Steel ladle binding agent, preparation method thereof and steel ladle

Abstract

The invention discloses a steel ladle binding agent, a preparation method thereof and a steel ladle, and belongs to the technical field of steel ladle refractory materials. The steel ladle binding agent comprises a magnesium aluminate spinel phase and a calcium aluminate phase, and the molar ratio of the magnesium aluminate spinel phase to the calcium aluminate phase is (40-50): (50-60). Crystal phases of the steel ladle binding agent comprise the magnesium aluminate spinel phase and the calcium aluminate phase, the magnesium aluminate spinel phase and the calcium aluminate phase are evenly dispersed and closely matched, the prepared refractory material can guarantee high mechanical strength at the high temperature, meanwhile, the corrosion resistance of a steel ladle to liquid metal and slag can be enhanced, and the service life of the steel ladle binding agent is prolonged. And therefore, the service life of the steel ladle is prolonged, and the refining effect of the steel ladle is improved.

Description

Technical Field

[0001] The present application relates to a ladle binder, a preparation method thereof, and a ladle, belonging to the technical field of ladle refractory materials. Background Art

[0002] With the development of ladle refining and continuous casting technologies in steel smelting, large ladles have gradually changed from single molten steel containers to ladle refining equipment with complex functions. The residence time of molten steel in the ladle is extended, resulting in an increase in tapping temperature to 1600°C - 1700°C. At the same time, the intensified circulating movement of molten steel during refining makes the scouring and wear on the ladle more serious. In addition, deep desulfurization and smelting operations during the molten steel refining process lead to high basicity and large amount of slag of the slag, and the erosion effect on the ladle is also significantly intensified. All these have made the working environment of the ladle more severe.

[0003] The change in the ladle working environment also poses higher requirements for the refractory materials used to line the ladle. In order to withstand the long-term high-temperature scouring of molten steel, the refractory materials need to have extremely high mechanical strength and high-temperature resistance, as well as high slag erosion resistance. Currently, carbon-containing products with good slag resistance, such as aluminous magnesia carbon bricks, alumina spinel carbon bricks and other refractory materials, are commonly used as the working lining of ladles. However, the use of carbon-containing products will increase the carbon content in molten steel, which is not conducive to the refining of low-carbon steel and clean steel. At the same time, carbon-containing products have a fast heat conduction rate and are prone to damage the steel shell on the outermost layer of the ladle. Summary of the Invention

[0004] Due to problems such as the increase in the carbon content in molten steel caused by carbon-containing refractory materials in the prior art, for the refining of clean steel or low-carbon steel, ladles made of low-carbon or carbon-free refractory materials are required. Ladle lining binders are divided into organic binders and inorganic binders, and organic binders will inevitably introduce carbon materials. When carbon-containing organic binder refractory materials are baked, harmful gases will be released, polluting the environment, and problems such as carbon increase in molten steel and excessive temperature of the steel shell will occur during use. Therefore, for the smelting of clean steel or ultra-low-carbon steel, low-carbon or carbon-free refractory materials are required to line or cast the ladle. When using inorganic binders, high-temperature binding materials matching aluminous magnesia and alumina spinel refractory materials need to be used. This binder can not only ensure the high-temperature strength and thermal shock resistance of the ladle lining, but also provide excellent slag erosion resistance, and does not introduce any carbon. Therefore, there is an urgent need to develop a new type of inorganic ladle lining binder that is pollution-free to the environment and molten steel and has a long service life to meet the smelting requirements of ultra-low-carbon steel or clean steel. This inorganic ladle lining binder can, if necessary, also be directly used for repair at the steelmaking site, and even re-cast the ladle lining.

[0005] The first object of the present application is to provide a ladle binder, which can improve the mechanical strength and high-temperature resistance of ladle refractories.

[0006] The second object of the present application is to provide a preparation method of a ladle binder, which can prepare a ladle binder that can improve the mechanical strength and high-temperature resistance of ladle refractories.

[0007] The third object of the present application is to provide a ladle with high mechanical strength and high-temperature resistance.

