KR100213320B1 - Process for producing spray deposit - Google Patents

Abstract

The present invention relates to a thermal spraying material for flame spraying repairing damaged parts of a magnesia-containing refractory material. By coating a powder material having a low melting point, a slip state of a composition and a particle size that can maximize the yield of the thermal spraying material is first manufactured, and thus, magnesia, etc. By spraying (spraying and spraying) the primary particles of the process to produce the sprayed material, the manufacturing process is simplified, the yield of the sprayed material is increased, and the properties of the sprayed body are improved through excellent fluidity. It is an object of the present invention to provide a method for producing a flame sprayed magnesia spray material that can be improved.

The present invention for achieving the above object is a method for producing a magnesia thermal spray material for flame by coating a slip composed of converter slag, spinel powder / alumina powder, an organic binder and water to magnesia, and adding a metal powder thereto The main point is to provide.

Description

Manufacturing method of magnesia thermal spray material for flame

1 is a manufacturing process diagram of a magnesia thermal spray material for use in flames to which the method of the present invention is applied.

2 is a block diagram of a magnesia thermal spraying material to which the method of the present invention is applied.

* Explanation of symbols for main parts of the drawings

1: particle coated with slip on magnesia particle

2: Particles in which two or more magnesia particles are coated on the slip

3: particle spheroidized only by slip itself

4: metal powder particles

The present invention is used for various industrial furnaces, especially steel industry converters, electric furnaces, vacuum degassing facilities, etc. Magnesia (MgO) used as interior refractory materials such as crosstalk cars, ladles, tundish, etc. used for the transport and storage of molten metal. A powder spray repair material for flame-repairing damaged parts of a refractory-containing refractories, namely magnesia, magnesia-chromium oxide, magnesia-carbonaceous, magnesia-spinel, magnesia-alumina refractories, and more specifically, The present invention relates to a method for manufacturing a flame spraying magnesia spray material which can be effectively used as a hot repair material for improving the lifespan of a furnace body and improving productivity.

Magnesia-based powder spraying material is a high melting point material with magnesia melting point of 2850 ℃, so that 2500 ℃ is not melted in the flame due to the combustion of flammable gas such as propane-oxygen or acetylene-oxygen. Flame spray does not adhere to the base metal by melting.

Therefore, magnesia-based powder spraying materials containing magnesia as a main component are usually manufactured by adding coke powder or metal powder for the purpose of adding a low melting point material such as slag or cement or increasing the flame temperature. At this time, a technique known as an effective method is to coat the low melting additives on the surface of magnesia particles, which is a high melting point material, and to produce coke powder or metal powder for the purpose of further improving the adhesion efficiency. Compared with the thermal spraying material prepared by simply adding an additive to the powder, it is possible to obtain an excellent adhesion rate during thermal spraying.

Many proposals have been made to date for such thermal spraying materials, including Japanese Patent Laid-Open No. 61-186258, Japanese Patent Laid-Open 59-97577, Japanese Patent Laid-Open 60-215579, Japanese Patent Laid-Open 59-223277, Japanese Patent Laid-Open 60- 161379, Japanese Patent Laid-Open No. 62-41772, and Korean Patent Application No. 93-23742 are representative.

The thermal spraying material of Japanese Patent Application Laid-Open No. 61-186258 is a magnesia oxide obtained by coating a particle surface of a high melting point refractory powder adjusted to a particle diameter of 200-10 μm with an ultrafine powder of isotropic oxide having an average particle diameter of 10-0.1 μm. This thermal spraying material is a refractory powder for flame-based flames. Since the thermal spraying material is a material having a melting point of about 2850 ° C., it is not melted at a flame temperature of 2500-2600 ° C. by propane gas and oxygen during thermal spraying. Phosphorous silica (SiO ₂ ), alumina (Al ₂ O ₃ ), spinel and the like are coated on the surface of the magnesia particle. However, this is a method in which magnesia particles are coated with an sinterable oxide, so that the adhesion rate is very low, at about 66-73%, which is economical and inferior in industrial practicality.

