Self-flowing tundish working lining dry material, tundish working lining and preparation method thereof

Abstract

The application provides a self-flowing tundish working lining dry material, a tundish working lining and a preparation method thereof. The self-flowing tundish working lining dry material is prepared from the following components in parts by mass: 83-90 parts of fine powder with a particle size of 0.075-0.5 mm, 5 parts of fine powder with a particle size of less than 0.044 mm, 4-9 parts of a composite binding agent and 1-3 parts of a sintering agent; wherein the fine powder is at least one of forsterite, magnesia-calcia sand, magnesia and quartz sand. The self-flowing tundish working lining dry material has the advantages of low bulk density, low thermal conductivity, self-flowing forming, no harmful irritating gas and high environmental protection.

Description

Technical Field

[0001] The invention belongs to the technical field of refractory materials, and in particular relates to a gravity-flow tundish working lining dry material, a tundish working lining and a preparation method thereof. Background Art

[0002] Since its introduction in the 1990s, dry vibrating materials have attracted widespread attention, combining the advantages of both insulation panels and spray coatings. Tundish dry vibrating materials are available in two types: magnesium and magnesium-calcium. Because dry vibrating materials utilize a waterless construction method, they are particularly advantageous for magnesium-calcium materials, avoiding direct contact with water and minimizing hydration. The working layer of dry vibrating material in the tundish can increase the service life of the working lining and reduce the contamination of refractory materials to the molten steel; it is easy to turn over and remove the tundish, and the density of the unsintered layer is low, which is beneficial to the insulation of the tundish; it is easy to construct, and due to waterless construction, it can be quickly baked and used directly, which increases the utilization rate of the tundish, extends the service life of the tundish, and thus reduces the number of spare tundishes; since the dry vibrating material does not contain moisture, it can reduce the chance of secondary oxidation of the molten steel in the tundish, reduce the hydrogen absorption of the molten steel, and improve the quality of the steel billet; compared with the smear material, the use of dry vibrating material can reduce the energy consumption during the baking of the tundish, reduce labor intensity, and improve labor productivity; the construction equipment is simple and the construction is convenient; the service life of the dry vibrating material is long, generally up to 20 hours or more, and up to 100 hours, which greatly improves the labor productivity of the steelmaking process.

[0003] Chinese patent document CN106083092B discloses a low-cost dry ladle material with good resistance to steel slag permeability and a method for preparing the same. The raw materials of the dry ladle include 30-40% sintered magnesia or fused sand with a particle size of 3.2-1mm, 30-45% sintered magnesia or fused sand with a particle size of ≤1mm, 25-35% sintered magnesia or fused sand with a particle size of 200 mesh, 0-5% quartz sand with a particle size of 1-0.12mm, 0-8% quartz sand with a particle size of ≤0.12mm, 0-3% phenolic resin, 2-5% modified phenolic resin, 2-6% magnesium sulfate heptahydrate, and 0-0.6% boric acid. Chinese patent document CN112624749A discloses a low-cost tundish dry material and its preparation method. The raw materials include 1-3 parts of olive sand with a particle size of 0mm < ≤ 1mm, 2-4 parts of olive sand with a particle size of 1mm < ≤ 3mm, 2-5 parts of olive sand with a particle size of 3mm < ≤ 5mm, 2-5 parts of dead-burned magnesia, 0.5-3 parts of binder, and 0.5-3 parts of T-L011.

[0004] However, currently, dry tundish materials have poor fluidity and a high bulk density, requiring 10-20 minutes of vibration during construction, resulting in high energy consumption. Furthermore, dry tundish materials have high thermal conductivity and poor insulation properties, which together contribute to high refractory steel consumption per ton. Furthermore, the most widely used and effective binder for dry tundish materials is thermoplastic phenolic resin. The residual fixed carbon in phenolic resin causes carbon accumulation in the molten steel, impacting the performance of ultra-low carbon steel grades such as automotive sheet steel. Carbon-containing materials have high thermal conductivity, hindering tundish insulation. The free phenols generated and the resulting gases combine to form fumes with a pungent odor, posing a certain degree of harm to on-site construction workers and the environment. Furthermore, phenolic resins are currently very expensive, significantly increasing production costs. Summary of the Invention

[0005] The technical problem solved by the present invention is to provide a dry material for a self-flowing tundish working lining, a tundish working lining and a preparation method thereof. The dry material has the advantages of low bulk density, low thermal conductivity, self-flow molding, no generation of harmful irritating gases, and strong environmental protection.

