JPH0141918B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for hot repair of a molten metal container, and more specifically to a horizontal portion of the molten metal container, a portion that can be made horizontal, or a portion that can store repair material using a core or the like. , for example, relates to a method for partial hot repair of converter charging walls, tapping walls, tapping ports, tuyeres, etc., degassing devices, pig iron mixers, ladles, ladle smelting furnaces, AODs, etc. Conventionally, hot repairs of converters have been carried out by spraying in areas where it is difficult to carry out seizing repairs, such as slag lines and trunnions. The dry method is the mainstream for this spraying repair, but since the spraying repair material is quick-curing, it instantly hardens on the high-temperature wall surface, leading to evaporation of water, so the spraying material once attached to the furnace wall may peel off or peel off. If not, it will harden while remaining coarsely filled, resulting in a poorly filled construction with high porosity.Moreover, during spraying, in order to improve adhesion to the furnace wall and reduce rebound loss, a blend with a low coarse particle content is required. As a result, the corrosion resistance of the constructed body was not completely satisfactory. In other words, although spray repair has good workability, it has the disadvantage that it does not provide sufficient durability. As a result of research into a hot repair method that solves the above-mentioned drawbacks and provides good workability and sufficient durability, the inventors found that it is not necessary to instantly adhere and harden the repair material to the furnace wall; It has been discovered that a dense construction body with good corrosion resistance can be obtained by imparting sufficient fluidity to the material with water and gradually hardening it by boiling it at high temperatures. When this hot repair method is applied at a high temperature of 1000°C or higher, good boiling can be obtained, and a construction body with high adhesion to the wall surface and high filling can be obtained. However, when repairing the tuyere of a converter, where the heat capacity is small and the furnace temperature drops in a short period of time, such as a degassing device, the hearth of various ladles, or the tuyere bricks are replaced, the temperature of the repaired surface is usually 800 to 400℃. It drops to the lowest level. Under these circumstances, the hot repair method involves boiling and hardening a slurry of repair material and water.
Due to the drop in furnace temperature, boiling power is weak and grain separation is likely to occur. In order to prevent this, even if the amount of water added is necessarily reduced from 20 to 40% in the high temperature range to 20% or less, the boiling effect is extremely small and it takes a long time for the water to evaporate. As a result, the apparent porosity of the constructed body becomes high, and the development of strength becomes extremely poor. As described above, particles were unevenly distributed inside the body constructed by the above-mentioned hot repair method at temperatures below 1000°C, and only a porous structure with extremely low structural strength could be obtained. As a result of various studies on the causes of this problem, we found that the condensed phosphate of the binder used in the repair material was under hot pouring conditions (high temperature requiring boiling, pH value in the acidic or alkaline range, or presence of salt). In addition, even if the water is reduced as described above, the boiling power is weak, resulting in grain separation, and the disadvantages are that deaeration, kneading, and thixotropy cannot be sufficiently achieved. It turned out that this was the result of the addition of . As a result of various studies to solve the above-mentioned drawbacks, the present inventors have found that by using a mixture of monohydric alcohol and water, a dense and high-strength construction body can be obtained and construction can be performed in an intermediate temperature range. This led to the completion of the present invention. In other words, the hot repair material is made into a slurry state with a mixture of monohydric alcohol and water at the part of the container that requires repair, and this slurry state material is heated in a furnace or heated so that it does not reach a boiling state even at an intermediate temperature of less than 1000°C. This is a hot repair method for molten metal containers in which the refractory material is sufficiently filled with the boiling force and then hardened. The hot repair method of the present invention is to slurry the repair material with a mixture of monohydric alcohol and water in order to obtain a construction body with high structural strength at intermediate temperatures (below 1000°C, for example around 800 to 400°C). It has been found that, as monohydric alcohols, those having an azeotropic point with water of 100°C or less, such as methyl alcohol, ethyl alcohol, propyl alcohol, and butyl alcohol, are useful for the effects of the present invention. Among these, ethyl alcohol is preferred because it has low toxicity, low odor, and low boiling point. The proportion of this monohydric alcohol used is between 5 and 95% of the mixture.
