Low-carbon magnesia-carbon brick for ladle slag line and preparation method thereof

Abstract

The application belongs to the technical field of low-carbon magnesia carbon brick preparation, and particularly relates to a low-carbon magnesia carbon brick for a ladle slag line and a preparation method thereof. # The electrically fused magnesia is coarse aggregate, and the 98 # The electrically fused magnesia is medium aggregate, and the 98 # The mixture of the electrically fused magnesia, the electrically fused magnesia-calcium sand and the zircon sand is powder, the scale graphite and the phenolic resin binder are added, the calcium hexaluminate, the siliconized magnesium, the chromium carbide and the rare earth compound are used as the additives, the raw materials are matched with each other and synergistically act to ensure that the prepared low-carbon magnesia carbon brick for the ladle slag line has excellent mechanical strength, oxidation resistance and slag resistance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of low-carbon magnesia carbon brick preparation, and particularly relates to a low-carbon magnesia carbon brick for a ladle slag line and a preparation method thereof. BACKGROUND

[0002] High-quality steel (high-quality alloy steel, ultra-low-carbon steel, clean steel, high-strength steel, etc.) requires strict control of the carbon content in the refractory material in the smelting process to reduce the carbon pick-up of the molten steel, and the temperature of the molten steel should be increased and decreased by a small range in the secondary refining, and the thermal conductivity of the ladle lining should be low, thus leading to more stringent conditions for the use of the ladle and a more severe working environment, and there is an urgent need for the emergence of a low-carbon magnesia carbon brick for a high-purity, non-polluting and high-durability ladle slag line. The magnesia carbon brick is a composite material prepared by using high-melting-point basic oxide magnesium oxide and graphite which is difficult to be wetted by slag as raw materials, and adding binders, antioxidants and other additives. It is generally believed that the magnesia carbon brick with C≤8% is a low-carbon magnesia carbon brick. Due to the reduction of the carbon content in the low-carbon magnesia carbon brick, the characteristics of high thermal conductivity, small thermal expansion coefficient and low elastic modulus of graphite are not embodied, leading to poor thermal shock resistance of the low-carbon magnesia carbon brick. At the same time, the wetting angle between the working surface of the low-carbon magnesia carbon brick and the slag is reduced, and the slag cannot effectively prevent the invasion of the brick structure, leading to poor slag penetration resistance of the magnesia carbon brick.

[0003] At present, metal or non-metal fine powder is usually added to the low-carbon magnesia carbon brick to improve its performance. Commonly used are Al, Si, SiC and B4C, etc. Excessive metal Al powder can form a large amount of Al4C3 in the use process, and Al4C3 is extremely easy to be hydrated, thus leading to serious cracking of the brick body; the metal Si powder finally forms a silicate low-melting phase, and if the amount of the metal Si powder added is too much, the slag erosion resistance of the material will be reduced; SiC forms SiO2 after oxidation, also forming a silicate low-melting phase, leading to the decrease of the slag erosion resistance of the material; B4C generates B2O3 low-melting point substance after oxidation, which is also not conducive to the slag erosion resistance of the material.

[0004] Therefore, it is necessary to explore a new type of low-carbon magnesia carbon brick for a ladle slag line. SUMMARY

[0005] The purpose of the application is to provide a low-carbon magnesia carbon brick for a ladle slag line. The low-carbon magnesia carbon brick has excellent mechanical strength, oxidation resistance and slag resistance; and the application also simultaneously provides a preparation method thereof.

[0006] The low-carbon magnesia carbon brick for a ladle slag line according to the application is prepared from the following raw materials in percentage by mass: 98 # fused magnesia 19.5-20.5%, 98 # fused magnesia 12.5-13.5%, 98# Fused magnesite 16-18%, 98 # Fused magnesite 11-13%, fine powder mixture with particle size <0.088mm 24-26%, flake graphite 2.7-2.9%, phenolic resin binder 4.6-5.2%, calcium hexaluminate 1.8-2.0%, chromium carbide 1.0-1.4%, rare earth complex 0.5-0.65%, and magnesium silicide 1.6-1.7%; wherein, the fine powder mixture with particle size <0.088mm is composed of the following raw materials: 98 # Fused magnesite 63-64%, fused magnesia-calcia sand 12.5-13.5%, and zircon 23-24%.

[0007] The rare earth complex is prepared by putting cerium oxide and praseodymium oxide into a mixer at a mass ratio of 7:3, mixing at room temperature at a speed of 20 r / min for 5 min.