[0006] In order to solve the above problems, the first aspect of the present invention provides a dry material for a self-flowing tundish working lining, wherein the raw materials for preparing the dry material include the following components calculated by weight:

[0007] 83-90 parts of fine powder with a particle size of 0.075-0.5mm, 5 parts of fine powder with a particle size less than 0.044mm, 4-9 parts of composite binder, and 1-3 parts of sintering agent;

[0008] Wherein, the fine powder is at least one of forsterite, magnesia calcium sand, magnesia sand and quartz sand.

[0009] Preferably, the raw materials for its preparation include the following components:

[0010] 15-35 parts of fine powder with a particle size of 0.25-0.5mm, 48-75 parts of fine powder with a particle size of 0.075-0.25mm, 5 parts of fine powder with a particle size less than 0.044mm, 4-9 parts of composite binder, and 1-3 parts of sintering agent.

[0011] Preferably, the composite binder comprises an organic binder and an inorganic binder; the organic binder is anhydrous glucose; the inorganic binder is magnesium chloride; and the mass ratio of the organic binder to the inorganic binder is 1:1.2-2.

[0012] Preferably, the mass ratio of the organic binder to the inorganic binder is 1:1.2.

[0013] Preferably, the sintering agent is a combination of at least two of sodium hexametaphosphate, sodium tripolyphosphate, Guangxi white mud, boric acid, glass powder, bentonite, and iron red.

[0014] Preferably, the sintering agent is a combination of sodium hexametaphosphate and boric acid, and the mass ratio of sodium hexametaphosphate to boric acid is 1:3.2-3.6.

[0015] Preferably, the mass ratio of sodium hexametaphosphate to boric acid in the sintering agent is 1:3.4.

[0016] The second aspect of the present application provides a tundish working lining prepared from the self-flowing tundish working lining dry material described above.

[0017] The third aspect of the present application provides a preparation method of the tundish working lining described above, comprising the following steps:

[0018] S1. mixing the fine powder, the composite binder and the sintering agent in different particle sizes according to selected mass fractions to obtain the self-flowing tundish working lining dry material;

[0019] S2. shaping and baking the self-flowing tundish working lining dry material to obtain the tundish working lining.

[0020] Preferably, step S1 specifically comprises:

[0021] first, premixing the composite binder according to selected mass fractions for 2-3 min and packing for standby; then, mixing the fine powder in different particle sizes for 1-2 min; and then, adding the composite binder and the sintering agent to the fine powder and mixing for 5-6 min to obtain the self-flowing tundish working lining dry material;

[0022] Step S2 specifically comprises:

[0023] pouring the self-flowing tundish working lining dry material between the outer wall of the tundish mold and the tundish permanent lining, without vibration or ramming, self-flowing forming, baking at a temperature of 200-400℃ for 1-2 h, and obtaining the tundish working lining after demolding.

[0024] Compared with the prior art, the present application has the following beneficial effects:

[0025] The dry material for the self-flowing tundish working lining of the application uses forsterite or magnesia-calcia sand or magnesia sand or quartz sand as the main raw material, and the main raw material is all fine powder with a particle size of 0.5 mm or less, which is obtained by screening after crushing the raw material bulk by a jaw crusher and other crushing equipment, has a small particle size, a good shape, no needle-shaped or flaky particles, and no relatively prominent edges and corners. Since there is no relatively large particle raw material in the dry material, the main raw material is all fine powder with a particle size of less than 0.5 mm, and the fine powder has a smoother shape than the relatively large particles, the rest angle of the dry material can be reduced, and the fluidity thereof is improved. The dry material can be self-flowing formed without vibration or ramming during construction, and a large amount of energy consumption can be saved. Moreover, since the relatively small fine powder raw material is used, the dry material has a lower bulk density and a lower thermal conductivity, the refractory ton steel consumption can be reduced, and the heat preservation performance of the dry material is improved.