%, preferably 7 to 20%, and if the monohydric alcohol is less than 5%, the effect of adding alcohol cannot be obtained and a high-strength construction body cannot be obtained. Furthermore, if the monohydric alcohol content exceeds 95%, the condensed phosphate as a binder is difficult to dissolve, making it impossible to obtain a high-strength construction body. When the repair material is made into a slurry using a mixture of monohydric alcohol and water, it is sufficiently boiled and hardened even at an intermediate temperature of less than 1000℃, has good filling properties, and forms a strong connective tissue. A dense construction body can be obtained. This effect is due to the fact that the mixture of monohydric alcohol and water exhibits unique properties in the construction body in the intermediate temperature range.
This unique property occurs between the mixture and the condensed phosphate as a binder added to the repair material, and as the phosphate dissolves in the mixture, the dehydration effect of the monohydric alcohol causes long-chain electrolytes to form. Micelles are formed by exceeding the critical micelle concentration of the solution,
Intermolecular forces act together with the intervening powder (refractory powder),
It is understood that these aggregate. This cohesive force also envelops the coarse aggregate and prevents particle separation. The refractory material aggregated in this way is
When put into the intermediate temperature range below 1000℃, monohydric alcohol (boiling point: methyl alcohol 64.6℃, ethyl alcohol 78.3℃, propyl alcohol 83~97℃)
Because the azeotropic point of butyl alcohol (83-118°C) is lower than that of water, the monohydric alcohol-rich mixture first comes to a boiling state, and eventually boils to water. This double boiling strengthens the boiling power and improves filling properties. With the disappearance of the monohydric alcohol that precedes this case,
The agglomeration effect also disappears and it becomes an aqueous fluid state, after which wettability is improved due to smooth fluid diffusion and the cooling effect on the surface of the base brick, and strong adhesive strength is obtained. The condensed phosphate binder in this repair material is under high temperature conditions required for boiling in the case of a slurry made only of water, and the pH value is acidic or alkaline, and salts (Na, K, Ca, Mg, ), hydrolysis proceeds relatively quickly on the order of minutes. However, even under the above conditions, the present invention has the effect of significantly retarding hydrolysis by using monohydric alcohol.
Due to this, high structural strength can be obtained even in construction in the intermediate temperature range. The mixture of monohydric alcohol and water can be used either by preparing a mixed solution before addition, or by adding the monohydric alcohol to a slurry using only water. The binder of the hot repair material used in the present invention is 0 to 100
A slow-hardening alkali metal that has the ability to dissolve water or a mixture of water and monohydric alcohol in the temperature range of °C,
Phosphates of alkaline earth metals. Among these, condensed phosphates are effective, such as pyrophosphates, tripolyphosphates, tetrapolyphosphates, metaphosphates, and ultraphosphates. Condensed sodium phosphate is preferred in terms of reaction characteristics. The amount of this binder to be used is 1 to 10%, preferably 3% to the outer layer of the repair material, in order to develop cohesive tissue strength, etc.
~8%. Refractory materials for this repair include basic refractory materials such as magnesia, dolomite, calcia, and forsterite, neutral refractory materials such as alumina, spinel, and chromium, acidic oxides such as silica and zircon, and silicon carbide. All refractory materials can be used, including carbides such as aluminum carbide, nitrides such as silicon nitride and boron nitride, and carbon source materials such as graphite, coke, and pitch. It is grainy. Among these, basic refractory materials such as magnesia and dolomite are suitable for converter repair in terms of durability. The mixing amount of the repair material used in the present invention varies depending on the type of refractory material and binder, particle size composition, construction temperature, amount and ratio of monohydric alcohol used, etc., but it depends on the suitable boiling time, curing time and density of the construction body omitted from etc.
