KR100484538B1 - Agent for Coating Pernament Lining of Hot Vessel - Google Patents

Abstract

The present invention relates to a coating agent that is applied to protect the permanent field of a high temperature vessel, such as a tundish for continuous casting of steelworks to take high-temperature molten steel, can be applied to the permanent field of the high temperature vessel by the warm construction method An object of the present invention is to provide a permanent coating agent for a high temperature container that can prevent the inflow of hydrogen into the molten steel received in the container.

Magnesium (MgO) or forsterite (2MgOSiO ₂ ): 80% by weight or more, fiber: 0.1-3.0% by weight, fluidizing agent: 0.1-1.5% by weight, curing regulator: 0.1-3.0% %, Medium temperature increasing agent: 0.5-7.0 weight%, thickening agent: 0.1-1.0 weight%, peptizing agent: 0.1-2.0 weight%, and anti-backflow agent: 0.1-2.0 weight%, and Permanent enteric coating agent of a high temperature container whose content of the particle | grains which have a particle size of 75 micrometers or less is 30-55 weight% is made into the summary.

Description

Agent for Coating Pernament Lining of Hot Vessel

The present invention relates to a coating agent that is applied to protect the permanent field of a high temperature vessel, such as a continuous casting tundish of a steelworks for taking high temperature molten steel, more specifically a high temperature vessel such as a continuous casting tundish, etc. Permanent field coating agent of high temperature container which can be warmed on permanent field by wet spray method in order to protect permanent field.

Hot containers used in mills are those for repairing hot molten iron or for taking molten steel, such as tundish, various ladles, and topedoca.

The high temperature vessel is usually composed of a shell, a heat insulating material, a permanent lining (pernament lining) and a consumable coating agent to protect the permanent field from the outside.

An important point to consider when applying the coating agent to the permanent field of the hot container is to prevent the introduction of hydrogen into the product manufactured by using the molten steel received in the hot container by the application of the coating agent.

As a coating method of the coating agent is known a trowel construction method using an iron hand or other tools, spraying method using a construction machine and vibration molding method of construction by a vibration filling method, double spray method is widely used.

In addition, the coating method of the coating method is a wet method and a dry method, and the dry method has a higher rebound loss and a higher dust generation rate than the wet method.

In order to construct the coating agent by the wet method, water must be added, and it is very important to remove water until just before operation after construction.

Thus, the wet spray method is widely used as a method of applying a coating agent to the permanent field of a high temperature container.

In the wet method, the drying method is largely composed of two processes: natural drying (air cooling drying) and forced drying (pre-heater).

In order to prevent the occurrence of hydrogen defects in the product, it is necessary to remove forced cooling and naturally cool and to prevent the moisture of the coating agent from being absorbed into the permanent field.

On the other hand, the method of applying the coating agent on the permanent device of the high temperature container is divided into a cold construction method for construction at 100 ℃ or less according to the construction temperature and a warm construction method for construction at 100 ℃ or more, 400 ℃ or less.

In the case of cold construction, after a certain time (approximately 3 hours after construction) after the application of moisture, the absorbent is absorbed into permanent field (inflow material), and some of it is naturally dried to finally be in equilibrium with the inflow material.

Under these equilibrium conditions, forced drying is carried out for the purpose of removing moisture as much as about 3-4 hours before the operation, but in this case, the moisture inside the coating agent can be completely removed, but the moisture inside the influent is not removed. Moisture is absorbed in the molten steel between the well block (inlet, discontinuity and nozzle connection), causing hydrogen defects in the product.

In the case of warm construction, unlike the cold construction method, water is evaporated immediately after construction and the inflow material is instantly cooled by the moisture, so that the moisture penetrates into the inflow material. After about 3 hours), the equilibrium temperature is maintained at about 110-160 ° C so that moisture does not remain in the coating agent and the inflow material.

Therefore, there is a demand for a coating agent that can be installed on the permanent device by the warm construction method.

As a conventional cold coating agent, a coating agent is known that is formed by artificially forming a bubble by adding a large amount of fiber for the purpose of low specific gravity and adding a foaming agent. By artificial bubble generation (low specific gravity), there is a problem in that it is impossible to warm the construction by sharply drop the adhesive force to the inflow material of the coating agent.

In addition, the conventional coating agent contains excessive moisture, so in the case of a tundish having an increased construction thickness, if a sufficient forced drying is not performed, a blasting phenomenon occurs due to evaporation of water during operation, which is very dangerous or hydrogen is finally produced. There is a problem that the product is incorporated into the product, causing product defects in a later process.