[0026] The fixed carbon of the conventional binder thermoplastic phenolic resin residue can cause the problem of carbonization of molten steel, the carbon-containing substance has a high thermal conductivity, which is not conducive to the heat preservation of the tundish, and the flue gas with irritating odor is easy to be generated. The dry material for the self-flowing tundish working lining of the application uses the non-toxic and harmless organic binder and the inorganic binder to replace the traditional binder phenolic resin, which has the advantages of green environmental protection, low price and the like. DETAILED DESCRIPTION

[0027] The technical solutions of the application will be described clearly and completely in combination with the embodiments of the application. Obviously, the described embodiments are only some of the embodiments of the application, but not all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the application.

[0028] The first aspect of the embodiment of the application provides a dry material for a self-flowing tundish working lining, and the preparation raw material thereof includes the following components in terms of mass fraction:

[0029] 83-90 parts of fine powder with a particle size of 0.075-0.5 mm, 5 parts of fine powder with a particle size of less than 0.044 mm, 4-9 parts of composite binder, and 1-3 parts of sintering agent.

[0030] The fine powder is at least one of forsterite, magnesia-calcia sand, magnesia sand and quartz sand.

[0031] The dry material for the self-flowing tundish working lining of the embodiment of the present application uses forsterite or magnesia-calcia sand or magnesia sand or quartz sand as the main raw material, and the main raw material all uses fine powder with a particle size of 0.5 mm or less, which is obtained by screening after crushing the large blocks of raw material by a jaw crusher and other crushing equipment, has a small particle size, a good shape, no needle-shaped and flaky particles, and no relatively prominent edges and corners. Since the dry material does not have relatively large particle raw materials, the main raw material is all fine powder with a particle size of less than 0.5 mm, and the fine powder has a smoother shape than the relatively large particles, the repose angle of the dry material can be reduced, and the flowability thereof is improved. The dry material for the self-flowing tundish working lining can be self-flowing formed without vibration or ramming during construction, and a large amount of energy consumption can be saved. Moreover, since the relatively small fine powder raw material is used, the dry material has a lower bulk density and a lower thermal conductivity, the refractory ton steel consumption can be reduced, and the heat preservation performance of the dry material is improved.

[0032] In some embodiments, the raw material comprises the following components:

[0033] 15-35 parts of fine powder with a particle size of 0.25-0.5 mm, 48-75 parts of fine powder with a particle size of 0.075-0.25 mm, 5 parts of fine powder with a particle size of less than 0.044 mm, 4-9 parts of composite binder, and 1-3 parts of sintering agent.

[0034] The dry material for the self-flowing tundish working lining of the embodiment of the present application further regulates the proportion of the fine powder with different particle sizes, so that the bulk density of the dry material for the self-flowing tundish working lining is reduced, the strength performance is not affected, and the dry material has a suitable bulk density, a high material strength, a high thermal conductivity, and a high slag penetration resistance. Through field tests on the above-optimized formula, and focusing on the influence of the dry material on the ultra-low carbon automobile plate steel of a steel plant, the increase of the carbon content of the molten steel in the continuous casting tundish link is not more than 5 ppm, and basically reaches the level of the coating material.

[0035] The 0.25-0.5 mm fine powder contains 0.5 mm fine powder and does not contain 0.25 mm fine powder; and the 0.075-0.25 mm fine powder contains 0.25 mm fine powder and does not contain 0.075 mm fine powder.

[0036] In some embodiments, the composite binder comprises an organic binder and an inorganic binder. The residual fixed carbon of the conventional binder, i.e. thermoplastic phenolic resin, can cause the problem of increasing the carbon content of the molten steel, and the carbon-containing substance has a high thermal conductivity, which is not conducive to the heat preservation of the tundish, and is also easy to produce irritating smoke. The dry material for the self-flowing tundish working lining of the embodiment of the present application uses the non-toxic and harmless organic binder and the inorganic binder to replace the traditional binder, i.e. phenolic resin, which has the advantages of green environmental protection and low price, and can give the material good demolding strength without producing irritating gases such as phenol and formaldehyde during the baking process.

