Tundish with microporous structure for ultra-pure steel smelting

Abstract

The utility model discloses an ultra-pure steel smelting tundish with a micropore structure, which comprises a tundish shell, a heat preservation layer, a permanent layer and a working layer, the heat preservation layer is arranged between the tundish shell and the permanent layer, the working layer with the micropore structure is arranged on the inner surface of the permanent layer, and the micropore structure is arranged on the outer surface of the working layer. The heat preservation layer is of a composite structure composed of a first heat preservation layer and a second heat preservation layer, and the first heat preservation layer and the second heat preservation layer are combined together through a high-temperature binder. According to the tundish, the excellent heat insulation performance of the tundish is improved, the quality of molten steel is guaranteed, meanwhile, the tundish has the effect of adsorbing inclusions in the molten steel, and the cleanliness of the molten steel can be improved.

Description

Technical Field

[0001] The utility model relates to the technical field of continuous casting in iron and steel metallurgy, in particular to a tundish for smelting ultra-pure steel with a microporous structure. Background Art

[0002] As an intermediate link connecting steelmaking and rolling, continuous casting is an important part of a steel plant. With the rapid development of metallurgical technology, higher requirements are put forward for the heat preservation function of the tundish. Stable superheat and good uniformity are the keys to ensuring the stable production efficiency of steelmaking-continuous casting and the quality of cast slabs. Good heat preservation performance of the tundish can not only reduce the tapping temperature of smelting, improve the quality of cast slabs, but also reduce the heat dissipation of the ladle shell and save energy. If the heat preservation performance of the tundish is poor, the temperature drop of the molten steel in the tundish is too fast, and the tapping temperature needs to be increased to meet the production of the continuous caster. Excessive pouring temperature not only aggravates the erosion of the refractory by the slag / molten steel, but also aggravates the secondary oxidation of the molten steel, affecting the quality of the molten steel. Therefore, it is urgent to improve the heat preservation performance of the continuous casting tundish.

[0003] The development of China's iron and steel metallurgy industry is facing huge challenges from quantitative change to qualitative change, and improving the purity of molten steel and controlling the quantity and size of non-metallic inclusions in molten steel are the keys to the development of ultra-pure steel. As the last metallurgical container in the continuous casting process, the tundish provides the last opportunity for the further purification of molten steel.

[0004] Magnesia refractory, as a traditional refractory, has been widely used in parts such as the working layer (lining) of the tundish. It is in direct contact with the molten steel, and magnesite can adsorb non-metallic inclusions in the molten steel through chemical reactions to improve the purity of the molten steel. However, the traditional dense magnesia refractory has a high thermal conductivity and large losses, resulting in waste of energy. If a large number of micropores are formed in the magnesia refractory, its functions of heat preservation and insulation and physical adsorption of non-metallic inclusions in molten steel can be exerted. Based on this, the utility model designs a tundish with heat preservation and insulation and inclusion adsorption functions that can be applied to ultra-pure steel from the perspectives of heat preservation and insulation and adsorption of non-metallic substances in molten steel.

[0005] The prior art, such as a tundish heat preservation structure disclosed in the patent with the authorized publication number CN212664884U and the patent name "A Tundish Heat Preservation Structure", improves the heat insulation performance of the tundish by optimizing the thermal conductivity of the permanent layer and introducing an insulating layer (heat preservation layer), but this utility model does not improve the purity of the molten steel, does not consider the influence of the working layer (lining) on the heat insulation performance and molten steel cleanliness of the tundish, and the insulating layer structure is single. Summary of the Invention

[0006] The purpose of the present utility model is to solve the deficiencies existing in the prior art. The present utility model provides a tundish for ultra-pure steel smelting with a microporous structure, which improves the excellent heat insulation and heat preservation performance of the tundish, ensures the quality of molten steel, and at the same time has the effect of adsorbing inclusions in the molten steel, and can improve the cleanliness of the molten steel.

