JPH0146473B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a monolithic refractory used for lining or repairing steelmaking containers such as electric furnaces, converters, molten steel ladle, molten gun troughs, mixed gun cars, and molten gun ladle. The durability of recent steelmaking containers has been decreasing due to harsher operating conditions and changes in steelmaking methods as the quality of steel increases. For this reason, attempts are being made to develop highly durable fireproof materials and hot repairs. Refractory materials that combine refractory aggregate and carbon have been available for some time, but it has been found that durability can be improved by increasing the amount of carbon blended and added as operating conditions become more severe. For example, various carbons such as alumina carbon type, alumina-carborundum-carborundum type, etc. are added as castables for pitch-impregnated Maguro bricks, magnesia carbon bricks, carbon bond spray materials, and gutter for converters and electric furnaces. The developed refractory materials are beginning to show results. Although carbon is weak against oxidation, it has poor wettability with slag and has high thermal conductivity, so it prevents structural spalling due to slag penetration into the refractory material, and has the advantage of significantly increasing resistance to thermal spalling. As a result, the amount of carbon used is increasing year by year. It can be said that the durability of refractory materials containing carbon is determined by the density and bond strength of the connective tissue. Therefore, bricks have a dense structure and high bonding strength, but monolithic refractories cannot be molded under high pressure, so not only the density but also the bonding strength can be obtained. It is difficult to obtain high quality products, and sufficient durability cannot be obtained. Conventional monolithic refractories containing carbon are made by combining a small amount of granular or powdered phenolic resin, furan resin, coal pitch, petroleum pitch, asphalt, etc., with carbon such as scaly graphite, earthy graphite, electrode scrap, coke, etc. was. When carbon is added in this way, in monolithic refractories that normally use water, the carbon is light and floats, making it difficult to wet with water, requiring the addition of large amounts of water, loosening the structure, and reducing bond strength. It gets lower. Furthermore, in the process where the organic resin is heated, melted, and carbonized, it is poorly compatible with carbon, and carbon bonds cannot be sufficiently developed, resulting in insufficient bond strength. The present invention improves the packing density of a monolithic refractory containing carbon, which is made by granulating carbon powder and an organic resin, and improves its durability. The applicant has already proposed the use of granules, for example, in Japanese Patent Publication No. 56-20329.
In the above publication, a method for hot spraying repair of converters using a spraying material containing pellets obtained by kneading and granulating refractory powder and molten tar was proposed, but the amount of residual carbon in the pellets was small, and There are many pores after the resin content volatilizes, and the effect of carbon cannot be obtained sufficiently. The present invention is an amorphous refractory composition that has increased packing density and improved durability by using carbon granules treated as described below. In other words, 65-98% by weight of carbon powder of 0.7 mm or less and 2-35% by weight of organic resin are mixed, 5-30% by weight of carbon granules granulated into particles of 2 mm or less, and refractory aggregate whose particle size is adjusted. It is an amorphous fireproof composition consisting of 70 to 95% by weight, characterized in that when blending the organic resin, the thermosetting resin is kept in an uncured state by kneading at room temperature, and the thermoplastic organic resin is kneaded by heating. In the present invention, the carbon powder used in the carbon granules includes scaly graphite, earthy graphite, artificial graphite for electrodes, coal-based coke, petroleum-based coke, etc.
Powders of 0.7 mm or less can be used alone or in combination of two or more, if necessary. Organic resins include phenolic resin, furan resin, coal pitch, petroleum pitch, creosote oil,
Various drying oils can be used, but organic resins with a residual carbon content of 40% by weight or more are preferred. Regarding the setting range of the organic resin content, if it is less than 2% by weight, it will be difficult to make carbon granules, and if it is more than 35% by weight, there will be a lot of volatile content and it will become porous.
A range of ~35% by weight is desirable. The thermosetting resin is kneaded with the carbon at room temperature, and the thermoplastic organic resin is kneaded with heating, and the mixture is granulated into pellets of 0.1 to 2 mm by known means. If the particle size of the carbon granules is 2 mm or more, dispersion into the refractory will be poor, and if the particle size is 0.1 mm or less, the surface area will increase and sufficient filling properties will not be obtained, which is not preferable. Regarding the setting range of carbon granules,
If it is less than 5% by weight, the effect of suppressing slag penetration by carbon is small, and if it is more than 30% by weight, carbon is granulated and, although the bulk specific gravity is increased, it is difficult to form a dense connective tissue, which is not preferable. For this reason, a range of 5 to 30% by weight is desirable. As the refractory aggregate used in the present invention, magnesia, dolomite, lime spinel, alumina, silicon carbide, silicon nitride, silica, waxite, zircon, etc. can be used singly or in combination as necessary. The amount added is 70-95% by weight. By mixing the carbon granules obtained in this way with a refractory aggregate whose particle size has been adjusted, monolithic refractories such as pouring materials, ramming materials, and injection materials can be obtained. In order to impart shape retention and adhesive properties to the monolithic refractory, a binder such as phosphate, silicate, alumina cement, etc. can be used in an amount of 15% by weight or less. Liquid organic resins such as liquid phenolic resin and creosote can also be used as binders. The carbon granules of the present invention have a small surface area and a high bulk specific gravity, so less water is added to the monolithic refractory and the filling properties are improved, resulting in lower porosity, less oxidation damage to carbon, and significantly improved corrosion resistance. do. Examples and reference examples of the products of the present invention are shown below. Reference Example 1 Table 1 shows the formulation of the carbon granules of the present invention.

[Table] Examples of monolithic refractories using the above carbon granules are shown below. Example 1 A slag test was conducted using the carbon granules of the present invention in a magnesia carbon casting caster. The formulation and slag test results are shown. The magnesia-carbon castable of the present invention has a much smaller amount of added water than conventional castables, and therefore has a dense structure and greatly improved corrosion resistance. The slag test was conducted using converter slag at 1650℃ for 4 hours.

[Table] Example 2 A slag test was conducted using the carbon granules of the present invention in a castable for pouring alumina.
Corrosion resistance was also improved in alumina castables by reducing the amount of added water. The slag test was conducted at 1550℃ for 4 hours using blast furnace slag.

【table】

[Table] Example 3 The carbon granules of the present invention were used as a basic dry stamp material. As a result, the bulk specific gravity and corrosion resistance were also improved. The slag test conditions were electric furnace slag at 1700°C for 4 hours.

【table】

[Table] As described above, the monolithic refractory composition of the present invention has significantly improved corrosion resistance compared to conventional carbon-containing monolithic refractories.

Claims (1)

[Claims] 1 65-98% by weight of carbon powder of 0.7 mm or less and 2-35% by weight of organic resin, 5-30% by weight of carbon granules granulated into particles of 2 mm or less, and refractory aggregate 70 whose particle size is adjusted 95% by weight, and is characterized in that when blending the organic resin, the thermosetting resin is kept in an uncured state by kneading at room temperature, and the thermoplastic organic resin is kneaded by heating.