JPS6156191B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a spraying material particularly suitable for hot repair of converters lined with carbon-containing refractories. (Purpose of the Invention) The linings of converters, electric furnaces, ladles, pig iron mixers, tap runners, etc. are chemically and
Since the furnace is locally damaged by mechanical action, the life of the furnace is extended by repairing the damaged area with spray material. The material for spraying materials is generally made of a fire-resistant material with phosphate or silicate added as a binder, but as furnace operations have become more severe in recent years, sufficient durability has not been achieved. Furthermore, it has poor adhesion to carbon-containing refractories such as magnesia-carbon refractories and alumina-silicon carbide-carbon refractories because of poor adhesion. Therefore, as a solution to the above-mentioned drawbacks, a spray material using carbonaceous resin as a binder has been proposed.
For example, JP-A-55-42251, JP-A-55-42218
No., JP-A-55-104978, JP-A-55-130868,
This is as described in Japanese Patent Application Laid-Open No. 140768/1983. When this spray material is sprayed onto a wall surface, the carbonaceous resin that is the binder is carbonized by the heat of the furnace wall surface, forming a carbon connective tissue, giving the spray material high corrosion resistance and high hot strength. Since carbonaceous resin is easily wetted by carbon,
It also has high adhesion to carbon-containing refractories. However, this type of sprayed material has a drawback in that the central part of the sprayed layer has poor structural strength at the initial stage of spraying. This seems to be because heat from the furnace wall surface and the atmosphere inside the furnace did not reach the center, and a sufficient carbonization reaction did not take place. This phenomenon is more pronounced as the temperature of the furnace wall surface at the time of repair is lower. Therefore, even if the thickness of the sprayed layer is increased, a proportional repair effect cannot be obtained. (Structure of the Invention) The first invention aims to solve the above-mentioned drawbacks of conventional materials, and is characterized by adding metal fibers to a compound consisting of a fire-resistant material and a carbonaceous resin. This is a spray material for hot repairs. Metal fibers have much better thermal conductivity than refractory materials, and because they are fiber-shaped, they act as a medium to conduct heat from the furnace wall surface or the atmosphere inside the furnace to the center of the sprayed layer, and carbonaceous resin The carbonization reaction is promoted to quickly and evenly transform the entire sprayed layer into a carbon connective tissue. In addition to this, metal fibers also have effects such as imparting spalling resistance and abrasion resistance, inhibiting the propagation of cracks caused by spalling, and preventing peeling. The configuration of the first invention will be explained in further detail. The fireproof material is not particularly limited, and is appropriately determined according to the lining material to be repaired. For example, one or more types selected from basic, neutral, and acidic refractory metal oxides such as magnesia, chromium, spinel, dolomite, calcia, alumina, silica, mullite, zircon, and zirconia. If necessary, carbon, carbide, nitride, slaked lime, etc. are further combined with this. When the spray material is for use in a converter, basic materials are preferred. The carbonaceous resin used in the present invention refers to an organic compound that carbonizes or turns into coke when heated to a high temperature, and specifically refers to a powdered thermosetting resin (e.g., phenol resin, furan resin, etc.). , epoxy resins, melamine resins), bituminous substances (various pitches, coal tar), powdered thermoplastic resins with added hardening agents (e.g. polybdenum resins, vinyl polymers), other resins (e.g. coumaron resins, atactic polypropylene) , polyester), etc., or two or more thereof may be used. Among these, generally preferred are pitch (carbonization rate: 52.5 wt%), phenol resin (52.1 wt%), furan resin (49.1 wt%), etc., which have a high residual carbon content. The ratio of the fireproof material and the carbonaceous resin may be the same as that of conventional spray materials of this type, and is not particularly limited, but preferably 2 to 55wt of the carbonaceous resin.
%, the remainder is fireproof material. If the carbonaceous resin is less than 2wt%, sufficient carbon connective tissue cannot be obtained, and if the carbonaceous resin is less than 2wt%,
If it exceeds , the amount of refractory material is too small and corrosion resistance tends to decrease. The preferred type of metal fiber is steel fiber. Generally speaking, it is preferable to use stainless steel fiber as it requires heat resistance and corrosion resistance, but carbon steel, special steel (Ni-Cr steel, Cr −Mo steel, Cr steel,
Fibers such as Cr-V steel), Al, Al alloy, CuCu alloy, etc. can be used. Various shapes and dimensions are used, such as lines, curves, chevrons, and waves.
It has a circular cross section of 0.01 to 3 mm, preferably 0.1 to 2 mm, or a modified cross section with an equivalent cross sectional area, and preferably has a length of about 100 times the diameter or less. The amount of steel fiber added to the above-mentioned composition of the fireproof material and carbonaceous resin is 15 wt% or less, preferably 0.5 to 10 wt%, although it depends on the shape and dimensions of the steel fiber. Since steel fiber is a low melting point substance, too much content will reduce the corrosion resistance of the sprayed material and will also worsen the dispersibility of the steel fiber. In addition, in order to improve the filling properties of the spray material, it is preferable to add a wetting agent to 10 wt% or less. Examples of wetting agents include ethylene glycol (boiling point 198°C), diethylene glycol (boiling point 245°C), propylene glycol (boiling point 188.2°C),
Polyhydric alcohols such as polyethylene glycol (198°C), glycerin (290°C), refined petroleum oils and waste oils such as kerosene, anthracene oil, light oil, heavy oil, and lubricating oil are used. Furthermore, in order to provide adhesion immediately after spraying,
For example, 15 wt% or less of phosphates, silicates, borates, bittern, etc. may be added. If it is too large, the strength of the sprayed material develops early, preventing the flow and diffusion of the carbonaceous resin and reducing the adhesion to the lining. The above-mentioned mixture may be mixed by simply mixing the particles adjusted to an appropriate particle size, or by, for example, JP-A-55
As seen in JP-A-42251 and JP-A-55-104978, the fireproof material and carbonaceous resin may be granulated and then other additives may be mixed therein. A spray material that uses carbon bonds to increase structural strength as in the present invention has a problem in that it has poor resistance to oxidation because it contains carbon. Therefore, it may be possible to add metal powder, which is well known as an antioxidant for refractories. Since metal powder is in powder form, it reacts quickly and is effective, but it has the disadvantage that it is only effective at the initial stage of use. However, due to the combination with steel fiber, metal powder and
After that, it was found that the steel fibers worked and the antioxidant effect lasted for a long time. This seems to be because steel fiber has a small surface area, so the reaction rate is low even at high temperatures. A second invention is characterized in that metal powder is further added to the spray material of the first invention. Specific examples of metal powder include aluminum, silicon,
These include chromium, magnesium, titanium, iron, ferrosilicon, ferrochrome, etc. alone, a combination of two or more, or an alloy thereof. Considering effectiveness and economy, aluminum is most preferred. The amount added is 15 wt% or less, preferably 0.3 to 15 wt%. If it is too large, the corrosion resistance of the sprayed material tends to decrease. The spray gun used for spraying may be of any conventionally known type, but from the viewpoint of workability, a dry type gun in which water is added to the spray material near the tip of the nozzle is preferred. (Example) Next, examples of the present invention and comparative examples thereof will be shown.

