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

Abstract

The invention belongs to the technical field of preparation of low-carbon magnesia carbon bricks, and particularly relates to a low-carbon magnesia carbon brick for a ladle slag line and a preparation method of the low-carbon magnesia carbon brick. According to the low-carbon magnesia carbon brick for the steel ladle slag line, 98 # fused magnesia with the particle size being larger than or equal to 3 mm and smaller than 5 mm, larger than or equal to 2 mm and smaller than 3 mm and larger than or equal to 1 mm and smaller than 2 mm serves as coarse aggregate, 98 # fused magnesia with the particle size being larger than or equal to 0.088 mm and smaller than 1 mm serves as medium aggregate, a mixture of 98 # fused magnesia with the particle size being smaller than 0.088 mm, fused magnesia-calcium sand and zircon sand serves as powder, crystalline flake graphite and a phenolic resin binding agent are added, and the low-carbon magnesia carbon brick for the steel ladle slag line is obtained through sintering. According to the low-carbon magnesia carbon brick for the steel ladle slag line, calcium hexaluminate, magnesium silicide, chromium carbide and a rare earth compound are used as additives, and the raw materials are mutually matched and have a synergistic effect, so that the prepared low-carbon magnesia carbon brick for the steel 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 reduction 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: (1) The raw materials are dried at 120-125 DEG C for 5-5.3 h respectively; (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. (3) The flake graphite is added to the third mixture and mixed for 3-5 min, and then the phenolic resin binder is added and mixed for 10-12 min to prepare a premix. (4) The premix is loaded into a mold for press molding, then demolding, drying, sintering, and cooling to room temperature to prepare the low-carbon magnesia-carbon brick for a ladle slag line.

[0010] Wherein: The mixing speed for preparing the first mixture in step (2) is 20-22 r / min, and the mixing temperature is room temperature; the mixing speed for preparing the second mixture is 18-20 r / min, and the mixing temperature is room temperature; and the mixing speed for preparing the third mixture is 18-20 r / min, and the mixing temperature is room temperature.

[0011] The mixing speed for adding flake graphite in step (3) is 17-19 r / min, and the mixing temperature is room temperature; and the mixing speed for adding the phenolic resin binder is 20-22 r / min, and the mixing temperature is room temperature.

[0012] 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.

[0013] 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.

[0014] The sintering atmosphere in step (4) is nitrogen, first heating from room temperature to 1000℃ at a heating rate of 3℃ / min, and then heating to 1450-1480℃ at a heating rate of 4℃ / min and keeping for 7 h.

[0015] The cooling to room temperature in step (4) is from 1450-1480℃ to room temperature at a cooling rate of 2℃ / min.

[0016] Compared with the prior art, the present application has the following beneficial effects: (1) The low-carbon magnesia-carbon brick for a ladle slag line has 98 # The fused magnesia is coarse aggregate, and the fused magnesia, the fused magnesia-calcium sand, and the zircon sand are 98 # The fused magnesia, the fused magnesia-calcium sand, and the 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, so that the raw materials cooperate with each other and synergistically act to ensure that the prepared low-carbon magnesia-carbon brick for a ladle slag line has excellent mechanical strength, oxidation resistance, and slag resistance.