The present inventors have conducted research and experiments to solve the above problems of the prior art, and based on the results, the present invention has been proposed, and the present invention can be applied to a permanent container of a high temperature container by a warm construction method, thereby providing a container. It is to provide a permanent field coating agent of a high temperature container that can prevent the introduction of hydrogen into the molten steel to be received, the purpose is.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated.

Magnesia (MgO) or forsterite (2MgO.SiO ₂ ): 80% by weight or more; One or two or more fibers selected from the group consisting of wood flour, expandable inorganic fibers, polypropylene fibers, pulverized paper and glass fibers: 0.1 to 3.0% by weight; Glidant: 0.1 to 1.5% by weight; Curing regulators: 0.1 to 3.0% by weight; Moderate temperature increasing agent: 0.5-7.0 weight%; Thickener: 0.1-1.0 wt%; Peptizer: 0.1-2.0 wt%; And a backflow inhibitor: 0.1 to 2.0% by weight, wherein the total content of the components is 100% by weight, the form is powder, and the powder has a particle size of 75 μm or less. The present invention relates to a permanent coating agent for high temperature containers with a content of 30 to 55% by weight.

In addition, the above-described coating agent of the present invention may further contain 10% by weight or less of ultrafine Al ₂ O ₃ as required.

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

Magnesia (MgO) and forsterite (2MgO · SiO ₂ ) added as main raw materials in the present invention are raw materials to improve the corrosion resistance to slag and to secure excellent thermal insulation against high temperature, when the content is less than 80% by weight. Since the corrosion resistance is sharply lowered and causes a problem in the slag line part, the content of magnesia (MgO) or forsterite (2MgO.SiO ₂ ) added as the main raw material is preferably set to 80% by weight or more.

The ultra fine Al ₂ O ₃ is a component that improves the fluidity of the slurry, but when the content exceeds 10% by weight, since the sintering proceeds rapidly at high temperature, there is a problem in securing thermal insulation, so the content of Al ₂ O ₃ is It is preferable to set it to 10 weight% or less. As said ultrafine powder Al ₂ O ₃ , the ultrafine powder whose average particle diameter is 0.1-7 micrometers is preferable.

The fiber is added to reduce the specific gravity of the coating agent is added to the 0.1% by weight or more to have the effect of adding, but when the amount is too large, the amount of added water is rapidly increased and causing cracks during drying after construction Therefore, it is preferable to select the content in 0.1 to 3.0 weight%.

As the fiber, one or two or more selected from the group of fibers consisting of wood flour, expandable inorganic fiber, polypropylene fiber, pulverized paper and glass fiber are used.

The fluidizing agent is a component that is added to smooth the transport in the slurry state after water addition to the coating agent to shorten the construction time, and should be added at least 0.1% by weight, but if the amount is too large, the fluidity is too high. Since there is a problem that it is sharply increased and the backprop is dropped immediately after the construction, and there is a problem that it is impossible to construct a coating agent of a certain thickness, the content is preferably selected to 0.1 to 1.5% by weight.

Preferably, the fluidizing agent may be used one or two or more selected from melamine, naphthaline, and lignin based fluidizing agents.

The curing regulator is added to increase the adhesion during the construction of the warm inlet coating agent, 0.1% by weight or more must be added to the effect, but if the amount is too large, the curing time is too fast to transfer during construction Since there is a problem that the construction is impossible to be cured in the tube, the content is preferably selected from 0.1 to 3.0% by weight.

As said hardening regulator, Preferably, 1 type (s) or 2 or more types can be used among a sulfate type and an acetate salt type hardening regulator.

The sulfate curing agent may be magnesium sulfate, sodium sulfate, lithium sulfate, sulfate ester, aluminum sulfate, potassium sulfate, calcium sulfate, ammonium sulfate, and the like, and the acetate salt curing agent may be aluminum acetate, potassium acetate, calcium Acetates and chromium acetates.

The medium temperature increasing agent is added to give strength to the coating agent during drying and to prevent dropping of the coating agent at elevated temperature, and at least 0.5% by weight should be added, but if the added amount is too large, Since the corrosion resistance is lowered and there is a problem in securing thermal insulation due to a rapid reaction at high temperature, the content is preferably selected from 0.5 to 7.0% by weight.

