Light heat preservation coating applied to interior of tundish

Abstract

The invention discloses a light thermal insulation coating applied to the interior of a tundish, and relates to the technical field of refractory thermal insulation materials, and the coating comprises the following components in parts by weight: 50-80 parts of diatomite, 10-40 parts of glass beads, 5-15 parts of high clay, 1-5 parts of floating beads, 1-5 parts of cellulose, 30-70 parts of silica sol, 5-15 parts of pure acrylic emulsion, 1-4 parts of an acetic acid solution, 0.5-2 parts of a coupling agent and 30-60 parts of water. The invention has the following beneficial effects: according to the technical scheme, diatomite is used as a base material of the thermal insulation material, the main component is porous silicon dioxide, and the thermal insulation material not only has good thermal insulation characteristic and lower production cost, but also is environment-friendly and convenient to recycle; the talcum powder and the attapulgite are added, so that the thermal expansion rate of the coating can be reduced, and the cracking condition of the coating is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of refractory and heat-insulating materials, and particularly to a lightweight heat-insulating coating applied inside a tundish. Background Art

[0002] In the steelmaking field, how to reduce heat loss in each link has always been a concern in the industry; as a container for storing molten steel, the tundish in the steelmaking process inevitably has heat loss of the molten steel temperature; even with the heat insulation of refractory materials such as the permanent layer and the heat-insulating layer, there is generally a high temperature of about 300 °C on the outer shell of the tundish; the common tundish in production has a steel shell - castable lining structure, and the steel shell of the tundish during operation is in a long-term high-temperature state, which exacerbates the oxidation rate of the steel shell, shortens the service life of the thermal equipment, and the operating workers face the risk of scalding when dealing with the tundish. Therefore, the research on the persistent heat insulation of the tundish in industrial production has always been a key topic; In industry, generally, attention is focused on using refractory materials to thicken the shell to reduce heat loss of the tundish, including increasing the thickness of the concrete permanent layer, adopting a sandwich vacuum structure for the steel shell of the tundish, etc.; however, the too-thick shell limits the capacity of the tundish and also increases the cost of the shell; from the perspective of lightweight, using a thin heat-insulating coating at the inner shell of the tundish to achieve good heat insulation of the tundish requires that the heat-insulating coating has the characteristics of low thermal conductivity, high strength and porosity, and long-term thermal stability; existing heat-insulating coatings, such as nano heat-insulating materials, have problems of high-temperature powdering and high cost, which are not conducive to industrialization promotion; therefore, it is of practical significance to develop a lightweight heat-insulating coating applied in the tundish, which has the characteristics of high strength and lightweight, good thermal stability, low cost, excellent heat insulation performance, etc. Summary of the Invention

[0003] To solve the above technical problems, the present invention provides a lightweight heat-insulating coating applied inside a tundish. The composition of the coating is as follows by weight: The composition of the coating is as follows by weight: 50 - 80 parts of diatomite, 10 - 40 parts of glass microspheres, 5 - 15 parts of high clay, 1 - 5 parts of cenospheres, 1 - 5 parts of cellulose, 30 - 70 parts of silica sol, 5 - 15 parts of pure acrylic emulsion, 1 - 4 parts of acetic acid solution, 0.5 - 2 parts of coupling agent, and 30 - 60 parts of water.

[0004] As a further supplement to the technical solution, the high clay is one or two of attapulgite, talc powder, and mica powder, and its average particle size ≤ 50 μm.

[0005] As a further supplement to the technical solution, the cellulose is one of carboxymethyl cellulose and hydroxypropyl methyl cellulose, where the molecular weight of carboxymethyl cellulose is 50,000 - 100,000, and the molecular weight of hydroxypropyl methyl cellulose is 100,000 - 200,000.

[0006] For further supplement to this technical solution, the silica sol is one of neutral silica sol or alkaline silica sol, the effective mass fraction of the silica sol ≥ 30 wt%, and the modulus: 2 - 4.

[0007] For further supplement to this technical solution, in the acetic acid solution, the mass fraction of acetic acid ≥ 25 wt%.

