A ladle slag line repair material and a method for preparing the same

Abstract

This invention discloses a ladle slag line repair material, the components of which, by mass percentage, include: 60-85% magnesia, 5-15% used magnesia-carbon brick powder, 2-11% iron-phosphorus powder, 0.3-2% metallic aluminum powder, 2-6% ultrafine graphite powder, 2-8% pig iron particles, 1-10% kaolin fine powder, and 1-5% spherical SiO2 micro powder; it also includes 2-20% waste machine oil, 0-16% aluminum dihydrogen phosphate, and 0.2-0.6% amine-terminated polyisobutylene. The ladle slag line repair material of this invention has good high-temperature resistance and adhesion properties, effectively improving adhesion to ladle slag lines and extending service life, and has wide applicability; moreover, the preparation method is relatively simple and has a short cycle, and it can realize the resource utilization of various solid and liquid wastes, resulting in significant economic and environmental benefits.

Description

Technical Field

[0001] This invention belongs to the field of steelmaking and refractory materials technology, specifically relating to a ladle slag line repair material and its preparation method. Background Technology

[0002] The ladle is one of the essential pieces of equipment in the steelmaking process. Besides holding and transporting molten steel, it also participates in refining and other processing steps. Extending the service life of the ladle is beneficial for improving steel plant production efficiency, reducing energy consumption, conserving resources, and minimizing environmental pollution. Among the various sections of the ladle lining, the slag line is the most rapidly eroded area due to slag corrosion and the radiation from the electric arc during ladle furnace smelting, representing a bottleneck in the lifespan of the ladle lining. To avoid replacing the entire working lining due to localized damage and to extend its service life, repair materials are needed to repair the ladle slag line working lining.

[0003] Currently, magnesia-carbon bricks are commonly used in the working layer of steel ladle slag lines in China. Conventional high-alumina water-based steel ladle repair materials typically have poor workability, unstable adhesion, and are prone to overall slippage and high rebound rates; some materials also tend to detach locally after baking. Water-based repair materials have high moisture content, resulting in long construction, curing, and baking cycles, and the moisture can also damage the magnesia-carbon bricks. All of these factors negatively impact the effectiveness of the repair materials and the subsequent use of the steel ladle slag lines. Summary of the Invention

[0004] The main objective of this invention is to address the problems and shortcomings of existing technologies by providing a steel ladle slag line repair material that can improve the high temperature resistance and adhesion performance of the repair material, effectively improve the adhesion effect on the steel ladle slag line, and extend its service life.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A steel ladle slag line repair material, comprising the following components and their respective mass percentages: 60-85% magnesia, 5-15% used magnesia-carbon brick powder, 2-11% iron-phosphorus powder, 0.3-2% metallic aluminum powder, 2-6% ultrafine graphite powder, 2-8% pig iron particles, 1-10% kaolin fine powder, and 1-5% spherical SiO2 micro powder; further comprising 2-20% waste engine oil, 0-16% aluminum dihydrogen phosphate, and 0.2-0.6% terminal amine polyisobutylene, respectively, by mass of the above raw materials.

[0007] In the above scheme, the magnesia contains magnesia aggregate particles of 1-5mm and magnesia fine powder with a particle size of less than 200 mesh, wherein the MgO content is ≥94wt%.

[0008] Furthermore, the content of magnesia aggregate particles in the magnesia is 55 wt% or more.

[0009] In the above scheme, the recycled magnesia-carbon brick powder is derived from the magnesia-carbon bricks used in the converter or ladle, and the original bricks have a carbon content ≥10wt% and an MgO content ≥60wt%.

[0010] In the above scheme, the particle size of the iron-phosphorus powder is less than 180 mesh, the phosphorus is recycled from self-rolled steel, and the TFe content is ≥70wt%.

[0011] In the above scheme, the particle size of the ultrafine graphite powder is less than 2000 mesh.

[0012] In the above scheme, the particle size of the pig iron particles is 1-3 mm.

[0013] In the above scheme, the fine kaolin powder has a particle size of less than 300 mesh.

[0014] In the above scheme, the spherical SiO2 micro powder has a particle size of less than 2000 mesh.

[0015] In the above scheme, the waste engine oil needs to be filtered and purified, and the solid impurity content should not exceed 0.5 wt% and the water content should not exceed 0.5%.

[0016] In the above scheme, the molecular weight of the terminal amine polyisobutylene is 400-1200.

[0017] The preparation method of the above-mentioned steel ladle slag line repair material includes the following steps:

[0018] 1) Weigh the ultrafine graphite powder according to the ratio and add it to the waste engine oil with added end-amine polyisobutylene. Stir and disperse evenly, then add all the magnesium sand aggregate and stir evenly. Seal.

