JPS6117791B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a spray material for repairing damaged parts of blast furnace walls. At the end of a blast furnace's life, problems such as red heat in the shell or cracks in the shell due to abrasion or falling off of the refractories on the furnace wall, such as gas leakage, occur, reducing the operating rate and efficiency of the blast furnace. descend. Therefore, recently, the contents of the furnace were reduced when the furnace was shut down.
It is known to spray repair damaged areas on the furnace wall using a spray nozzle inserted through the upper opening.
There are other methods of blast furnace repair in which refractory material is press-fitted into the furnace through the steel shell, but compared to this method, spray repair is more accurate and accurate since it can be carried out after checking the damage location and degree of damage. It can be repaired efficiently. The present invention provides a spraying material suitable for spraying repair of the blast furnace wall. BACKGROUND ART Spraying repairs have been widely used in molten metal containers such as converters. however,
Blast furnace walls are required to have properties not found in other furnaces, such as resistance to abrasion caused by the falling contents of the furnace, coke, alkali from iron ore, and retention of cooling effects. I was unable to respond to this. The present invention has the above characteristics, and is a refractory material whose main material is 5 to 40% by weight of alumina cement and the remainder is one or more selected from silica-alumina, high alumina, and alumina. This is a spraying material for repairing blast furnace walls, which is equipped with a water-cooled cooler containing 0.5 to 15% by weight of clay and 0.5 to 10% by weight of stainless steel fiber in a formulation consisting of: The aggregate is mainly one or more types selected from silica-alumina, high alumina, and alumina. These materials have a lower coefficient of thermal expansion than magnesia and dolomite materials, which are often used in conventional spray materials, and have excellent thermal shock resistance, so they have high adhesive strength after the spray materials are attached. . It has a higher melting point than siliceous materials and has excellent alkali resistance. Furthermore, the alumina component in the material has high hardness and contributes to the abrasion resistance of the spray material. Alumina-silica materials include kaolin and various types of syamoto obtained by calcining shale clay, or loite, and high alumina materials include pauxite, sillimanite, argillaceous rock, kyanite, mullite, andalyusite, etc. The quality is sintered or electrofused alumina, or K ₂ O,
β-alumina containing Na ₂ O is exemplified. The weakening of the spray material structure due to alkali is caused by SiO ₂ ―
Since the Al ₂ O ₃ component is generated by reacting with an alkali, high alumina materials and alumina materials with low SiO ₂ content are preferred among the above refractory materials. In the present invention, the above-mentioned refractory material is used as the main material, and other refractory materials may be used in combination. For example, when silicon carbide is used in combination, the alkali resistance and thermal conductivity of the spray material of the present invention can be further improved due to the excellent alkali resistance and high thermal conductivity of silicon carbide. The particle size of aggregate is coarse, medium, or coarse depending on the degree of filling.
The particles are suitably adjusted to fine particles, and although not limited in any way, examples include 5 to 1 mm, 20 to 70 weight %, 1 mm or less, 0 to 50 weight %, and 0.074 mm or less, 0 to 50 weight %. As is well known, alumina cement as a binder is mainly composed of calcium aluminate, and is usually used in fine powder of 180 mesh or less, and has an internal weight of 5 to 40 mesh relative to the refractory material. %
Blend. If it is less than 5% by weight, the effect as a binder is insufficient, and if it exceeds 40% by weight, the proportion of refractory material decreases accordingly, resulting in a decrease in corrosion resistance and abrasion resistance. In addition, from the standpoint of alkali resistance, the SiO ₂ component is
High alumina cement of 0.5% by weight or less is more preferred. In conventional spray materials, phosphates, silicates, etc. are commonly used as binders, but while they have excellent adhesion, they are inferior in imparting strength. Alumina cement provides much better strength than other binders, and by incorporating it, the spray material can withstand the severe abrasion caused by the falling contents of the furnace. Clay has the role of adhesion to the furnace wall. The outer weight is 0.5 to 20% by weight, preferably 2 to 10% by weight. If it is less than 0.5% by weight, there will be a lot of rebound loss during spraying and the repair efficiency will be poor. If it exceeds 20% by weight, the alkali resistance of the spray material will decrease due to the SiO ₂ component coming from the clay, and since the clay is a fine powder, the particle size structure of the spray material will result in an excessive amount of fine powder, which is undesirable. Stainless steel fibers improve the thermal conductivity of the spray material. Blast furnaces use water-cooled coolers to extend the life of the furnace walls, but the inclusion of steel fiber increases thermal conductivity, and the cooling effect improves the durability of the sprayed material. In addition, blast furnaces are generally equipped with a cooler inside the outer shell, and when the gap between the coolers, which inevitably arises from the manufacturing and structural aspects of the cooler, is filled with spray material, high thermal conductivity due to the steel fibers is achieved. This has the effect that the cooling effect is continuously applied to the entire furnace wall. Stainless steel fibers provide spalling and abrasion resistance, prevent the growth of cracks caused by spalling, and play an important role in preventing the spray material from falling off. The steel fiber was made of stainless steel because it has excellent heat resistance and oxidation resistance. The cross-sectional shape may be either circular or polygonal.
The length is preferably 5 to 50 mm; if it is less than 5 mm, the surface area is small and the traction support of the spray material structure is poor. If it exceeds 50 mm, volumetric expansion due to carbon deposition tends to cause cracks in the sprayed material, and fiber balls are also likely to form, reducing workability. The blending amount is 0.5 to 10% by weight.
If it is less than 0.5% by weight, no effect will be observed, and if it exceeds 10% by weight, the fluidity of the spray material will decrease and nozzle clogging will easily occur. In addition to straight shapes, any shape can be used, such as wavy, twisted, dog-bone shapes with bulges at both ends. Furthermore, in order to improve filling properties and sintering properties, slaked lime and silica flour refractory ultrafine powder are added to the outside.
It may be added in an amount of 10% by weight or less. Further, 3% by weight or less of a dispersant may be added for water reduction effect and imparting hydrophilicity. Examples of dispersants include alkali metal phosphates, alkali metal polyphosphates, alkali metal carboxylates, lignin sulfonates, vinyl acetate resins, β-naphthalene sulfonates, and polystyrene sulfonates. In particular, lignin sulfonate is effective. In order to repair the blast furnace wall with the above-mentioned spray material, the charging speed of the furnace contents is slowed down to lower the level of the furnace contents, the air is rested, and then the blast furnace is suspended from the opening at the top of the blast furnace. Aim the lowered nozzle at the damaged area of the furnace wall,
Spray using this nozzle. Spraying equipment is generally of the wet type, which sprays a mixture of spray material and water that has been mixed in advance, and the dry type, which sprays the spray material with water added to it by pressure through a nozzle.
It is further divided into a semi-dry type in which water is added during pressure feeding through a nozzle, but the semi-dry type is preferred from the viewpoint of workability. As mentioned earlier, the spray material of the present invention has the abrasion resistance, alkali resistance, spalling resistance, and high thermal conductivity required for repairing the walls of blast furnaces equipped with water-cooled coolers. If repairs are carried out, the life of the furnace wall will be significantly extended, and as a result, the operating rate and operation rate of the blast furnace can be improved. Next, examples of the present invention will be given, as well as experimental examples that do not belong to the present invention, and conventional examples, and test results of various characteristics will be shown for each.