As the medium temperature increasing agent, preferably, one or two or more types selected from ultra fine powder silica, ultra fine clay and ultra fine magnesia may be used. As the medium temperature increasing agent, ultrafine powder having an average particle diameter of 0.1 to 7 μm is preferable. .

The thickener is added in order to increase the dynamic viscosity to improve adhesion, and at least 0.1% by weight should be added, but if the amount is too large, the viscosity of the slurry is increased so much that the flow tube and frictional force are rather increased. Since there is a problem that the fluidity is further increased and the fluidity is lowered, the content thereof is preferably selected from 0.1 to 1.0% by weight.

As the thickener, one or two or more selected from polyvinyl acetate, polyvinyl alcohol and methyl cellulose may be preferably used.

The peptizing agent is a component added in order to prevent aggregation of particles to impart fluidity under low moisture, and at least 0.1% by weight of the peptizing agent is added, but when the amount is too large, the peptizing degree is accelerated. As a result, the water and particles are separated and settled during a certain period of time during the construction to separate the water and particles, so that the next construction is impossible. Therefore, the content is preferably selected from 0.1 to 2.0% by weight.

As the peptizing agent, one or two or more selected from sodium phosphate, lithium phosphate, potassium phosphate, calcium phosphate, monobasic sodium phosphate and powdered sodium silicate and powdered potassium silicate may be used.

The anti-backprop agent is a component added to suppress the property of the coating agent to move downward immediately after construction and to reduce the property of the coating agent to be sag due to gravity after drying after construction. If the addition amount is too large, there is a problem in securing the thermal insulation due to a decrease in the corrosion resistance in the slag line and a rapid reaction at a high temperature, so the content is preferably selected from 0.1 to 2.0% by weight.

As the bag prevention agent, preferably one or two of potassium silicate and bentonite may be used. The total content of the components constituting the coating agent of the present invention should be 100% by weight.

The coating agent of the present invention is in the form of a powder, and it is preferable that the content of particles having a particle size of 75 μm or less in the powder is 30 to 55% by weight, for the purpose of application by wet spraying.

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

Example

The coating agent having the composition of Table 1 was constructed under the conditions of Table 2 to evaluate the construction properties, physical properties and chemical properties, and the results are shown in Table 2 below.

In Table 1, a lignin-based fluidizing agent is used as a fluidizing agent, potassium acetate is used as a curing modifier, ultrafine silica is used as a medium temperature increasing agent, methylcellulose is used as a thickener, and a peptizing agent is used. Sodium phosphate was used, and potassium silicate was used as a backprop inhibitor.

Example No. Coating agent (% by weight) Particle Content Below 75㎛ MgO Al ₂ O ₃ fiber Glidants Hardening agent Moderate temperature increase Thickener Discourse Back Proof Preventer Inventive Example One 91.3 - 1.5 0.3 1.0 3.5 0.1 0.3 2 40 2 89.3 - 1.5 0.3 3 3.5 0.1 0.3 2 34 3 91.8 - 0.5 0.3 1.5 3.5 0.1 0.3 2 54 4 83.2 - 3.0 1.5 3.0 6.5 0.5 0.3 2 40 5 88.3 5 1.5 0.3 1.0 1.5 0.1 0.3 2 52 6 84.9 10 1.5 0.7 1.5 0.5 0.1 0.3 0.5 45 7 90.6 - 1.3 0.5 1.0 5 0.6 0.3 0.7 45 8 89.2 - 1.3 0.5 0.8 4 0.2 2.0 2 45 9 93.1 - 0.8 0.5 0.2 4 0.1 0.3 One 45 10 91.3 1.5 0.3 1.0 3.5 0.1 0.3 2 40 Comparative example One 92.8 - 0.3 1.0 3.5 0.1 0.3 2 45 2 92.6 1.5 - - 3.5 0.1 0.3 2 45 3 94.8 1.5 0.3 1.0 - 0.1 0.3 2 60 4 87.9 3.5 0.3 1.0 3.5 1.5 0.3 2 50 5 87.1 1.5 2.0 3.5 3.5 0.1 0.3 2 30 6 71.4 1.5 0.3 1.0 8 0.5 0.3 2 45 7 91.7 1.5 0.3 1.0 3.5 - - 2 45 8 93.3 1.5 0.3 1.0 3.5 0.1 0.3 - 60 9 75.8 1.5 0.3 1.0 3.5 0.1 0.3 2.5 45