The thermal spraying material of Japanese Patent Application Laid-Open No. 59-97577 is 60-80% by weight of magnesia and chromium ore with a mixture ratio of magnesia-chromium ore 80 / 20-50 / 50% by weight, and 1-5% by weight of chromium oxide powder. It is a thermal spraying material for magnesia-chromium oxide refining furnace containing 20-40% by weight, and this thermal spraying material uses magnesia-chromium ore as the main aggregate, which may cause high temperature evaporation of chromium oxide when spraying. Since the coke powder is used, the actual spraying amount is inefficient because the spray material must be sprayed as much as the amount of coke powder.

The thermal spraying composition of Japanese Patent Application Laid-Open No. 60-215579 is a basic refractory composition for magnesia-dolomite-based flames. Since the thermal spraying material is used by adding only Portland cement to MgO aggregates, the adhesion rate is low to 75-85%, and the efficiency is high. It is a problem.

Japanese Patent Application Laid-Open No. 59-223277 is a mounting and repair material for magnesia-oxide type flame, whose thermal spraying material has a particle size of 3.0-0.5mm and 0.5mm or less, and the additive is 0.5mm or less in the particle size of the raw material itself. The carbonaceous raw material is less than 0.2mm, respectively, and it is difficult to obtain a high adhesion rate due to the large amount of refractory particles that do not melt in the flame.

The thermal spraying material of Japanese Patent Application Laid-Open No. 60-161379 is a thermal spraying material manufactured by coating a metal powder having a particle size of 44 μm or less on a high melting point material of magnesia.性) Because only metal powder is used, it does not melt the raw material of high melting point sufficiently, so the spraying efficiency is very low as 60%.

Japanese Patent Application Laid-Open No. 62-41772 relates to a method of manufacturing a thermal spraying material by adding coke powder for the purpose of increasing the flame temperature and improving the adhesion rate of the thermal spraying material. It has the same drawbacks as the thermal spraying material of Japanese Patent Application Laid-Open No. 59-23277.

Republic of Korea Patent Application No. 93-23742 relates to a method of manufacturing a thermal spraying material by coating a fine low melting point material on the magnesia particles, and the thermal spraying material produced by this method is made of magnesia powder alone or magnesia and spinel powder The coating is manufactured by coating a low melting point powder having a maximum particle size of 44 μm or less, resulting in a small particle size difference between the coated primary particles and the coated particles, resulting in a coarse size of the final coated particle and inferior fluidity of the thermal spray material itself. . Therefore, the regrinding and reclassification process must be carried out, and in this process, the yield of the thermal spray material product or the coating layer are separated.

Accordingly, the present inventors have a low adhesion rate and a low remanufacture yield in the manufacture of the thermal spraying materials, which have a method of simply mixing, kneading, and controlling the size of each raw material in the conventional thermal spraying materials and coating a single or double coating on the magnesia particles. In order to solve various problems such as complicated process, the present invention was proposed based on the results, and the present invention maximizes the yield of the thermal spray material by coating the powder material of low melting point. Slip state of the composition and particle size that can be raised to the first, and then sprayed on the primary particles such as magnesia by spray method to manufacture the spray material, simplifying the manufacturing process, spray material products Manufacture of flame-resistant magnesia thermal spray materials that can improve the properties of thermal sprayed body by increasing the yield and excellent fluidity To provide for the law, it is an object.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated.

The present invention relates to a method of manufacturing a thermal spraying material for repairing a molten portion of a refractory containing a magnesia, the converter slag: 8.5-25% by weight, the spinel powder: 28% by weight or less, the water-soluble organic binder: 0.4-2% by weight or less Remainder: It is made of water, and the slip of the converter slag and the spinel powder is manufactured to a slip of 50% by weight or less, and then sprayed onto 50-90% by weight of magnesia powder having a particle diameter of 210 µm or less, coated, sieved, and then 0.1 It relates to a method for producing a magnesia thermal spraying material for flames comprising adding and kneading -5% by weight of metal powder.