[0017] (2) The low-carbon magnesia-carbon brick for the slag line of a steel ladle disclosed by the application is made of 98 # The fused magnesia is coarse aggregate, 98 # The content of magnesia in the fused magnesia is greater than or equal to 98%, the volume stability at high temperature is excellent, the coarse aggregate is distributed according to the three-level particle size hierarchy, a continuous and stable main skeleton structure is formed, and the high-temperature compressive strength and thermal shock stability of the low-carbon magnesia-carbon brick are directly ensured; the fused magnesia with a particle size of 0.088mm≤particle size<1mm is 98 # The fused magnesia is medium aggregate, after the medium aggregate is filled, the porosity of the coarse aggregate is reduced, a foundation for subsequent densification of the powder is laid, and the composition of the medium aggregate and the coarse aggregate is consistent, the structural integrity of the low-carbon magnesia-carbon brick is further improved, and the apparent porosity of the finished low-carbon magnesia-carbon brick is reduced; the fused magnesia with a particle size of <0.088mm is 98 # The mixture of the fused magnesia, the fused magnesia-calcium sand and the zircon sand is powder, and the content of the fused magnesia with a particle size of <0.088mm in the powder is 98 # The fused magnesia is filled in the micropores remaining in the medium aggregate, a dense matrix is formed, the content of MgO is supplemented, the ability to resist the corrosion of alkaline slag is strengthened, the fused magnesia-calcium sand powder provides a small amount of calcium oxide, reacts with silicon dioxide and ferrous oxide in the slag to generate a high-viscosity calcium silicate phase, plays a role in viscosity increase and slag resistance, the zircon sand powder is decomposed to generate zirconia at high temperature, reacts with calcium oxide to generate a calcium zirconate high-melting solid solution phase, forms an isolation layer on the slag-brick surface, blocks the penetration of the slag into the interior, and reduces the slag corrosion resistance rate. In this way, the coarse aggregate, the medium aggregate and the powder are synergized through the three-level cooperation of “skeleton support-pore filling-dense strengthening”, not only the mechanical strength of the low-carbon magnesia-carbon brick is ensured, but also the low-carbon magnesia-carbon brick has good slag resistance.

[0018] (3) The low-carbon magnesia-carbon brick for the slag line of a steel ladle disclosed by the application, the calcium hexaluminate, the magnesium silicide, the chromium carbide and the rare earth compound in the raw materials synergize to improve the oxidation resistance and the slag resistance of the low-carbon magnesia-carbon brick. The calcium hexaluminate has good hydration resistance and alkali corrosion resistance, the calcium hexaluminate reacts with SiO2 and FeO in the slag to generate a high-viscosity aluminosilicate phase, reduces the adhesion and penetration of the slag. The 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 circulates and chemically adsorbs residual O2, both of which complete oxygen inhibition in the whole temperature range. In addition, Cr2O3 reacts with MgO to generate magnesia-chromite spinel, the magnesia-chromite spinel has high Mohs hardness, and can improve the erosion resistance of the low-carbon magnesia-carbon brick. CeO2 in the rare earth compound changes from Ce 4+ / Ce 3+ O2 at a temperature higher than 1000℃, a large number of oxygen vacancies are generated, and O2 can be actively adsorbed (O 4+ Ce 3+ 2 is generated, and the low-carbon magnesia-carbon brick has good oxidation resistance and slag resistance.2- The magnesium silicide reduces the contact between O2 and carbon from the source, thereby playing an antioxidation role. The magnesium silicide is directly oxidized to generate MgO and SiO2 at a medium or low temperature, and the SiO2, B2O3 generated by the decomposition of the boron phenolic resin, and the oxidation product Cr2O3 of the chromium carbide form a borosilicate glass phase, and the liquid phase has a high viscosity and can tightly block the micropores and microcracks and block the secondary penetration of oxygen. The MgO generated by the oxidation of the magnesium silicide reacts with the trace Al2O3 in the matrix to generate magnesium aluminate spinel. During the slag resistance process, the magnesium aluminate spinel, the magnesium-chromium spinel, and the calcium hexaluminate interact, so that the prepared low-carbon magnesia carbon brick can resist the erosion and penetration of the molten slag for a long time. Thus, the synergistic effect among the calcium hexaluminate, the magnesium silicide, the chromium carbide, and the rare earth compound in the raw materials improves the oxidation resistance and the slag resistance of the low-carbon magnesia carbon brick.

[0019] (4) The preparation method of the low-carbon magnesia carbon brick for a ladle slag line has process parameters that are easy to control, and the prepared low-carbon magnesia carbon brick has stable performance. DETAILED DESCRIPTION

[0020] Example 1 The low-carbon magnesia carbon brick for a 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%, a fine powder mixture with a particle size of less than 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%, and magnesium silicide 1.7%; wherein the fine powder mixture with a particle size of less than 0.088 mm is composed of the following raw materials in mass percentage: 98 # fused magnesia 63.5%, fused magnesia-calcium sand 13.5%, and zircon sand 23%.

[0021] 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 20 r / min for 5 min.

