JPH0329747B2 - - Google Patents

Description

[Detailed description of the invention]

Technical field The present invention is directed to injecting a mixture of a carbonaceous solid fuel and a refractory material into a kiln or a molten metal container together with an oxygen stream. A spray repair material used for hot repair by flame spraying, in which a part (surface) or all of the above refractory material is melted through high-temperature flames caused by combustion, and pressure welded to the damaged area of the lining refractory wall to repair it. It is. BACKGROUND ART Hot spray repair technology using flame spraying is used for hot repair of refractories lining molten metal refining containers such as converters, and has achieved great results. Conventional spray repair materials used to implement this technology have almost the same composition as the converter lining refractory, such as dead-burned magnesite,
It consists of basic refractory particles such as dead dolomite and coke particles. Furthermore, all the particles in this mixture have a particle size of 0.5 mm or less. Particle size is 0.5mm
When using the spray repair material consisting of the following particles:
When the coke that is injected together comes into contact with oxygen and burns in an air stream to form a high-temperature flame, dead-burned magnesite, dead-burned dolomite, etc. are often fine particles, so they are The whole thing will melt. As a result, each particle adheres firmly to each other and to the furnace wall refractory, and damaged parts of the refractory can be repaired. The adhesion layer formed by this method has a density equivalent to that of brick and can withstand several batch refinings, but it cannot be used for long periods of time at high temperatures, mainly due to the fine grain size of the refractory material. In the case of time batch refining (for example stainless steel refining), 1
It was only possible to use the product about 2 times. In this respect, the conventional technology has limitations. OBJECTS AND SUMMARY OF THE INVENTION An object of the present invention is to overcome the drawbacks of conventional flame spray repair materials, mainly that they are inferior in terms of durability. To this end, the present invention provides a method for spraying which is a mixture of carbonaceous solid fuel powder and a granular non-combustible component which collectively considers the ash content, refractory material and additives in the carbonaceous solid fuel powder. In repair materials, fireproof materials have coarse particles with a particle size of more than 0.5 mm and less than 3.0 mm.
The particle size is 10 to 50% by weight, and the balance is fine particles with a particle size of 0.5 mm or less.The non-fuel component excluding the refractory material consists of fine particles with a particle size of 0.5 mm or less, and the chemical composition of the entire non-combustible component is MgO and CaO. 80% by weight or more in total amount of Al ₂ O ₃ , SiO ₂ and
The total amount of Fe ₂ O ₃ is 5 to 20% by weight, and
A spray repair material for flame spraying, characterized in that Al ₂ O ₃ , SiO ₂ and Fe ₂ O ₃ constitute fine particles of non-combustible components, is provided as a material useful for overcoming the above-mentioned drawbacks. It is. The flame-sprayed repair material for hot repair of the present invention can be applied to repairing the inner walls of various metallurgical furnaces and molten metal storage vessels lined with basic refractories, but the following is applicable to the repair of inner walls of metallurgical furnaces and molten metal containers lined with basic refractories. This will be explained using an example of materials used in the furnace. First, the particle size of the refractory material, which is the first feature of the present invention, will be explained. Generally, the particles of refractory material in conventional spray repair materials used for flame spraying hot repairs have a particle size of 0.5 mm or less, more preferably 0.2 mm or less.
It was limited. The reason for choosing such a particle size is as follows. (1) A mixture consisting of refractory material and carbonaceous solid fuel is transported from the material storage tank to the spray nozzle by a carrier gas, but if the particle size is too large, smooth transport will be difficult. , problems such as pulsation and separation of coarse and fine particles occur. (2) Needless to say, in order to quickly melt part or all of the surface of a refractory material in a high-temperature flame, smaller particle sizes are preferable because heat transfer to the particles is better. If the particle size is large, the particles will not melt sufficiently during the flight time until they reach the furnace wall after being injected from the nozzle, and as a result, strong adhesion between the particles or between the particles and the furnace wall refractories will not be achieved. . In general, when it comes to the durability of the adhesion layer, as with ordinary refractory bricks, if the adhesion layer contains appropriate proportions of coarse, medium, and fine particles, the density will be higher and the total pore volume will be higher. It can be said that this decreases the penetration of slag and increases the strength and durability. Therefore, the inventors investigated a spray repair material that added coarse particles to the conventional material, which was composed only of fine particles, and found that the durability of the adhesion layer could be improved. As a result, the present invention as described below was completed. In other words, in order to avoid hindering the transportability even if coarse particles are mixed, the following particle size composition is used:
It was used as a spray repair material. By limiting the particle size and weight ratio of the coarse particles to be newly mixed, problems such as pulsation during conveyance and separation of coarse particles and fine particles can be avoided.
Transport by gas is possible. According to experiments, the appropriate particle size of coarse particles is more than 0.5 mm and less than 3.0 mm, preferably 0.5 to 2.0 mm.