In addition, the present invention is a method for producing a thermal spraying material for repairing the molten portion of the refractory containing magnesia, converter slag: 8.5-25% by weight, alumina powder: 24.3% by weight or less, water-soluble organic binder: 0.4-2% by weight 5 Below and the rest: It is made of water, and the slip of the converter slag and the alumina powder is prepared in 50% by weight or less, and then sprayed on 50-90% by weight of magnesia powder having a particle diameter of 210㎛ or less, and sieved The present invention relates to a method of producing a magnesia thermal spraying material for flames comprising adding and kneading 0.1-5% by weight of metal powder.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

Since magnesia powder is a high melting point material, when spraying powder spray material mainly containing magnesia particles having a larger particle size than the low melting point material, the magnesia particles are not easily melted and it is very difficult to increase the adhesion rate to the maximum. Therefore, magnesia powder particles have been used by adding a small amount of low melting powder raw material or by coating the sinterable powder or diacid-based metal powder in order to allow the sprayed body weight to be attached as a fireproof aggregate. There is a problem that the adhesion rate of the sprayed material is low or the yield of the product when the sprayed material is manufactured, the physical and mechanical properties of the sprayed body is lowered.

The present invention is a low melting point to reduce the product yield, the reduction in spraying efficiency produced by adding a binder to the magnesia powder of the conventional method as described above, kneading first, and then coating and manufacturing a fine powder having a low melting point Powder material was prepared in the best sulphate state containing a binder, and then sprayed and coated at high speed while swirling the magnesia particles to prepare a coating powder having excellent fluidity, and to which a metal powder having good fluidity was added. The solution can be solved by kneading and manufacturing a thermal spray material.

In other words, the present invention has the advantage that it can significantly improve the poor product yield, poor spraying workability during the production of the sandblasting material of the conventional magnesia-based spherical powder or coating spraying material.

Unlike the conventional magnesia-based spraying material, the thermal spraying material of the present invention has a converter slag having a suitable particle size as a main raw material as shown in Table 1 below, and spinel powder alumina powder and a binder are added to water at an appropriate ratio for 24 hours in a ball mill. After sufficiently pulverizing, the optimum slits are firstly manufactured, and the slips are coated at high speed while swirling the magnesia particles, and then sieved to a particle size (0.5 mm or less) suitable for the thermal burner nozzles. A metal powder having good fluidity is added and kneaded in a predetermined amount to prepare a thermal spraying material.

The converter slag mainly used in the present invention has a refractory degree (about 15 (1435 ° C.) and belongs to a low melting point material as a refractory material, but magnesia powder is usually more than 42 (2000 ° C.) of fire resistance and can be easily measured by the method of KSL 3113. Therefore, magnesia powder, low melting point material, and metal powder are best used to obtain a thermal spraying material having good thermal spraying properties at 2200-2600 ° C, which is a flame temperature caused by propane-oxygen or acetylene-oxygen during thermal spraying. Effective treatment to produce the best thermal spray material is a challenge.

The magnesia that can be used in the present invention may be made from natural magnesite or magnesia clinker prepared from seawater, but magnesia clinker having a purity of magnesia content of 95% by weight or more is preferable, and the particle size of the product yield after coating and In consideration of the spray efficiency through the burner nozzle of the thermal spraying device, 0.21 mm (210 μm) or less is preferable, but less than that may be used.

Such magnesia may be limited depending on the size of the burner nozzle used for flame spraying, and is generally used from about 1 mm to about 5 mm, so that the particle size is limited to a maximum of 0.21 mm (210 μm) in consideration of the particle size after coating. . Therefore, although magnesia having a particle size of 0.21 mm or less can be used, it is preferable to have a particle size of 0.21 mm or less in consideration of the durability of the thermal sprayed body. When coating the low melting point material using a particle coating apparatus, magnesia can be used at least 50% by weight or more and up to 90% by weight.

This is because when the magnesia is less than 50% by weight, an excessively low melting point material is added or the magnesia content is too low to show the excellent corrosion resistance inherent in basic refractory materials. In addition, when the magnesia becomes a thermal spraying material of more than 90% by weight, the amount of slag, which is a low melting point material coated on the magnesia particles, is too small, and the adhesion rate is significantly decreased due to the insufficient liquid phase during thermal spraying.

