JPH0531517B2 - - Google Patents

Description

[Detailed description of the invention]

(Field of Industrial Application) The present invention relates to a spraying material used for repairing worn parts of industrial kilns. (Prior art) RH/DH vacuum degassing furnace used in the steel industry,
In industrial furnaces such as hot metal/molten steel ladles, electric furnaces, and converters, the refractory linings or coatings are worn out by contact with molten iron and slag, but the progress of this wear is uneven. Therefore, it is common practice to spray repair mainly on the parts that are severely worn out in order to extend the life of the furnace. Here, the spraying materials used in conventional spraying repairs will be explained as follows. (a) As taught in Japanese Patent Publication No. 55-6598,
A spraying material based on basic materials such as magnesia and maguro. (b) JP-A-49-108113 and JP-A-50-49311
As taught in the above publication, a spray material to which phosphates, silicates or calcium salts of alkali metals or alkaline earth metals are added as binder auxiliaries. (c) JP-A-56-104781 and JP-A-50-101409
As taught in No. 1, spraying materials are mainly designed with consideration given to the composition of the binder, such as using potassium phosphate, sodium phosphate, or silicate as the binder. (Problems to be Solved by the Invention) However, all of the sprayed materials according to the above-mentioned conventional techniques (a) to (c) suffer from chemical wear due to slag, abrasion due to molten iron and slag, or peeling over time from the adhesion interface after adhesion. There is a problem with one of the following,
Therefore, it could not be said that the durability was sufficient. The present invention has been made to solve the above-mentioned drawbacks of conventional sprayed materials, and by blending zircon sand, zircon flour, or a mixture thereof in a predetermined ratio with magnesia refractory raw material, it can be made into sprayed materials. It is intended to provide residual swelling properties and to take advantage of the properties of basic spray materials while preventing their drawback, ie, peeling. (Means for Solving the Problems) The configuration of the present invention will be described below. That is, the gist of the present invention is as follows:
A spraying material for repairing industrial kilns, characterized by containing a refractory raw material composition consisting of 5 to 50 wt% of zircon sand, zircon flour, or a mixture thereof, the remainder being a magnesia refractory raw material, and an appropriate amount of a binder. be. As is well known, zircon sand is a refractory raw material mined in Australia, America, India, etc., and has a particle size of mainly 50 to 300 μm. On the other hand, zircon flour is made by crushing zircon sand into fine particles.The particle size cannot be specified because it is adjusted appropriately depending on the purpose of use, but it is generally 200 mesh or less, 325 mesh or less, etc. be. The blending ratio of this zircon sand, zircon flour, or a mixture thereof is 5% to the magnesia refractory raw material.
~50wt%, and the reason for limiting it in this way is 5wt%
If it is less than 50wt%, the peeling prevention effect will be poor, and if it exceeds 50wt%, the erosion resistance will decrease. Particularly preferably 8~
It is 35wt%. On the other hand, as the magnesia-based refractory raw material, synthetic or natural magnesia clinker or brick waste containing these magnesia clinkers as a main component can be used. In addition, in some cases, a part of the magnesia refractory raw material may be replaced with dolomite clinker,
Spinel clinker, limestone, and other refractory raw materials can also be substituted, but it is desirable to reduce the proportion thereof as much as possible so as not to impair the effectiveness of magnesia clinker. Also,
The particle size of the magnesia refractory raw material is similar to that of conventional spray materials, for example, 7 mm or less, preferably 5 mm or less. Furthermore, commonly used binders may be used, but examples include phosphates, silicates of alkali metals and alkaline earth metals,
One or more selected from borates, aluminum phosphates, etc. can be used.
The addition ratio of these binders is preferably about 2 to 10 wt% in terms of external percentage to the refractory raw material mixture. In addition to this, the spray material of the present invention may contain plasticizers such as bentonite, clay, dextrin,
One or more selected from CMC, etc. may be added, and as a hardening accelerator for the binder, selected from slaked lime, sodium silicate, aluminum chloride, calcium chloride, magnesium sulfate, dicalcium silicate, chromium slag, etc. There is no problem in adding one or more of the following. The addition ratio thereof is preferably 10 wt % or less based on the refractory raw material composition so as not to impair the effects of the present invention. By the way, the zircon sand or zircon flour used in the present invention has a specific gravity of about 4.5 to 4.7, which is particularly large among refractory raw materials. Although it is easy to separate in specific gravity from the refractory raw material, by adding fibers in advance at the stage of blending the raw materials, specific gravity separation can be prevented, and the effect of the present invention will be even more remarkable by making the structure uniform. By the way, the fibers that can be added include inorganic fibers such as glass fiber, asbestos, magnesia fiber, silica fiber, alumina fiber, silica/alumina fiber, metallic fiber such as stainless steel fiber, iron fiber, and aluminum fiber, and vinylon fiber. There are organic materials such as polyester fiber, cotton, wool, thread waste, and beaten waste paper. All of these have the effect of preventing specific gravity separation, but organic substances that are burnt out and decomposed when heated during use and do not remain as impurities are particularly preferred. The proportion of these fibers to be added varies depending on the specific gravity of the material used, so it is not particularly limited, but taking organic materials as an example, it is 3 wt% or less, preferably 0.01 to 1 wt%. Further, the dimensions are, for example, 50 mm or less in length and 1 mm or less in diameter. Further, in the case of inorganic fibers, the addition ratio is 5 wt% or less, preferably 0.1 to 2 wt%. The method for spraying the spraying material of the present invention configured as described above uses a dry or wet gun to spray the material onto the surface to be repaired, as in the conventional method. (Function) After the spraying material of the present invention adheres to the surface to be repaired, when it is heated in the high-temperature atmosphere in a furnace or in contact with molten iron, it releases zircon (ZrO ₂ /SiO ₂ ), which is the main component of zircon sand and zircon flour. is monoclinic _ZnO2 at high temperature
and amorphous SiO ₂ , and the resulting zirconia (ZrO ₂ ) expands due to the monoclinic-to-tetragonal transition at around 1000°C, imparting residual expandability to the sprayed material and sintering. This prevents the volumetric shrinkage that occurs due to knotting and prevents the spray material from peeling off from the surface to be repaired. It is also a component of magnesia refractory raw materials.
MgO is SiO ₂ of the zircon component ZrO ₂ / SiO ₂
In the present invention, the combination with the magnesia refractory raw material further promotes the dissociation of zircon. (Example) Next, examples of the present invention will be described together with comparative examples. Using the main raw materials listed in Table 1, the spraying material has the composition shown in Table 2 (invention examples Nos. 1 to 13,
Comparative Examples 1 to 4) were adjusted to improve adhesion hot strength (hot bending strength) volume stability (linear change rate) corrosion resistance (erosion dimension) peeling resistance (number of times until peeling) durability (number of times it can be used) ) were examined for each test item. Of these, Comparative Example 1 and Comparative Example 2 have a proportion of zircon refractory aggregate that is outside the range of the present invention, and Comparative Example 3 is a conventional type basic sprayed material that does not contain zircon refractory material. shows,
Comparative Example 4 shows a non-basic material mainly composed of zircon and silica. Among the raw materials used in the present invention,
The chemical analysis values of the main raw materials are shown in Table 1 (units are wt%)