[0008] The phenolic resin binder is composed of resol and boron phenolic resin, and the mass ratio of the resol and the boron phenolic resin is 8:2. The resol and the boron phenolic resin are stirred at room temperature for 20 min to be uniformly mixed to prepare the phenolic resin binder. The resol is produced by Wuhan Meiqilin New Material Co., Ltd. and has a model number of MQ-8022. The boron phenolic resin is produced by Lvlilian (Jining) Chemical Technology Co., Ltd. and has a product model number of TY03.

[0009] The preparation method of the low-carbon magnesia-carbon brick for a ladle slag line according to the application comprises the following steps:

[0010] (1) The raw materials are dried at 120-125℃ for 5-5.3h respectively;

[0011] (2) 98 # Fused magnesite, 98 # Fused magnesite, and 98 # Fused magnesite is mixed for 5-7 min, and 98 # The fused magnesite is continuously mixed for 5-7 min to prepare a first mixture. The chromium carbide, the rare earth complex, and the magnesium silicide are mixed for 3-5 min and then added to the first mixture to be continuously mixed for 5-7 min to prepare a second mixture. The fine powder mixture with particle size <0.088mm and the calcium hexaluminate are added to the second mixture to be continuously mixed for 5-7 min to prepare a third mixture.

[0012] (3) The flake graphite is added to the third mixture to be mixed for 3-5 min, and then the phenolic resin binder is added to be mixed for 10-12 min to prepare a premix.

[0013] (4) The premix is loaded into a mold for press molding, then demolding for drying, sintering, and cooling to room temperature to prepare the low-carbon magnesia-carbon brick for ladle slag line.

[0014] Wherein:

[0015] The mixing speed for preparing the first mixture in step (2) is 20-22 r / min, the mixing temperature is room temperature, the mixing speed for preparing the second mixture is 18-20 r / min, the mixing temperature is room temperature, and the mixing speed for preparing the third mixture is 18-20 r / min, the mixing temperature is room temperature.

[0016] The mixing speed for adding flake graphite in step (3) is 17-19 r / min, the mixing temperature is room temperature, and the mixing speed for adding phenolic resin binder is 20-22 r / min, the mixing temperature is room temperature.

[0017] The press molding in step (4) is first pre-pressing at 10 MPa for 1 min, and then pressure maintaining at 45 MPa for 3 min.

[0018] The drying atmosphere in step (4) is nitrogen, first heat preservation at 100-103℃ for 8 h, then heat preservation at 140-145℃ for 12 h, and finally heat preservation at 195-198℃ for 6 h.

[0019] The sintering atmosphere in step (4) is nitrogen, first heating from room temperature to 1000℃ at a heating rate of 3℃ / min, then heating to 1450-1480℃ at a heating rate of 4℃ / min and heat preservation for 7 h.

[0020] The cooling to room temperature in step (4) is from 1450-1480℃ to room temperature at a cooling rate of 2℃ / min.

[0021] Compared with the prior art, the present application has the following beneficial effects:

[0022] (1) The low-carbon magnesia-carbon brick for ladle slag line has 98 # The fused magnesia is coarse aggregate, and the fused magnesia, fused magnesia-calcium sand, and zircon sand are 98 # The fused magnesia is coarse aggregate, and the fused magnesia, fused magnesia-calcium sand, and zircon sand are 98 # The mixture of the fused magnesia, the fused magnesia-calcium sand, and the zircon sand is powder, and the flake graphite and the phenolic resin binder are added, and the calcium hexaluminate, the siliconized magnesium, the chromium carbide, and the rare earth compound are added as additives, and the raw materials cooperate with each other and synergistically act to ensure that the prepared low-carbon magnesia-carbon brick for ladle slag line has excellent mechanical strength, oxidation resistance, and slag resistance.