Example No. Added moisture (%) Limit construction temperature (℃) Construction body specific gravity (110 ℃ × 24 hours) Discharge amount (kg / min) Workability (Prevention of Back Proof) Construction limit thickness (mm) 1000 ℃ Compressive Strength (kg / ㎠) Heat insulation Corrosion Resistance (Erosion + Penetration) Explosion oil, nothing Inventive Example One +23.6 398 1.75 28-30 ◎ 70-75 6.5 ◎ ◎ radish 2 +23.4 445 1.72 28-33 ◎ 95-100 7 ◎ ● radish 3 +20.4 415 1.92 30 to 33 ● 80 to 85 10.4 ● ◎ radish 4 +28.9 289 1.64 24-27 ◎ 90-95 8.5 ◎ ● radish 5 +24.5 380 1.70 34-36 ◎ 80 to 85 4.3 ◎ ◎ radish 6 +25 420 1.80 34-36 ● 90-95 2.1 ◎ ◎ radish 7 +24.5 400 1.80 36-39 ◎ 90-95 6.2 ● ● radish 8 +21.6 400 166 24 to 25 ◎ 80 to 85 8.8 ◎ ● radish 9 +22.6 400 1.84 26-29 ● 70-75 5.8 ● ● radish 10 +23.6 398 1.75 28-30 ◎ 70-75 6.5 ◎ ◎ radish Comparative example One +21 200 2.31 30 to 33 ● 50 to 55 7.4 × ◎ U 2 +25.6 80 2.14 20-23 × 30 to 35 6.9 ● ● U 3 +22.4 150 1.90 22-25 × 40 to 45 0.6 ◎ ◎ radish 4 +31.2 150 1.65 16-20 × 30 to 35 1.1 ◎ × radish 5 +23.6 400 1.72 28-30 × 0 6.8 ● ◎ radish 6 +22.8 350 1.90 35 to 39 ◎ 80 to 85 11.8 × × radish 7 +28.4 250 1.85 26-28 ● 60 to 65 6.5 ● × U 8 +25.6 300 1.94 28-30 × 30 to 35 6.4 × ◎ radish 9 +24.6 350 1.75 30 to 33 ◎ 80 to 85 8.8 × × radish

In Table 2, the limit construction temperature (° C.) may be applied while adjusting the coating distance of the coating material to 100 to 200 mm on the surface of the influent (castabul with an Al ₂ O ₃ content of 50% or more). The maximum temperature when the adhesion rate was about 95% or more was set.

At this time, the spray coating machine used was a machine of M-Tec, a German manufacturer.

Volumetric specific gravity measurement in Table 2 is added to the construction equipment can be added moisture

It was formed in a 40 × 40 × 160 mm mold and measured in accordance with KSL 3114 standard, set to the construction conditions similar to the following site.

The discharge amount in Table 2 was evaluated by measuring the feed amount of the coating agent per unit in the end state (using 200 tons of the coating agent) life of the mono pump (Mono Pump) life using the construction equipment to move the coating agent

The workability in Table 2 was to evaluate the degree to which the first coating agent moves when the first thickness is 30 to 40 mm and the second construction is 50 to 60 mm, when the surface of the inflow material is maintained at 90 degrees. If the surface of the primary construction body is about 1mm or less, it is good (◎), if it is 3mm or less, it is normal (●), and if the primary surface is collapsed or more than 3mm, it is evaluated as bad (X).

The construction limit thickness in Table 2 was obtained by measuring the maximum construction thickness that does not collapse when evaluating the constructability

1000 ℃ compressive strength in Table 2 is a numerical value representing the resistance to the flow of molten steel when put into operation after the temperature rise is an essential factor for stable operation and measured and evaluated in accordance with KSL3115 standards.

The thermal insulation (degree of sintering) in Table 2 was evaluated by comparing the difference in compressive strength of the same specimen as the specific gravity measuring method and dried and fired at 1500 ℃ × 3 hours

If the difference value is 200 or more, it is marked as bad (X), if it is 100 to 200, it is normal (●) and if it is 100 or less, it is good (◎).

Corrosion resistance (erosion + penetration) in Table 2 was evaluated using a 1550 ℃ × 10 (60 minutes / performance) test using the slag (C / S = 1.0 ~ 1.5) used in the chamber based on Example 1 Evaluated

The presence or absence of the thermal explosion in Table 2 confirmed the collapse phenomenon immediately after the temperature was raised to about 1 hour with a direct flame after 10 hours of natural drying after construction.