[0022] 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 of MQ-8022 produced by Wuhan Meiqilin New Material Co., Ltd., and the boron phenolic resin is of TY03 produced by Lvlilian (Jinan) Chemical Technology Co., Ltd.

[0023] The preparation method of the low-carbon magnesia carbon brick for a ladle slag line according to the present embodiment 1 comprises the following steps: (1) The raw materials are dried at 123 ℃ for 5.2 h respectively; (2) 98 # fused magnesia with a particle size of 2 mm≤particle size<3 mm, 98 # fused magnesia with a particle size of 2 mm≤particle size<3 mm, 98 # fused magnesia with a particle size of 2 mm≤particle size<3 mm, 98 # fused magnesia with a particle size of 2 mm≤particle size<3 mm, 98 # fused magnesia with a particle size of 2 mm≤particle size<3 mm, 98 # fused magnesia with a particle size of 2 mm≤particle size<3 mm, 98 (3) The scale graphite is added to 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; (4) The premix is loaded into a mold for pressure molding, and then demolded for drying and sintering, and then cooled to room temperature to prepare the low-carbon magnesia carbon brick for a ladle slag line.

[0024] In the present embodiment, the following applies: In step (2), the first mixture is prepared at a mixing speed of 21 r / min and a mixing temperature of room temperature, the second mixture is prepared at a mixing speed of 19 r / min and a mixing temperature of room temperature, and the third mixture is prepared at a mixing speed of 19 r / min and a mixing temperature of room temperature.

[0025] In step (3), the scale graphite is added at a mixing speed of 19 r / min and a mixing temperature of room temperature, and the phenolic resin binder is added at a mixing speed of 21 r / min and a mixing temperature of room temperature.

[0026] In step (4), the pressure molding is first pre-pressed at a pressure of 10 MPa for 1 min, and then pressed at a pressure of 45 MPa for 3 min.

[0027] The drying atmosphere in step (4) is nitrogen, first at 101℃ for 8h, then at 143℃ for 12h, and finally at 197℃ for 6h.

[0028] The sintering atmosphere in step (4) is nitrogen, first at a heating rate of 3℃ / min from room temperature to 1000℃, then at a heating rate of 4℃ / min to 1465℃ for 7h.

[0029] The cooling to room temperature in step (4) is at a cooling rate of 2℃ / min from 1465℃ to room temperature.

[0030] Example 2 The low-carbon magnesia-carbon brick for the ladle slag line in this example 2 is composed of the following raw materials in mass percentage: 98 # fused magnesia, 98 # fused magnesia, 98 # fused magnesia, 98 # fused magnesia, 24% of fine powder mixture with particle size <0.088mm, 2.8% of flake 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 <0.088mm is composed of the following raw materials in mass percentage: 98 # fused magnesia, 12.5% of fused magnesia-calcium sand, and 23.5% of zircon.

[0031] 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 speed of 20r / min for 5min.

[0032] 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 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. with model number MQ-8022. The boron phenolic resin is produced by Lvlilian (Jining) Chemical Technology Co., Ltd. with product model number TY03.

[0033] The preparation method of the low-carbon magnesia-carbon brick for the ladle slag line in this example 2 is composed of the following steps: (1) The raw materials are dried at 120℃ for 5.3h respectively; (2) 98 # fused magnesia, 98# fused magnesia and 98% fused magnesia with a particle size of 1mm ≤ and 2mm # Mix fused magnesia for 5 minutes, then add 98% pure magnesia with a particle size of 0.088mm ≤ 1mm. # The fused magnesia was mixed for 7 minutes to prepare the first mixture. Chromium carbide, rare earth composite and magnesium silicide were mixed for 5 minutes and then added to the first mixture and mixed for 7 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 6 minutes to prepare the third mixture. (3) Add flake graphite to the third mixture and mix for 5 min, then add phenolic resin binder and mix for 12 min to prepare a premix; (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.

[0034] in: In step (2), the mixing speed for preparing the first mixture is 22 r / min and the mixing temperature is room temperature. The mixing speed for preparing the second mixture is 18 r / min and the mixing temperature is room temperature. The mixing speed for preparing the third mixture is 18 r / min and the mixing temperature is room temperature.