[0008] The ladle binder of the present application adopts the following scheme:

[0009] A ladle binder includes a magnesia-alumina spinel phase and a calcium aluminate phase, and the molar ratio of the magnesia-alumina spinel phase to the calcium aluminate phase is (40-50):(50-60). The crystal phases of the ladle binder provided by the present application include a magnesia-alumina spinel phase and a calcium aluminate phase. Among them, the calcium aluminate phase can promote the bonding performance between the binder and the refractory, and can ensure a high bonding strength after the hydration reaction. It can be used as a binder for carbon-free refractories such as magnesia-aluminum and alumina-spinel refractories to improve the mechanical strength of the refractories. In the present application, the magnesia-alumina spinel phase refers to the MgAl2O4 phase. The magnesia-alumina spinel phase is beneficial to improving the high-temperature resistance of the refractory, thereby improving its thermal shock resistance when the refractory is in high-temperature service. The binder adopts an inorganic carbon-free design, and the magnesia-alumina spinel phase and the calcium aluminate phase are evenly dispersed. The two phases cooperate with each other, and the prepared refractory can also ensure a high mechanical strength at high temperatures. Moreover, the components are tightly combined, optimizing problems such as capillary cracks, which is beneficial to enhancing the corrosion resistance of the ladle to liquid metal and slag, thereby prolonging the service life of the ladle and contributing to improving the refining effect of the ladle.

[0010] Preferably, the molar ratio of the magnesia-alumina spinel phase to the calcium aluminate phase is (42-47):(53-58).

[0011] Preferably, the calcium aluminate phase is composed of a CaAl2O4 phase and a CaAl4O7 phase, and the molar ratio of the CaAl2O4 phase to the CaAl4O7 phase is (35-55):(1-15). Using a larger amount of the CaAl2O4 phase is beneficial to improving the early strength of the refractory during the hydration reaction, enabling the refractory to maintain a high bonding strength both when making ladle bricks or directly pouring the ladle. At the same time, cooperating with the CaAl4O7 phase and the magnesia-alumina spinel phase is beneficial to further improving the high-temperature mechanical strength of the ladle.

[0012] Furthermore, the molar ratio of the CaAl2O4 phase to the CaAl4O7 phase is (38-42):(4-5).

[0013] The technical scheme adopted for the preparation method of the ladle binder of the present application is as follows:

[0014] A preparation method of any one of the above ladle binders, comprising the following steps:

[0015] 1) Take corresponding masses of alumina and calcium- and magnesium-containing ore, mix and ball-mill them to obtain mixed fine powder;

[0016] 2) Perform balling treatment on the mixed fine powder to obtain balled particles;

[0017] 3) Dry the balled particles, then sinter and crush them to obtain the ladle binder. In this application, after mixing and ball-milling alumina and calcium- and magnesium-containing ore, a well-homogenized mixed fine powder of alumina and calcium- and magnesium-containing ore can be obtained. After balling and sintering, in-situ reactions occur between the alumina and calcium- and magnesium-containing ore fine powder in the balled particles, forming uniformly distributed magnesium aluminate spinel phase and calcium aluminate phase in the binder. The two phases cooperate with each other. When applied in refractories, it can ensure relatively high mechanical strength of the refractories at high temperatures, and at the same time is conducive to enhancing the corrosion resistance of the ladle to liquid metal and slag, thereby helping to extend the service life of the ladle. The sintered spherical particles are crushed and ground, which is beneficial to improving the subsequent application effect.

[0018] Preferably, the mass ratio of alumina to calcium- and magnesium-containing ore is (50 - 60):(40 - 50).

[0019] Preferably, the calcium- and magnesium-containing ore includes CaO and MgO; based on the mass of the calcium- and magnesium-containing ore and alumina, the mass content of CaO is 20 - 22%, such as 21%; the mass content of MgO is 13 - 15%.

[0020] Limiting the chemical composition of the calcium- and magnesium-containing ore results in a suitable molar ratio of magnesium aluminate spinel phase and calcium aluminate phase in the obtained binder after sintering, which is beneficial for the two to cooperate to improve the mechanical strength and high-temperature stability of the refractories.

[0021] Preferably, the calcium- and magnesium-containing ore includes at least two of calcite, limestone, magnesite, and brucite. When the above calcium- and magnesium-containing ores are sintered, the resulting binder has low impurity content and good comprehensive performance. Through ball-milling, it can better form a homogenized mixed fine powder with the alumina raw material, and calcium and magnesium ions are uniformly arranged in the octahedral unit cell. The in-situ generated magnesium aluminate spinel phase and calcium aluminate phase closely cooperate during subsequent sintering, which is beneficial for further improving the bonding performance and high-temperature resistance of the refractories, thereby obtaining refractories or ladles with excellent high-temperature strength and thermal shock resistance.

