A low-carbon magnesia-carbon brick for slag line of refining ladle, its preparation method and application

Abstract

The invention discloses a low-carbon magnesia-carbon brick for the slag line of a refining ladle, its preparation method and application, belonging to the technical fields of metallurgy and refractories. The magnesia-carbon brick is prepared from the following raw materials in parts by weight: 20-25 parts of 98% ordinary fused magnesia with a particle size of 3-5 mm, 25-35 parts of 98% ordinary fused magnesia with a particle size of 1-3 mm, 20-25 parts of 98% ordinary fused magnesia with a particle size of 0-1 mm, 0-10 parts of 98% ordinary fused magnesia with a particle size of ≤0.074 mm, 10-15 parts of tantalum carbide powder with a particle size of ≤0.045 mm, 1-5 parts of tungsten metal powder with a particle size of ≤0.045 mm, 1-3 parts of graphite powder with a particle size of ≤0.15 mm, and 2-3 parts of binder. The low-carbon magnesia-carbon brick for the slag line of the refining ladle in the invention has a long service life, excellent resistance to molten slag erosion, excellent thermal shock performance and excellent high-temperature performance.

Description

Technical Field

[0001] The present invention belongs to the technical fields of metallurgy and refractories, and relates to a low-carbon magnesia-carbon brick for the slag line of a refining ladle, a preparation method thereof, and an application thereof. Background Art

[0002] The molten steel ladle is used in steel mills and foundries to receive molten steel in front of open-hearth furnaces, electric furnaces or converters, for secondary refining outside the furnace, and for continuous casting pouring operations. The ladle plays a very important role in the iron and steel metallurgy system, and the service life of the ladle directly determines the smelting efficiency.

[0003] In the past decade, with the structural adjustment and industrial upgrading of iron and steel enterprises, high-quality steel varieties have become the leading products of large enterprises. For example: the proportion of steel grades such as high-quality alloy steel, ultra-low carbon steel, clean steel, and high-strength steel has increased year by year. The carbon content requirements are strict during the smelting of high-quality steel varieties. Further, it is required that the lining refractory of the refining ladle be low-carbon and carbon-free to reduce the carbon addition to the molten steel and prevent secondary pollution of the molten steel by the lining refractory of the refining ladle.

[0004] At present, the bottom and wall lining refractories of the working lining of large and medium-sized refining ladles in China have basically been carbon-free, and the following methods are adopted: 1. The working lining of the ladle bottom and the working lining of the ladle wall use carbon-free corundum spinel castables. 2. The working lining of the ladle bottom and the working lining of the ladle wall use carbon-free corundum spinel precast blocks. 3. The working lining of the ladle bottom uses a carbon-free corundum spinel castable, and the working lining of the ladle wall uses a carbon-free corundum spinel precast block.

[0005] Restricted by the harsh smelting environment at the slag surface of the refining ladle, at present, the slag line part of the working lining of the refining ladle is still mainly magnesia-carbon bricks. The total carbon content of ordinary magnesia-carbon bricks for the slag line of the ladle is generally 10-18%. During the secondary refining of molten steel, it is extremely easy to cause secondary carbon addition to the molten steel, resulting in secondary pollution to the molten steel. Moreover, during secondary refining, the temperature of the molten steel should increase and decrease slightly, and the thermal conductivity of the ladle lining should be low. Therefore, the use conditions of the refining ladle are more demanding and the working environment is more severe. There is an urgent need for the emergence of high-quality low-carbon magnesia-carbon bricks for the slag line of the refining ladle that are pollution-free to molten steel and highly durable.

[0006] One of the main reasons for the damage of the low-carbon magnesia-carbon brick for the slag line of the refining ladle is that after the carbon content is reduced, the carbon in the brick is more prone to oxidation, so that the steel slag is more likely to penetrate, resulting in increased erosion. At the same time, after the carbon content in the magnesia-carbon brick is reduced, the thermal shock resistance decreases significantly, and phenomena such as fracture and spalling are likely to occur during use. However, the current research on low-carbon magnesia-carbon bricks mainly focuses on the research of raw materials such as metal additives, oxides and non-oxides additives, and nano-carbon, and there is no research on forming special ceramic bonds inside the low-carbon slag line magnesia-carbon bricks to improve the use performance.

