A dry material for a tundish for high-quality steel

Abstract

The application provides a tundish dry material for high-quality steel, and relates to the technical field of unshaped refractory materials.The tundish dry material for high-quality steel comprises the following raw materials in parts by mass: magnesia 80-117 parts, composite binder 2-5 parts and additive 0.5-5 parts; the composite binder is polyglucose, polycarboxylic acid and sorbitol.The tundish dry material for high-quality steel prepared by compounding magnesia, composite binder and additive is environment-friendly, and the raw materials are easy to obtain and have low cost; the slag line part of the tundish can significantly improve the service life of the product and reduce environmental pollution.According to the results of the examples, the tundish dry material for high-quality steel provided by the application has MgO content of 90wt.% or more, SiO2 content of 2.5wt.% or less, excellent low-temperature and high-temperature bending and compression strength, and does not produce irritating gas during baking, and is environment-friendly.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of unshaped refractory, and particularly relates to a tundish dry mix for high-quality steel. BACKGROUND

[0002] The dry mix belongs to one of unshaped refractory, and has been widely used as working lining of tundish in recent years due to its long service life, simple process and high work efficiency. The dry mix in the prior art mainly uses alkaline magnesia material and a binder as raw materials, and forms a working layer through vibration and baking, which is used to resist the erosion, scouring and penetration of molten steel / steel slag.

[0003] In the prior art, the commonly used binder in the dry mix includes phenolic resin, rosin, monosaccharide (such as glucose and fructose), disaccharide (such as sucrose), sodium silicate and boric acid. Among them, phenolic resin and glucose are the most common. Phenolic resin has been widely used in various dry mixes, but it is expensive and releases a large amount of irritating gases (such as formaldehyde, phenol and ammonia) during baking, which is harmful to the environment and human health. Although glucose can replace phenolic resin to some extent as an environmentally friendly binder, its bending and compressive strength is much lower than that of phenolic resin under the same amount of addition, so its amount of addition is usually 5-8% in actual use, which limits the adjustment space of the tundish dry mix for high-quality steel to some extent.

[0004] In addition, the production of high-quality steel in the prior art needs to strictly control each link, and requires that the MgO content in the tundish dry mix for high-quality steel is greater than or equal to 90wt%, and the SiO2 content is less than or equal to 2.5wt%. SUMMARY

[0005] The present application aims to provide a tundish dry mix for high-quality steel, which has a MgO content of greater than or equal to 90wt%, a SiO2 content of less than or equal to 2.5wt%, and is environmentally friendly.

[0006] In order to achieve the purpose of the present application, the present application provides the following technical solutions:

[0007] A tundish dry mix for high-quality steel, according to the mass fraction, comprises the following raw materials: magnesia 80-117 parts, composite binder 2-5 parts and additive 0.5-5 parts; the composite binder is polyglucose, polycarboxylic acid and sorbitol.

[0008] Preferably, the polycarboxylic acid includes one or more of citric acid, tartaric acid, oxalic acid, ethylenediaminetetraacetic acid and fumaric acid.

[0009] Preferably, the mass ratio of polyglucose, polycarboxylic acid and sorbitol is 25-35:1-5:0.5-3.

[0010] Preferably, the magnesia includes sintered magnesia and fused magnesia; the mass ratio of the magnesia including sintered magnesia and fused magnesia is 5-15:75-92.

[0011] Preferably, the MgO content in the sintered magnesia is ≥95wt.%, and the SiO2 content is ≤2.2wt.%; the MgO content in the fused magnesia is ≥94wt.%, and the SiO2 content is ≤2.0wt.%.

[0012] Preferably, the gradation of the sintered magnesia and the fused magnesia is independently as follows: the particle size of 3-5mm accounts for 8-14%, the particle size of 1-3mm accounts for 20-30%, the particle size of 0.074-1mm accounts for 25-35%, and the particle size of <0.074mm accounts for 20-35%.

[0013] Preferably, the additive is one or more of borax, aluminum powder, magnesium sulfate and boron carbide.

[0014] Preferably, the MgO content in the intermediate ladle dry material for high-quality steel is ≥90wt.%, and the SiO2 content is ≤2.5wt.%.