[0023] (2) The low-carbon magnesia-carbon brick for the slag line of a ladle, 98 # The fused magnesia is coarse aggregate, 98 # The content of magnesia in the fused magnesia is ≥98%, which has excellent volume stability at high temperature, the coarse aggregate is distributed according to the three-level particle size hierarchy, forming a continuous and stable main skeleton structure, which directly guarantees the high-temperature compressive strength and thermal shock stability of the low-carbon magnesia-carbon brick; 98 # The fused magnesia is medium aggregate, after the medium aggregate is filled, the porosity of the coarse aggregate is reduced, laying a foundation for the subsequent densification of the powder, and the composition of the medium aggregate and the coarse aggregate is consistent, further improving the structural integrity of the low-carbon magnesia-carbon brick and reducing the apparent porosity of the finished low-carbon magnesia-carbon brick; 98 # The mixture of the fused magnesia, the fused magnesia-calcium sand and the zircon sand is powder, and the content of the particle size <0.088 mm in the powder is 98 # The fused magnesia is filled in the micropores remaining in the medium aggregate, forming a dense matrix and supplementing the content of MgO, thereby strengthening the ability to resist the erosion of alkaline slag; the fused magnesia-calcium sand powder provides a small amount of calcium oxide, which reacts with silicon dioxide and ferrous oxide in the slag to generate a high-viscosity calcium silicate phase, thereby playing a role in increasing viscosity and resisting slag; the zircon sand powder decomposes to generate zirconia at high temperature, which reacts with calcium oxide to generate calcium zirconate high-melting solid solution, thereby forming an isolation layer on the slag-brick surface, blocking the penetration of the slag into the interior and reducing the slag erosion resistance. Through the three-level synergy of "skeleton support-pore filling-dense strengthening", the coarse aggregate, the medium aggregate and the powder not only guarantee the mechanical strength of the low-carbon magnesia-carbon brick, but also ensure that the low-carbon magnesia-carbon brick has good slag resistance.

[0024] (3) The low-carbon magnesia-carbon brick for the slag line of a ladle, the synergistic effect between calcium hexaluminate, magnesium silicide, chromium carbide and rare earth compounds in the raw material improves the oxidation resistance and slag resistance of the low-carbon magnesia-carbon brick. Calcium hexaluminate has good hydration resistance and alkali erosion resistance, and calcium hexaluminate reacts with SiO2 and FeO in the slag to generate a high-viscosity aluminosilicate phase to reduce the adhesion and penetration of the slag. Chromium carbide is preferentially oxidized to generate Cr2O3 at high temperature, rapidly consumes local oxygen, reduces the interfacial oxygen partial pressure, and the subsequent CeO2 further chemisorbs residual O2, and both of them complete oxygen inhibition in the whole temperature range. In addition, Cr2O3 reacts with MgO to generate magnesia-chromite, which has high Mohs hardness and can improve the erosion resistance of the low-carbon magnesia-carbon brick. CeO2 in the rare earth compound reacts with O2 to generate Ce2O3 at a temperature higher than 1000℃, and Ce2O3 further reacts with O2 to generate CeO2, thereby completing the Ce 4+ / Ce 3+ cycle, and both of them complete oxygen inhibition in the whole temperature range. In addition, Cr2O3 reacts with MgO to generate magnesia-chromite, which has high Mohs hardness and can improve the erosion resistance of the low-carbon magnesia-carbon brick. CeO2 in the rare earth compound reacts with O2 to generate Ce2O3 at a temperature higher than 1000℃, and Ce2O3 further reacts with O2 to generate CeO2, thereby completing the Ce 4+ Ce 3+Valence state transition, generating a large number of oxygen vacancies, can actively adsorb O2 (form O 2- Fill vacancies) and metal ions in the slag, reducing the contact of O2 with carbon from the source, thereby playing an anti-oxidation role. Magnesium silicide directly oxidizes at medium and low temperatures to generate MgO and SiO2, SiO2 and B2O3 generated by the decomposition of boron phenolic resin, the oxidation product Cr2O3 of chromium carbide form borosilicate glass phase, the liquid phase has high viscosity, can tightly block micropores and microcracks, and block the secondary penetration of oxygen. The MgO generated by the oxidation of magnesium silicide reacts with trace Al2O3 in the matrix to form magnesium aluminate spinel. During slag resistance, magnesium aluminate spinel, magnesium chromium spinel and calcium hexaluminate interact, so that the prepared low-carbon magnesia carbon brick can resist slag erosion and penetration for a long time. Thus, the synergistic effect between calcium hexaluminate, magnesium silicide, chromium carbide and rare earth complex in the raw materials improves the oxidation resistance and slag resistance of the low-carbon magnesia carbon brick.