[0007] Therefore, how to develop a low-carbon magnesia-carbon brick for the slag line of a refining ladle that forms a special metal-ceramic bond inside at the service temperature (about 1600 - 1650 °C), has excellent slag erosion resistance, excellent thermal shock resistance, and excellent high-temperature performance, as well as its preparation method and application, are problems that those skilled in the art urgently need to solve. Summary of the Invention

[0008] In view of this, the present invention provides a low-carbon magnesia-carbon brick for the slag line of a refining ladle, its preparation method, and its application.

[0009] In order to achieve the above object, the present invention adopts the following technical solutions:

[0010] A low-carbon magnesia-carbon brick for the slag line of a refining ladle is prepared from the following raw materials in parts by weight:

[0011] 20 - 25 parts of 98% ordinary fused magnesia with a particle size of 3 - 5 mm, 25 - 35 parts of 98% ordinary fused magnesia with a particle size of 1 - 3 mm, 20 - 25 parts of 98% ordinary fused magnesia with a particle size of 0 - 1 mm, 0 - 10 parts of 98% ordinary fused magnesia with a particle size of ≤0.074 mm, 10 - 15 parts of tantalum carbide powder with a particle size of ≤0.045 mm, 1 - 5 parts of tungsten metal powder with a particle size of ≤0.045 mm, 1 - 3 parts of graphite powder with a particle size of ≤0.15 mm, and 2 - 3 parts of binder.

[0012] Further, in the above 98% ordinary fused magnesia, the content of MgO is > 98 wt%, and the content of SiO2 is < 1.0 wt%.

[0013] Further, in the above tantalum carbide powder, the content of tantalum carbide is ≥99.5 wt%.

[0014] Further, in the above tungsten metal powder, the content of tungsten metal is ≥99.5 wt%.

[0015] Further, in the above graphite powder, the content of carbon is ≥98 wt%.

[0016] Further, the above binder is liquid phenolic resin, and the residual carbon of the above liquid phenolic resin is ≥40 wt%, the moisture content is ≤3.0 wt%, and the viscosity is 16000 - 19000 cps at 25 °C.

[0017] The present invention also provides a preparation method for a low-carbon magnesia-carbon brick for the slag line of a refining ladle, including the following steps:

[0018] 1) Weighing: Weigh each raw material according to the above-mentioned low-carbon magnesia-carbon brick for the refining ladle slag line. Mix 98% ordinary fused magnesia with a particle size of 3 - 5 mm, 98% ordinary fused magnesia with a particle size of 1 - 3 mm, 98% ordinary fused magnesia with a particle size of 0 - 1 mm, 98% ordinary fused magnesia with a particle size of ≤0.074 mm, tantalum carbide powder with a particle size of ≤0.045 mm, tungsten metal powder with a particle size of ≤0.045 mm, and graphite powder with a particle size of ≤0.15 mm to obtain a mixed material.

[0019] 2) Kneading: Put the obtained mixed material into a high-speed kneader for kneading. First, start low-speed kneading, then add the binder, and then start high-speed kneading to obtain a mud material.

[0020] 3) Machine pressing and forming: Put the obtained mud material into a mold for the low-carbon slag line magnesia-carbon brick of the ladle and press it by machine to obtain a low-carbon slag line magnesia-carbon brick blank.

[0021] 4) Drying: Dry the obtained brick blank to produce a low-carbon magnesia-carbon brick for the refining ladle slag line.

[0022] Furthermore, in step 2), first start low-speed kneading for more than 3 minutes, preferably 4 - 6 minutes, then add the binder, and then start high-speed kneading for 20 - 30 minutes, and the temperature of the mud material is 35 - 55 °C.

[0023] Furthermore, in step 2), the low-speed kneading speed is 60 rpm, and the high-speed kneading speed is 120 rpm.

[0024] The beneficial effect of adopting the above further technical solution is that at low speed, it is beneficial for the resin to wrap the aggregate, and at high speed, it is beneficial for graphite to adhere to the resin, enabling the graphite to fully wrap the aggregate and making the fine particles more uniform, while raising the temperature of the mud material to obtain the best forming strength.

