strength is increased, the elution into the molten metal is less likely to occur, so that the corrosion resistance is improved.

  From the above, it can be seen that the addition amount of titania is preferably 3 to 8 wt%.

  Table 2 shows the effect of the addition amount of alumina powder on the brick properties. In Comparative Example 4, since there are many fine powders, low pressure molding is used.

  According to this, although the comparative example 3 with a small amount of alumina added has better spalling resistance than MC13, it cannot be said that it is greatly improved. In Comparative Example 4 where the amount of alumina added is large, although the amount of alumina is large, the coefficient of thermal expansion is lowered and there is an effect of spalling resistance, but no significant improvement is observed in corrosion resistance. Looking at the heat oxidation, in Comparative Example 3, spinel is generated by the reaction between the added alumina and magnesia, and this microcrack has a slight effect in improving the spalling resistance, but has not yet been greatly improved. .

  In addition, the volatile matter is scattered by heating, and the porosity is increased due to the expansion due to the generation of spinel, and the corrosion resistance tends to be deteriorated as a whole. In particular, the corrosion resistance of Comparative Example 4 is lower than that of MC13.

  Therefore, it can be seen that the addition amount of alumina is preferably 5 to 15 wt%.

  Table 3 shows the influence of the amount of barium titanate added on the brick properties.

  With the addition of barium titanate, a change is seen after heat oxidation. That is, it turns out that intensity | strength improves as the addition amount of barium titanate increases. The number of occurrences of cracks is proportional to strength if the values of elastic modulus, thermal expansion coefficient, and thermal conductivity are substantially the same, indicating that the spalling resistance after oxidation is improved. Moreover, since the elution of particles into the molten metal decreases as the strength increases, it can be said that the corrosion resistance is also improved. However, as shown in Comparative Example 5, if the amount is less than 0.5 wt%, the effect is not obtained so much. Moreover, when the addition amount is too large, the proportion of fine powder increases, and when the addition amount is 7 wt% or more as in Comparative Example 6, low pressure molding is required, which is not preferable.

  Considering these points, the addition amount of barium titanate is preferably 0.5 to 5 wt%.

  Table 4 shows the influence of the amount of zirconia powder added on the brick properties.

  In Examples 11 to 13, the corrosion resistance is improved by the addition of zirconia. This is because zirconia has a high melting point of about 2950 ° C. Moreover, after heat oxidation, the effect of improving the spalling resistance is also seen by the generation of microcracks due to the phase transition of zirconia.

  Even in Comparative Example 7 and Comparative Example 8, although some effects are obtained in spalling resistance and corrosion resistance as compared with MC13, the effects are small.

  Considering that the raw material of zirconia is expensive, it can be said that the amount of zirconia added is preferably 3 to 8 wt%.

  Table 5 shows the effect of the amount of zircon powder added on the brick properties.

  Examples 14 to 16 in this table exhibit effects excellent in spalling resistance and corrosion resistance. On the other hand, as shown in Table 4, compared to the case of adding zirconia powder, in Comparative Examples 9 and 10 to which zircon powder was added, the spalling resistance was improved, but the corrosion resistance was inferior. . This is particularly noticeable after heat oxidation. This is because the silica contained in the zircon powder produces a low melting point product.

  From this, it can be seen that the amount of zircon powder added is preferably 3 to 8 wt%.

  Table 6 shows the influence of the added amount on the characteristics of the brick when the titania powder is combined with the zirconia powder or the zircon powder.

  In this blending configuration, the amount of fine powder inevitably increases, so low-pressure molding results, and the overall spalling resistance and corrosion resistance tend to decrease. Nevertheless, if the added amount is 3 to 8 wt%, an excellent effect is obtained as compared with MC13. When combining these, it can be said that even better results can be obtained if the fine powder amount is adjusted to about 25 to 30%.

  Therefore, even when the titania powder is combined with the zirconia powder or the zircon powder, it is desirable that each component is 3 to 8 wt%.

  Table 7 shows examples of the low-carbon non-fired brick described in the second embodiment.

  Table 7 shows the effect of the amount of carbon added on the brick properties.

  As carbon increases, the apparent porosity decreases and the compressive strength decreases. Further, the spalling resistance is improved as the carbon increases, but the corrosion resistance is improved in proportion to the amount of carbon, and then decreases when the amount exceeds a certain amount. This is because, in a range where the amount of carbon is small, the corrosion resistance is improved because carbon does not easily wet the molten metal, but when the amount of carbon increases, the porosity increases due to the effects of liquid phase oxidation and gas phase oxidation in the molten metal.