[0008] For further supplement to this technical solution, the coupling agent is one of KH560 and KH570.

[0009] For further supplement to this technical solution, the particle size of the diatomite is 325 mesh, the average particle size of the glass microspheres is 50 - 100 μm, and the average particle size of the cenospheres is 600 - 1000 μm.

[0010] A preparation method of a lightweight thermal insulation coating applied to the inside of a tundish, comprising the following steps: Step 1: 50 - 80 parts of diatomite, 10 - 40 parts of glass microspheres, 5 - 15 parts of kaolin clay, 1 - 5 parts of cenospheres, and 1 - 5 parts of cellulose form the dry powder part; 30 - 70 parts of silica sol, 5 - 15 parts of pure acrylic emulsion, 1 - 4 parts of acetic acid solution, 0.5 - 2 parts of coupling agent, and 30 - 60 parts of water; Step 2: Stir the dry powder part and the bonding solution in Step 1 respectively, then mix and stir the two for 5 - 10 minutes, and evenly apply them on the inner surface of the tundish by air spraying, with a thickness of 3 - 5 mm, and cure at room temperature for 24 - 36 hours to obtain the lightweight thermal insulation coating.

[0011] Its beneficial effects are as follows: 1. This technical solution uses diatomite as the base material of the thermal insulation material, the main component of which is porous silica. It not only has good thermal insulation properties and low production costs, but is also environmentally friendly and easy to recycle; adding talc powder and attapulgite can reduce the thermal expansion rate of the coating and improve the coating cracking situation; 2. The present invention uses air spraying to construct a 3 - 5 mm lightweight thermal insulation coating on the inner wall of the tundish, which does not require heat source heating and cures at room temperature; it can stably exist in a high - temperature environment of 600 °C for a long time; it adapts to tundishes with different angles and different models; it does not affect the subsequent processing of the formed tundish and does not affect the internal capacity of the tundish; 3. The present invention uses silica sol as the main binder, and its dehydration product after curing is amorphous silica. The curing time and the strength after curing can be adjusted by adding acetic acid. The heat insulation performance of the silica sol dehydration product is better than that of common industrial binders such as sodium silicate, and the anti - thermal shock cracking performance is better; 4. The present invention adopts a mode of combining organic and inorganic coatings. Adding cellulose and pure acrylic emulsion can improve the surface strength and toughness of the lightweight thermal insulation coating after curing at room temperature, and improve the crack resistance of the coating in a rapidly heating environment. When the coating works in an environment of 600°C for a long time, if the inside of the tundish is an anaerobic environment, the organic components will be converted into black amorphous carbon with low thermal conductivity, which hinders the heat transfer in the form of radiation. If the inside of the tundish is an aerobic environment, the organic components will be completely oxidized into carbon dioxide and dissipated. This behavior increases the porosity of the lightweight thermal insulation coating and further improves the heat insulation efficiency of the coating in an environment below 600°C. 5. The lightweight thermal insulation coating constructed by the present invention has a bulk density of 0.60 - 0.70 g / cm 3 after curing; a room temperature thermal conductivity of 0.09 - 0.15 W / (m·K); a linear change rate of <5.0% after calcination at 600°C; after calcination in a muffle furnace at 1000°C for 4 hours, there is no cracking or powdering, and it can stably exist on the inner surface of the tundish steel shell for a long time. Brief Description of the Drawings

[0012] Figure 1 is a schematic diagram of the lightweight thermal insulation coating of the first embodiment of the present invention; Figure 2 is a schematic diagram of the lightweight thermal insulation coating of the first embodiment of the present invention; Figure 3 is a schematic diagram of the lightweight thermal insulation coating of the first embodiment of the present invention. Detailed Description of the Invention

[0013] For the convenience of those skilled in the art to understand the technical solution more clearly, the technical solution of the present invention will be elaborated in detail below in combination with the attached Figures 1-3 drawings: Example 1: A lightweight thermal insulation coating applied to the inside of a tundish. The coating composition by raw material components and parts by weight is as follows: the dry powder part includes 60 - 80 parts of diatomaceous earth, 10 - 20 parts of glass microspheres, 5 - 10 parts of attapulgite, 3 - 5 parts of cenospheres, and 1 - 2 parts of carboxymethyl cellulose; the bonding solution includes 40 - 50 parts of neutral silica sol with a modulus of 3, 10 - 15 parts of pure acrylic emulsion, 1 - 3 parts of acetic acid solution, 1 - 2 parts of KH560 liquid, and 40 - 60 parts of water.