[0025] Furthermore, in step 3), the pressure for high-pressure forming is 8300 - 1500 KN, and it is pressed 3 - 5 times.

[0026] The beneficial effect of adopting the above further technical solution is that the obtained brick blank has a compressive strength of 50 - 60 Mpa and a bulk density of 3.02 - 3.06 g / cm 3 .

[0027] Furthermore, in step 4), the drying temperature is 150 - 180 °C, and the drying time is 8 - 12 h.

[0028] The beneficial effect of adopting the above further technical solution is that it cures the phenolic resin binder to obtain sufficient strength.

[0029] The present invention also provides an application of the above-mentioned low-carbon magnesia-carbon brick for the refining ladle slag line or the low-carbon magnesia-carbon brick for the refining ladle slag line prepared by the above method in the slag line part of the refining ladle.

[0030] Advantages of the present invention: 1) The present invention avoids the addition of metallic aluminum powder and other metal antioxidants (which are also sintering agents themselves). At the service temperature (1600 - 1650 °C), there will be no volume expansion caused by the reaction between the molten metal and other substances in the brick (for example, the addition of metallic aluminum powder will cause a 7% volume expansion due to the reaction of magnesium aluminate spinel at the service temperature (1600 - 1650 °C)), enabling a dense sintered body to be obtained inside the low-carbon slag line magnesia-carbon brick for refining ladles. This increases the bulk density of the low-carbon slag line magnesia-carbon brick for refining ladles and reduces the porosity, closing the penetration and erosion channels of molten steel and steel slag, thereby improving the resistance of the low-carbon slag line magnesia-carbon brick for refining ladles to the penetration and erosion of molten steel and steel slag.

[0031] 2) The present invention introduces tantalum carbide, tungsten metal, and graphite into the matrix. When the low-carbon magnesia-carbon brick for the slag line of the refining ladle is at the service temperature (1600 - 1650 °C) and the inside of the brick is in a reducing atmosphere, a special cermet structure of tantalum carbide - tungsten metal is formed. The formation of the tantalum carbide - tungsten metal ceramic structure enables the low-carbon slag line magnesia-carbon brick for refining ladles to form a well-developed organizational structure, obtain a dense sintered body, increase the high-temperature hot strength of the low-carbon slag line magnesia-carbon brick for refining ladles, and thus improve the resistance of the low-carbon slag line magnesia-carbon brick for refining ladles to the erosion by molten steel and the thermal shock stability under sudden temperature changes.

[0032] 3) The low-carbon magnesia-carbon brick for the slag line of the refining ladle prepared by the present invention is tested: the erosion index in the static crucible method for slag resistance at 1600 °C is 2% - 3%, and the penetration index is 4 - 6%. The existing low-carbon magnesia-carbon brick for the slag line of the refining ladle is tested: the erosion index in the static crucible method for slag resistance at 1600 °C is 10% - 15%, and the penetration index is 15% - 23%.

[0033] 4) The low-carbon magnesia-carbon brick for the slag line of the refining ladle prepared by the present invention is tested: the flexural strength under hot state at 1400 °C * 30 min is 25 - 35 Mpa. The existing low-carbon magnesia-carbon brick for the slag line of the refining ladle is tested: the flexural strength under hot state at 1400 °C * 30 min is 15 - 18 Mpa.

[0034] 5) The low-carbon magnesia-carbon brick for the slag line of the refining ladle prepared by the present invention is tested: after being air-quenched rapidly 8 times at 1100 °C * 20 min, the residual strength is 35 - 40 Mpa. The existing low-carbon magnesia-carbon brick for the slag line of the refining ladle is tested: after being air-quenched rapidly 8 times at 1100 °C * 20 min, the residual strength is 20 - 25 Mpa.

