JP6386317B2 - Silica brick for hot repair - Google Patents

Description

  The present invention relates to a hot repair silica brick for hot repair of a furnace wall such as a coke oven.

  For example, in a silica brick constituting a furnace wall of a coke oven, a damaged silica brick is replaced with a hot repair silica brick at a temperature of 300 ° C. or higher. This hot repair silica brick is required to have a spalling resistance as compared to the first lined brick. For this reason, amorphous silica such as fused silica is used as a refractory raw material for hot repair silica bricks in order to impart spalling resistance. Since this amorphous silica has a very small coefficient of thermal expansion, the thermal expansion of the hot repair brick can be reduced, and the spalling resistance of the brick can be improved.

For example, in Patent Document 1, the content of fused silica (amorphous silica) is 35 to 50% by weight, the particle size of fused quartz is 15 to 30% by weight when the particle size is less than 1 mm, and the particle size is 1 mm or more. Is disclosed, and a silica particle brick for hot repair is disclosed in which the fine particle size composition of the remaining fired silica (crystalline silica) is 0.5 to 35% by weight is 15 to 35% by weight. A fine powder of calcined quartzite of 0.5 mm or less is required to achieve a compressive strength of 200 kg / cm ² (paragraph 0014 of Patent Document 1).

  However, in this hot repair silica brick, only a maximum of 30% by weight of fused silica in a fine powder portion of less than 1 mm that forms the matrix phase of the brick is used, so the content of the fused silica in the matrix phase is insufficient and anti-spalling resistance. Sex is not enough.

  On the other hand, Patent Document 2 includes fused silica (amorphous silica) containing 40 to 70% by weight of an aggregate of a siliceous material (crystalline silica) having a particle size of 0.5 mm or more, and the balance being less than 0.5 mm. Consists of fused quartz and siliceous material aggregate, the content of fused quartz is more than 10% by weight and less than 50% by weight, and the matrix phase forms a dense fused quartz structure A heat shock resistant hot repair silica brick is disclosed. And, by forming a dense fused quartz structure in the matrix phase, both the thermal shock resistance (spalling resistance) expression and the strength expression are compatible. Thus, if the matrix phase of the brick is made of a dense fused quartz structure, the coarse grain portion does not necessarily need to be fused quartz with low thermal expansion and high thermal shock resistance, and ordinary silica bricks are used. It is said that thermal shock resistance is exhibited even with crystalline quartzite, that is, cristobalite, tridymite, or quartz constituting the structure (paragraph 0012 of Patent Document 2).

  In the brick of this Patent Document 2, in the example, 25 to 50% by weight of fused silica of 0.5 mm or less is used, but at the same time, 30 to 55% by weight of siliceous material of 1 mm or less is used. The spalling resistance is not sufficient due to the influence.

  Specifically, hot repair is performed at a coke oven temperature of 300 to 500 ° C. If the spalling resistance of the hot repair brick is insufficient, heat is applied immediately after lining the hot repair brick. Cracks due to impact may occur and new hot repair bricks may have to be used again. Therefore, in order to prevent the crack which generate | occur | produces immediately after construction, the furnace temperature must be lowered more, and there exists a problem that construction time, ie, an operation stop period, will become long. Even if there are no cracks immediately after construction, cracks may be found by observation in the furnace immediately after the start of operation. In this case, repairs are required again.

JP-A-5-132355 Japanese Patent No. 3811315

  The problem to be solved by the present invention is to provide a hot repair silica brick that has high spalling resistance and can be repaired in a short time.

The inventors of the present invention use crystalline silica having a particle size of 1 mm or more in a refractory raw material composition for hot repair silica bricks in an amount of 15% by mass or more and 25% by mass or less , and an amorphous silica having a particle size of less than 1 mm. It has been found that by increasing the content to 30 to 60% by mass, the spalling resistance can be dramatically improved while maintaining the wear resistance of the hot repair silica brick.

That is, according to one aspect of the present invention, the amorphous silica having a particle size of 1 mm or more is 15% by mass to 45% by mass, the amorphous silica having a particle size of less than 1 mm is 30% by mass to 60% by mass, and the particle size is Amorphous silica and crystalline silica containing 15% by mass or more and 25% by mass or less of crystalline silica having a particle size of less than 1 mm and containing 15% by mass or less (including 0) of crystalline silica of 1 mm or more Thus, there is provided a hot repair silica brick obtained by kneading, forming, and heat-treating a refractory raw material composition having a total amount of 95% by mass or more.

  Hereinafter, the present invention will be specifically described.

  For example, when considering the operating conditions as wall bricks in a coke oven carbonization chamber, the wall bricks are not only exposed to high temperatures, but are also subject to repeated wear due to the input coal or product coke mass. receive. The abrasion resistance of the amorphous silica coarse particles is inferior to that of the crystalline silica coarse particles, and is further inferior in the hot state. As a result, when there are many amorphous silica coarse particles, the wear and wear of the repaired part at the early stage of the operation start after the hot repair becomes remarkable. For this reason, the balance between the amorphous silica and the crystalline silica in a coarse particle region having a particle size of 1 mm or more is important.