[0015] The present application provides an intermediate ladle dry material for high-quality steel, which comprises the following preparation raw materials in mass fraction: 80-117 parts of magnesia, 2-5 parts of composite binder and 0.5-5 parts of additive; the composite binder is polydextrose, polycarboxylic acid and sorbitol. The intermediate ladle dry material for high-quality steel prepared by compounding magnesia, composite binder and additive is environment-friendly, and the preparation raw materials are easy to obtain and have lower cost; the slag line part of the intermediate ladle can significantly improve the product life and reduce environmental pollution. According to the results of the examples, the MgO content in the intermediate ladle dry material for high-quality steel provided by the present application is ≥90wt.%, and the SiO2 content is ≤2.5wt.%; at the same time, the material has excellent low-temperature and high-temperature bending and compressive strength, does not produce irritating gas during baking, is environment-friendly, and has the advantage of being more environmentally friendly. DETAILED DESCRIPTION

[0016] The present application provides an intermediate ladle dry material for high-quality steel, which comprises the following preparation raw materials in mass fraction: 80-117 parts of magnesia, 2-5 parts of composite binder and 0.5-5 parts of additive; the composite binder is polydextrose, polycarboxylic acid and sorbitol.

[0017] In the present application, all the preparation raw materials are preferably commercially available products well known to those skilled in the art, unless otherwise specified.

[0018] In the present application, the preparation raw material of the high-quality steel tundish dry material preferably comprises 80-117 parts of magnesia, more preferably 94-96 parts, and further preferably 95-95.5 parts, in terms of mass fraction. In the present application, the magnesia preferably comprises sintered magnesia and fused magnesia. In the present application, the mass ratio of the sintered magnesia and the fused magnesia is preferably 5-15:75-92, more preferably 8-14:81-86, further preferably 10-13:82-85.5, and most preferably 12:84. In the present application, the content of MgO in the sintered magnesia is preferably ≥ 95 wt.%, and the content of SiO2 is preferably ≤ 2.2 wt.%. In the present application, the content of MgO in the fused magnesia is preferably ≥ 94 wt.%, and the content of SiO2 is preferably ≤ 2.0 wt.%. In the present application, the independent gradation of the sintered magnesia and the fused magnesia is preferably 3-5 mm: 5-15%, 1-3 mm: 20-30%, 0.074-1 mm: 25-35%, and <0.074 mm: 20-35%; and more preferably 3-5 mm: 10-13%, 1-3 mm: 25-30%, 0.074-1 mm: 25-30%, and <0.074 mm: 22-30%. In the present application, the magnesia has the effect of resisting erosion and scouring of molten steel as an aggregate, and improving the high-temperature stability of the high-quality steel tundish dry material. Moreover, the present application selects the sintered magnesia and the fused magnesia with the above-mentioned contents of MgO and SiO2, which is conducive to reducing the preparation cost of the high-quality steel tundish dry material.

[0019] In the present application, the preparation raw material of the high-quality steel tundish dry material preferably comprises 2-5 parts of a composite binder, more preferably 3-4 parts, and further preferably 3.5 parts, in terms of mass fraction of magnesia. In the present application, the composite binder is polydextrose, polycarboxylic acid, and sorbitol. In the present application, the polycarboxylic acid preferably comprises one or more of citric acid, tartaric acid, oxalic acid, ethylenediaminetetraacetic acid, and fumaric acid, and more preferably tartaric acid. In the present application, the mass ratio of the polydextrose, the polycarboxylic acid, and the sorbitol is preferably 25-35:1-5:0.5-3, and more preferably 30:3:1. In the present application, the composite binder has the effect of improving the bending strength and the compressive strength.

[0020] In the present application, the preparation raw material of the tundish dry mix for high-quality steel preferably comprises 0.5-5 parts of additives, more preferably 1-2.5 parts, and further preferably 1.5 parts, based on the mass fraction of magnesia. In the present application, the additives are preferably one or more of borax, aluminum powder, magnesium sulfate and boron carbide, and more preferably aluminum powder. In the present application, the gradation of the aluminum powder is preferably 50% by mass of particle size 0.045-0.075 mm and 50% by mass of particle size <0.045 mm. In the present application, the additives have the effect of adjusting the high-temperature strength and erosion resistance of the dry mix.