[0035] 6) Therefore, compared with the existing low-carbon slag line magnesia-carbon bricks for refining ladles, the low-carbon slag line magnesia-carbon bricks of the present invention have excellent resistance to molten slag erosion, excellent thermal shock performance, and excellent high-temperature performance. The prepared low-carbon slag line magnesia-carbon bricks for refining ladles are actually applied to a 100-ton ladle in a certain branch factory of Angang Steel. The average service life is 45 times, while the average service life of the existing low-carbon slag line magnesia-carbon bricks for refining ladles is 30 times. The service life is significantly higher than that of the existing low-carbon slag line magnesia-carbon bricks for refining ladles. It improves the utilization rate of the refining ladle, reduces the average cost of the refining ladle, and makes the production organization of the steel plant run more smoothly. Detailed implementation mode

[0036] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0037] Embodiment 1

[0038] A preparation method of a low-carbon magnesia-carbon brick for the slag line of a refining ladle includes the following steps:

[0039] 1) Weighing: Weigh 23 kg of 98 ordinary fused magnesia with a particle size of 3 - 5 mm, 30 kg of 98 ordinary fused magnesia with a particle size of 1 - 3 mm, 23 kg of 98 ordinary fused magnesia with a particle size of 0 - 1 mm, 7.5 kg of 98 ordinary fused magnesia with a particle size of ≤0.074 mm, 10 kg of tantalum carbide powder with a particle size of ≤0.045 mm, 1 kg of tungsten metal powder with a particle size of ≤0.045 mm, 3 kg of graphite powder with a particle size of ≤0.15 mm, and 2.5 kg of binder;

[0040] In the 98 ordinary fused magnesia, the content of MgO is >98 wt%, and the content of SiO2 is <1.0 wt%; in the tantalum carbide powder, the content of tantalum carbide is ≥99.5 wt%; in the tungsten metal powder, the content of tungsten metal is ≥99.5 wt%. In the graphite powder, the content of carbon is ≥98 wt%; the binder is liquid phenolic resin, the residual carbon of the liquid phenolic resin is ≥40 wt%, the moisture content is ≤3.0 wt%, and the viscosity is 16000 - 19000, 25 °C (cps);

[0041] Mix all the 98 ordinary fused magnesia, tantalum carbide powder, tungsten metal powder, and graphite powder to obtain a mixture;

[0042] 2) Kneading: Put the obtained mixture into a high-speed kneader for kneading. First, start kneading at low speed for 5 minutes, then add the binder, and then start kneading at high speed for 25 minutes. The temperature of the mud is 50°C, the rotation speed of low-speed kneading is 60 rpm, and the rotation speed of high-speed kneading is 120 rpm to obtain the mud;

[0043] 3) Machine pressing and forming: Put the obtained mud into a tundish low-carbon slag line magnesia-carbon brick mold for machine pressing and forming. Use a 1000-ton electric screw brick press, the forming pressure is 1500 KN, and press 5 times to obtain a low-carbon slag line magnesia-carbon brick blank with a compressive strength of 50 - 60 Mpa and a bulk density of 3.02 - 3.06 g / cm 3 ;

[0044] 4) Drying: Dry the obtained brick blank at a drying temperature of 180°C for 10 hours to obtain a low-carbon magnesia-carbon brick for the slag line of a refining ladle.

[0045] Example 2

[0046] A preparation method of a low-carbon magnesia-carbon brick for the slag line of a refining ladle, comprising the following steps:

[0047] 1) Weighing: Weigh 23 kg of 98% ordinary fused magnesia with a particle size of 3 - 5 mm, 30 kg of 98% ordinary fused magnesia with a particle size of 1 - 3 mm, 23 kg of 98% ordinary fused magnesia with a particle size of 0 - 1 mm, 5.5 kg of 98% ordinary fused magnesia with a particle size of ≤0.074 mm, 11 kg of tantalum carbide powder with a particle size of ≤0.045 mm, 2 kg of tungsten metal powder with a particle size of ≤0.045 mm, 3 kg of graphite powder with a particle size of ≤0.15 mm, and 2.5 kg of binder;

[0048] In the 98% ordinary fused magnesia, the content of MgO is > 98 wt%, and the content of SiO2 is < 1.0 wt%; in the tantalum carbide powder, the content of tantalum carbide is ≥ 99.5 wt%; in the tungsten metal powder, the content of tungsten metal is ≥ 99.5 wt%. In the graphite powder, the carbon content is ≥ 98 wt%; the binder is liquid phenolic resin, the residual carbon of the liquid phenolic resin is ≥ 40 wt%, the moisture content is ≤ 3.0 wt%, and the viscosity is 16000 - 19000, 25°C (cps);