[0037] In some embodiments, the organic binder is anhydrous glucose; and the inorganic binder is magnesium chloride. The organic binder generally has higher debinding strength, and the lining surface has better flatness and smoothness than the organic binder. However, the strength of the organic binder decreases more after decarburization and oxidation. The inorganic binder can form a ceramic bond at medium temperature, which can compensate for the low medium temperature strength of the organic binder. The combination of the two binders can meet the strength requirements of the dry material at different temperature stages. Preferably, the mass ratio of the organic binder to the inorganic binder is 1:1.2-2. Further preferably, the mass ratio of the organic binder to the inorganic binder is 1:1.2.

[0038] In some embodiments, the sintering agent is a combination of at least two of sodium hexametaphosphate, sodium tripolyphosphate, Guangxi white mud, boric acid, glass powder, bentonite, and iron red. Different sintering agents are used in combination according to their melting points or softening temperatures, so that the dry material can be gradually sintered during the heating process, absorbing part of the refractory high-temperature expansion stress, while avoiding the concentrated generation of a large amount of liquid phase when using a single sintering agent, which affects the high-temperature creep performance.

[0039] Preferably, the sintering agent is a combination of sodium hexametaphosphate and boric acid, and the mass ratio of sodium hexametaphosphate to boric acid is 1:3.2-3.6. Further preferably, the mass ratio of sodium hexametaphosphate to boric acid in the sintering agent is 1:3.4.

[0040] The second aspect of the embodiment of the present application provides a tundish working lining prepared from the self-flowing tundish working lining dry material described above.

[0041] The third aspect of the embodiment of the present application provides a preparation method of the tundish working lining described above, which comprises the following steps:

[0042] S1. Mixing the fine powder, the composite binder, and the sintering agent in different particle sizes according to selected mass fractions to obtain the self-flowing tundish working lining dry material;

[0043] S2. Shaping and baking the self-flowing tundish working lining dry material to obtain the tundish working lining.

[0044] In some embodiments, step S1 specifically comprises:

[0045] First, the composite binder is premixed for 2-3 minutes according to selected mass fractions, and is ready for use; then, the fine powder in different particle sizes is mixed for 1-2 minutes; and then, the composite binder and the sintering agent are added to the fine powder and mixed for 5-6 minutes to obtain the self-flowing tundish working lining dry material;

[0046] Step S2 specifically comprises:

[0047] The self-flowing tundish working lining dry material is poured between the tundish mold outer wall and the tundish permanent lining, without vibration or ramming, self-flowing forming, baking at a temperature of 200-400°C for 1-2h, and the tundish working lining is obtained after demolding.

[0048] Example 1

[0049] The self-flowing tundish working lining dry material of the present example, in terms of mass fraction, comprises the following components:

[0050] Fine powder: 15 parts of forsterite with a particle size of 0.25-0.5mm, 74 parts of forsterite with a particle size of 0.075-0.25mm, and 5 parts of magnesite with a particle size of ≤0.044mm.

[0051] Composite binder: 2 parts of magnesium chloride and 2 parts of anhydrous glucose. Sintering agent: 0.47 parts of sodium hexametaphosphate and 1.53 parts of boric acid.

[0052] The preparation method of the tundish working lining of the present example comprises the following steps:

[0053] S1. The composite binder is premixed for 2min according to the above mass fraction, and is ready for use after being packed; the fine powders with different particle sizes are mixed for 2min; and then the composite binder and the sintering agent are added to the fine powders and mixed for 5min to obtain the self-flowing tundish working lining dry material;

[0054] S2. The self-flowing tundish working lining dry material is poured between the tundish mold outer wall and the tundish permanent lining, without vibration or ramming, self-flowing forming, baking at a temperature of 200°C for 1h, and the tundish working lining is obtained after demolding.

[0055] Example 2

[0056] The self-flowing tundish working lining dry material of the present example, in terms of mass fraction, comprises the following components:

[0057] Fine powder: 20 parts of magnesia-calcium sand with a particle size of 0.25-0.5mm, 69 parts of magnesia-calcium sand with a particle size of 0.075-0.25mm, and 5 parts of magnesite with a particle size of ≤0.044mm.