[0022] Preferably, the median particle size of the mixed fine powder is 5 - 8 μm. By controlling the particle size of the mixed fine powder obtained through ball milling treatment, it is beneficial to obtain ultrafine spinel phases in the ladle binder in cooperation with the subsequent sintering process, and it is easier to be evenly distributed in the refractory material, thereby further improving the high-temperature mechanical properties of the refractory material.

[0023] Preferably, the ball forming treatment includes: forming balls after mixing the mixed fine powder with water; wherein, the mass ratio of the mixed fine powder to water is (6.5 - 7.5):1.

[0024] Preferably, the median particle size of the ball formed particles is 18 - 30 mm.

[0025] Preferably, in step 3), after drying the ball formed particles, sintering and crushing are carried out, including: drying the ball formed particles through a drying tower, and then subjecting the dried ball formed particles to shaft kiln sintering; wherein, the drying temperature is 300 - 400 °C, the drying time is 4 - 7 h; the temperature of shaft kiln sintering is 1400 - 1450 °C, and the sintering time is 2 - 4 h.

[0026] Preferably, in step 3), after drying the ball formed particles, sintering and crushing are carried out, including: drying the ball formed particles using a rotary drum dryer, and then subjecting the dried ball formed particles to rotary kiln sintering; wherein, the drying temperature is 100 - 200 °C, the drying time is 8 - 10 h; the temperature of rotary kiln sintering is 1400 - 1450 °C, and the sintering time is 2 - 4 h. In this application, by controlling the moisture content of the ball formed particles before sintering through drying treatment, problems such as cracking and broken balls are not likely to occur during high-temperature sintering, which is beneficial to the smooth progress of the sintering process. Through the sintering conditions of a relatively short time at high temperature, it is beneficial to promote the formation of aluminum-magnesium spinel phases, CaAl2O4 phases, and CaAl4O7 phases, enabling the obtained binder to have better binding properties and promoting effects on mechanical strength and high-temperature stability. At the same time, it also has the advantages of saving energy and time costs and shortening the process.

[0027] Preferably, the method further includes: inputting the waste heat in the rotary kiln into the rotary drum dryer; after the sintered ladle binder is crushed, it is ground into ladle binder fine powder in a ball mill, the grinding medium of the ball mill is corundum grinding balls, and the particle size D50 of the ladle binder fine powder is 2.5 - 3.5 um.

[0028] The technical solution adopted for the ladle in this application is:

[0029] A ladle includes any one of the above ladle binders and / or any one of the ladle binders obtained by the preparation method of any one of the above ladle binders. The ladle of the present application uses a ladle binder including a magnesia-alumina spinel phase and a calcium aluminate phase. Among them, the calcium aluminate phase can promote the bonding performance between the binder and the refractory material, and can ensure a relatively high bonding strength after the hydration reaction, so that the ladle has a relatively high mechanical strength; the magnesia-alumina spinel phase is beneficial to improving the high-temperature resistance of the refractory material, so that the ladle has a relatively high thermal shock resistance during high-temperature service; the two phases of the binder are uniformly dispersed and cooperate with each other, and the prepared refractory material can also ensure a relatively high mechanical strength at high temperatures, and each component is tightly combined, optimizing problems such as capillary cracks, which is beneficial to enhancing the erosion resistance of the ladle to liquid metal and slag, and further enabling the ladle to have the advantages of long service life and good refining effect. Description of the Drawings

[0030] Figure 1 XRD pattern of the ladle binder of Example 1;

[0031] Figure 2 XRD pattern of the ladle binder of Comparative Example 1. Detailed Description of the Embodiments

[0032] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0033] For simplicity, the present application only explicitly discloses some numerical ranges. However, any lower limit can be combined with any upper limit to form a range not explicitly recorded; and any lower limit can be combined with other lower limits to form a range not explicitly recorded. Similarly, any upper limit can be combined with any other upper limit to form a range not explicitly recorded. In addition, although not explicitly recorded, each point or single value between the range endpoints is included in this range. Therefore, each point or single value can be used as its own lower limit or upper limit and combined with any other point or single value or combined with other lower limits or upper limits to form a range not explicitly recorded.