[0049] Mix all the 98% ordinary fused magnesia, tantalum carbide powder, tungsten metal powder and graphite powder to obtain a mixture;

[0050] 2) Kneading: Put the obtained mixture into a high-speed kneader for kneading. First, start kneading at low speed for 5 minutes, then add the binder, and then start kneading at high speed for 25 minutes. The temperature of the mud is 50°C, the rotation speed of low-speed kneading is 60 rpm, and the rotation speed of high-speed kneading is 120 rpm to obtain the mud;

[0051] 3) Machine pressing: Put the obtained mud into the mold of the ladle low-carbon slag line magnesia-carbon brick and press it into shape by machine. Use a 1000-ton electric screw brick press, with a forming pressure of 1500 KN, and press 5 times to obtain a low-carbon slag line magnesia-carbon brick blank with a compressive strength of 50 - 60 Mpa and a bulk density of 3.02 - 3.06 g / cm 3 of the low-carbon slag line magnesia-carbon brick blank;

[0052] 4) Drying: Dry the obtained brick blank at a drying temperature of 180 °C for 10 h to produce a low-carbon magnesia-carbon brick for the slag line of the refining ladle.

[0053] Example 3

[0054] Preparation method of a low-carbon magnesia-carbon brick for the slag line of a refining ladle, comprising the following steps:

[0055] 1) Weighing: Weigh 23 kg of 98 ordinary fused magnesia with a particle size of 3 - 5 mm, 30 kg of 98 ordinary fused magnesia with a particle size of 1 - 3 mm, 23 kg of 98 ordinary fused magnesia with a particle size of 0 - 1 mm, 3.5 kg of 98 ordinary fused magnesia with a particle size of ≤0.074 mm, 12 kg of tantalum carbide powder with a particle size of ≤0.045 mm, 3 kg of tungsten metal powder with a particle size of ≤0.045 mm, 3 kg of graphite powder with a particle size of ≤0.15 mm, and 2.5 kg of binder;

[0056] In the 98 ordinary fused magnesia, the content of MgO is >98 wt%, and the content of SiO2 is <1.0 wt%; in the tantalum carbide powder, the content of tantalum carbide is ≥99.5 wt%; in the tungsten metal powder, the content of tungsten metal is ≥99.5 wt%. In the graphite powder, the carbon content is ≥98 wt%; the binder is liquid phenolic resin, the residual carbon of the liquid phenolic resin is ≥40 wt%, the water content is ≤3.0 wt%, and the viscosity is 16000 - 19000, 25 °C (cps);

[0057] Mix all the 98 ordinary fused magnesia, tantalum carbide powder, tungsten metal powder and graphite powder to obtain a mixture;

[0058] 2) Kneading: Put the obtained mixture into a high-speed kneader for kneading. First, start low-speed kneading for 5 min, then add the binder, and then start high-speed kneading for 25 min. The temperature of the mud is 50 °C, the low-speed kneading speed is 60 rpm, and the high-speed kneading speed is 120 rpm to obtain the mud;

[0059] 3) Machine pressing: Put the obtained mud into the mold of the ladle low-carbon slag line magnesia-carbon brick and press it into shape by machine. Use a 1000-ton electric screw brick press, with a forming pressure of 1500 KN, and press 5 times to obtain a low-carbon slag line magnesia-carbon brick blank with a compressive strength of 50 - 60 Mpa and a bulk density of 3.02 - 3.06 g / cm 3 of the low-carbon slag line magnesia-carbon brick blank;

[0060] 4) Drying: The obtained green bricks are dried at a drying temperature of 180 °C for 10 h to obtain the low-carbon magnesia-carbon bricks for the slag line of refined ladles.