[0025] (4) The preparation method of the low-carbon magnesia carbon brick for the ladle slag line has process parameters easy to control, and the prepared low-carbon magnesia carbon brick has stable performance. DETAILED DESCRIPTION

[0026] Example 1

[0027] The low-carbon magnesia carbon brick for the ladle slag line described in this embodiment 1 has the following raw material composition in mass percentage: 98 # Fused magnesia 19.5%, 98 # Fused magnesia 12.5%, 98 # Fused magnesia 18%, 98 # Fused magnesia 11%, fine powder mixture with particle size <0.088mm 26%, flake graphite 2.7%, phenolic resin binder 4.6%, calcium hexaluminate 2.0%, chromium carbide 1.4%, rare earth complex 0.6%, magnesium silicide 1.7%; wherein the fine powder mixture with particle size <0.088mm is composed of the following raw materials in mass percentage: 98 # Fused magnesia 63.5%, fused magnesia-calcium sand 13.5%, zircon 23%.

[0028] The rare earth complex is prepared by putting cerium oxide and praseodymium oxide into a mixer at a mass ratio of 7:3, mixing at room temperature at a speed of 20 r / min for 5 min.

[0029] The phenolic resin binder is prepared by mixing the resol phenolic resin and the boron phenolic resin at room temperature for 20 min, wherein the mass ratio of the resol phenolic resin to the boron phenolic resin is 8:2, the resol phenolic resin is produced by Wuhan Meiqilin New Material Co., Ltd. and has a model of MQ-8022, and the boron phenolic resin is produced by Lvlilian (Jinan) Chemical Technology Co., Ltd. and has a product model of TY03.

[0030] The preparation method of the low-carbon magnesia carbon brick for a ladle slag line in the embodiment 1 comprises the following steps:

[0031] (1) The raw materials are dried at 123 ℃ for 5.2 h respectively;

[0032] (2) 98 # fused magnesia with a particle size of 2 mm≤particle size<3 mm, 98 # fused magnesia with a particle size of 1 mm≤particle size<2 mm, and 98 # fused magnesia with a particle size of 0.088 mm≤particle size<1 mm are mixed for 6 min, 0.088 mm≤particle size<1 mm of the fused magnesia is added and mixed for 6 min continuously, to prepare a first mixture; # The chromium carbide, the rare earth compound and the magnesium silicide are mixed for 4 min, and then added into the first mixture and mixed for 5 min continuously, to prepare a second mixture, the fine powder mixture with a particle size of <0.088 mm and calcium hexaluminate are added into the second mixture and mixed for 7 min continuously, to prepare a third mixture;

[0033] (3) The flake graphite is added into the third mixture and mixed for 4 min, and then the phenolic resin binder is added and mixed for 11 min, to prepare a premix;

[0034] (4) The premix is loaded into a mold for press forming, and then demolded for drying and sintering, and then cooled to room temperature, to prepare the low-carbon magnesia carbon brick for the ladle slag line.

[0035] In the preparation of the first mixture in step (2), the mixing speed is 21 r / min and the mixing temperature is room temperature, in the preparation of the second mixture, the mixing speed is 19 r / min and the mixing temperature is room temperature, and in the preparation of the third mixture, the mixing speed is 19 r / min and the mixing temperature is room temperature.

[0036] In step (3), the mixing speed is 19 r / min and the mixing temperature is room temperature when the flake graphite is added, and the mixing speed is 21 r / min and the mixing temperature is room temperature when the phenolic resin binder is added.

[0037] In step (3), the mixing speed is 19 r / min and the mixing temperature is room temperature when the flake graphite is added, and the mixing speed is 21 r / min and the mixing temperature is room temperature when the phenolic resin binder is added.

[0038] The press molding in step (4) is first pre-pressing at a pressure of 10 MPa for 1 min, and then pressure-keeping at a pressure of 45 MPa for 3 min.

[0039] The drying atmosphere in step (4) is nitrogen, first keeping at 101 ℃ for 8 h, then keeping at 143 ℃ for 12 h, and finally keeping at 197 ℃ for 6 h.

[0040] The sintering atmosphere in step (4) is nitrogen, first increasing the temperature from room temperature to 1000 ℃ at a temperature increasing rate of 3 ℃ / min, and then increasing the temperature to 1465 ℃ at a temperature increasing rate of 4 ℃ / min and keeping for 7 h.

[0041] The decreasing to room temperature in step (4) is decreasing from 1465 ℃ to room temperature at a temperature decreasing rate of 2 ℃ / min.