[0034] In order to solve the above problems, the present application proposes a ladle binder, and the technical solution adopted is:

[0035] A ladle binder includes a magnesia-alumina spinel phase and a calcium aluminate phase, and the molar ratio of the magnesia-alumina spinel phase to the calcium aluminate phase is (40-50):(50-60).

[0036] In some specific embodiments, the molar proportion of the magnesia-alumina spinel phase in the ladle binder is 40-50%, and the molar proportion of the calcium aluminate phase is 50-60%.

[0037] Exemplarily, the molar proportion of the magnesium aluminate spinel phase in the ladle binder is selected from the range composed of any two values selected from 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%. The molar proportion of the calcium aluminate phase in the ladle binder is selected from the range composed of any two values selected from 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%. For example, the molar proportion of the calcium aluminate phase in the ladle binder is 53 - 58%, and the molar proportion of the magnesium aluminate spinel phase is 42 - 47%.

[0038] In some specific embodiments, the calcium aluminate phase is composed of CaAl2O4 phase and CaAl4O7 phase, and the molar ratio of the CaAl2O4 phase to the CaAl4O7 phase is (35 - 55):(1 - 15).

[0039] In some specific embodiments, the molar proportion of the CaAl2O4 phase in the ladle binder is 35 - 55%, and the molar proportion of the CaAl4O7 phase is 1 - 15%.

[0040] Exemplarily, the molar proportion of the CaAl2O4 phase in the ladle binder is selected from the range composed of any two values selected from 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%; the molar proportion of the CaAl4O7 phase in the ladle binder is selected from the range composed of any two values selected from 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%. For example, the molar proportion of the CaAl2O4 phase in the ladle binder is 38 - 42%, and the molar proportion of the CaAl4O7 phase is 4 - 5%.

[0041] In this application, the magnesium aluminate spinel phase refers to the MgAl2O4 phase, that is, Figure 1 the spinel phase in Figure 1 whose chemical composition can be expressed as MgO·Al2O3; the CaAl2O4 phase is Figure 1 the krotite phase in

[0042] whose chemical composition can be expressed as CaO·Al2O3; the CaAl4O7 phase, that is, the calcium dialuminate phase, appears as the Grossite phase in

[0043] 1) Take corresponding masses of alumina and calcium - and - magnesium - containing ore for mixing and ball - milling to obtain a mixed fine powder;

[0044] 2) Perform spheronization on the mixed fine powder to obtain spherical particles;

[0045] 3) Dry the spherical particles, then sinter and crush them to obtain the ladle binder.

[0046] In some specific embodiments, the mass ratio of alumina to calcium- and magnesium-containing ore is (50-60):

[0047] (40-50).

[0048] In some specific embodiments, the calcium- and magnesium-containing ore includes CaO and MgO; based on the mass of the alumina and calcium- and magnesium-containing ore, the mass content of CaO is 20-22%; the mass content of MgO is 13-15%. In this application, the mass content of CaO in the calcium- and magnesium-containing ore refers to the percentage of CaO in the total mass of the alumina and calcium- and magnesium-containing ore, and the mass content of MgO refers to the percentage of MgO in the total mass of the alumina and calcium- and magnesium-containing ore. For example, when the calcium- and magnesium-containing ore is selected from the combination of calcite and brucite, the mass content of CaO is the percentage of CaO in calcite in the total mass of alumina, calcite and brucite, and the mass content of MgO is the percentage of MgO in brucite in the total mass of alumina, calcite and brucite.

[0049] In some specific embodiments, the median particle size of the mixed fine powder is 5-8 μm. The median particle size in this application refers to D50, that is, the particle size of 50% of the cumulative mixed fine powder is 5-8 μm, including 5 μm and 8 μm.

[0050] In some specific embodiments, the spheronization treatment includes: mixing the mixed fine powder with water and then spheronizing; wherein, the mass ratio of the mixed fine powder to water is (6.5-7.5):1. Among them, the water can be pure water.

[0051] In some specific embodiments, the mass of water in the spheronization treatment is 11-13% of the mass of the wet balls.

[0052] In some specific embodiments, in step 3), after drying the spherical particles, sintering and crushing are performed, including: drying the spherical particles in a drying tower, and then subjecting the dried spherical particles to shaft kiln sintering; wherein, the drying temperature is 300-400 °C, the drying time is 4-7 h; the temperature of the shaft kiln sintering is 1400-1450 °C, and the sintering time is 2-4 h.