[0061] Example 4

[0062] A preparation method of low-carbon magnesia-carbon bricks for the slag line of refined ladles, comprising the following steps:

[0063] 1) Weighing: Weigh 23 kg of 98% ordinary fused magnesia with a particle size of 3 - 5 mm, 30 kg of 98% ordinary fused magnesia with a particle size of 1 - 3 mm, 23 kg of 98% ordinary fused magnesia with a particle size of 0 - 1 mm, 2.5 kg of 98% ordinary fused magnesia with a particle size of ≤0.074 mm, 13 kg of tantalum carbide powder with a particle size of ≤0.045 mm, 3 kg of tungsten metal powder with a particle size of ≤0.045 mm, 3 kg of graphite powder with a particle size of ≤0.15 mm, and 2.5 kg of binder;

[0064] In the 98% ordinary fused magnesia, the content of MgO is >98 wt%, and the content of SiO2 is <1.0 wt%; in the tantalum carbide powder, the content of tantalum carbide is ≥99.5 wt%; in the tungsten metal powder, the content of tungsten metal is ≥99.5 wt%. In the graphite powder, the carbon content is ≥98 wt%; the binder is liquid phenolic resin, the residual carbon of the liquid phenolic resin is ≥40 wt%, the moisture content is ≤3.0 wt%, and the viscosity is 16000 - 19000, 25 °C (cps);

[0065] Mix all the 98% ordinary fused magnesia, tantalum carbide powder, tungsten metal powder and graphite powder to obtain a mixture

[0066] 2) Kneading: Put the obtained mixture into a high-speed kneader for kneading. First, knead at low speed for 5 min, then add the binder, and then knead at high speed for 25 min. The temperature of the mud is 50 °C, the rotation speed of low-speed kneading is 60 rpm, and the rotation speed of high-speed kneading is 120 rpm to obtain the mud;

[0067] 3) Machine pressing and forming: Put the obtained mud into the mold of low-carbon slag line magnesia-carbon bricks for ladles for machine pressing and forming. Use a 1000-ton electric screw brick press, the forming pressure is 1500 KN, and press 5 times to obtain low-carbon slag line magnesia-carbon bricks with a compressive strength of 50 - 60 Mpa and a bulk density of 3.02 - 3.06 g / cm 3 of green bricks;

[0068] 4) Drying: The obtained green bricks are dried at a drying temperature of 180 °C for 10 h to obtain the low-carbon magnesia-carbon bricks for the slag line of refined ladles.

[0069] Example 5

[0070] 1) Weighing: Weigh 20 kg of 98% ordinary fused magnesia with a particle size of 3 - 5 mm, 35 kg of 98% ordinary fused magnesia with a particle size of 1 - 3 mm, 20 kg of 98% ordinary fused magnesia with a particle size of 0 - 1 mm, 1.5 kg of 98% ordinary fused magnesia with a particle size of ≤0.074 mm, 15 kg of tantalum carbide powder with a particle size of ≤0.045 mm, 5 kg of tungsten metal powder with a particle size of ≤0.045 mm, 1 kg of graphite powder with a particle size of ≤0.15 mm, and 2.5 kg of binder;

[0071] In the 98% ordinary fused magnesia, the content of MgO is >98 wt%, and the content of SiO2 is <1.0 wt%; in the tantalum carbide powder, the content of tantalum carbide is ≥99.5 wt%; in the tungsten metal powder, the content of tungsten metal is ≥99.5 wt%. In the graphite powder, the carbon content is ≥98 wt%; the binder is liquid phenolic resin, the residual carbon of the liquid phenolic resin is ≥40 wt%, the moisture content is ≤3.0 wt%, and the viscosity is 16000 - 19000, 25℃ (cps);

[0072] Mix all the 98% ordinary fused magnesia, tantalum carbide powder, tungsten metal powder and graphite powder to obtain a mixed material

[0073] 2) Kneading: Put the obtained mixed material into a high - speed kneader for kneading. First, knead at low speed for 5 min, then add the binder, and then knead at high speed for 25 min. The temperature of the mud is 50℃, the low - speed kneading speed is 60 rpm, and the high - speed kneading speed is 120 rpm to obtain the mud;

[0074] 3) Machine - pressing forming: Put the obtained mud into the mold of the ladle low - carbon slag line magnesia - carbon brick and perform machine - pressing forming. Use a 1000 - ton electric screw brick - pressing machine, the forming pressure is 1500 KN, and press 5 times to obtain a low - carbon slag line magnesia - carbon brick blank with a compressive strength of 50 - 60 Mpa and a bulk density of 3.02 - 3.06 g / cm 3 ;

[0075] 4) Drying: Dry the obtained brick blank at a drying temperature of 180℃ for 12 h to obtain the low - carbon magnesia - carbon brick for the refining ladle slag line.