[0058] Composite binder: 2 parts of magnesium chloride and 3 parts of anhydrous glucose. Sintering agent: 0.22 parts of sodium hexametaphosphate and 0.78 parts of boric acid.

[0059] The preparation method of the tundish working lining of the present example is the same as that of example 1.

[0060] Example 3

[0061] The self-flowing tundish working lining dry material of the present example, in terms of mass fraction, comprises the following components:

[0062] Fine powder: 30 parts of magnesia with a particle size of 0.25-0.5mm; 56.4 parts of magnesia with a particle size of 0.075-0.25mm; 5 parts of magnesia with a particle size of ≤0.044mm.

[0063] Composite binder: 3 parts of magnesium chloride, 3.6 parts of anhydrous glucose. Sintering agent: 0.45 parts of sodium hexametaphosphate, 1.55 parts of boric acid.

[0064] The preparation method of the tundish working lining of this embodiment is the same as that of Example 1.

[0065] Example 4

[0066] The dry material for the self-flowing tundish working lining of this embodiment includes the following components, calculated by weight:

[0067] Fine powder: 35 parts of quartz sand with a particle size of 0.25-0.5mm; 48 parts of quartz sand with a particle size of 0.075-0.25mm; 5 parts of quartz sand with a particle size of ≤0.044mm.

[0068] Composite binder: 4.5 parts of magnesium chloride, 4.5 parts of anhydrous glucose. Sintering agent: 0.71 parts of sodium hexametaphosphate, 2.29 parts of boric acid.

[0069] The preparation method of the tundish working lining of this embodiment is the same as that of Example 1.

[0070] Example 5

[0071] The dry material for the self-flowing tundish working lining of this embodiment includes the following components, calculated by weight:

[0072] Fine powder: 35 parts of magnesia with a particle size of 0.25-0.5mm; 52 parts of magnesia with a particle size of 0.075-0.25mm; 5 parts of magnesia with a particle size of ≤0.044mm.

[0073] Composite binder: 3 parts of magnesium chloride, 4 parts of anhydrous glucose. Sintering agent: 0.22 parts of sodium hexametaphosphate, 0.78 parts of boric acid.

[0074] The preparation method of the tundish working lining of this embodiment is the same as that of Example 1.

[0075] Example 6

[0076] The dry material for the self-flowing tundish working lining of this example is prepared using the same raw materials as in Example 3, with the exception of 15 parts of magnesia with a particle size of 0.25-0.5 mm and 71.4 parts of magnesia with a particle size of 0.075-0.25 mm. The preparation method for the tundish working lining of this example is the same as in Example 1.

[0077] Example 7

[0078] The dry mix for the self-flowing tundish working lining of this example was prepared using the same components as in Example 3, except that 35 parts of magnesia having a particle size of 0.25-0.5 mm and 51.4 parts of magnesia having a particle size of 0.075-0.25 mm were used in the fine powder. The tundish working lining of this example was prepared in the same manner as in Example 1.

[0079] Example 8

[0080] The dry mix for the self-flowing tundish working lining of this example was prepared using the same components as in Example 3, except that 10 parts of magnesia having a particle size of 0.25-0.5 mm and 76.4 parts of magnesia having a particle size of 0.075-0.25 mm were used in the fine powder. The tundish working lining of this example was prepared in the same manner as in Example 1.

[0081] Example 9

[0082] The dry mix for the self-flowing tundish working lining of this example was prepared using the same components as in Example 3, except that 50 parts of magnesia having a particle size of 0.25-0.5 mm and 36.4 parts of magnesia having a particle size of 0.075-0.25 mm were used in the fine powder. The tundish working lining of this example was prepared in the same manner as in Example 1.

[0083] Example 10

[0084] The dry mix for the self-flowing tundish working lining of this example was prepared using the same components as in Example 3, except that 3.3 parts of magnesium chloride and 3.3 parts of anhydrous glucose were used in the composite binder. The tundish working lining of this example was prepared in the same manner as in Example 1.