[0053] In this application, a shaft kiln refers to a high-temperature calcination kiln with a vertically cylindrical kiln body; a drying tower refers to a conical or cylindrical vertical drying equipment, where hot air enters the drying bin from the bottom, and the material to be dried enters the drying bin from the upper part, and heat exchange is completed in the drying bin. The drying tower and the shaft kiln are used in combination, with high drying efficiency, large production capacity, and small floor area. In some specific embodiments, the upper limit of the sintering temperature of the shaft kiln is selected from any value among 1410°C, 1420°C, 1430°C, 1440°C, and 1450°C, the lower limit of the sintering temperature of the shaft kiln is selected from any value among 1400°C, 1410°C, 1420°C, 1430°C, and 1440°C, and the sintering temperature of the shaft kiln is selected from the range formed by arbitrarily taking one value from the upper limit of the sintering temperature of the shaft kiln and the lower limit of the sintering temperature of the shaft kiln.

[0054] In some specific embodiments, the sintering time of the shaft kiln is selected from the range formed by any two values among 2h, 3h, and 4h.

[0055] In some specific embodiments, after drying the pelleted particles in step 3), sintering is carried out, including: drying the pelleted particles using a rotary drum dryer, and then sintering the dried pelleted particles in a rotary kiln; wherein, the drying temperature is 100 - 200°C, the drying time is 8 - 10h; the sintering temperature of the rotary kiln is 1400 - 1450°C, and the sintering time is 2 - 4h.

[0056] In this application, a rotary kiln refers to a rotating high-temperature calcination kiln, and the kiln body is a steel cylinder installed on a supporting device with a slope of 1 - 6%; a rotary drum dryer refers to a rotating continuous drying equipment with a slightly inclined cylindrical body as the main body.

[0057] In this application, using a rotary kiln for rotating calcination in the horizontal direction can better control the sintering process. During the rotation process, particles or broken balls with poor pelletizing state can be discharged, which is beneficial to ensuring the excellent performance of the final binder. In addition, the waste heat of the rotary kiln can be used to supply heat for the drying step, enabling full utilization of energy and having the advantages of energy conservation and cost reduction.

[0058] In some specific embodiments, the upper limit of the sintering temperature of the rotary kiln is selected from any value among 1410°C, 1420°C, 1430°C, 1440°C, and 1450°C, the lower limit of the sintering temperature of the rotary kiln is selected from any value among 1400°C, 1410°C, 1420°C, 1430°C, and 1440°C, and the sintering temperature of the rotary kiln is selected from the range formed by arbitrarily taking one value from the upper limit of the sintering temperature of the rotary kiln and the lower limit of the sintering temperature of the rotary kiln.

[0059] In some specific embodiments, the sintering time of the rotary kiln is selected from the range formed by any two values among 2h, 3h, and 4h.

[0060] In some specific embodiments, the purity of alumina is above 99.7%; the purity of calcium and magnesium-containing ore is above 99.5%. By limiting the purity of the alumina raw material and the calcium and magnesium-containing ore raw material, the impurity content of the binder product is controlled, the influence of impurities on the performance of the binder is avoided, the phase quality of the binder is ensured, and it is beneficial to further improve the promotion effect of the ladle binder on mechanical strength and high-temperature stability.

[0061] Example

[0062] The technical solution of the present application will be described below in conjunction with specific embodiments. The raw materials used in the following embodiments are all from ordinary commercially available products, and the devices or equipment used are all purchased from conventional market sales channels. Unless otherwise specified, the "%" and "parts" and ratios involved are in mass ratios.

[0063] Example 1

[0064] A preparation method of a ladle binder includes the following steps:

[0065] 1) Mix raw materials with a mass percentage of 50% alumina, 28% calcite, and 22% magnesite. The purity of the alumina is 99.7%, and the purity of the calcite and magnesite is 99.5%. Based on the total mass of alumina, calcite, and magnesite, the mass percentage of CaO is 20.28% and the mass percentage of MgO is 13.66%. After mixing, put the mixed raw materials into a ball mill for ball milling until the median particle size D50 is 7 μm to obtain mixed fine powder;

[0066] 2) Put the mixed fine powder into a pelletizer and add water for pelletizing. The mass ratio of the mixed fine powder to water is 7:1 to obtain pelletized particles with a median particle size D50 of 25 mm;