[0076] Example 6

[0077] 1) Weighing: Weigh 25 kg of 98% ordinary fused magnesia with a particle size of 3 - 5 mm, 25 kg of 98% ordinary fused magnesia with a particle size of 1 - 3 mm, 25 kg of 98% ordinary fused magnesia with a particle size of 0 - 1 mm, 2.5 kg of 98% ordinary fused magnesia with a particle size of ≤0.074 mm, 14 kg of tantalum carbide powder with a particle size of ≤0.045 mm, 4 kg of tungsten metal powder with a particle size of ≤0.045 mm, 2 kg of graphite powder with a particle size of ≤0.15 mm, and 2.5 kg of binder;

[0078] In 98% ordinary fused magnesia, the content of MgO is > 98 wt%, and the content of SiO2 is < 1.0 wt%; in tantalum carbide powder, the content of tantalum carbide is ≥ 99.5 wt%; in tungsten metal powder, the content of tungsten metal is ≥ 99.5 wt%. In graphite powder, the content of carbon is ≥ 98 wt%; the binder is liquid phenolic resin, the residual carbon of the liquid phenolic resin is ≥ 40 wt%, the moisture content is ≤ 3.0 wt%, and the viscosity is 16000 - 19000, 25 °C (cps);

[0079] Mix all 98% ordinary fused magnesia, tantalum carbide powder, tungsten metal powder and graphite powder to obtain a mixed material

[0080] 2) Kneading: Put the obtained mixed material into a high-speed kneader for kneading. First, knead at low speed for 5 minutes, then add the binder, and then knead at high speed for 25 minutes. The temperature of the mud is 50 °C, the rotation speed of low-speed kneading is 60 rpm, and the rotation speed of high-speed kneading is 120 rpm to obtain the mud;

[0081] 3) Machine pressing and forming: Put the obtained mud into a ladle low-carbon slag line magnesia-carbon brick mold for machine pressing and forming. Use a 1000-ton electric screw brick press, the forming pressure is 1500 KN, and press 5 times to obtain a low-carbon slag line magnesia-carbon brick blank with a compressive strength of 50 - 60 Mpa and a bulk density of 3.02 - 3.06 g / cm 3 of the low-carbon slag line magnesia-carbon brick;

[0082] 4) Drying: Dry the obtained brick blank, the drying temperature is 180 °C, and the drying time is 10 h to obtain a low-carbon magnesia-carbon brick for the slag line of a refining ladle.

[0083] Effect experiment

[0084] Detection: The hot state flexural strength (Mpa) is detected according to GB / T3002 - 2017; the slag erosion resistance is detected according to GB / T8931 - 2007; the thermal shock performance is detected according to GB / T30873 - 2014; the compressive strength is according to GB / T5072 - 2008.

[0085] Table 1: Performance inspection of the finished low-carbon slag line magnesia-carbon brick of Examples 1 - 4

[0086]

[0087] Select the low-carbon magnesia-carbon brick for the slag line of the refining ladle in Example 3 for actual application test in a 100-ton refining ladle in a certain branch factory of Angang.

[0088] Construction of the low-carbon slag line magnesia-carbon brick for the refining ladle;

[0089] Laying: Lay the low-carbon slag line magnesia-carbon bricks of Example 3 on the slag line part of the refining ladle according to the number of layers and positions required by the design drawings. Among them, for every 10 slag line bricks, place 1 piece of 1-mm yellow cardboard paper with vertical joints staggered;

[0090] Baking: Divide it into low fire for 24 hours - medium fire for 24 hours - high fire for 24 hours according to the flame length of the steel plant baking. After a total of 72 hours, it can be put into use on the production line.