Conveyance was possible if the weight ratio was in the range of 10 to 50%, preferably 10 to 40%. This particle size is determined by the refractory material that accounts for most of the non-combustible components in the sprayed material, and the remainder of the refractory material other than this particle size is 0.5 mm or less, and other Additives as non-combustible components or powdered fuel such as coke also have a particle size of 0.5 mm or less. The delay in melting rate that occurs when coarse particles are used can be addressed by the following measures. That is, in addition to limiting the particle size and weight ratio of the coarse particles as described above, this is done by limiting the chemical composition of the non-combustible components in the spray repair material. In this way, even if coarse particles are used, it is possible to strengthen the fusion between the refractory material particles or between the refractory material particles and the furnace wall refractory. The reason is that even if a certain amount of coarse particles are included in the refractory material, there are
If a certain amount of Al ₃ O ₃ , SiO ₂ , and Fe ₂ O ₃ components that form low-melting point compounds are contained, they will melt in a high-temperature flame and act as an adhesive, making them fireproof. This is because the materials or their particles and the furnace wall refractories are firmly fused together. Moreover, even if the remaining coarse grains are made of high-purity refractory particles, for example, the fine grains contain Al ₂ O ₃ , SiO ₂ , Fe ₂ O _{3 .}
If there are many melting point lowering components such as, a sufficiently strong fusion is possible even if the surface of the coarse grains is insufficiently melted during the flight time from the nozzle to the furnace wall. In this regard, traditionally, refractory materials were made using Al ₂ O ₃ as much as possible,
It was common to use materials with low SiO ₂ and Fe ₂ O ₃ components. This forms a low melting point compound
This is because if the Al ₂ O ₃ , SiO ₂ , and Fe ₂ O ₃ components are too large, the corrosion resistance of the adhesion layer will deteriorate. However, as mentioned above, it is effective to include an appropriate amount of Al ₂ O ₃ + SiO ₂ + Fe ₂ O ₃ in order to add coarse particles to increase the durability of the adhesion layer. is essential in the present invention. To summarize what has been explained above, the particle size composition of the refractory material that enables strong fusion and does not reduce the corrosion resistance of the adhesion layer, and the chemical composition of the non-combustible components in the spray repair material are as follows. That is,
The appropriate particle size of the coarse particles to be contained in the refractory material is more than 0.5 mm and less than 3.0 mm, preferably 0.5 to 2.0 mm, and the content is as shown in Figure 1. Thus, 10 to 50% by weight, more preferably 10 to 40% by weight, was suitable. In addition, the preferred chemical composition of the non-combustible components in the spray repair material is MgO
+CaO80wt%, _20wt % _Al2O3 + _SiO2 +
Fe ₂ O ₃ in the range of 5% by weight, preferably MgO + CaO
85% by weight, 15% by weight Al ₂ O ₃ + SiO ₂ + Fe ₂ O ₃
It is in the range of 5% by weight. With this chemical composition,
Even if coarse particles are added, strong fusion can be achieved between the particles of the refractory material or between the refractory material and the furnace wall refractory without lowering the corrosion resistance of the adhesion layer. The reason for this numerical limitation is, for example, Al ₂ O ₃ + SiO ₂ + Fe ₂ O ₃
If the total amount is less than 5% by weight, strong fusion between the refractory materials or between the refractory materials and the furnace wall refractories will not be achieved, and if the total amount is more than 20% by weight, the corrosion resistance will decrease and the durability will be reduced. This is because the sex becomes worse. There are various combinations of carbonaceous solid fuel, refractory materials, and optionally melting point lowering additives that bring the chemical composition of the non-combustible components during the spray repair into the range of the present invention. For example, a method of combining low-purity magnesia clinker or low-purity dolomite clinker with coke with a low ash content, a method of combining a high-purity raw material such as fused magnesia with coke with a high ash content, or a method of combining a high-purity raw material such as fused magnesia with coke with a high ash content, or a method of combining a high-purity raw material such as fused magnesia. Various methods can be considered, such as adding slag or olivine to coke with a low ash content, but these combinations are not _{particularly limited} .
If the combination is within the composition range of SiO ₂ +Fe ₂ O ₃ , a highly corrosion-resistant adhesion layer can be obtained. In particular, it is effective to control the overall chemical composition using the refined slag of the furnace where the repair is performed. Note that if the Al ₂ O ₃ + SiO ₂ + Fe ₂ O ₃ components are contained in coarse particles, they will not melt in the flame and will not function as a fusion agent. ,
Demonstrate its effectiveness. In addition, for the part of the refractory material exceeding 0.5 mm and 3.0 mm or less, dead-burning magnesite, dead-burning dolomite, magnesia clinker, dolomite clinker, fused magnesia grains, fused dolomite grains, etc. are used alone or in combination. These are appropriately selected depending on the wall surface material to be sprayed. Examples Table 1 shows examples in which flame spraying was applied to a steel refining converter lined with magnesia dolomite material. Using the five types of spray repair materials shown in Table 1, the converter trunnion was hot repaired by flame spraying. The spraying thickness is approx. for all 5 types.
It was sprayed to a thickness of 30 mm. Spraying is carried out while stainless steel blowing is continuing, and the wear rate (mm/
ch) was measured. In addition, the same type of spray repair material is sprayed on magnesia dolomite bricks (thickness
30mm), and the corrosion resistance method was investigated using the high frequency furnace method. As is clear from Table 1, when compared with the two comparative examples, the use of the sprayed repair material of the present invention significantly improves corrosion resistance, proving that it is effective in reducing the unit consumption of refractories. .