[0067] 3) Dry the pelletized particles using a rotary drum dryer at a drying temperature of 200 °C and a drying time of 10 h; put the dried pelletized particles into a rotary kiln for sintering at a sintering temperature of 1400 °C and a sintering time of 2 h. The waste gas of the rotary kiln is recycled to supply heat to the rotary drum dryer. After sintering, the sintered mature pelletized particles are crushed and then ground into ladle binder fine powder in a ball mill. The grinding medium of the ball mill is corundum grinding balls, and the particle size D50 of the ladle binder fine powder is 2.5 μm, thus obtaining the ladle binder of this embodiment.

[0068] Perform XRD analysis on the ladle binder of this embodiment. The XRD pattern is as Figure 1 shown. From Figure 1 it can be seen that for the ladle binder of this embodiment, the phase composition is 48.1% magnesium aluminate spinel phase, 46.0% CaAl2O4 phase, and 5.9% CaAl4O7 phase.

[0069] The preparation method of the ladle binder in Example 2 is only different from that in Example 1 in that: the mass ratio of alumina, calcite and magnesite in the raw materials is adjusted so that the phase composition of the prepared ladle binder is 40.2% of magnesium aluminate spinel phase, 46.6% of CaAl2O4 phase and 13.2% of CaAl4O7 phase.

[0070] The preparation method of the ladle binder in Example 3 is only different from that in Example 1 in that: the mass ratio of alumina, calcite and magnesite in the raw materials is adjusted so that the phase composition of the prepared ladle binder is 42.6% of magnesium aluminate spinel phase, 53.3% of CaAl2O4 phase and 4.1% of CaAl4O7 phase.

[0071] The preparation method of the ladle binder in Example 4 is only different from that in Example 1 in that: the mass ratio of alumina, calcite and magnesite in the raw materials is adjusted so that the phase composition of the prepared ladle binder is 46.9% of magnesium aluminate spinel phase, 48.4% of CaAl2O4 phase and 4.7% of CaAl4O7 phase.

[0072] Comparative Example 1

[0073] The preparation method of the ladle binder in Comparative Example 1 is only different from that in Example 1 in that: the mass ratio of alumina, calcite and magnesite in the raw materials is adjusted so that the phase composition of the prepared ladle binder is 77.6% of magnesium aluminate spinel phase, 16.8% of CaAl2O4 phase and 5.6% of CaAl4O7 phase. The XRD analysis was carried out on the ladle binder of this example, and the XRD pattern is as Figure 2 shown.

[0074] Example 5

[0075] The preparation method of the ladle binder in this example is only different from that in Example 1 in that in step 3), the formed balls are dried in a drying tower at a drying temperature of 400 °C and a drying time of 5 h; the dried formed balls are put into a shaft kiln for sintering at a sintering temperature of 1400 °C and a sintering time of 2 h. After the sintering is completed, the ladle binder of this example is obtained.

[0076] Example 6

[0077] The preparation method of the ladle binder in this example is only different from that in Example 1 in that in step 3), the sintering temperature is 1450 °C and the sintering time is 3 h.

[0078] Test Example

[0079] Using electrofused white corundum and pre-synthesized spinel as raw materials, with a raw material ratio of 85:15, adding the ladle binders of Examples 1 to 6 and Comparative Example 1, and the mass of the ladle binder being 6% of the mass of the raw materials, the ladle bricks are prepared through processes of mixing, forming, drying, and sintering.

[0080] The cold crushing strength of the ladle bricks is tested according to GB / T 5072.2 - 2004 (Test method for cold crushing strength of dense shaped refractory products - Part 2: Cushion test method), and the hot modulus of rupture of the ladle bricks at 1450 °C is tested according to GB / T 3002 - 2004 (Test method for hot modulus of rupture of refractories). The data of the cold crushing strength and hot modulus of rupture are shown in Table 1 below.

[0081] Table 1 Performance data of ladle bricks made with the binders of Examples 1 to 6 and Comparative Example 1

[0082] Number Normal temperature compressive strength / MPa High temperature flexural strength / MPa Example 1 140 25.3 Example 2 143 24.8 Example 3 148 24.4 Example 4 145 24.6 Example 5 140 25.2 Example 6 136 25.3 Comparative Example 1 120 23.0

[0083] As can be seen from Table 1, in the ladle binder regulated in this application, the molar ratio of the magnesium aluminate spinel phase to the calcium aluminate phase is (40 - 50):(50 - 60), which is beneficial to improving the mechanical strength at normal temperature and high temperature during subsequent application in refractories. In particular, when the molar ratio of the magnesium aluminate spinel phase to the calcium aluminate phase is (42 - 47):(53 - 58), the mechanical strength of the refractory can be further improved.

