JPH0742162B2 - Basic brick manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a molten metal container, a metal refining reaction container, a magnesia material used as a lining material for a kiln furnace used at high temperatures such as a cement rotary kiln, and magnesia.・ Regarding the manufacturing method of spinel bricks.

<Prior Art> Basic bricks such as magnesia bricks and magnesia-spinel bricks are widely used as refractory linings in kilns. Although these have a high melting point and excellent slag resistance, they have a high thermal expansion coefficient and thus have a drawback of weak spalling resistance.

Until now, various proposals have been made to improve the spalling resistance of basic bricks, but depending on the conditions of use, they still cannot be said to have sufficient spalling resistance. Especially in magnesia bricks, the brick structure is composed of almost a single crystal phase, and the growth and development of cracks are extremely fast. In addition, the second group of magnesia
Although magnesia-spinel bricks with spinel have better spalling resistance than magnesia bricks, it is necessary to further improve spalling resistance in order to expand the range of application.

The inventors of the present invention have made various studies to improve spalling resistance by adding a second phase to magnesia bricks and a third phase to magnesia-spinel bricks, and the results show that the brick components MgO and Al We have focused attention on zirconia as an oxide which itself does not form a low melting point compound with ₂ O ₃ but has a high melting point and corrosion resistance.

Examples of patent publications conventionally disclosed in the technology of adding zirconia to basic bricks include JP-B-43-28716, JP-A-54-163910, and JP-A-60-108361. By the way, in the above-mentioned publication, regarding the particle size of zirconia used, JP-B-43-28716 discloses that optimum results are obtained when the total amount passes through 325 mesh, and JP-A-54-163910. It is stated in the publication that if the particle size is preferably finer than 0.2 mm, the reactivity during firing is not sufficient, and the effects in terms of hot strength and porosity are not exhibited, and JP-A-60-108361. The publication states that 74μ (2
00 mesh) There is a statement that the following is preferable. In addition, if the amount of zirconia added exceeds 7%,
Both the hot strength and the porosity are markedly improved, and zirconia is generally expensive, so the limit is 10% mainly due to economic reasons. If there is too much zirconia, the sinterability as a brick decreases. The point to do is also described. That is, the addition of zirconia seen in the above patent publication was intended to improve the erosion resistance by densifying the structure by utilizing the sinterability of zirconia or increasing the strength.

As shown in these techniques, the use of fine zirconia powder densifies the structure by the sintering effect of zirconia and increases the strength at hot and room temperature, but it has no effect on the improvement of spalling resistance. According to the test results of the inventors, it was found that even the tendency to be worse was seen. Therefore, the inventors of the present invention have re-questioned about the particle size of zirconia added, and have completed the present invention described below.

<Means for Solving Problems> In the present invention, 1 to 10 of zirconia is added to magnesia or magnesia / spinel bricks containing few impurities such as SiO ₂ and Fe ₂ O _3.
In the method of manufacturing a basic brick, in which a weight part is added and molded and fired, the particle size of zirconia to be added is to make coarse particles in which fine powder of 88 μ or less is suppressed to 5% by weight or less.

The total amount of zirconia added is in the range of 1 to 10 parts by weight,
Addition of less than 1 part by weight has almost no effect on the improvement of spalling resistance. Further, if added in an amount of 10 parts by weight or more, the erosion resistance decreases when there are many coarse particles of zirconia. When 5% or more of fine powder having a particle size of zirconia of 88 μ or less is contained, it has little effect on the improvement of spalling resistance and may decrease.

The zirconia used can be unstabilized products containing 90% or more as ZrO ₂ , partially stabilized products, completed stabilized products, and vaterite ores.As stabilizers for partially stabilized products and fully stabilized products, Any of MgO, CaO, Y ₂ O _{3 and the} like can be used.
In particular, forming a low melt in the above publication, CaO-stabilized zirconia that is said to be harmful, magnesia that is the subject of the present invention, magnesia-spinel bricks are SiO ₂ ,
Since it contains almost no impurities such as Fe ₂ O ₃ , it can be used.

<Effects of the Invention> In the present invention, by specifying the particle size of zirconia to be added as described above, it is possible to obtain a magnesia or magnesia-spinel brick with significantly improved spalling resistance.

<Examples> Example 1. With respect to a composition in which zirconia was added to 100 parts by weight of high-purity magnesia clinker whose particle size was adjusted, the addition amount of zirconia and the fine powder amount of 88 μ or less in zirconia were changed and kneaded, and 200 After molding into × 250 × 100 mm, it was fired at 1800 ° C to obtain a brick. A 200 x 100 mm surface of this brick was used as a heating surface, and a single-sided heating spall test was performed. The spalling resistance was compared by the average number of times of peeling in three tests. The results are shown in FIG.

Also, a rotary erosion furnace was used to compare erosion resistance.
A 114 × 100 mm test piece was set in a cylindrical shape, and while rotating at 5 rpm, the temperature was raised to 1750 ° C. with an oxygen-propane-burner and corroded by steelmaking slag for 5 hours. After cooling to room temperature, the temperature was re-increased to cause erosion, and the erosion resistance was compared by the amount of erosion. The composition of the slag used was C / S = 1.1
8, Fe ₂ O ₃ = 0.5%. The results are shown in Table 1.

Example 2. From a formulation of zirconia added to 60 parts by weight of particle size adjusted magnesia clinker and 40 parts by weight of spinel clinker,
A fired brick was obtained in the same manner as in Example 1. A spall test and an erosion test were performed in the same manner as in Example 1, and the results shown in FIG. 2 and Table 2 were obtained.

[Brief description of drawings]

1 shows the comparison result of spalling resistance in Example 1, and FIG. 2 shows the comparison result of spalling resistance in Example 2. As shown in FIG.

Claims (1)

[Claims] 1. A method for forming and burning 1 to 10 parts by weight of zirconia to a magnesia brick and a magnesia-spinel brick, and molding and firing the zirconia having a particle size of 88 μ or less to 5% by weight or less. A manufacturing method characterized in that it is made into particles.