  Amorphous silica having a particle size of 1 mm or more is used in an amount of 15 to 45% by mass, preferably 25 to 45% by mass, in order to improve the spalling resistance. If the amount used is less than 15% by mass, the spalling resistance is insufficient, and if it exceeds 45% by mass, the crystalline silica is relatively insufficient, resulting in insufficient wear resistance.

  Amorphous silica having a particle size of less than 1 mm is 30% by mass to 60% by mass, preferably 35% by mass to 50% by mass in order to improve spalling resistance and at the same time form a matrix and form a strong connective structure. Used in the following. When the amount used is less than 30% by mass, the spalling resistance is insufficient, and when it exceeds 60% by mass, the wear resistance is insufficient.

  Crystalline silica having a particle size of 1 mm or more is effective in improving abrasion resistance, and is used in an amount of 10% by mass to 30% by mass, preferably 15% by mass to 25% by mass. If the amount used is less than 10% by mass, the wear resistance is insufficient, and if it exceeds 30% by mass, the amorphous silica is relatively insufficient and the spalling resistance is lowered.

  Since the spalling resistance improves as the amount of crystalline silica having a particle size of less than 1 mm decreases, it is better not to use from the viewpoint of spalling resistance, but the amount used is 30% by mass or less, preferably 15% by mass or less. If there is, the decrease in the spalling resistance is small and the wear resistance is improved, so that it can be used when importance is attached to the wear resistance. However, if it exceeds 30% by mass, the spalling resistance is not at a practical level.

  The total amount of amorphous silica and crystalline silica is 95% by mass or more, preferably 98% by mass in the refractory raw material composition. That is, if it is less than 5 mass%, another refractory raw material can also be included. Examples of other refractory raw materials include alumina, zirconia, and alumina silica.

  In order to further improve the spalling resistance, the content of amorphous silica in the refractory raw material composition is preferably 50% by mass to 80% by mass, more preferably 60% by mass to 80% by mass. The following. The content of crystalline silica in the refractory raw material composition is preferably 20% by mass or more and 50% by mass or less, and more preferably 20% by mass or more and less than 40% by mass. Thereby, it is possible to obtain a hot repair silica brick which is further excellent in wear resistance and spalling resistance.

  The silica brick for hot repair according to the present invention is more excellent in spalling resistance than the conventional silica brick for hot repair, so that the brick due to thermal shock or the like is hardly cracked after repair. Therefore, the frequency of re-repair can be reduced. Moreover, since it is not necessary to repair at a lower temperature than necessary, the time for cooling the inside of the furnace is shortened, the work efficiency is improved, the repair work can be performed in a short time, and the operation stoppage period accompanying the repair work can be shortened.

  As the crystalline silica to be blended in the refractory raw material composition of the hot repair silica brick according to the present invention, quartz, calcined quartz that is commonly used as a raw material of ordinary silica brick, fired quartz, that is, quartzite composed of cristobalite and tridymite, and silica brick 1 type (s) or 2 or more types can be used among recycling raw materials.

  As amorphous silica, one of fused silica, a fused silica refractory recycled product that is widely used as a raw material for conventional hot repair silica brick, and a recycled silica brick containing fused silica, or the like Two or more types can be used. In addition, when it is desired to improve the strength of hot repair bricks, the amorphous silica having a small particle size, that is, a ratio of 44 μm or less can be increased.

  Further, as a method of manufacturing the hot repair silica brick of the present invention, a conventional method of adding a sintering aid and a binder to a refractory raw material composition, kneading to form a clay, molding the clay, and heat-treating. Can be adopted.

  The sintering aid is used for accelerating the sintering of the fine powder portion of the refractory raw material, and a known one can be used as a sintering aid for silica brick or hot repair silica brick. For example, 1 type (s) or 2 or more types can be used among clay, such as bentonite, lime, and iron oxide.

  As the binder, an appropriate amount of a known binder can be used for each of the fired brick and the non-fired brick. For example, an organic binder such as a phenol resin, a furan resin, a polyurethane resin, or a pitch can be used.

  The silica brick for hot repair of the present invention becomes a non-fired type when heat treated at 100 to 400 ° C, and becomes a fired type when heat treated at 1000 to 1400 ° C.

  Non-fired type hot repair silica bricks, when installed at the repair site, have the necessary mechanical strength and wear resistance as furnace wall materials because the sintering progresses due to heat from the coke oven walls during operation. And spalling resistance are exhibited. Thereby, the function as a furnace wall material stable for a long time is maintained. That is, since the same effect as firing is obtained by raising the temperature of the furnace after repair, the same effect as fired brick can be obtained and can be used stably for a long time.

  Examples and Comparative Examples of the present invention are shown in Tables 1 and 2.

  Add 2% by mass phenolic resin as a binder to the refractory raw material composition and sintering aid shown in Table 1 and Table 2 and knead to make a clay. It was molded into a shape of 300 × 100 × 100 mm, dried, and fired at 1200 ° C. for 5 hours to obtain a test brick, and its properties were examined.