[0035] In step (3), the mixing speed when adding flake graphite is 17 r / min and the mixing temperature is room temperature. When adding phenolic resin binder, the mixing speed is 20 r / min and the mixing temperature is room temperature.

[0036] 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.

[0037] The drying atmosphere described in step (4) is nitrogen. First, the temperature is kept at 100℃ for 8 hours, then at 140℃ for 12 hours, and finally at 195℃ for 6 hours.

[0038] 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 1450℃ at a heating rate of 4℃ / min and held for 7 hours.

[0039] The cooling to room temperature mentioned in step (4) is achieved by cooling from 1450°C to room temperature at a cooling rate of 2°C / min.

[0040] Example 3 The low-carbon magnesia-carbon bricks for the ladle slag line described in Example 3 have the following raw material composition by mass percentage: 98% of the bricks have a particle size of 3mm ≤ particle size < 5mm. #Fused magnesite 20.5%, 98 # Fused magnesite 13.5%, 98 # Fused magnesite 16%, 98 # Fused magnesite 13%, fine powder mixture 24.5%, flake graphite 2.9%, phenolic resin binder 4.7%, calcium hexaluminate 1.8%, chromium carbide 1.0%, rare earth complex 0.5%, and magnesium silicide 1.6%; wherein, the fine powder mixture with particle size <0.088 mm is composed of the following raw materials in mass percentage: 98 # Fused magnesite 63%, fused magnesia-calcia sand 13%, and zircon 24%.

[0041] 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.

[0042] 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.

[0043] The preparation method of the low-carbon magnesia-carbon brick for a ladle slag line according to the present embodiment 3 comprises the following steps: (1) The raw materials are dried at 125℃ for 5.0 h respectively; (2) 98 # Fused magnesite, 98 # Fused magnesite, and 98 # Fused magnesite are mixed for 7 min, and 98 # The fused magnesite is continuously mixed for 5 min to prepare a first mixture. Chromium carbide, a rare earth complex, and magnesium silicide are mixed for 3 min and then added to the first mixture to be continuously mixed for 6 min to prepare a second mixture. A fine powder mixture with particle size <0.088 mm and calcium hexaluminate are added to the second mixture to be continuously mixed for 5 min to prepare a third mixture. (3) Flake graphite is added to the third mixture to be mixed for 3 min, and then a phenolic resin binder is added to be mixed for 10 min to prepare a premix; (4) The premix is loaded into a mold for press molding, then demolded for drying, sintering, and cooling to room temperature to prepare the low-carbon magnesia-carbon brick for ladle slag line.

[0044] wherein: The mixing speed in step (2) is 20 r / min, and the mixing temperature is room temperature.

[0045] The mixing speed in step (3) is 18 r / min when the flake graphite is added, and the mixing temperature is room temperature; and the mixing speed is 22 r / min when the phenolic resin binder is added, and the mixing temperature is room temperature.

[0046] The press molding in step (4) is first pre-pressing at 10 MPa for 1 min, and then pressure-keeping at 45 MPa for 3 min.

[0047] The drying atmosphere in step (4) is nitrogen, first keeping at 103℃ for 8 h, then keeping at 145℃ for 12 h, and finally keeping at 198℃ for 6 h.

[0048] The sintering atmosphere in step (4) is nitrogen, first heating from room temperature to 1000℃ at a heating rate of 3℃ / min, and then heating to 1480℃ at a heating rate of 4℃ / min and keeping for 7 h.

[0049] The cooling to room temperature in step (4) is from 1480℃ to room temperature at a cooling rate of 2℃ / min.

[0050] Comparative Example 1 The preparation method of the low-carbon magnesia-carbon brick for ladle slag line in Comparative Example 1 is the same as that in Example 1, and the only difference is that the raw material composition is different. The raw material composition of the low-carbon magnesia-carbon brick for ladle slag line in Comparative Example 1 is as follows, in mass percentage: 98 # fused magnesia 20%, 98 # fused magnesia 13%, 98 # fused magnesia 18.5%, 98 # fused magnesia 11.5%, fine powder mixture with particle size <0.088 mm 26%, flake graphite 2.7%, phenolic resin binder 4.6%, chromium carbide 1.4%, rare earth complex 0.6%, and magnesium silicide 1.7%; wherein, the fine powder mixture with particle size <0.088 mm is composed of the following raw materials, in mass percentage: 98 #Fused magnesite 63.5%, fused magnesia-calcia 13.5%, zirconia 23%.