The converter slug for slip manufacturing is a low melting point material with a basicity (CaO / SiO ₂ ratio) 3-4, which is usually produced as a mass, and is used as a raw material for the manufacture of thermal spray materials. The powder state of is good or more. However, when the particle diameter of the converter slag is 0.149mm or more, the product yield decreases when the thermal spray material is manufactured, and considering the 95% or more product yield, the converter slag having a particle diameter of 0.149mm or less is preferable, and in particular, the manufacturing cost of the thermal spray material according to the present invention. In view of the fact that it is expensive compared to the usual powder material, when considering the product yield of 90% or more, a converter slag of 0.21 mm or less may be used. The spinel powder is usually sufficient to have a particle diameter of 0.044 mm or less, which is a 325 mesh pass through commercially available.

Hereinafter, the particle size of the converter slag will be described through the results of the demonstration in Table 1 below.

In the manufacturing of the sprayed spray material as shown in FIG. 2 by the spraying material manufacturing process of FIG. 1, the product yield of the sprayed material up to 0.5 mm or less of the coated sprayed material should be 95% or more, but to be a sprayed material having good fluidity. The particle size of converter slag before ball milling should be less than 0.149mm for two bottles of 100 mesh passage.

Table 1 shows the converter slag and spinel powder in the ratio of 1: 1 by weight by crushing the bulky converter slag, which is calculated as a by-product in the steelmaking bottom of the steel mill, and sieving the converter slag having an arbitrary particle size. Add 0.4 wt% of PVA solids to this mixture, add about 2 times the water by weight to the combined amount of converter slag and spinel powder, and add a ball mill with alumina balls for 24 hours, 30 hours, and 50 hours. It shows the size of the particles contained in the slip when crushed by using the maximum particle diameter and average particle diameter of the powder in the slip, and the weight ratio of the powder and the magnesia powder in the slip by using the produced slip so that the weight ratio of 3: 7 The result of calculating the product yield when the thermal spraying material was manufactured by coating on magnesia is shown.

In the case of refractory particle coating using a particle coating apparatus, in general, the finer the coating material and the higher the binding force of the binder used, the better the coating property. The smaller the later particle size is, the better the coating property is. Thus, the yield of the thermal spray material product is also improved. That is, in the case of converter slag, if the particle size is 0.149 mm or less, 95% or more of the coated magnesia spray material product yield can be obtained by converter slag-spinel-type slip manufactured by ball milling for 24 hours or more. However, as the production volume of the product decreases as the ball milling time becomes longer, it is common to set the ball milling time to about 24-30 hours in general due to the factory operation pattern.

The content of such tactical glags is preferably 8.5-25% by weight, because when the content of converter slag is less than 8.5% by weight (hereinafter, referred to as '%'), the adhesion of the liquid generated during spraying is insufficient. There is a problem that is sharply lowered, if more than 25% is due to the problem of poor corrosion resistance of the sprayed body due to the excess liquid generation during spraying.

In addition, in the present invention, the spinel or alumina which can be used for the preparation of the slip together with the converter slag is a fine-grained material, and the fine powder having a particle diameter of 44 μm or less or 74 μm or less is preferable, and if it is more than that, the fine powder is lengthened by the grinding time by a ball mill. This is preferred.

In this case, the amount of spinel powder is preferably 28% or less, and the amount of alumina powder is preferably 24.3% or less, because the amount of the spinel powder is 28% or more and the amount of the alumina powder is 24.3% or more. This is because there is a problem that the role of the tactical slag in the material is lowered.

In order to maintain and secure the good flowability of the coating spray material, the bonding force of the coating layer on the surface of the magnesia particle should be excellent. This should be a fine particle of the fine powder in the slip, but the added binder is important. In the present invention, as a binder, in general, saodi is usually a water-soluble binder such as polyvinyl alcohol (PVA) or polyvinyl butyral (PVB), arabic gum, carboxymethyl cellulose (CMC), molasses, etc. A water-soluble organic binder used for producing a slip is sufficient, and a content of 0.4-2% by weight, which is a general addition range showing a viscosity that can be sprayed into a range of use, is sufficient.