It is 12-30%. A general explanation of the hot repair method of the present invention using a spraying device will be as follows. The repair material, which is a sufficient mixture of refractory material and binder, is made into a slurry using a spraying device with a mixture of monohydric alcohol and water, and then hot-carried onto the area requiring repair in the intermediate temperature range of the molten metal container. The slurry is boiled by the scorching heat of the furnace wall, first by a monohydric alcohol with a low boiling point, and finally by water. This double boiling strengthens the boiling power and sufficiently fills the refractory material. In this case, since monohydric alcohol is used in the slurry, it exhibits cohesive force and also envelops the coarse aggregate to prevent particle separation. Next, as the monohydric alcohol disappears, the cohesive effect also disappears, resulting in a water-based boiling state, which improves wettability due to smooth flow diffusion and cooling effect on the surface of the base brick, resulting in strong adhesive strength. . Further, the slurry is hardened by evaporation of water by scorching heat. As a result, by using the condensed phosphate as a binder and a mixture of monohydric alcohol and water, a constructed body with high structural strength in the intermediate temperature range can be obtained. The method of introducing the repair material used in the present invention may be determined depending on the maximum particle size of the repair material used and the repair location, and can be determined using a spraying device, a casting device, a press-in device, a charging method,
Although a method such as a shoot may be used, in consideration of workability and reliability of construction, it is preferable to use a spraying device when a large amount is to be used. Although the hot repair method of the present invention has been described in an intermediate temperature range, below 1000°C, for example 400 to 800°C, a dense construction body having high strength can be obtained even in a high temperature range of 1000°C or higher. The present invention will be explained below by way of examples. Examples 1 to 4 A slurry of the hot repair material shown in Table 1 made of a mixture of monohydric alcohol and water was framed in advance with refractory bricks and placed in a resistance heating element electric furnace maintained at a temperature of 600°C. With the furnace temperature maintained,
This slurry was boiled and hardened. The cured product obtained in this way is taken out after cooling,
The test results shown in Table 1 were obtained. In addition, comparison

【table】

[Table] As an example, Table 1 shows the results of using a hot repair material in a slurry state using only water in the same manner as in the example.
However, the curing time is as follows: a metal ball weighing 300g is placed at a height of 100
It was dropped from mm to the time it stopped penetrating. The above results indicate that the example using a mixture of monohydric alcohol and water has significantly improved tissue strength and greater durability than the comparative example using only water. . Example 5 The repair material of Example 4 was made into a slurry using a spraying device and was charged into the damaged tap wall of a 150-ton converter whose furnace temperature had dropped to 500 to 600°C. This repair material boiled and hardened due to the furnace temperature, resulting in a dense construction body. As a result, the repaired body using this repair method was able to wear and tear evenly without flaking, and had a service life of 19 charges. Comparative Example 2 was also prepared using the same method.
When the repair material was used, peeling occurred after 3 to 4 charges, and the product had a service life of 7 charges. Example 6 Bauxite 5-1 mm 45%, 1-0.032 mm 28%,
Add 2% ethyl alcohol and 15% water to a repair material consisting of 27% sintered alumina 0.032 mm or less and 4% sodium tetrapolyphosphate, stir the slurry using a hand mixer, and heat the mixture to a furnace temperature of 500 to 600.
It was poured into the worn part of a 100 ton ladle at ℃. This repair material boiled and hardened due to the furnace temperature, resulting in a dense construction body. As a result, the construction work performed using this repair method was uniformly eroded and damaged without flaking and had a service life of 11 charges. In addition, a comparative example, which was obtained by adding only 16% water to the above-mentioned repair material without using ethyl alcohol, showed hollow-shaped erosion after one charge. , it only lasted 3 charges.

Claims (1)

[Claims] 1 In a hot repair method in which the hot repair material is made into a slurry state at the point of the container that requires repair, and this slurry state material is boiled and hardened, the hot repair material is made into a slurry state with a mixture of monohydric alcohol and water. A hot repair method for a molten metal container characterized by turning it into a product.