[0042] Example 2

[0043] The low-carbon magnesia-carbon brick for the ladle slag line in this example 2 is prepared from the following raw materials in mass percentage: 98 # 20% of fused magnesia, 98 # 13% of fused magnesia, 98 # 17% of fused magnesia, 98 # 12.5% of fused magnesia, 24% of fine powder mixture with particle size <0.088 mm, 2.8% of flaky graphite, 5.2% of phenolic resin binder, 1.9% of calcium hexaluminate, 1.3% of chromium carbide, 0.65% of rare earth compound, and 1.65% of siliconized magnesia; wherein the fine powder mixture with particle size <0.088 mm is prepared from the following raw materials in mass percentage: 98 # 64% of fused magnesia, 12.5% of fused magnesia-calcium, and 23.5% of zircon.

[0044] The rare earth compound is prepared by putting cerium oxide and praseodymium oxide into a mixer at a mass ratio of 7:3, and mixing at room temperature at a rotation speed of 20 r / min for 5 min.

[0045] The phenolic resin binder is prepared by mixing 8 parts of resol and 2 parts of boron phenolic resin at room temperature for 20 min, wherein the resol is produced by Wuhan Meiqilin New Material Co., Ltd. with a model number of MQ-8022, and the boron phenolic resin is produced by Lvlilian (Jining) Chemical Technology Co., Ltd. with a product model number of TY03.

[0046] The preparation method of the low-carbon magnesia-carbon brick for the ladle slag line in this example 2 comprises the following steps:

[0047] (1) Dry the raw materials at 120°C for 5.3h respectively;

[0048] (2) Mix 98 # fused magnesia with particle size of 2mm≤particle size<3mm, 98 # fused magnesia with particle size of 1mm≤particle size<2mm, and 98 # fused magnesia with particle size of 0.088mm≤particle size<1mm for 5min, and then add 98 # fused magnesia with particle size of 0.088mm≤particle size<1mm for 7min to prepare a first mixture, mix chromium carbide, rare earth compound and magnesium silicide for 5min, and then add them to the first mixture for 7min to prepare a second mixture, mix the fine powder mixture with particle size<0.088mm and calcium hexaluminate into the second mixture for 6min to prepare a third mixture;

[0049] (3) Add flake graphite into the third mixture for 5min, and then add phenolic resin binder for 12min to prepare a premix;

[0050] (4) Put the premix into a mold for press forming, then demold, dry and sinter, and then cool to room temperature to prepare the low-carbon magnesia-carbon brick for slag line of a ladle.

[0051] Wherein:

[0052] In the preparation of the first mixture in step (2), the mixing speed is 22r / min and the mixing temperature is room temperature; in the preparation of the second mixture, the mixing speed is 18r / min and the mixing temperature is room temperature; in the preparation of the third mixture, the mixing speed is 18r / min and the mixing temperature is room temperature.

[0053] In step (3), the mixing speed is 17r / min and the mixing temperature is room temperature when flake graphite is added; the mixing speed is 20r / min and the mixing temperature is room temperature when phenolic resin binder is added.

[0054] In step (4), the press forming is first pre-pressed at a pressure of 10MPa for 1min, and then pressed at a pressure of 45MPa for 3min.

[0055] In step (4), the drying atmosphere is nitrogen, first heat at 100°C for 8h, then heat at 140°C for 12h, and finally heat at 195°C for 6h.

[0056] In step (4), the sintering atmosphere is nitrogen, first heat at a rate of 3°C / min from room temperature to 1000°C, and then heat at a rate of 4°C / min to 1450°C and heat for 7h.

[0057] The said reducing to room temperature in step (4) is reducing from 1450℃ to room temperature at a cooling rate of 2℃ / min.

[0058] Example 3

[0059] The low-carbon magnesia carbon brick for the ladle slag line in this example 3 is composed of the following raw materials in mass percentage: 98 # electrofused magnesia 20.5%, 98 # electrofused magnesia 13.5%, 98 # electrofused magnesia 16%, 98 # electrofused magnesia 13%, fine powder mixture with particle size <0.088mm 24.5%, flake graphite 2.9%, phenolic resin binder 4.7%, calcium hexaluminate 1.8%, chromium carbide 1.0%, rare earth compound 0.5%, and magnesium silicide 1.6%; wherein the fine powder mixture with particle size <0.088mm is composed of the following raw materials in mass percentage: 98 # electrofused magnesia 63%, electrofused magnesia calcia sand 13%, and zircon 24%.

[0060] The rare earth compound is prepared by putting cerium oxide and praseodymium oxide into a mixer at a mass ratio of 7:3, mixing at room temperature at a speed of 20r / min for 5min.