[0019] 2) At the repair site, add the remaining dry materials (used magnesia-carbon brick powder, iron-phosphorus powder, metallic aluminum powder, pig iron particles, kaolin fine powder, spherical SiO2 micro powder) and aluminum dihydrogen phosphate according to the proportion and mix them evenly before using them for repair work.

[0020] Furthermore, by adjusting the ratio of fine kaolin powder to spherical SiO2 powder, the fluidity and plasticity of the resulting repair material can be effectively controlled. Specifically, the repair material exhibits better fluidity when the mass ratio of fine kaolin powder to spherical SiO2 powder is 1:2-3; better plasticity when the mass ratio is 2-3:1; the viscosity of the material can be adjusted by adjusting the amount of aluminum dihydrogen phosphate added; the fluidity of the repair material can be adjusted by adjusting the amount of waste engine oil added; and the temperature of the repair material after construction can be controlled by changing the amount of pig iron added. Combined with the adjustment of the fluidity of the repair material, the adhesion of steel slag to the required parts of the repair layer can be controlled, and steel slag can be adhered to form a protective layer for the repair layer as needed.

[0021] The ladle slag line repair material obtained by the above scheme can be applied to the repair of ladle slag lines or other parts of furnaces using magnesia-carbon brick linings. Specifically, the ladle slag line repair material can be applied to the part to be repaired by smearing or self-flowing methods to form a repair layer.

[0022] Furthermore, the ladle slag line repair material can be applied under cold conditions or by self-flowing under hot conditions (800-1200℃) for repair construction.

[0023] The principle of this invention is as follows:

[0024] This invention prepares a steel ladle slag line repair material using magnesia, used magnesia-carbon brick powder, and iron-phosphorus powder as the main raw materials. To reduce the adverse effects of high carbon content on molten steel quality, ultrafine carbonaceous raw materials (ultrafine graphite powder) are first mixed with liquid grease using an ultradispersant to improve dispersion uniformity and reduce the amount of carbon raw materials added. The liquid grease is used to pre-coat the magnesia raw materials to prevent magnesia hydration from affecting the performance of the repair material. Furthermore, by combining kaolin fine powder, spherical SiO2 micro powder, and pig iron particles, the fluidity, plasticity, and surface temperature of the repair layer after construction are adjusted. This controls the ability of the repair material to adhere to steel slag, and, as needed, steel slag can adhere to the surface of the repair layer to form a protective layer, further improving the repair life.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] 1) The steel ladle slag line repair material of the present invention has good high temperature resistance and adhesion properties, which can effectively improve the adhesion effect on the steel ladle slag line and extend its service life.

[0027] 2) This invention can adjust the fluidity, plasticity, and viscosity of the repair material according to the on-site needs of the damaged area and severity of the ladle slag line, so as to meet different repair construction requirements such as self-flowing pouring at high temperature or cold application; while ensuring the repair effect, it can effectively shorten the repair period and improve the service life of the ladle slag line.

[0028] 3) This invention can regulate the surface temperature of the repair layer after the repair material is applied, control the performance of the repair layer in adhering to steel slag, and further effectively adhere steel slag to the surface of the repair layer as needed to protect the repair material and further improve the repair life.

[0029] 4) This invention mixes ultrafine graphite powder in liquid grease under the action of terminal amine polyisobutylene, which can effectively reduce the amount of carbonaceous raw materials added and reduce the pollution of high-quality molten steel; at the same time, premixing magnesia into liquid grease can avoid the hydration of magnesia and improve the shelf life of repair materials. Detailed Implementation

[0030] The present invention will be further described below with reference to specific embodiments. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0031] In the following embodiments, the raw material composition of the ladle slag line repair material includes, by weight percentage: 55-75% magnesia, 5-15% used magnesia-carbon brick powder, 0-11% iron-phosphorus powder, 0.5-2% metallic aluminum powder, 2-6% ultrafine graphite powder, 2-6% pig iron particles, 2-10% kaolin fine powder, 1-4% spherical SiO2 micro powder; 2-20% waste engine oil; 0-16% aluminum dihydrogen phosphate; and 0.2-0.6% terminal amine polyisobutylene.

[0032] In the following examples, the magnesia raw material used is mainly aggregate particles with a particle size of 1-5 mm and fine powder with a particle size of less than 200 mesh; wherein, the content of magnesia aggregate particles is ≥50wt%.

[0033] Used magnesia-carbon brick powder is recycled from magnesia-carbon bricks used in rotary kilns or ladles. The original bricks contained 12.7 wt% carbon and 66.2 wt% MgO. Iron-phosphorus powder is recycled from iron-phosphate bricks and crushed to a particle size of less than 180 mesh.