[0085] Example 11

[0086] The dry mix for the self-flowing tundish working lining of this example was prepared using the same components as in Example 3, except that 2.7 parts of magnesium chloride and 3.9 parts of anhydrous glucose were used in the composite binder. The tundish working lining of this example was prepared in the same manner as in Example 1.

[0087] Example 12

[0088] The dry mix for the self-flowing tundish working lining of this example was prepared using the same components as in Example 3, except that 2.2 parts of magnesium chloride and 4.4 parts of anhydrous glucose were used in the composite binder. The tundish working lining of this example was prepared in the same manner as in Example 1.

[0089] Example 13

[0090] The dry material of the self-flowing tundish working lining of the present example is prepared from the same components as in Example 3, except that in the composite binder, 4.4 parts of magnesium chloride and 2.2 parts of anhydrous glucose are used. The tundish working lining of the present example is prepared in the same way as in Example 1.

[0091] Example 14

[0092] The dry material of the self-flowing tundish working lining of the present example is prepared from the same components as in Example 3, except that in the sintering agent, 0.47 parts of sodium hexametaphosphate and 1.53 parts of boric acid are used. The tundish working lining of the present example is prepared in the same way as in Example 1.

[0093] Example 15

[0094] The dry material of the self-flowing tundish working lining of the present example is prepared from the same components as in Example 3, except that in the sintering agent, 0.44 parts of sodium hexametaphosphate and 1.56 parts of boric acid are used. The tundish working lining of the present example is prepared in the same way as in Example 1.

[0095] Example 16

[0096] The dry material of the self-flowing tundish working lining of the present example is prepared from the same components as in Example 3, except that in the sintering agent, 0.5 parts of sodium hexametaphosphate and 1.5 parts of boric acid are used. The tundish working lining of the present example is prepared in the same way as in Example 1.

[0097] Example 17

[0098] The dry material of the self-flowing tundish working lining of the present example is prepared from the same components as in Example 3, except that in the sintering agent, 0.4 parts of sodium hexametaphosphate and 1.6 parts of boric acid are used. The tundish working lining of the present example is prepared in the same way as in Example 1.

[0099] Example 18

[0100] The dry material of the self-flowing tundish working lining of the present example is prepared from the same components as in Example 3, except that in the sintering agent, 0.45 parts of boric glass powder and 1.55 parts of borax are used. The tundish working lining of the present example is prepared in the same way as in Example 1.

[0101] Comparative Example 1

[0102] The dry material of the tundish working lining of the present comparative example is prepared from the following components in parts by mass:

[0103] 20 parts of forsterite with a particle size of 3-5 mm, 25 parts of forsterite with a particle size of 1-3 mm, 25 parts of forsterite with a particle size of 0.075-1 mm, and 24 parts of magnesia with a particle size of ≤0.075 mm.

[0104] Composite binder: magnesium chloride 2 parts, anhydrous glucose 2 parts. Sintering agent: sodium hexametaphosphate 0.47 parts, boric acid 1.53 parts.

[0105] The intermediate ladle working lining of the present comparative example was prepared by the same method as that of Example 1.

[0106] Comparative Example 2

[0107] The dry mix of the intermediate ladle working lining of the present comparative example, calculated in mass parts, comprised the following components as raw materials for preparation:

[0108] Magnesia sand with particle size of 5-3 mm 20 parts, magnesia sand with particle size of 3-1 mm 25 parts, magnesia sand with particle size of 1-0.075 mm 25 parts, magnesia sand with particle size of ≤0.075 mm 24 parts.

[0109] Composite binder: magnesium chloride 2 parts, anhydrous glucose 3 parts. Sintering agent: sodium hexametaphosphate 0.22 parts, boric acid 0.78 parts.

[0110] The intermediate ladle working lining of the present comparative example was prepared by the same method as that of Example 1.

[0111] Comparative Example 3

[0112] The dry mix of the intermediate ladle working lining of the present comparative example, calculated in mass parts, comprised the following components as raw materials for preparation:

[0113] Magnesia sand with particle size of 5-3 mm 20 parts, magnesia sand with particle size of 3-1 mm 25 parts, magnesia sand with particle size of 1-0.075 mm 25.4 parts, magnesia sand with particle size of ≤0.075 mm 21 parts.