[Table] The stainless steel fibers contained in the spray materials in Tables 2 to 4 are all SUS430, width 0.5
mm x thickness 0.3mm x length 25mm.

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[Table] The test conditions are as follows. (1) Abrasion resistance: Samples were heated to 1000°C in Table 2 and 1200°C in Tables 3 and 4, and measured by the sandplast method. The smaller the value, the better the wear resistance. (2) Alkali resistance: Table 2 shows 1200℃ x 5 hours 6 times with the sample inserted into a mixture of potassium carbonate and coke powder (weight ratio 4:1); Tables 3 and 4 show
After repeating the test at 1300°C for 5 hours 6 times, the compressive strength was measured. The higher the number, the better the alkali resistance. (3) Spalling resistance: Table 2 shows the number of times heating and cooling is repeated from 1000°C to water cooling, and Tables 3 and 4 show the number of times heating and cooling is repeated from 1300°C to water cooling until cracks are observed in the sample. The larger the value, the better the spalling resistance. (4) Thermal conductivity; measured by hot wire method. at300℃ The larger the value, the higher the thermal conductivity. (5) Adhesion: Adhesion rate when sprayed on a refractory surface heated to 400℃. The larger the number, the better the adhesion. (6) Compressive strength;
In Tables 3 and 4, 1300℃ x 3
After heating for a time, measure the compressive strength. The larger the number, the greater the compressive strength.

Claims (1)

[Claims] 1 A mixture consisting of 5 to 40% by weight of alumina cement and the balance being a refractory material whose main material is one or more selected from silica-alumina, high alumina, and alumina, and an outer coating of 0.5 to 15% clay. weight%
A spray material for repairing blast furnace walls equipped with a water cooler containing 0.5 to 1.0% by weight of stainless steel fiber.