[0061] The phenolic resin binder is composed of resol and boron phenolic resin, and the mass ratio of resol and boron phenolic resin is 8:2. The resol and boron phenolic resin are mixed uniformly at room temperature by stirring for 20min to prepare the phenolic resin binder. The resol is produced by Wuhan Meiqilin New Material Co., Ltd. and the model is MQ-8022. The boron phenolic resin is produced by Lvlilian (Jining) Chemical Technology Co., Ltd. and the product model is TY03.

[0062] The preparation method of the low-carbon magnesia carbon brick for the ladle slag line in this example 3 is composed of the following steps:

[0063] (1) The raw materials are dried at 125℃ for 5.0h respectively;

[0064] (2) 98 # electrofused magnesia, 98 # electrofused magnesia, and 98 # electrofused magnesia are mixed for 7min, and 98 #The fused magnesia was mixed for 5 minutes to prepare the first mixture. Chromium carbide, rare earth composite and magnesium silicide were mixed for 3 minutes and then added to the first mixture and mixed for 6 minutes to prepare the second mixture. A fine powder mixture with a particle size <0.088mm and calcium hexaaluminate were added to the second mixture and mixed for 5 minutes to prepare the third mixture.

[0065] (3) Add flake graphite to the third mixture and mix for 3 min, then add phenolic resin binder and mix for 10 min to prepare a premix;

[0066] (4) The premixed material is loaded into the mold and pressed into shape. Then it is demolded, dried, sintered, and cooled to room temperature to prepare low carbon magnesia-carbon bricks for ladle slag lines.

[0067] in:

[0068] In step (2), the mixing speed for preparing the first mixture is 20 r / min and the mixing temperature is room temperature. The mixing speed for preparing the second mixture is 20 r / min and the mixing temperature is room temperature. The mixing speed for preparing the third mixture is 20 r / min and the mixing temperature is room temperature.

[0069] In step (3), the mixing speed when adding flake graphite is 18 r / min and the mixing temperature is room temperature. When adding phenolic resin binder, the mixing speed is 22 r / min and the mixing temperature is room temperature.

[0070] The pressure molding described in step (4) involves first pre-pressing at 10 MPa for 1 minute, and then holding at 45 MPa for 3 minutes.

[0071] The drying atmosphere described in step (4) is nitrogen. First, the temperature is kept at 103℃ for 8 hours, then at 145℃ for 12 hours, and finally at 198℃ for 6 hours.

[0072] The sintering atmosphere in step (4) is nitrogen. First, the temperature is increased from room temperature to 1000℃ at a heating rate of 3℃ / min, and then increased to 1480℃ at a heating rate of 4℃ / min and held for 7 hours.

[0073] The cooling to room temperature mentioned in step (4) is achieved by cooling from 1480°C to room temperature at a cooling rate of 2°C / min.

[0074] Comparative Example 1

[0075] The preparation method of the low-carbon magnesia-carbon bricks for ladle slag lines described in Comparative Example 1 is the same as that in Example 1, the only difference being the raw material composition. The low-carbon magnesia-carbon bricks for ladle slag lines described in Comparative Example 1, by mass percentage, have the following raw material composition: 98% by weight of materials with a particle size of 3mm ≤ particle size < 5mm. #Fused magnesite 20%, 2mm≤particle size<3mm 98 # Fused magnesite 13%, 1mm≤particle size<2mm 98 # Fused magnesite 18.5%, 0.088mm≤particle size1mm 98 # Fused magnesite 11.5%, fine powder mixture with particle size <0.088mm 26%, flake graphite 2.7%, phenolic resin binder 4.6%, chromic carbide 1.4%, rare earth complex 0.6%, siliconized magnesium 1.7%; wherein, in mass percentage, the fine powder mixture with particle size <0.088mm is composed of: 98 # Fused magnesite 63.5%, fused magnesia-calcia sand 13.5%, zircon sand 23%.

[0076] Comparative Example 2

[0077] The preparation method of the low-carbon magnesia-carbon brick for ladle slag line described in Comparative Example 2 is the same as that of Example 1, and the only difference lies in the raw material composition. The low-carbon magnesia-carbon brick for ladle slag line described in Comparative Example 2 is composed of, in mass percentage: 98 # Fused magnesite 20%, 2mm≤particle size<3mm 98 # Fused magnesite 13%, 1mm≤particle size<2mm 98 # Fused magnesite 18.2%, 0.088mm≤particle size1mm 98 # Fused magnesite 11.2%, fine powder mixture with particle size <0.088mm 26%, flake graphite 2.7%, phenolic resin binder 4.6%, calcium hexaluminate 2.0%, rare earth complex 0.6%, siliconized magnesium 1.7%; wherein, in mass percentage, the fine powder mixture with particle size <0.088mm is composed of: 98 # Fused magnesite 63.5%, fused magnesia-calcia sand 13.5%, zircon sand 23%.