As shown in Table 2, when applied using a coating agent according to the present invention (Invention Example 1-10) it can be seen that the excellent workability, strength, heat insulation and corrosion resistance.

On the other hand, in the case of not adding the fibers to reduce the amount of construction and improve the air permeability (Comparative Example 1), the construction requirements are rapidly increased and the explosion during heating up.

In addition, when the hardening regulator was not added (Comparative Example 2) or when it was added too much (Comparative Example 5), the workability was particularly poor.

In addition, when the temperature increase agent which adds strength to the coating agent during the improvement of the workability and the temperature increase is not added (Comparative Example 3), the strength may drop sharply immediately after the temperature increase, and the operation initial coating agent may collapse, thus making it impossible to apply.

In addition, when the fiber was added beyond the scope of the present invention (Comparative Example 4), it was not possible to apply due to the rapid decrease in the corrosion resistance of the slag line as a result of the increase in the construction time and the erosion test due to the decrease in construction (discharge amount).

In addition, when the particle content of the coating agent is less than 74㎛ particle content exceeding the scope of the present invention (Comparative Example 8) or less than the scope of the present invention (Comparative Example 5), the sintering property is increased and the thermal insulation is sharply reduced and it is not applicable.

In addition, when the calcined and sintered Al ₂ O ₃ content is outside the scope of the present invention (Comparative Example 6 and Comparative Example 9), the construction properties are excellent, but the corrosion resistance and heat insulation rapidly dropped.

In addition, when the thickener and the peptizing agent were not added (Comparative Example 7), there was a problem in that the amount of added water was rapidly increased and the corrosion resistance was lowered.

In addition, when the back anti-propellant is not added (Comparative Example 8), the workability is lowered, and when the anti-back propellant is added beyond the scope of the present invention (Comparative Example 9), the insulation and corrosion resistance are deteriorated. This occurred.

As described above, the present invention can be more suitably applied to the production of high-grade steel by providing a coating agent in which the hydrogen concentration in the player decreases rapidly during operation and the hydrogen pickup content in the molten steel is sharply lowered compared to the wet coating agent which can be applied only in the conventional cold. It is effective.

Claims (9)

Magnesia (MgO) or forsterite (2MgO.SiO ₂ ): 80% by weight or more; One or two or more fibers selected from the group consisting of wood flour, expandable inorganic fibers, polypropylene fibers, pulverized paper and glass fibers: 0.1 to 3.0% by weight; Glidant: 0.1 to 1.5% by weight; Sulfate-based curing modifiers including magnesium sulfate, sodium sulfate, lithium sulfate, sulfate esters, aluminum sulfate, potassium sulfate, calcium sulfate and ammonium sulfate and acetate salt curing based on aluminum acetate, potassium acetate, calcium acetate and chromium acetate One or two or more curing modifiers selected from the group consisting of regulators: 0.1 to 3.0 wt%; One or two or more medium temperature increasing agents selected from the group consisting of ultra-fine silica, clay and magnesia having an average particle diameter of 0.1 to 7 µm: 0.5 to 7.0 wt%; Thickener: 0.1-1.0 wt%; Peptizer: 0.1-2.0 wt%; And a backflow inhibitor: 0.1 to 2.0% by weight, the total content of the components is 100% by weight, the form is powder, And the coating material for the permanent container of the high temperature container, wherein the content of the particles having a particle size of 75 μm or less is 30 to 55 wt%. 2. The permanent coating agent for high temperature containers according to claim 1, further comprising 10 wt% or less of ultra fine powder Al ₂ O ₃ having an average particle diameter of 0.1 to 7 µm. delete According to claim 1 or 2, wherein the fluidizing agent is one or two or more selected from the melamine-based, naphthalin-based, and lignin-based fluidizing agent, the coating agent for the permanent container of the high temperature container. delete delete According to claim 1 or claim 2, wherein the thickener is one or two or more selected from the group consisting of polyvinyl acetate, polyvinyl alcohol and methyl cellulose, the coating agent for the long-term container of the high temperature container. The method according to claim 1 or 2, wherein the peptizing agent is one or two or more selected from sodium phosphate, lithium phosphate, potassium phosphate, calcium phosphate, sodium phosphate monobasic and powdered sodium silicate and powdered potassium silicate. Permanent long coat of high temperature container 3. The permanent coating agent for high temperature containers according to claim 1 or 2, wherein the backprop prevention agent is one or two of potassium silicate and bentonite.