[0021] In the present application, the MgO content in the tundish dry mix for high-quality steel is preferably ≥90 wt.%, more preferably 90.16-91.35 wt.%, and further preferably 90.50 wt.%, 90.75 wt.% or 91.13 wt.%; and the SiO2 content is preferably ≤2.5 wt.%, more preferably 1.74-2.40 wt.%, and further preferably 2.09 wt.%, 2.26 wt.% or 2.38 wt.%.

[0022] The present application does not have special limitations on the preparation method of the tundish dry mix for high-quality steel described in the above technical solution, and a preparation method well known to those skilled in the art can be used. In the present application, the magnesia, composite binder and additives are mixed to obtain the tundish dry mix for high-quality steel.

[0023] In order to further illustrate the present application, the tundish dry mix for high-quality steel provided by the present application is described in detail below in conjunction with examples, but they should not be understood as limiting the scope of protection of the present application.

[0024] The sources and parameters of the preparation raw materials in the following examples and comparative examples of the present application are as follows:

[0025] Sintered magnesia: particle size 3-5 mm; MgO content ≥95 wt.%, SiO2 content ≤2.2 wt.%;

[0026] Fused magnesia: particle size 1-3 mm, 0.074-1 mm and <0.074 mm; MgO content ≥94 wt.%, SiO2 content ≤2.0 wt.%;

[0027] Aluminum powder: continuous gradation 50% by mass of particle size 0.045-0.075 mm and 50% by mass of particle size <0.045 mm.

[0028] Example 1

[0029] Sintered magnesia 8 kg, fused magnesia 86 kg, composite binder 3.5 kg (3.1 kg of polyglucose, 0.3 kg of tartaric acid and 0.1 kg of sorbitol) and aluminum powder 2.5 kg were weighed and mixed to obtain the tundish dry mix for high-quality steel.

[0030] Example 2

[0031] Sintered magnesia 10 kg, fused magnesia 85.5 kg, composite binder 3.5 kg (3.1 kg of polyglucose, 0.3 kg of tartaric acid and 0.1 kg of sorbitol) and aluminum powder 1 kg were weighed and mixed to obtain the tundish dry mix for high-quality steel.

[0032] Example 3

[0033] Sintered magnesia 12 kg, fused magnesia 84 kg, composite binder 3.5 kg (3.1 kg of polyglucose, 0.3 kg of tartaric acid and 0.1 kg of sorbitol) and aluminum powder 0.5 kg were weighed and mixed to obtain the tundish dry mix for high-quality steel.

[0034] Example 4

[0035] Sintered magnesia 14 kg, fused magnesia 81 kg, composite binder 3.5 kg (3.1 kg of polyglucose, 0.3 kg of tartaric acid and 0.1 kg of sorbitol) and aluminum powder 1.5 kg were weighed and mixed to obtain the tundish dry mix for high-quality steel.

[0036] Example 5

[0037] Sintered magnesia 13 kg, fused magnesia 82 kg, composite binder 3.5 kg (3.1 kg of polyglucose, 0.3 kg of tartaric acid and 0.1 kg of sorbitol) and aluminum powder 1.5 kg were weighed and mixed to obtain the tundish dry mix for high-quality steel.

[0038] Comparative Example 1

[0039] Sintered magnesia 10 kg, fused magnesia 85.5 kg, glucose 3.5 kg and aluminum powder 1 kg were weighed and mixed to obtain the tundish dry mix for high-quality steel.

[0040] Comparative Example 2

[0041] Sintered magnesia 10 kg, fused magnesia 85.5 kg, composite binder (3.1 kg and 0.4 kg) 3.5 kg and aluminum powder 1 kg were weighed and mixed to obtain the tundish dry mix for high-quality steel.