  The spalling resistance in each table is a result of observing the state after inserting a 300 × 100 × 100 mm room temperature test brick into a furnace maintained at a temperature of 1000 ° C. In the table, ○ indicates that no abnormality was found in the brick, Δ indicates the occurrence of a microcrack, and × indicates the occurrence of a crack or a crack.

  Since it is expected that all amorphous silica (fused silica) in the hot repair silica brick is crystallized during regular operation of the actual furnace after repair, the evaluation of wear resistance is based on the test brick. This was carried out after re-baking at 1400 ° C. for a long time to completely crystallize amorphous silica into cristobalite and / or tridymite. The wear resistance in the table indicates the weight reduction rate (%) of brick when a predetermined amount of zircon sand is sprayed on the test brick with a sand blast tester.

  The apparent specific gravity and the apparent porosity were measured by cutting a specimen from a test brick and measuring it according to the procedure described in JIS R 2205. Moreover, the compressive strength was measured by the method of JIS-R2206, and the thermal expansion coefficient was measured by the method of JIS-R2207-1.

In Table 1, Reference Example 1, Examples 2 and 3, Reference Examples 4 and 5, and Comparative Examples 1 and 2 are examples in which the amount of crystalline silica (silica stone) is constant and the particle size configuration is different. As the coarse particles of crystalline silica (1 mm or more and 3 mm or less) are reduced, the wear resistance is reduced, and in Comparative Example 2, it is greatly reduced to a practically problematic level. In Comparative Example 1, the wear resistance is good, but the spalling resistance is low enough to cause a practical problem.

Example 6 , Reference Example 7 and Comparative Example 3 are examples in which the compounding amount of crystalline silica of less than 1 mm is different. In Example 6 in which the blending amount is within the range of the present invention, both the spalling resistance and the abrasion resistance are good. On the other hand, in Comparative Example 3, the crystalline silica of less than 1 mm exceeds 40% by mass and exceeds the upper limit of the present invention, and is inferior in spalling resistance.

  In Table 2, Examples 8 to 11 and Comparative Examples 4 to 6 are examples in which the blending amount of amorphous silica (fused silica) of less than 1 mm is different. In Examples 8 to 11 in which the blending amount is within the range of the present invention, both the spalling resistance and the abrasion resistance are good. On the other hand, Comparative Example 4 and Comparative Example 5 are inferior in spalling resistance because there are few amorphous silicas of less than 1 mm. Moreover, since the comparative example 6 has too many amorphous silicas less than 1 mm, spalling resistance is favorable, but it is inferior to abrasion resistance.

  Examples 12 and 13 are examples containing refractory raw materials other than crystalline silica and amorphous silica, but both spalling resistance and wear resistance are good. As refractory raw materials other than crystalline silica and amorphous silica, spinel, zircon, sillimanite, and homogeneous images thereof can be used in addition to those in Examples 12 and 13.

  Although the comparative example 7 is the brick disclosed by the said patent document 2, since there are many compounding quantities of crystalline silica (silica stone) less than 1 mm as 40 mass%, it is inferior to spalling resistance.

  Next, Table 3 shows examples of non-fired types.

  To the refractory raw material composition and the sintering aid shown in Table 3, 3% by mass of phenol resin as an outer binder is added and kneaded to form a clay, and this clay is 300 × 100 using a 250-ton friction press. It was molded into a shape of × 100 mm and heat-treated at 250 ° C. for 5 hours to obtain a test brick, and its characteristics were examined by the same method as in Tables 1 and 2 described above.

Example 15 and Reference Example 16 were obtained from the same refractory raw material composition as Example 6 and Reference Example 4, respectively, and only the heat treatment temperature was different .

It can be seen that the characteristics of Example 15 and Reference Example 16, particularly the spalling resistance and wear resistance, are almost the same as those of Example 6 and Reference Example 4. That is, if the refractory raw material composition specified in the present invention is used, it can be said that a stable function as a coke oven furnace wall material can be maintained for a long time regardless of the heat treatment temperature.

Claims (4)

15% by mass to 45% by mass of amorphous silica having a particle size of 1 mm or more, 30% by mass to 60% by mass of amorphous silica having a particle size of less than 1 mm, and 15% by mass of crystalline silica having a particle size of 1 mm or more The content of crystalline silica containing 25% by mass or less and having a particle size of less than 1 mm is 15% by mass or less (including 0), and the total amount of amorphous silica and crystalline silica is 95% by mass or more. Silica brick for hot repair, which is obtained by kneading, molding, and heat-treating a certain refractory raw material composition.   2. The silica brick for hot repair according to claim 1, wherein the content of amorphous silica having a particle size of 1 mm or more in the refractory raw material composition is 25% by mass or more and 45% by mass or less.   The hot repair silica brick according to claim 1 or 2, wherein the content of amorphous silica having a particle size of less than 1 mm in the refractory raw material composition is 35% by mass or more and 50% by mass or less. The content of crystalline silica in the refractory raw material formulation is 20 wt% to 40 wt% or less, one of claims 1 to 3 content of amorphous silica is 80 wt% or less than 60 wt% Silica brick for hot repair as described in Crab.