[0114] Composite binder: magnesium chloride 3 parts, anhydrous glucose 3.6 parts. Sintering agent: sodium hexametaphosphate 0.45 parts, boric acid 1.55 parts.

[0115] The intermediate ladle working lining of the present comparative example was prepared by the same method as that of Example 1.

[0116] Comparative Example 4

[0117] The dry mix of the intermediate ladle working lining of the present comparative example, calculated in mass parts, comprised the following components as raw materials for preparation:

[0118] Quartz sand with particle size of 5-3 mm 20 parts, quartz sand with particle size of 3-1 mm 25 parts, quartz sand with particle size of 1-0.075 mm 25 parts, quartz sand with particle size of ≤0.075 mm 18 parts.

[0119] Composite binder: magnesium chloride 4.5 parts, anhydrous glucose 4.5 parts. Sintering agent: sodium hexametaphosphate 0.71 parts, boric acid 2.29 parts.

[0120] The preparation method of the tundish working lining of this comparative example is the same as that of Example 1.

[0121] Comparative Example 5

[0122] The dry material for the tundish working lining of this comparative example is prepared from the following raw materials, calculated by weight:

[0123] 20 parts of magnesia with a particle size of 5-3mm, 25 parts of magnesia with a particle size of 3-1mm, 25 parts of magnesia with a particle size of 1-0.075mm, and 22 parts of magnesia with a particle size of ≤0.075mm.

[0124] Composite binder: 3 parts of magnesium chloride, 4 parts of anhydrous glucose. Sintering agent: 0.22 parts of sodium hexametaphosphate, 0.78 parts of boric acid.

[0125] The preparation method of the tundish working lining of this comparative example is the same as that of Example 1.

[0126] Comparative Example 6

[0127] The dry material for the tundish working lining of this comparative example has the same content of other components as those in Example 3, except that the fine powder includes: 56.4 parts of magnesia with a particle size of 0.5-1 mm, 30 parts of magnesia with a particle size of 0.25-0.5 mm; and 5 parts of magnesia with a particle size of ≤0.044 mm.

[0128] Performance testing of tundish working lining

[0129] The bulk density and compressive strength of the dry materials for the tundish working lining obtained in the above-mentioned Examples and Comparative Examples were tested. The test results are shown in Table 1. The difference between Example 1 and Comparative Example 1 is that the main raw material, forsterite, contains larger particles with particle sizes of 3-5 mm, 1-3 mm, and 0.075-1 mm. In comparison, the dry material of Example 1 has a lower bulk density, approximately 30% lower than that of Comparative Example 1. Furthermore, the tundish working lining maintains good compressive strength and can be self-flowed during on-site construction without vibration, while the dry material of Comparative Example 1 requires vibration molding. The differences between Example 2 and Comparative Example 2, Example 3 and Comparative Example 3, Example 4 and Comparative Example 4, and Example 5 and Comparative Example 5 are similar. The effects of each Example compared to the corresponding comparative example are the same as those of Example 1. Comparative Example 6 differs from Example 3 in that magnesia with a particle size of 0.5-1 mm is added. Compared to Example 3, the compressive strength of Comparative Example 6 is significantly reduced.

[0130] Compared with Examples 3, 6-9, the difference is that the particle size of the magnesium-calcium sand is 0.25-0.5 mm, and the particle size of the magnesium-calcium sand is 0.075-0.25 mm. The test results show that the compressive strength of Examples 8 and 9 is significantly lower than that of Examples 3, 6 and 7, so it can be concluded that the different proportions of the magnesium-calcium sand with a particle size of 0.25-0.5 mm and the magnesium-calcium sand with a particle size of 0.075-0.25 mm have a significant impact on the strength of the dry material, and the proportions of Examples 3, 6 and 7 are the preferred range. Compared with Examples 3, 10-13, the difference is that the proportions of magnesium chloride and glucose in the binder are different, wherein the dry material of Examples 3, 11 and 12 has better compressive strength, indicating that the proportions of magnesium chloride and glucose in the binder of Examples 3, 11 and 12 are the preferred range. Compared with Examples 3, 14-17, the difference is that the proportions of sodium hexametaphosphate and boric acid in the sintering agent are different, wherein the dry material of Examples 3, 14 and 15 has better compressive strength, indicating that the proportions of sodium hexametaphosphate and boric acid in the sintering agent of Examples 3, 14 and 15 are the preferred range. Compared with Example 3, the difference of Example 18 is that a combination of boron glass powder and borax is used as a sintering agent, and the compressive strength of the dry material of Example 3 is significantly higher than that of Example 18.