[0042] Test Example 1

[0043] The chemical components of the tundish dry mix for high-quality steel according to Examples 1-5 and Comparative Example 1 were detected according to GB-T21114-2019 "X-ray fluorescence spectrometric chemical analysis of refractories - Melting and casting glass flake method", and the detection results are shown in Table 1.

[0044] Table 1: Detection results of chemical components of tundish dry mix for high-quality steel according to Examples 1-5 and Comparative Example 1

[0045]

[0046] As can be seen from the results in Table 1, the MgO content of the tundish dry mix for high-quality steel provided by the present application is ≥ 90 wt.%, and the SiO2 content is ≤ 2.5 wt.%.

[0047] Test Example 2

[0048] The tundish dry mix for high-quality steel according to Examples 1-5 and Comparative Example 1 was baked at 200℃ for 3h and at 1500℃ for 3h, respectively, and the bending strength, compressive strength and linear change rate were tested, and the test results are shown in Table 2.

[0049] Table 2: Test results of mechanical properties of tundish dry mix for high-quality steel according to Examples 1-5 and Comparative Example 1

[0050]

[0051] As can be seen from the results in Table 2, after baking at 200℃, the bending strength and compressive strength of the tundish dry mix for high-quality steel according to the present application are significantly higher than those of the tundish dry mix for high-quality steel according to Comparative Example 1. After baking at 1500℃ for 3h, the bending strength and compressive strength of the tundish dry mix for high-quality steel according to the present application do not change significantly, and the linear change rate of the tundish dry mix for high-quality steel according to the present application is -0.6 to -0.4%, which proves that the addition of the composite binder in the present application does not affect the thermal expansion coefficient of the tundish dry mix for high-quality steel, and the tundish dry mix for high-quality steel according to the present application has excellent low-temperature strength, high-temperature strength and stable linear change rate. Compared with the glucose binder, the present application reduces the addition amount of the composite binder by 4%, which can add more magnesia or additives, and has more free addition amount selection, so as to greatly reduce the purity requirement of magnesia, thereby reducing the cost. Compared with the phenolic resin binder, the composite binder used in the present application has lower cost, and does not produce irritating gas during baking, which is more environmentally friendly.

[0052] Although the above examples have made a detailed description of the present application, it is only a part of the examples of the present application, not all examples, and other examples can be obtained under the premise of no creativity according to the present examples, which all belong to the protection scope of the present application.

Claims

1. A high-quality steel tundish dry-mix material, characterized in that, The raw materials prepared by weight are: 80-117 parts of magnesia, 2-5 parts of composite binder and 0.5-5 parts of additives; the composite binder is polydextrose, polycarboxylic acid and sorbitol. The mass ratio of the polydextrose, polycarboxylic acid and sorbitol is 25-35:1-5:0.5-3.

2. The high-quality steel tundish dry feed according to claim 1, characterized in that, The polycarboxylic acids include one or more of citric acid, tartaric acid, oxalic acid, ethylenediaminetetraacetic acid, and fumaric acid.

3. The high-quality steel tundish dry feed according to claim 1, characterized in that, The magnesia includes sintered magnesia and fused magnesia; the mass ratio of sintered magnesia to fused magnesia is 5-15:75-92.

4. The high-quality steel tundish dry feed according to claim 3, characterized in that, The sintered magnesia contains MgO content ≥ 95 wt.% and SiO2 content ≤ 0.2 wt.%; the fused magnesia contains MgO content ≥ 94 wt.% and SiO2 content ≤ 2.0 wt.%.

5. The high-quality steel tundish dry feed according to claim 3, characterized in that, The sintered magnesia and fused magnesia are independently graded as follows: 5-15% for particles with a diameter of 3-5 mm, 20-30% for particles with a diameter of 1-3 mm, 25-35% for particles with a diameter of 0.074-1 mm, and 20-35% for particles with a diameter <0.074 mm.

6. The high-quality steel tundish dry feed according to claim 1, characterized in that, The additive is one or more of borax, aluminum powder, magnesium sulfate, and boron carbide.

7. The high-quality steel tundish dry feed according to claim 1, characterized in that, The high-quality steel tundish dry feed contains MgO content ≥90wt.% and SiO2 content ≤2.5wt.%.

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