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[Table] As described above, considering the results of the experimental examples and comparative examples according to the present invention, it is found that the conventional basic spray material (Comparative Example 3) has poor peeling resistance, and that the zircon-silica spray repair The material (Comparative Example 4) has poor corrosion resistance. On the other hand, according to the sprayed material of the embodiment of the present invention, the drawback of the basic sprayed material, which is the peeling caused by sintering shrinkage, can be solved without reducing the corrosion resistance of the basic sprayed material. As a result, in actual furnace tests, durability was approximately 1.5 to 3 times longer than conventional products. Regarding the corrosion resistance test, according to the rotary erosion test, the slag penetration depth of the product of the present invention was significantly shallower than that of conventional magnesia-based sprayed materials, and this is thought to be one of the reasons for the improvement in corrosion resistance. This is thought to be because SiO ₂ generated by dissociation of zircon becomes vitrified and prevents slag penetration. It is generally known that zircon refractory raw materials are inferior in corrosion resistance to basic slag, but in the present invention, by combining them with magnesia refractory raw materials and by limiting the amount added to a specific range, the corrosion resistance can be reduced. do not have. (Effects of the Invention) When the spray material of the present invention configured as described above is applied to the repair of damaged parts of industrial kilns, it has good adhesion, extremely excellent durability after adhesion, and is easy to peel off. Since there is no occurrence of drying, effects such as stabilization of the drying furnace, reduction in repair costs by reducing the unit consumption of spray material and repair man-hours, and improvement in furnace operating efficiency by reducing the number of repairs can be obtained.

[Brief explanation of drawings]

Figure 1 shows the magnesia-zircon spray material with the amount of zircon sand and the temperature of 1400℃.
A graph showing the relationship between linear change rate after time firing,
FIG. 2 is a graph showing the relationship between the amount of zircon sand mixed and corrosion resistance in magnesia-zircon sprayed materials.

Claims (1)

[Claims] 1. A spraying material for repairing industrial kilns, which comprises a refractory raw material composition consisting of 5 to 50 wt% of zircon sand, zircon flour, or a mixture thereof, and the remainder being a magnesia refractory raw material, and an appropriate amount of a binder.