[0014] First, mix and stir diatomaceous earth, glass microspheres, attapulgite, cenospheres, and carboxymethyl cellulose for later use; then mix and stir neutral silica sol, pure acrylic emulsion, acetic acid solution, KH560, and water for 5 minutes. Finally, mix and stir the mixed dry powder and solution for another 5 minutes to obtain a white viscous coating. Use air spraying to evenly coat the inner surface of the tundish with a thickness of 3 mm and cure at room temperature for 30 hours to obtain the lightweight thermal insulation coating, as shown in Figure 1 .

[0015] The lightweight thermal insulation coating prepared in this example was tested: the bulk density was 0.65 - 0.70 g / cm 3 ; the thermal conductivity at room temperature was 0.10 - 0.12 W / (m·K); the linear change rate after calcination at 600 °C for 12 h was < 5.0%; after calcination in a muffle furnace at 1000 °C for 4 h, there was no cracking or pulverization. During actual use on the production line, compared with without the coating, the temperature of the outermost side of the tundish decreased by 80 - 85 °C.

[0016] Example 2: A lightweight thermal insulation coating applied to the inside of a tundish. The coating composition by raw material components and parts by weight is as follows: the dry powder part includes 60 - 70 parts of diatomite, 15 - 25 parts of glass microspheres, 5 - 10 parts of talc powder, 1 - 5 parts of cenospheres, and 1 - 2 parts of carboxymethyl cellulose; the bonding solution includes 40 - 50 parts of alkaline silica sol with a modulus of 2, 5 - 10 parts of pure acrylic emulsion, 1 - 2 parts of acetic acid solution, 0.5 - 1 part of KH560 liquid, and 40 - 60 parts of water.

[0017] First, mix and stir neutral silica sol, pure acrylic emulsion, acetic acid solution, KH560, water, and carboxymethyl cellulose for 3 minutes, and then successively add diatomite, glass microspheres, attapulgite, and cenospheres and stir to obtain a beige viscous coating. Use air spraying to evenly coat the inner surface of the tundish with a thickness of 4 mm and cure at room temperature for 28 hours to obtain the lightweight thermal insulation coating, as Figure 2 .

[0018] The lightweight thermal insulation coating prepared in this example was tested: the bulk density was 0.60 - 0.70 g / cm 3 ; the thermal conductivity at room temperature was 0.10 - 0.15 W / (m·K); the linear change rate after calcination at 600 °C for 12 h was < 5.0%; after calcination in a muffle furnace at 1000 °C for 4 h, there was no cracking or pulverization. During actual use on the production line, compared with without the coating, the temperature of the outermost side of the tundish decreased by 110 - 120 °C.

[0019] Example 3: A lightweight thermal insulation coating applied to the inside of a tundish. The coating composition by raw material components and parts by weight is as follows: the dry powder part includes 50 - 70 parts of diatomite, 20 - 25 parts of glass microspheres, 5 - 10 parts of talc powder, 3 - 5 parts of cenospheres, and 1 - 3 parts of hydroxypropyl methylcellulose; the bonding solution includes 50 - 70 parts of alkaline silica sol with a modulus of 2, 10 - 15 parts of pure acrylic emulsion, 1 - 3 parts of acetic acid solution, 0.5 - 1.5 parts of KH570 liquid, and 40 - 60 parts of water.

[0020] First, mix diatomaceous earth, glass beads, talcum powder, floating beads, and hydroxypropyl methylcellulose, and keep the dry powder; then mix alkaline silica sol, pure acrylic emulsion, acetic acid solution, KH570, and water for 5 minutes. Finally, mix the previously mixed dry powder and solution for 5 minutes to obtain a white viscous coating. Use air spray to evenly apply it on the inner surface of the tundish with a thickness of 5mm. Curing at room temperature for 36 hours will obtain a lightweight thermal insulation coating, such as Figure 3 .