[0051] Comparative Example 2 The preparation method of the low-carbon magnesia-carbon brick for ladle slag line in the present comparative example 2 is the same as that in Example 1, the only difference is that the raw material composition is different. The raw material composition of the low-carbon magnesia-carbon brick for ladle slag line in the present comparative example 2 is shown as follows in mass percentage: 98 # Fused magnesite 63.5%, fused magnesia-calcia 13.5%, zirconia 23%. # Fused magnesite 63.5%, fused magnesia-calcia 13.5%, zirconia 23%. # Fused magnesite 63.5%, fused magnesia-calcia 13.5%, zirconia 23%. # Fused magnesite 63.5%, fused magnesia-calcia 13.5%, zirconia 23%. # Fused magnesite 63.5%, fused magnesia-calcia 13.5%, zirconia 23%.

[0052] Comparative Example 3 The preparation method of the low-carbon magnesia-carbon brick for ladle slag line in the present comparative example 3 is the same as that in Example 1, the only difference is that the raw material composition is different. The raw material composition of the low-carbon magnesia-carbon brick for ladle slag line in the present comparative example 3 is shown as follows in mass percentage: 98 # Fused magnesite 63.5%, fused magnesia-calcia 13.5%, zirconia 23%. # Fused magnesite 63.5%, fused magnesia-calcia 13.5%, zirconia 23%. # Fused magnesite 63.5%, fused magnesia-calcia 13.5%, zirconia 23%. # Fused magnesite 63.5%, fused magnesia-calcia 13.5%, zirconia 23%. # Fused magnesite 63.5%, fused magnesia-calcia 13.5%, zirconia 23%.

[0053] Comparative Example 4 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 raw material composition of the low-carbon magnesia-carbon brick for ladle slag line in the present comparative example 4 is shown as follows in mass percentage: 98# Electric fused magnesia 20%, 2mm≤particle size<3mm 98 # Electric fused magnesia 13%, 1mm≤particle size<2mm 98 # Electric fused magnesia 18.5%, 0.088mm≤particle size1mm 98 # Electric fused magnesia 11.2%, 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%; wherein, the fine powder mixture with particle size <0.088mm is composed of the following raw materials in mass percentage: 98 # Electric fused magnesia 63.5%, electric fused magnesia-calcium sand 13.5%, zircon 23%.

[0054] The low-carbon magnesia-carbon bricks prepared in Examples 1-3 and Comparative Examples 1-4 were subjected to performance tests, 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 being 1400℃*0.5h; the oxidation resistance was tested according to GB / T 13244 “Test Method for Oxidation Resistance of Carbon-containing Refractory Materials”, the testing condition being 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 testing condition being 1600*3h; and the results are shown in Table 1 below: Table 1 Performance test results of low-carbon magnesia-carbon bricks

[0055] As can be seen from Table 1, the performance of the low-carbon magnesia-carbon bricks prepared in Examples 1-3 is obviously superior to that of Comparative Examples 1-4. The absence of any one of calcium hexaluminate, chromium carbide, rare earth complex or siliconized magnesium in the raw materials of Comparative Examples 1-4 results in the performance of the prepared low-carbon magnesia-carbon bricks being reduced.