[0007] In order to achieve the above purpose, the present utility model adopts the following technical solutions:

[0008] A tundish for ultra-pure steel smelting with a microporous structure, including a shell, a heat preservation layer, a permanent layer and a working layer. A heat preservation layer is arranged between the shell and the permanent layer, and a working layer with a microporous structure is arranged on the inner surface of the permanent layer. The heat preservation layer is a composite structure composed of a first heat preservation layer and a second heat preservation layer, and the two are bonded together by a high-temperature binder.

[0009] The present utility model further defines the technical solution:

[0010] Preferably, the first heat preservation layer is an aerogel layer, and the heat preservation layer is a nanoboard layer, wherein the aerogel layer is adjacent to the shell, and the nanoboard layer is adjacent to the permanent layer.

[0011] Preferably, the first heat preservation layer and the second heat preservation layer have the same thickness, both being 5-10 mm.

[0012] Preferably, the permanent layer is a lightweight brick made of corundum-mullite material, and its thickness is 80-160 mm.

[0013] Preferably, the working layer is made of magnesia refractory material, with a thickness of 60-100 mm. The internal micropores are circular or elliptical pores with a size of 5-100 μm, which can adsorb non-metallic inclusions with a size of several microns in the molten steel, and improve the cleanliness of the molten steel.

[0014] Compared with the prior art, the beneficial effects of the present utility model are:

[0015] The heat preservation layer of the present utility model is composed of a first heat preservation layer and a second heat preservation layer made of two materials with different thermal conductivities. The first heat preservation layer close to the shell is aerogel, and the second heat preservation layer close to the permanent layer is a nanoboard layer. The combination of the two can significantly reduce the temperature in the continuous casting and steel pouring work area, improve the working environment of continuous casting, avoid the time of heatstroke of workers in summer, and at the same time reduce the surface temperature of the shell and improve its service life;

[0016] The permanent layer of the present utility model is a lightweight brick made of corundum-mullite material with a thermal conductivity less than 0.20 W / (m·K), which replaces the traditional high-alumina castable with a thermal conductivity less than 0.62 W / (m·K). It not only significantly improves the heat preservation performance of the tundish, but also can reduce the thickness of the permanent layer, increase the capacity of the tundish, and the low linear change rate of re-firing ensures the safety of use;

[0017] The utility model adopts a magnesia refractory with a microporous structure as the working layer. Compared with the traditional dense magnesia refractory, its thermal conductivity at 1000°C has decreased by more than half, significantly improving the heat preservation effect of the tundish. Moreover, the proportion of pores smaller than 20μm in the microporous magnesia refractory is significantly higher than that in the dense magnesia refractory. The microporous magnesia refractory has regular shapes and uniform distributions. The magnesia working layer with a microporous structure can physically and chemically adsorb micron-sized non-metallic inclusions at the steel nozzle, reducing non-metallic inclusions smaller than 5μm in the molten steel and significantly improving the cleanliness of the molten steel. Description of the Drawings

[0018] Figure 1 It is a schematic structural diagram of the utility model. Detailed Embodiments

[0019] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described in conjunction with the drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all of the embodiments. Embodiment

[0020] Referring to Figure 1 , a tundish for ultra-pure steel smelting with a microporous structure includes a shell 1, a heat preservation layer, a permanent layer 4, and a working layer 5. The permanent layer is a lightweight brick made of corundum-mullite, with a thickness of 80mm, a thermal conductivity of 0.18 W / (m·K), and a linear change rate of re-firing of 1.2%. The working layer is made of magnesia refractory, with a thickness of 80mm and a thermal conductivity of 0.95 W / (m·K). A heat preservation layer is provided between the shell and the permanent layer. The permanent layer is a lightweight brick, which is combined with the heat preservation layer by masonry. A working layer with a microporous structure is provided on the inner surface of the permanent layer. The working layer is adhered to the inner surface of the permanent layer by applying an adhesive. The internal micropores of the working layer are circular or elliptical pores with a size of 35μm, which can adsorb non-metallic inclusions with a size of several microns at the steel nozzle of the molten steel and improve the cleanliness of the molten steel;