The amount of water added in order to grind the raw material and the binder of a predetermined blending ratio into the ball mill is usually sufficient to be used for ball milling, and in the present invention, the raw material solids: water = 1: 2-5 Is good. Normally, a ball mill is crushed for 24 to 50 hours, and the resulting slip passes through the 425 mesh classification network, and can be coated by spraying in a good state with a spray nozzle toward the magnesia particles vortexed in the cylindrical coating box of the particle coating apparatus. have.

In addition, in the converter slag-spinel-based or converter slag-alumina slip, which is an important element of the present invention, the content thereof is limited, the combined amount of converter slag and spinel does not exceed 50%, more preferably 50-8.5%. It is easy to coat | cover, and an excellent thermal spraying agent can be obtained. At this time, the amount of converter slag added should be more than spinel or alumina. The reason is that the converter slag is a low melting point material that generates a liquid phase during the spraying process, and the spinel and alumina play a role of controlling the viscosity of the liquid phase at the flame temperature of 2500-2600 ° C. so that the adhesion is excellent. If the amount of spinel and alumina is relatively high, the viscosity of the liquid is lowered, and the adhesion rate is lowered, thereby reducing the spraying efficiency. In addition, when the content of the converter slag-spinel-based or converter slag-alumina content to be coated exceeds 50%, the amount of the liquid phase increases or the coating thickness becomes thick, thereby decreasing the spraying efficiency of increasing the porosity of the construction body.

In the present invention, after manufacturing the slip to satisfy the above conditions, it is preferable to coat it on the magnesia, wherein, the injection time, the injection speed and the air temperature causing the vortex of the magnesia particles, etc. Although it depends on the capacity, in order to ensure good fluidity of the coated thermal spraying material, it is preferable to set the injection time to 30-1 hours.

In order to increase the flame spraying temperature during the construction of the thermal spraying materials, the thermal spraying materials are manufactured by adding metal powders. In this case, if the metallic powder includes Mg or Al such as Mg-Al alloy powder, Al powder, and Mg powder, It can be used, but considering the stability of economical use Mg-Al-based metal powder is advantageous, the proper addition amount can be from 0.1% to 5% by weight. In the thermal spraying material, the metal powder is mainly used for the purpose of increasing the flame temperature during spraying and promoting the formation of liquid phase to improve the adhesion rate during the spraying, and the addition of at least 0.1% by weight and at most 5% by weight is preferred. Preferably around 1% is ideal, and the spraying efficiency is relatively low when less than 0.1% by weight or no addition. On the basis of 5% by weight, it is difficult to expect good constructions due to porosity of the constructions due to excessive heat generation.

Hereinafter, the present invention will be described in more detail with reference to the following examples.

EXAMPLE

1 shows a method of manufacturing the magnesia-based powder material of the present invention. When the tactical slag-spinel-based or converter slag-alumina-slip is applied and coated on the magnesia interest, the moisture contained in the slip is removed. Hot air at around 100 ° C. is used as air vortexing magnesia particles. Therefore, when a material such as Mg-Al alloy powder is kneaded and coated together with magnesia powder in a particle box at the same time, there is a risk of explosion or fire. Therefore, in the present invention, as a basic manufacturing process, the proper composition and the appropriate particle size as shown in Table 2 are prepared primarily by the tactical slag-spinel-based or converter slag-alumina-based slip, and then the predetermined weight ratio to magnesia as shown in Table 2 below. Magnesium particles are coated with slip for a certain period of time, and sprayed through a 35 mesh feed network so that the spraying material of the sheathing arc does not exceed a maximum of 0.5 mm to allow good spraying of the spray nozzles during the construction of flame spraying. The metal powder having good fluidity was mixed at room temperature as shown in Table 2 to prepare a final staring material.

Using the thermal spraying material prepared in this way, it was applied to the magnesia-chromium refractory brick under flame conditions of propane (LPG) 15Nm 2 / hr and acid th (O) 80N80N / hr, and then the adhesion rate pores, which are the characteristics of the construction body, were folded. The results of strength and product feeding are shown in Table 2 below.