[0021] The lightweight thermal insulation coating prepared in this embodiment was tested: the volume density is 0.60~0.65g / cm 3 ; Thermal conductivity at room temperature 0.09~0.12W / (m·K); Linear change rate <5.0% after calcination at 600℃ for 12h; No cracking or powdering after calcination in a 1000℃ muffle furnace for 4h. When actually used on the production line, the temperature of the outermost side of the tundish is reduced by 140~150℃ compared to without coating.

[0022] Therefore, the lightweight thermal insulation coating applied to the inside of the tundish prepared in this specific embodiment has the characteristics of being porous, having low thermal conductivity and being resistant to thermal shock. It is suitable for long-term operation in an environment of 600°C, reducing heat loss during the steelmaking process, and taking into account both protecting the steel plate outside the tundish and saving energy.

[0023] The above technical solutions only reflect the preferred technical solutions of the technical solutions of the present invention. Some changes that may be made to certain parts thereof by technicians in this technical field all reflect the principles of the present invention and fall within the protection scope of the present invention.

Claims

1. A lightweight thermal insulation coating applied to the interior of a tundish, characterized in that: The coating composition is as follows by weight: 50-80 parts of diatomaceous earth, 10-40 parts of glass microbeads, 5-15 parts of high clay, 1-5 parts of floating beads, 1-5 parts of cellulose, 30-70 parts of silica sol, 5-15 parts of pure acrylic emulsion, 1-4 parts of acetic acid solution, 0.5-2 parts of coupling agent and 30-60 parts of water.

2. A lightweight thermal insulation coating for use inside a tundish according to claim 1, characterized in that: The high clay is one or two of attapulgite, talc powder and mica powder, and the average particle size thereof is ≤50 μm.

3. A lightweight thermal insulation coating for use inside a tundish according to claim 2, characterized in that: The cellulose is one of carboxymethyl cellulose and hydroxypropyl methyl cellulose, wherein the molecular weight of the carboxymethyl cellulose is 50,000-100,000, and the molecular weight of the hydroxypropyl methyl cellulose is 100,000-200,000.

4. The lightweight thermal insulation coating for use inside a tundish according to claim 1, characterized in that: The silica sol is one of neutral silica sol and alkaline silica sol, the effective mass fraction of the silica sol is ≥30wt%, and the modulus is 2-4.

5. The lightweight thermal insulation coating applied to the interior of a tundish according to claim 1, characterized in that: In the acetic acid solution, the mass fraction of acetic acid is ≥25wt%.

6. The lightweight thermal insulation coating applied to the interior of a tundish according to claim 1, characterized in that: The coupling agent is one of KH560 and KH570.

7. The lightweight thermal insulation coating applied to the interior of a tundish according to claim 1, characterized in that: The diatomaceous earth particle size is 325 mesh, the average particle size of the glass microbeads is 50-100 mm, and the average particle size of the floating beads is 600-1000 mm.

8. A method for preparing a lightweight thermal insulation coating for use inside a tundish according to any one of claims 1 to 7, characterized in that: The following steps are involved: Step 1: Prepare the dry powder part by mixing 50-80 parts of diatomaceous earth, 10-40 parts of glass beads, 5-15 parts of high clay, 1-5 parts of floating beads and 1-5 parts of cellulose; The bonding solution is composed of 30-70 parts of silica sol, 5-15 parts of pure acrylic emulsion, 1-4 parts of acetic acid solution, 0.5-2 parts of coupling agent and 30-60 parts of water; Step 2: Stir the dry powder and the bonding solution in step 1 separately, then mix and stir the two for 5 to 10 minutes, and apply them evenly on the inner surface of the tundish by air spraying, with a thickness of 3 to 5 mm. Curing at room temperature for 24 to 36 hours will obtain a lightweight thermal insulation coating.

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