[0131] The test results show that, compared with the comparative examples, the dry material of the lightweight environmentally friendly self-flowing tundish working lining of the application has a lower bulk density, and the bulk density is reduced by about 30%, and the tundish working lining has better compressive strength.

[0132] Table 1

[0133]

[0134]

[0135] The self-flowing dry material of each embodiment of the application is tested on a double-flow slab tundish in a certain steel plant, which can be self-formed without vibration, and the dust is significantly reduced during the construction process, and no irritating gas is discharged during the baking process, which is friendly to the health of the construction personnel and the environment. The steel is poured out after 10 hours, and the steel grade is ultra-low carbon steel. The working lining is slightly eroded, with an erosion of about 10 mm, no peeling and tundish collapse, and the tundish is successfully turned over. In addition, the steel plant test data shows that the average carbon pickup value of molten steel during the tundish stay is 3.8 ppm, which does not exceed 5 ppm, basically reaching the carbon pickup level of the tundish, and can meet the requirements of pouring ultra-low carbon steel.

[0136] Obviously, the above embodiments are merely example for clearly illustrating but not limitation to the embodiments. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. Here, all the embodiments need not and can not be enumerated. The obvious changes or variations derived from the above description are still within the protection scope of the present application.

Claims

1. A dry material for the working lining of a gravity-flow tundish, characterized in that: Calculated by mass, the raw materials for its preparation include the following components: 15-35 parts of fine powder with a particle size of 0.25-0.5mm, 48-75 parts of fine powder with a particle size of 0.075-0.25mm, 5 parts of fine powder with a particle size less than 0.044mm, 4-9 parts of composite binder, and 1-3 parts of sintering agent; Wherein, the fine powder is at least one of forsterite, magnesia sand, magnesia sand, and quartz sand; The composite binder comprises an organic binder and an inorganic binder; the organic binder is anhydrous glucose; the inorganic binder is magnesium chloride; the mass ratio of the inorganic binder to the organic binder is 1:1.2-2; The sintering agent is a combination of sodium hexametaphosphate and boric acid, and the mass ratio of sodium hexametaphosphate to boric acid is 1:3.2-3.

6.

2. The dry material for the self-flowing tundish working lining according to claim 1, characterized in that: The mass ratio of the inorganic binder to the organic binder is 1:1.

2.

3. The dry material for the self-flowing tundish working lining according to claim 1, characterized in that: The mass ratio of sodium hexametaphosphate to boric acid in the sintering agent is 1:3.

4.

4. A tundish working lining, prepared using the gravity-flowing tundish working lining dry material according to any one of claims 1 to 3.

5. A method for preparing a tundish working lining according to claim 4, characterized in that: The following steps are involved: S1. The fine powder of different particle sizes, the composite binder, and the sintering agent are mixed in accordance with the selected mass fraction to obtain the dry material of the self-flowing tundish working lining; S2. shaping and baking the dry material of the self-flowing tundish working lining to obtain the tundish working lining.

6. The preparation method according to claim 5, characterized in that: Step S1 specifically includes: Premix the composite binder according to the selected mass fraction for 2-3 minutes and bag it for later use; then mix the fine powders of different particle sizes for 1-2 minutes; then add the composite binder and the sintering agent to the fine powder and mix for 5-6 minutes to obtain the dry material for the self-flowing tundish working lining; Step S2 specifically includes: The self-flowing tundish working lining dry material is poured between the outer wall of the tundish mold and the permanent lining of the tundish, and is formed by self-flowing without vibration or ramming. It is baked at a temperature of 200-400°C for 1-2 hours, and the tundish working lining is obtained after demoulding.

Images