  In Comparative Example 13 and Comparative Example 14, the spalling resistance is improved as compared with MC13. However, when corrosion resistance is included, no significant improvement as in Examples 21 to 24 is observed. In particular, the corrosion resistance after heat oxidation is reduced.

  Therefore, the carbon content is preferably 1 to 8 wt%.

  Table 8 shows the influence of the amount of alumina powder added on the brick properties. Note that Comparative Example 16 is low-pressure molded because there are many fine powders.

  Since the overall coefficient of thermal expansion decreases as the alumina powder increases, the spalling resistance is improved. However, the lime in the slag reacts with alumina to form a low melting point product, so the corrosion resistance decreases. After the thermal oxidation, alumina and magnesia react, and micro-cracks are generated due to the expansion of the spinel, so that the spalling resistance is improved. The apparent porosity is increased due to the volatilization of the binder, while the strength is decreased, so that the corrosion resistance is decreased.

  Considering the balance between spalling resistance and corrosion resistance, it can be said that the addition amount of alumina powder is preferably 5 to 15 wt%.

  Table 9 shows the influence of the addition amount of barium titanate on the brick properties.

  By adding barium titanate, the strength after heat oxidation is improved. In Comparative Example 16, the amount of fine powder constituting the brick was as large as 30% or more, and low-pressure molding was required to prevent cracking after molding, and a decrease in strength was observed. Even if the addition amount of barium titanate is small, a certain degree of strength improvement can be obtained, but it is inferior to Examples 28-30.

  Therefore, the preferable addition amount of barium titanate is 0.5 to 5 wt%.

  Table 10 shows the influence of the amount of zirconia powder added on the brick properties.

  Since the melting point of zirconia is as high as about 2950 ° C., in Examples 31 to 33, the corrosion resistance is improved as the amount of zirconia added is increased. After thermal oxidation, microcracks are generated due to the phase transition of zirconia, and the spalling resistance is also improved. In Comparative Example 18, the amount of fine powder was large and low pressure molding was required, the porosity increased and the strength decreased. Considering the degree of influence of the addition amount, the addition amount of zirconia is preferably 3 to 8 wt%.

  Table 11 shows the influence of the amount of zircon powder added on the brick properties.

  As for the brick after drying, both Examples 34 to 36 and Comparative Examples 19 and 20 have improved spalling resistance. This is because the coefficient of thermal expansion is small due to the influence of silica contained in zircon. Although spalling resistance is improved after heat oxidation, the corrosion resistance decreases as the amount of zircon increases due to the influence of silica. In particular, Comparative Example 20 has a large amount of fine powder, and has low porosity due to low pressure molding, resulting in a decrease in strength.

  Considering the balance between corrosion resistance and spalling resistance, it can be said that the addition amount of zircon powder is preferably 3 to 8 wt%.

  As described above, the non-fired brick according to the present invention has been described based on each embodiment and examples. However, the present invention is not limited to this, and the object of the present invention can be achieved and the gist of the invention can be achieved. Various design changes can be made without departing from the scope, and they are all included in the scope of the present invention.

  For example, in addition to the above-described configuration, 2-4 wt% of clay for maintaining shape retention after molding may be added to the unfired brick of each embodiment.

  Non-fired bricks according to the present invention include steelmaking converters and ladles, ash melting furnaces for melting incinerated ash generated by incineration, gasification melting furnaces, waste liquid incinerators, aluminum smelting furnaces, zinc smelting furnaces, copper It can be used as a refractory for lining used in non-ferrous industrial furnaces such as refining furnaces.

Claims (4)

  Add hardener to 100 wt% of compounding composition with alumina powder 5-15 wt%, titania powder 3-8 wt%, barium titanate 0.5-5 wt% and the balance magnesia, knead and mold, then dry Non-fired bricks characterized by   The unfired brick according to claim 1, wherein 3-8 wt% of zirconia powder or zircon powder is further added to the unfired brick.   Addition of a curing agent to 5 to 15 wt% of alumina powder, 3 to 8 wt% of zirconia powder or 3 to 8 wt% of zircon powder, 0.5 to 5 wt% of barium titanate, and 100 wt% of magnesia as the balance, and kneading -Non-fired bricks characterized by being dried after being molded.   Carbon 1-8 wt%, alumina powder 5-15 wt%, barium titanate 0.5-5 wt%, zirconia powder 3-8 wt% or zircon powder 3-8 wt%, and the composition is cured to 100 wt% with magnesia as the balance A non-fired brick, which is prepared by adding an agent, kneading and forming, and then drying.