[0078] Comparative Example 3

[0079] The preparation method of the low-carbon magnesia-carbon brick for ladle slag line described in Comparative Example 3 is the same as that of Example 1, and the only difference lies in the raw material composition. The low-carbon magnesia-carbon brick for ladle slag line described in Comparative Example 3 is composed of, in mass percentage: 98 # Fused magnesite 19.8%, 2mm≤particle size<3mm 98 # Fused magnesite 12.8%, 1mm≤particle size<2mm 98 # Fused magnesite 18%, 0.088mm≤particle size1mm 98 #Fused magnesia 11%, fine powder mixture with particle size <0.088 mm 26%, flake graphite 2.7%, phenolic resin binder 4.6%, calcium hexaluminate 2.0%, chromium carbide 1.4%, magnesium silicide 1.7%; wherein the fine powder mixture with particle size <0.088 mm consists of, by mass percentage:98 # Fused magnesia 63.5%, fused magnesia-calcia sand 13.5%, zirconia 23%.

[0080] Comparative Example 4

[0081] The preparation method of the low-carbon magnesia-carbon brick for ladle slag line in the present comparative example 4 is the same as that in Example 1, the only difference is that the raw material composition is different. The low-carbon magnesia-carbon brick for ladle slag line in the present comparative example 4 has the following raw material composition, by mass percentage:98 # Fused magnesia 20%, 2mm≤particle size<3mm 98 # Fused magnesia 13%, 1mm≤particle size<2mm 98 # Fused magnesia 18.5%, 0.088mm≤particle size1mm 98 # Fused magnesia 11.2%, fine powder mixture with particle size <0.088 mm 26%, flake graphite 2.7%, phenolic resin binder 4.6%, calcium hexaluminate 2.0%, chromium carbide 1.4%, rare earth compound 0.6%; wherein the fine powder mixture with particle size <0.088 mm consists of, by mass percentage:98 # Fused magnesia 63.5%, fused magnesia-calcia sand 13.5%, zirconia 23%.

[0082] The low-carbon magnesia-carbon bricks prepared in Examples 1-3 and Comparative Examples 1-4 were tested for performance, wherein the cold crushing strength was determined according to GB / T5072-2023 “Test Method for Cold Crushing Strength of Refractory Materials”; the hot modulus of rupture was tested according to GB / T 3002-2017 “Test Method for Hot Modulus of Rupture of Refractory Materials”, the heating condition was 1400℃*0.5h; the oxidation resistance was tested according to GB / T 13244 “Test Method for Oxidation Resistance of Carbon-Containing Refractory Materials”, the test condition was 1600*3h; the slag resistance was tested according to GB / T 8931-2017 “Test Method for Slag Resistance of Refractory Materials (Static Crucible Method)”, the test condition was 1600*3h; the results are shown in Table 1 below:

[0083] Table 1 Performance test results of low-carbon magnesia-carbon bricks

[0084]

[0085] From Table 1, it can be seen that the properties of the low-carbon magnesite carbon bricks prepared in Examples 1-3 are obviously superior to those of Comparative Examples 1-4. The properties of the low-carbon magnesite carbon bricks prepared in Comparative Examples 1-4 are decreased due to the absence of any one of calcium hexaluminate, chromium carbide, rare earth compound or magnesium silicide in the raw materials.

[0086] The above description is only the preferred embodiments of the present application, and does not limit the present application in any form. Although the present application has been disclosed with the preferred embodiments as above, it is not intended to limit the present application. Any person skilled in the art can make some changes or modifications to the above disclosed technical content to obtain equivalent embodiments with equivalent changes, without departing from the technical solution of the present application. Any modification, change and modification of the above embodiments, equivalent changes and modifications, which do not depart from the technical solution of the present application, are still within the scope of the technical solution of the present application.