[0091] The low-carbon slag line magnesia-carbon bricks of the refining ladle prepared in this example are actually applied to the slag line part of a 100-ton refining ladle in a certain branch of Angang Steel. The average service life is 45 times. The average service life of the low-carbon slag line magnesia-carbon bricks of the prior art is 30 times. The service life is significantly higher than that of the low-carbon slag line magnesia-carbon bricks of the prior art.

[0092] The description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A low-carbon magnesia-carbon brick for the slag line of a refining ladle, characterized in that, It is prepared from the following raw materials in parts by weight: 20 - 25 parts of 98% ordinary fused magnesia with a particle size of 3 - 5 mm, 25 - 35 parts of 98% ordinary fused magnesia with a particle size of 1 - 3 mm, 20 - 25 parts of 98% ordinary fused magnesia with a particle size of 0 - 1 mm, 0 - 10 parts of 98% ordinary fused magnesia with a particle size of ≤0.074 mm, 10 - 15 parts of tantalum carbide powder with a particle size of ≤0.045 mm, 1 - 5 parts of tungsten metal powder with a particle size of ≤0.045 mm, 1 - 3 parts of graphite powder with a particle size of ≤0.15 mm, and 2 - 3 parts of binder.

2. The low-carbon magnesia-carbon brick for slag line of refined ladle according to claim 1, characterized in that, In the 98% ordinary fused magnesia, the content of MgO is >98 wt% and the content of SiO2 is <1.0 wt%.

3. The low-carbon magnesia-carbon brick for slag line of refined ladle according to claim 1, characterized in that, In the tantalum carbide powder, the content of tantalum carbide is ≥99.5 wt%.

4. The low-carbon magnesia-carbon brick for slag line of refined ladle according to claim 1, characterized in that, In the tungsten metal powder, the content of tungsten metal is ≥99.5 wt%.

5. The low-carbon magnesia-carbon brick for slag line of refined ladle according to claim 1, characterized in that, In the graphite powder, the content of carbon is ≥98 wt%.

6. The low-carbon magnesia-carbon brick for slag line of refined ladle according to claim 1, characterized in that, The binder is liquid phenolic resin. The residual carbon of the liquid phenolic resin is ≥40 wt%, the moisture content is ≤3.0 wt%, and the viscosity is 16000 - 19000 cps at 25°C.

7. A preparation method of the low-carbon magnesia-carbon brick for the slag line of a refined ladle according to any one of claims 1-6, characterized in that, It includes the following steps: 1) Weighing: Weigh each raw material, and mix 98% ordinary fused magnesia with a particle size of 3 - 5 mm, 98% ordinary fused magnesia with a particle size of 1 - 3 mm, 98% ordinary fused magnesia with a particle size of 0 - 1 mm, 98% ordinary fused magnesia with a particle size of ≤0.074 mm, tantalum carbide powder with a particle size of ≤0.045 mm, tungsten metal powder with a particle size of ≤0.045 mm, and graphite powder with a particle size of ≤0.15 mm to obtain a mixture. 2) Kneading: Put the obtained mixture into a high - speed kneader for kneading. First, start kneading at low speed, then add the binder, and then start kneading at high speed to obtain a mud. 3) Machine pressing and forming: Put the obtained mud into a ladle low - carbon slag line magnesia - carbon brick mold for machine pressing and forming to obtain a low - carbon slag line magnesia - carbon brick blank. 4) Drying: Dry the obtained brick blank to obtain a low - carbon magnesia - carbon brick for the slag line of a refining ladle.

8. The preparation method of a low-carbon magnesia-carbon brick for the slag line of a refining ladle according to claim 7, characterized in that, In step 2), first start kneading at low speed for more than 3 min, then add the binder, and then start kneading at high speed for 20 - 30 min, and the temperature of the mud is 35 - 55°C.

9. The preparation method of a low-carbon magnesia-carbon brick for the slag line of a refining ladle according to claim 7, characterized in that, In step 3), the pressure for machine pressing and forming is 8300 - 1500 KN, and it is pressed 3 - 5 times.

10. Application of the low - carbon magnesia - carbon brick for the slag line of a refining ladle according to any one of claims 1 - 6 or the low - carbon magnesia - carbon brick for the slag line of a refining ladle prepared by the method according to any one of claims 7 - 9 in the slag line part of a refining ladle.

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