[Table] In the above example, a converter for steel refining was shown, but it is also effective for other metal refining furnaces that perform refining in a molten state. It can also be applied to high-temperature containers lined with other refractories that come into contact with slag and are subject to significant erosion by the slag. Effects of the Invention As explained above, the spray repair material of the present invention has excellent durability of the repaired surface and is effective in reducing the unit consumption of refractories.

[Brief explanation of drawings]

Figure 1 is a graph showing the relationship between the mixing ratio of coarse particles with a particle size of more than 0.5 mm and 3.0 mm or less in the fireproof material and the wear depth of the adhesion layer, and Figure 2 is the non-combustible component in the spray repair material. It is a graph showing the relationship between the ratio of Al ₂ O ₃ +SiO ₂ +Fe ₂ O ₃ composition occupied in the adhesive layer and the wear depth of the adhesion layer.

Claims (1)

[Scope of Claims] 1. A spray repair material that is a mixture of carbonaceous solid fuel powder and a powdery non-combustible component that includes the ash content, fireproof material, and additives in the carbonaceous solid fuel powder. , Refractory materials consist of coarse particles with a particle size of more than 0.5 mm and less than 3.0 mm.
The particle size is 10 to 50% by weight, and the balance is fine particles with a particle size of 0.5 mm or less.The non-combustible component excluding the refractory material consists of fine particles with a particle size of 0.5 mm or less, and the chemical composition of the entire non-combustible component is MgO and CaO. 80% by weight or more in total amount of Al ₂ O ₃ , SiO ₂ and
The total amount of Fe ₂ O ₃ is 5 to 20% by weight, and
A spray repair material for flame thermal spraying, characterized in that Al ₂ O ₃ , SiO ₂ and Fe ₂ O ₃ constitute fine particles of non-combustible components.