[0034] The ultrafine graphite powder used has a particle size of less than 2000 mesh; the pig iron particles have a particle size of 1-3 mm; and the kaolin fine powder has a particle size of less than 300 mesh.

[0035] The waste engine oil used must be filtered and purified, and the solid impurity content must not exceed 0.5%, and the water content must not exceed 0.5%.

[0036] The molecular weight of the terminal amine polyisobutylene used is 400-1200.

[0037] The repair material is prepared by adding ultrafine graphite powder to waste engine oil containing terminal amine polyisobutylene and stirring until evenly dispersed. Then, all the fine magnesia powder particles are added and stirred until evenly mixed. The mixture is then sealed in a container. At the repair site, the remaining dry materials (used magnesia-carbon brick powder, iron-phosphorus powder, aluminum powder, pig iron particles, kaolin powder, and spherical SiO2 powder) and aluminum dihydrogen phosphate are added according to the specified ratio and mixed thoroughly before use for repair. The fluidity, plasticity, and adhesion of this repair material can be adjusted by varying the ratio of engine oil and aluminum dihydrogen phosphate. The repair application method can be either cold application or hot self-flowing.

[0038] Example 1

[0039] A steel ladle slag line repair material comprises the following raw materials and their mass percentages: 55% magnesia granules, 16% magnesia fine powder, 14% used magnesia-carbon brick powder, 0.5% metallic aluminum powder, 3.5% ultrafine graphite powder, 2% iron-phosphorus powder, 2% pig iron granules, 2% kaolin fine powder, and 5% spherical SiO2 micro powder; it also includes 2% waste engine oil, 0.2% terminal amine polyisobutylene, and 16% aluminum dihydrogen phosphate.

[0040] The preparation method of the ladle slag line repair material includes the following steps:

[0041] First, add ultrafine graphite powder to waste engine oil with added end-amine polyisobutylene and stir to disperse evenly. Then add magnesia granules and fine magnesia powder and stir evenly. Seal the container and package it. At the repair site, add the remaining dry material and aluminum dihydrogen phosphate according to the ratio and mix evenly.

[0042] Tests showed that the obtained repair material has high fluidity at room temperature, which can meet the requirements of self-flowing casting. It has moderate plasticity and adhesion. The surface temperature of the shell after the obtained repair material is cured on the lining surface is about 30-50℃ lower than that of ordinary repair materials. The compressive strength at 110℃×24h is 28.6MPa, and the compressive strength at 1500℃×3h is 57.3MPa. The self-flowing repair method is suitable for repairing large-area or thick local damage to the slag line of the ladle under cold conditions.

[0043] Example 2

[0044] A steel ladle slag line repair material, comprising the following raw materials and their mass percentages: 55% magnesia granules, 12% magnesia fine powder, 9% used magnesia-carbon brick powder, 0.5% metallic aluminum powder, 3.5% ultrafine graphite powder, 4% iron-phosphorus powder, 4% pig iron granules, 3% kaolin fine powder, and 9% spherical SiO2 micro powder; it also includes 6% waste engine oil, 0.3% terminal amine polyisobutylene, and 9% aluminum dihydrogen phosphate.

[0045] The preparation method of the ladle slag line repair material includes the following steps:

[0046] First, add ultrafine graphite powder to waste engine oil with added end-amine polyisobutylene and stir to disperse evenly. Then add magnesia granules and fine magnesia powder and stir evenly. Seal the container and package it. At the repair site, add the remaining dry material and aluminum dihydrogen phosphate according to the ratio and mix evenly.

[0047] Tests showed that the obtained repair material had low fluidity at room temperature but high plasticity and adhesion. The surface temperature of the shell after curing on the lining was about 50-80℃ lower than that of ordinary repair materials. The compressive strength at 110℃ for 24 hours was 25.7MPa, and the compressive strength at 1500℃ for 3 hours was 52.4MPa. The application method is suitable for repairing small areas or thin local damage to the slag line of the ladle under cold conditions.

[0048] Example 3

[0049] A steel ladle slag line repair material comprises the following raw materials by weight percentage: 60% magnesia granules, 4% magnesia fine powder, 12% used magnesia-carbon brick powder, 11% iron-phosphorus powder, 2% metallic aluminum powder, 5% ultrafine graphite powder, 2% pig iron granules, 1% kaolin fine powder, and 3% spherical SiO2 micro powder; it also includes 16% waste engine oil and 0.6% terminal amine polyisobutylene.

