JPS6139595B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for lining a molten metal container. Conventionally, the refractories used for lining molten metal containers are mainly high silicic materials containing 60% or more of SiO ₂ , zircon materials containing 25% or more of ZrO _{2 ,} or 50% or more of A ₂ O ₃ It was made of high alumina bricks or monolithic refractories. All of these are acidic or neutral refractories, and while they have excellent characteristics such as being hard to crack under thermal shock and having excellent spalling resistance, they have the disadvantage of being extremely susceptible to reaction and erosion with molten metal and basic slag. In particular, it easily reacts with active components such as CaO, FeO, MnO, etc., which are the main components of slag, and forms a reaction product with a low melting point, which causes large erosion during use, and due to its nature, it can be used for a long time. Although it can be said that these materials cannot withstand long-term use, these refractories have excellent spalling resistance as mentioned above, and can be used at temperatures of 1650℃ to 500℃ or less, which is the operating condition of normal melting containers. Currently, these refractories are used in most molten metal containers, etc., because they have sufficient durability against thermal shock caused by repeated changes. On the other hand, basic materials can be considered as refractory linings for molten metal containers, but basic refractories have a high degree of fire resistance and are basic, contrary to acidic or neutral refractories. Although it is excellent as a refractory in that it is less prone to erosion due to slag, it has poor spalling resistance, and the refractory is susceptible to peeling and damage due to thermal spalling that occurs during pouring, especially in the early stages of use. Furthermore, the current situation is that materials, methods of use, and techniques that can be used regularly have not been obtained. When considering the mechanism by which molten metal container linings made of basic monolithic refractories are damaged, we first consider the formation of cracks inside the lining material due to localized heating during preheating drying from room temperature to 1400°C. 150℃
Due to the difficulty in controlling the heating speed, microcracks are formed due to rapid evaporation of water and local evaporation of water, and these are the key to early peeling damage. In the early stages of use of a molten metal container, the surface of the lining material is rapidly heated by the incoming hot water, making it easy to cause thermal spalling, which is exacerbated by cracking during drying and causing peeling damage to the lining material. Therefore, if it is possible to dry uniformly during preheating drying, reduce the heating speed below 150℃, and reduce thermal spalling during the initial use due to receiving hot water, the life of the molten metal container will be greatly increased. is inferred. Based on the above-mentioned knowledge, the present inventors have conducted various studies and have succeeded in developing a construction method for lining a molten metal container according to the present invention. As specified in . To explain the present invention more specifically, before heating and drying a molten metal container lined with a basic monolithic refractory, a powdery basic coating material that is the same or similar in material to the lining material is applied to the surface of the lining material. Apply.
This basic coating material may be castable material, plastic material, ramming material, spraying material, repair material, etc., and coating methods include troweling, compressed air spraying, and centrifugal projecting. Projection lining method, pouring method, etc. can be used. The particle size of the coating material is desirably 5 mm or less from the viewpoint of compatibility with the lining material, and in order to provide adhesive strength between the coating material and the lining material, phosphates, alkali silicate salts,
Clay or organic binder must be added. According to the construction method of the present invention, the coating material acts as a thermal buffer during heating and drying, making it possible to uniformly heat and dry the lining material. In addition, for lining materials that are prone to explosions, the initial drying speed below 150°C, which is the time when water evaporates, can be reduced, thereby preventing explosions. In addition, lining material
1650℃ at receiving hot water after heating and drying to 1400℃
The coating layer acts as a buffer wall to prevent thermal spalling of the lining material due to sudden thermal changes in molten metal. In addition, since a steady temperature gradient is obtained inside the lining material before the coating material wears out and disappears due to use, a healthy sintered layer is formed on the working surface of the lining material, making it difficult for structural spalling to occur. Become. In addition, since the material used as the coating material is the same or similar to the basic monolithic refractory used for the lining material, the coating layer alone can last for 10 to 15 charges, depending on the thickness, which extends the lifespan of the molten metal container. It will be an improvement. Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples, and changes and modifications within the gist of the present invention are of course included in the present invention. Example 1 Basic monolithic refractory A shown in Table 1 below was applied to the side wall of a 320-ton molten steel ladle lining using a slinger machine to a thickness of 150 to 210 mm depending on the location, and air-dried for 24 hours. After that, apply the first layer to the lining surface.
Approximately 30mm of basic coating material B is applied to the entire side wall.
It was sprayed to a thickness of . After spray drying, it was left to stand naturally for 8 hours and then heated to 1200°C for 48 hours.
When used under the same conditions as a ladle without coating, when only basic monolithic refractory A was used, the service life was 32 times, but by spraying before drying, the service life was increased to 85 times. The effect was that the lifespan was extended. Example 2 The basic monolithic refractory C shown in Table 1 was poured into the side wall of a 250-ton ladle, and after the poured material had hardened, it was removed from the frame and cured at room temperature for 24 hours. Approx. basic coating material B in Table 1
20mm spraying was carried out. After 10 hours of natural drying
It was dried by heating to 1200°C for 48 hours. When compared with a ladle without coating under the same conditions, the basic monolithic refractory C alone had a service life of 36 cycles, but by applying a coating before drying, the service life could be extended to 76 cycles.

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Claims (1)

[Claims] 1. A molten metal container is lined with a basic amorphous refractory, and before the lining is heated and dried, the surface of the lining is coated with a powdery basic coating material. Method for lining molten metal containers. 2. The method for lining a molten metal container according to claim 1, wherein the basic coating material is a castable material, a plastic material, a ramming material, a spraying material, a repair material, or the like. 3. The method for lining a molten metal container according to claim 1, wherein the basic coating material has a particle size of 5 mm or less. 4. The method for lining a molten metal container according to claim 1, wherein a phosphate, an alkali silicate, clay, or an organic binder is added to the basic coating material. 5. The method for lining a molten metal container according to claim 1, wherein the coating method is a method such as troweling, spraying with compressed air, projection lining with a centrifugal projector, or pouring.