Claims

1. A low-carbon magnesia-carbon brick for a ladle slag line, characterized by: The raw material composition in mass percent is as follows: 98 # Electrically fused magnesite 19.5-20.5%, 2 mm≤particle size<3 mm, 98 # Electrically fused magnesite 12.5-13.5%, 1 mm≤particle size<2 mm, 98 # Electrically fused magnesite 16-18%, 0.088 mm≤particle size<1 mm, 98 # Electrically fused magnesite 11-13%, fine powder mixture with particle size <0.088 mm 24-26%, flake graphite 2.7-2.9%, phenolic resin binder 4.6-5.2%, calcium hexaluminate 1.8-2.0%, chromium carbide 1.0-1.4%, rare earth complex 0.5-0.65%, magnesium silicide 1.6-1.7%; wherein the fine powder mixture with particle size <0.088 mm consists of the following raw materials in mass percent: 98 # Electrically fused magnesite 63-64%, electrically fused magnesia-calcia sand 12.5-13.5%, zircon 23-24%; The rare earth compound is prepared by putting cerium oxide and praseodymium oxide in a mass ratio of 7:3 into a mixer, and mixing at room temperature for 5 min at a speed of 20 r / min. The phenolic resin binder is composed of resol and boron phenolic resin, and the mass ratio of resol and boron phenolic resin is 8:

2. The two are stirred at room temperature for 20 min to mix uniformly to prepare the phenolic resin binder.

2. A method for producing the low-carbon magnesia-carbon brick for a ladle slag line according to claim 1, characterized by: The method comprises the following steps: (1) drying the raw materials at 120-125℃ for 5-5.3h; (2) 98 wt% of fused magnesia with a particle size of 3 mm < particle size < 5 mm # fused magnesia, 98 wt% of fused magnesia with a particle size of 2 mm < particle size < 3 mm # fused magnesia, and 98 wt% of fused magnesia with a particle size of 1 mm < particle size < 2 mm # fused magnesia were mixed for 5-7 min, and 98 wt% of fused magnesia with a particle size of 0.088 mm < particle size < 1 mm was added # The fused magnesia was continuously mixed for 5-7 min to obtain a first mixture, chromium carbide, a rare earth compound, and magnesium silicide were mixed for 3-5 min, and then added to the first mixture to continuously mix for 5-7 min to obtain a second mixture, and the fine powder mixture with a particle size < 0.088 mm and calcium hexaluminate were added to the second mixture to continuously mix for 5-7 min to obtain a third mixture; (3) adding flake graphite to the third mixture and mixing for 3-5 min, then adding the phenolic resin binder and mixing for 10-12 min to prepare a premix; (4) loading the premix into a mold for press molding, then demolding, drying, sintering, and cooling to room temperature to prepare the low-carbon magnesia carbon brick for slag line of a ladle.

3. The method of producing low-carbon magnesia-carbon brick for a ladle slag line according to claim 2, characterized by: The mixing speed in step (2) for preparing the first mixture is 20-22 r / min, the mixing temperature is room temperature, the mixing speed in step (3) for preparing the second mixture is 18-20 r / min, the mixing temperature is room temperature, and the mixing speed in step (4) for preparing the third mixture is 18-20 r / min, the mixing temperature is room temperature.

4. The method of producing a low-carbon magnesia-carbon brick for a ladle slag line according to claim 2, characterized by: The mixing speed in step (3) for adding flake graphite is 17-19 r / min, the mixing temperature is room temperature, the mixing speed in step (4) for adding the phenolic resin binder is 20-22 r / min, and the mixing temperature is room temperature.

5. The method of producing low-carbon magnesia-carbon brick for a ladle slag line according to claim 2, characterized by: The press molding in step (4) is first pre-pressing at a pressure of 10 MPa for 1 min, and then pressure-keeping at a pressure of 45 MPa for 3 min.

6. The method of producing low-carbon magnesia-carbon brick for a ladle slag line according to claim 2, characterized by: The drying atmosphere in step (4) is nitrogen, first keeping at 100-103℃ for 8 h, then keeping at 140-145℃ for 12 h, and finally keeping at 195-198℃ for 6 h.

7. The method of producing low-carbon magnesia-carbon brick for a ladle slag line according to claim 2, characterized by: The sintering atmosphere in step (4) is nitrogen, first heating from room temperature to 1000℃ at a heating rate of 3℃ / min, then heating to 1450-1480℃ at a heating rate of 4℃ / min and keeping for 7 h.

8. The method of producing low-carbon magnesia-carbon brick for a ladle slag line according to claim 2, characterized by: The cooling to room temperature in step (4) is from 1450-1480℃ to room temperature at a cooling rate of 2℃ / min.

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