As can be seen in Table 2 above, in the case of AI (A), which is a thermal spray material satisfying the scope of the present invention, it is attached, and the comparative example deviating from the scope of the present invention in bending strength and product yield (JM And superior construction properties equivalent to those of conventional (NR).

As described above, the present invention first prepares a granular state of composition and particle size capable of sounding the product yield of the thermal spray material to the maximum, and coats the monovalent particles such as magnesia by spraying to manufacture the thermal spray material, thereby making various industries for the steel industry. It can be effectively used as a hot spraying repair material for damages of various basic refractory materials, which are magnesia used in the urinary tract, and show higher adhesion rate and physical and mechanical properties than the conventional magnesia powder spraying repair material. Can be improved, the service life of an industrial furnace and the performance of an acidity can be improved. In particular, the thermal spraying material of the present invention is characterized in that the spraying coating in the coating apparatus can produce a sprayed material product of uniform performance, there is an advantageous effect even during the manufacturing by automation.

Claims (16)

In the manufacturing method of the thermal spraying material for repairing the molten portion of the refractory containing magnesia, converter slag: 8.5-25 wt%, spinel powder: 28 wt% or more, water-soluble organic binder: 0.4-2 wt% or less and the rest: After preparing a slip which is composed of water and the sum of the converter slag and the spinel powder is 50% by weight or less, it is sprayed onto 50-90% by weight of magnesia powder having a particle diameter of 210 μm or less, coated, sieved, and then 0.1- A method for producing a magnesia thermal spray material for flames comprising adding and kneading 5% by weight of metal powder. Magnesium-based spraying material for flame whose converter slag has a particle size of 149㎛ or less. The magnesia thermal spraying material for flame of Claim 1 whose particle diameter of a spinel punam is 44 micrometers or less. The flame-retardant organic binder according to claim 1, wherein the water-soluble organic binder is one selected from the group consisting of polyvinyl alcohol (PVA), polyvinyl butyral (PVB), arabic gum, carboxymethyl cellulose (CMC), and the same day. Magnesia Spray Material The magnesia thermal spray material for flame according to claim 1, wherein the sum of converter slag and spinel powder is in the range of 8.5-50% by weight. The magnesia thermal spraying material for flame according to claim 1, wherein the ratio between the raw material solids and the water in the slip is in the range of 1: 2-5. Metal powder is a magnesia thermal spray material used for flame which is one of the group containing Mg or Al. The magnesia thermal spraying material for flame use of Claim 1 whose particle diameter of a thermal spraying material is 0.5 mm or less. In the manufacturing method of the thermal spraying material for repairing the molten portion of the refractory containing magnesia, converter slag: 8.5-25% by weight, alumina powder: 24.3% by weight, water-soluble organic binder: 0.4-2% by weight or less, and the composition: water After preparing a slip of which the sum of the converter slag and the alumina powder is 50% by weight or less, it is sprayed onto 50-90% by weight of magnesia powder having a particle diameter of 210 μm or less, coated, sieved, and then 0.1-5% by weight A method for producing a magnesia thermal spraying material for flames comprising adding and kneading a metal powder. 10. The magnesia thermal spraying material for flames according to claim 9, wherein the converter slag has a particle diameter of 149 µm or less. 10. The magnesia thermal spraying material for flames of Claim 9 whose particle diameter of alumina powder is 74 micrometers or less. The flame-retardant organic binder according to claim 9, wherein the water-soluble organic binder is one selected from the group consisting of polyvinyl alcohol (PVA), polyvinyl butyral (PVB), arabic gum, carboxymethyl cellulose (CMC), and the same day. Use magnesia thermal spray material. 10. The magnesia thermal spray material for flame according to claim 9, wherein the sum of converter slag and spinel powder is in the range of 8.5-50% by weight. 10. The magnesia thermal spraying material for flame according to claim 9, wherein the ratio between the raw material solids and the water in the slip is in the range of 1: 2-5. 10. The magnesia spray material for flame use according to claim 9, wherein the metal powder is one of Mg or Al. 10. The fireless magnesia thermal spraying material according to claim 9, wherein the thermal spraying material has a particle diameter of 0.5 mm or less.