[0056] The above description is only the preferred embodiments of the present application and is not intended to 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 make equivalent embodiments with equivalent changes, as long as they do not deviate from the technical solution of the present application. Any modification, equivalent change and modification made to the above embodiments according to the technical essence 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 steel ladle slag lines, characterized in that: The raw material composition, by mass percentage, is as follows: 98% of particles with a size between 3mm and 5mm. # 98% fused magnesia, 19.5-20.5% purity, with a particle size of 2mm ≤ and 3mm. # 98% fused magnesia, 12.5-13.5% purity, particle size ≤ 1mm < 2mm. # 98% fused magnesia, 16-18% purity, with a particle size of 0.088mm ≤ 1mm. # The mixture comprises 11-13% fused magnesia, 24-26% fine powder with a particle size <0.088mm, 2.7-2.9% flake graphite, 4.6-5.2% phenolic resin binder, 1.8-2.0% calcium hexaaluminate, 1.0-1.4% chromium carbide, 0.5-0.65% rare earth composite, and 1.6-1.7% magnesium silicide; wherein, by mass percentage, the fine powder mixture with a particle size <0.088mm is composed of the following raw materials: 98 # Fused magnesia 63-64%, fused magnesia-calcium sand 12.5-13.5%, zircon sand 23-24%.

2. The low-carbon magnesia-carbon brick for ladle slag lines according to claim 1, characterized in that: The rare earth composite was prepared by mixing cerium oxide and praseodymium oxide in a mixer at a mass ratio of 7:3 at room temperature for 5 minutes at a speed of 20 r / min.

3. The low-carbon magnesia-carbon brick for ladle slag lines according to claim 1, characterized in that: The phenolic resin binder is composed of methyl phenolic resin and boron phenolic resin, with a mass ratio of methyl phenolic resin to boron phenolic resin of 8:

2. The two are stirred at room temperature for 20 minutes to mix evenly and obtain the phenolic resin binder.

4. A method for preparing low-carbon magnesia-carbon bricks for ladle slag lines as described in claim 1, characterized in that: It consists of the following steps: (1) Dry the raw materials at 120-125℃ for 5-5.3 hours; (2) 98% of particles with a particle size of 3mm ≤ particle size < 5mm # fused magnesia, 98% molten magnesia with a particle size of 2mm ≤ and 3mm. # fused magnesia and 98% fused magnesia with a particle size of 1mm ≤ and 2mm # Mix fused magnesia for 5-7 minutes, then add 98% pure magnesia with a particle size of 0.088mm ≤ 1mm. # Continue mixing the fused magnesia for 5-7 minutes to prepare the first mixture. Mix chromium carbide, rare earth composite and magnesium silicide for 3-5 minutes, then add them to the first mixture and continue mixing for 5-7 minutes to prepare the second mixture. Add the fine powder mixture with a particle size <0.088mm and calcium hexaaluminate to the second mixture and continue mixing for 5-7 minutes to prepare the third mixture. (3) Add flake graphite to the third mixture and mix for 3-5 min, then add phenolic resin binder and mix for 10-12 min to prepare a premix. (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.

5. The method for preparing low-carbon magnesia-carbon bricks for ladle slag lines according to claim 4, characterized in that: In step (2), the mixing speed for preparing the first mixture is 20-22 r / min and the mixing temperature is room temperature. The mixing speed for preparing the second mixture is 18-20 r / min and the mixing temperature is room temperature. The mixing speed for preparing the third mixture is 18-20 r / min and the mixing temperature is room temperature.

6. The method for preparing low-carbon magnesia-carbon bricks for ladle slag lines according to claim 4, characterized in that: In step (3), the mixing speed when adding flake graphite is 17-19 r / min and the mixing temperature is room temperature. When adding phenolic resin binder, the mixing speed is 20-22 r / min and the mixing temperature is room temperature.

7. The method for preparing low-carbon magnesia-carbon bricks for ladle slag lines according to claim 4, characterized in that: 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.

8. The method for preparing low-carbon magnesia-carbon bricks for ladle slag lines according to claim 4, characterized in that: The drying atmosphere described in step (4) is nitrogen. First, the temperature is kept at 100-103℃ for 8 hours, then at 140-145℃ for 12 hours, and finally at 195-198℃ for 6 hours.

9. The method for preparing low-carbon magnesia-carbon bricks for ladle slag lines according to claim 4, characterized in that: 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 1450-1480℃ at a heating rate of 4℃ / min and held for 7 hours.

10. The method for preparing low-carbon magnesia-carbon bricks for ladle slag lines according to claim 4, characterized in that: The cooling to room temperature mentioned in step (4) is achieved by cooling from 1450-1480℃ to room temperature at a cooling rate of 2℃ / min.

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