[0084] Particularly, during the preparation process of the ladle binder, regulating the sintering temperature to 1400 - 1450 °C can further improve the mechanical strength of the refractory at normal temperature and high temperature.

Claims

1. A ladle binder, characterized in that, It includes a magnesia-alumina spinel phase and a calcium aluminate phase, and the molar ratio of the magnesia-alumina spinel phase to the calcium aluminate phase is (40-50):(50-60).

2. The ladle binder according to claim 1, characterized in that, The molar ratio of the magnesia-alumina spinel phase to the calcium aluminate phase is (42-47):(53-58).

3. The ladle binder according to claim 1, characterized in that, The calcium aluminate phase is composed of a CaAl2O4 phase and a CaAl4O7 phase, and the molar ratio of the CaAl2O4 phase to the CaAl4O7 phase is (35-55):(1-15).

4. The ladle binder according to claim 3, characterized in that, The molar ratio of the CaAl2O4 phase to the CaAl4O7 phase is (38-42):(4-5).

5. A method for preparing a ladle binder according to any one of claims 1 to 4, characterized in that, It includes the following steps: 1) Take corresponding masses of alumina and calcium-magnesium-containing ore, mix and ball-mill them to obtain mixed fine powder; 2) Perform ball-forming treatment on the mixed fine powder to obtain ball-formed particles; 3) Dry the ball-formed particles, then sinter and crush them to obtain the ladle binder.

6. The preparation method of the ladle binder according to claim 5, wherein The mass ratio of the alumina to the calcium-magnesium-containing ore is (50-60):(40-50).

7. The preparation method of the ladle binder according to claim 6, characterized in that, The calcium-magnesium-containing ore includes CaO and MgO; Based on the masses of the alumina and the calcium-magnesium-containing ore, the mass content of CaO is 20-22%; the mass content of MgO is 13-15%.

8. The preparation method of the ladle binder according to claim 5, characterized in that, The calcium-magnesium-containing ore includes at least two of calcite, limestone, magnesite, brucite, etc.

9. The preparation method of the ladle binder according to claim 5, characterized in that, The median particle size of the mixed fine powder is 5-8μm.

10. The preparation method of the ladle binder according to claim 5, characterized in that, The ball-forming treatment includes: mixing the mixed fine powder with water and then forming balls; Among them, the mass ratio of the mixed fine powder to water is (6.5-7.5):

1.

11. The preparation method of the ladle binder according to claim 10, characterized in that, The median particle size of the ball-formed particles is 18-30mm.

12. The preparation method of the ladle binder according to claim 5, characterized in that, In step 3), drying the ball-formed particles and then sintering and crushing them includes: Pass the ball-formed particles through a drying tower for drying, and then perform shaft kiln sintering on the dried ball-formed particles; Among them, the drying temperature is 300-400°C, and the drying time is 4-7h; The temperature of the shaft kiln sintering is 1400-1450°C, and the sintering time is 2-4h.

13. The preparation method of the ladle binder according to claim 5, characterized in that, In step 3), drying the ball-formed particles and then sintering and crushing them includes: Dry the ball-formed particles using a rotary drum dryer, and then perform rotary kiln sintering on the dried ball-formed particles; Among them, the drying temperature is 100-200°C, and the drying time is 8-10h; The temperature of the rotary kiln sintering is 1400-1450°C, and the sintering time is 2-4h.

14. The preparation method of the ladle binder according to claim 13, characterized in that, The method further includes: inputting the waste heat in the rotary kiln into the rotary drum dryer; The sintered ladle binder is crushed and then ground into ladle binder fine powder in a ball mill. The grinding medium of the ball mill is corundum grinding balls, and the particle size D50 of the ladle binder fine powder is 2.5-3.5um.

15. A ladle, characterized in that, The ladle includes any one of the ladle binders described in any one of claims 1 to 4 or the ladle binder obtained by the preparation method of the ladle binder described in any one of claims 5 to 14.

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