【table】

[Table] Table 2 shows an example of blending a granulated product of magnesia clinker fine powder and pitch.

[Table] Details of the test methods in Tables 1 and 2 are as follows. *1 Carbonization rate: Measured according to JIS K-2421. *2 Bending strength: 30 at each temperature in an oxidizing atmosphere
Measure after heating for minutes. *3 Compressive strength: packed in coke breeze,
Measured after heating at 1200℃ for each hour. In the above measurements, the sprayed material after being sprayed with a dry gun was used as a test piece. The granulated material *4 in Table 2 is a mixture of magnesia clinker of 0.5 mm or less and heated and melted pitch, which is granulated to a size of 5 mm or less by the dropping method. (Effect of the invention) In Tables 1 and 2, the examples of the present invention are
The bending strength is large even after heating at either 1200℃ or 1400℃, and the difference is small. This is probably because the spray material of the present invention has excellent oxidation resistance at all temperatures. In addition, regarding the compressive strength, the examples of the present invention show large values even when the heating time was relatively short, but this is thought to be because the formation of carbon connective tissue was promoted by the heat conduction effect of the steel fiber. . A portion of each of the examples shown in Table 1 was used for hot repair of a 250 ton converter lined with magnesia-carbon bricks. The effects are shown in Table 3.

[Table] Note that in all of the above examples, magnesia clinker was used as the fire-resistant aggregate, but almost similar results were obtained with other types of fire-resistant aggregate.

Claims (1)

[Scope of Claims] 1. A spray material for hot repairs made by adding metal fibers to a compound consisting of a fire-resistant material and a carbonaceous resin. 2. A spray material for hot repairs made by adding metal fibers and metal powder to a compound consisting of a fire-resistant material and a carbonaceous resin.