[0021] The heat preservation layer is a composite structure composed of a first heat preservation layer 3 and a second heat preservation layer 4. The two are the same, both with a thickness of 10mm, and they are combined together by a high-temperature binder. The first heat preservation layer is an aerogel layer, and the heat preservation layer is a nanoboard layer, with thermal conductivities of 0.019W / (m·K) and 0.04W / (m·K) respectively. The aerogel layer is adjacent to the shell, and the nanoboard layer is adjacent to the permanent layer.

[0022] The thermal insulation layer of this embodiment is composed of two materials with different thermal conductivities, namely thermal insulation layer one and thermal insulation layer two. Thermal insulation layer one, which is in close contact with the cladding, is aerogel, and thermal insulation layer two, which is in close contact with the permanent layer, is a nanoblate layer. The combination of the two can significantly reduce the temperature in the continuous casting steel pouring work area, improve the working environment of continuous casting, avoid the heatstroke time of staff in summer, and at the same time reduce the problems on the surface of the cladding and improve its service life;

[0023] The permanent layer of this embodiment is a lightweight corundum-mullite brick with a thermal conductivity less than 0.20 W / (m·K). It replaces the traditional high-alumina castable with a thermal conductivity less than 0.62 W / (m·K), which not only significantly improves the thermal insulation performance of the tundish, but also reduces the thickness of the permanent layer, increases the capacity of the tundish, and the low linear change rate of re-firing ensures the safety of use;

[0024] This embodiment uses a magnesia refractory with a microporous structure as the working layer. Compared with the traditional dense magnesia refractory, its thermal conductivity at 1000 °C has decreased by more than one time, significantly improving the thermal insulation effect of the tundish. Moreover, the proportion of pores less than 20 μm in the microporous magnesia refractory is significantly higher than that in the dense magnesia refractory, and the shape of the microporous magnesia refractory is regular and evenly distributed. And the magnesia working layer with a microporous structure can adsorb micron-sized non-metallic inclusions at the steel nozzle physically and chemically, reducing non-metallic inclusions in the molten steel with a size less than 5 μm, and significantly improving the cleanliness of the molten steel.

[0025] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "coaxial", "bottom", "one end", "top", "middle", "the other end", "upper", "one side", "top", "inner", "front", "center", "both ends", etc. are based on the orientation or positional relationships shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, so it cannot be understood as a limitation to the present invention.

[0026] The above is only the preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. A tundish for ultrapure steel smelting with a microporous structure, comprising a cladding, an insulation layer, a permanent layer and a working layer, characterized in that: An insulation layer is arranged between the cladding and the permanent layer, a working layer with a microporous structure is arranged on the inner surface of the permanent layer, and the insulation layer is a composite structure consisting of an insulation layer 1 and an insulation layer 2, which are bonded together by a high-temperature adhesive.

2. The tundish for smelting ultrapure steel with a microporous structure according to claim 1, characterized in that: The first thermal insulation layer is an aerogel layer, and the thermal insulation layer is a nanoplate layer, wherein the aerogel layer is adjacent to the shell, and the nanoplate layer is adjacent to the permanent layer.

3. The tundish for smelting ultrapure steel with a microporous structure according to claim 2, characterized in that: The thickness of the first insulation layer and the second insulation layer is the same, both of which are 5-10 mm.

4. The tundish for smelting ultrapure steel with a microporous structure according to claim 1, characterized in that: The permanent layer is a light brick made of corundum-mullite and has a thickness of 80-160 mm.

5. The tundish for smelting ultrapure steel with a microporous structure according to claim 1, characterized in that: The working layer is made of magnesia refractory material with a thickness of 60-100 mm, and its internal micropores are round or elliptical pores with a diameter of 5-100 μm.

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