[0050] The preparation method of the ladle slag line repair material includes the following steps:

[0051] Add ultrafine graphite powder to waste engine oil with added amino-terminated polyisobutylene and stir to disperse evenly. Then add magnesia granules and fine magnesia powder and stir evenly. Finally, add the remaining dry material and mix and stir evenly.

[0052] Tests showed that the obtained repair material has high fluidity at high temperatures (1000℃). The surface temperature of the shell after curing on the lining surface is about 30-50℃ lower than that of ordinary repair materials. The compressive strength at 1500℃ for 3 hours is 29.5MPa. The self-flowing repair method under hot conditions is suitable for repairing large areas or localized damage to the slag line of the ladle under hot conditions.

[0053] Example 4

[0054] A steel ladle slag line repair material comprises the following raw materials by weight percentage: 56% magnesia granules, 4% magnesia fine powder, 13% used magnesia-carbon brick powder, 8% iron-phosphorus powder, 2% metallic aluminum powder, 5% ultrafine graphite powder, 6% pig iron granules, 2% kaolin fine powder, and 4% spherical SiO2 micro powder; it also includes 12% waste engine oil and 0.4% terminal amine polyisobutylene.

[0055] The preparation method of the ladle slag line repair material includes the following steps:

[0056] Add ultrafine graphite powder to waste engine oil and stir to disperse it evenly. Then add magnesia fine powder and stir evenly. Finally, add the remaining dry material and mix and stir evenly.

[0057] Tests showed that the obtained repair material has high fluidity at high temperatures (1000℃) and a compressive strength of 24.2MPa at 1500℃ for 3 hours. The self-flowing repair method under hot conditions is suitable for repairing severe local damage to the slag line in hot conditions. The surface temperature of the shell after the obtained repair material is cured on the lining surface is 150-200℃ lower than that of ordinary repair materials. This allows some of the lower melting point steel slag components to solidify on the shell surface of the repair material, reducing fluidity and giving the repair material a higher slag adhesion ability, thus providing additional protection for the slag line.

[0058] Other embodiments vary within this range. This invention is not limited to the above-described embodiments. For those skilled in the art, various improvements and modifications can be made without departing from the principles of this invention, and these improvements and modifications are also considered within the scope of protection of this invention. Content not described in detail in this specification belongs to the prior art known to those skilled in the art.

Claims

1. A repair material for steel ladle slag lines, characterized in that, The components and their respective mass percentages include: 60-85% magnesia, 5-15% used magnesia-carbon brick powder, 2-11% iron-phosphorus powder, 0.3-2% metallic aluminum powder, 2-6% ultrafine graphite powder, 2-8% pig iron particles, 1-10% kaolin fine powder, and 1-5% spherical SiO2 micro powder; it also includes 2-20% waste engine oil, 0-16% aluminum dihydrogen phosphate, and 0.2-0.6% terminal amine polyisobutylene, each accounting for 2-20% of the total mass of the above components. The pig iron particles have a particle size of 1-3 mm.

2. The ladle slag line repair material according to claim 1, characterized in that, The magnesia contains magnesia aggregate particles of 1-5 mm and magnesia fine powder with a particle size of less than 200 mesh, wherein the MgO content is ≥94wt%.

3. The ladle slag line repair material according to claim 1, characterized in that, The content of magnesia aggregate particles in the magnesia is above 55 wt%.

4. The ladle slag line repair material according to claim 1, characterized in that, The MgO content in the used magnesia-carbon brick powder is ≥60wt%.

5. The ladle slag line repair material according to claim 1, characterized in that, The iron-phosphorus powder has a particle size of less than 180 mesh and a TFe content of ≥70wt%.

6. The ladle slag line repair material according to claim 1, characterized in that, The ultrafine graphite powder has a particle size of less than 2000 mesh; the kaolin fine powder has a particle size of less than 300 mesh; and the spherical SiO2 micro powder has a particle size of less than 2000 mesh.

7. The ladle slag line repair material according to claim 1, characterized in that, The waste engine oil contains less than 0.5 wt% solid impurities and less than 0.5 wt% water.

8. The ladle slag line repair material according to claim 1, characterized in that, The molecular weight of the terminal amine polyisobutylene is 400~1200.

9. A method for preparing the ladle slag line repair material according to any one of claims 1 to 8, characterized in that, Includes the following steps: 1) Weigh the ultrafine graphite powder according to the ratio and add it to the waste engine oil with added amine-terminated polyisobutylene. Stir and disperse evenly, then add magnesium sand and stir evenly. Seal the container. 2) Add the used magnesium carbon brick powder, iron phosphorus powder, metallic aluminum powder, pig iron particles, kaolin fine powder, spherical SiO2 micro powder and aluminum dihydrogen phosphate according to the proportion, mix and stir evenly to obtain the steel ladle slag line repair material.