RH dip pipe castable and production method thereof

Abstract

The invention relates to the technical field of refractory materials, and discloses an RH dip pipe castable and a production method thereof.The RH dip pipe castable is formed by mixing fused white corundum particles, sintered corundum, 90 alumina, a metamorphic-layer-free reclaimed material and the like as raw materials, by accurately controlling the adding amount of the raw materials, the advantages of the raw materials are fully exerted, and the production cost is lowered. The produced RH dip pipe castable has the characteristic of balanced performance, namely, proper demolding strength, is convenient to transport in the production process, a certain number of nanoscale micropores exist in aggregate and a matrix in the use process, generated cracks are small and few, a proper amount of slag can be adhered, the cracks can be bridged, and the RH dip pipe castable has the characteristics of high high-temperature breaking strength, good thermal shock performance, high strength, high strength, high strength and the like. And the effect of prolonging the service life of the RH dip pipe is remarkable.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of refractory materials, in particular to a RH dip tube castable and a production method thereof. BACKGROUND

[0002] The RH refining furnace is a multifunctional furnace outside refining equipment, which can carry out vacuum decarburization, powder spraying desulfurization, alloy adding to adjust composition and other process operations. The RH refining furnace is composed of dip tubes (upward pipes and downward pipes), upper tanks, lower tanks and hot bending pipes. The inside of the dip tube is generally built with magnesia-chrome bricks or magnesia-alumina spinel bricks, and the outside of the steel structure is generally corundum spinel castable. When the RH refining furnace processes molten steel, the dip tube has to withstand the erosion of argon and molten steel, slag and large thermal stress caused by repeated temperature changes. Such harsh conditions lead to cracks in the RH dip tube castable during use, poor resistance to erosion and short service life. There is no report on the RH dip tube castable which has balanced performance, that is, appropriate demolding strength, small and few cracks during use, appropriate amount of slag, crack healing, high high-temperature bending strength, good thermal shock resistance, good resistance to erosion and other characteristics.

[0003] At present, most of the RH dip tube castable is low-cement or ultra-low-cement aluminum-magnesium (spinel) castable. Since SiO2 micro powder is prone to produce low-melting phase and gas phase defects during use, it is generally not added. Pure calcium aluminate cement is used as a binder, which has certain defects. If the amount is small, the demolding strength is low, which is not conducive to transportation. If the amount is large, low-melting phase is prone to be produced. In addition, if too much CA6 is generated, it may produce a large volume expansion during use, thereby reducing the service life.

[0004] Based on this, the present application provides a RH dip tube castable, which can solve the problems in the prior art. SUMMARY

[0005] In order to solve the problems mentioned in the background art, the purpose of the present application is to provide a RH dip tube castable and a production method thereof.

[0006] The purpose of the present application can be achieved by the following technical solutions: A RH dip tube castable comprises the following raw materials in terms of weight percentage: 15-25 parts of fused white corundum particles, 20-30 parts of sintered corundum, 5-15 parts of 90 bauxite, 20-30 parts of non-modified layer recycled material, 1-2 parts of fused magnesia, 10-20 parts of composite micro powder, 5-15 parts of fused white corundum powder, 1.5-4.5 parts of composite binder, 0.1-0.3 parts of organic carboxylic acid water reducing agent, 0.5-2.0 parts of steel fiber and 0.05-0.10 parts of organic fiber.

[0007] As a further embodiment of the present invention, the non-deteriorated recycled material is a mixture of ladle precast bricks, ladle seat bricks and permeable bricks, with a mass ratio of 55-65:15-25:15-25.

[0008] As a further embodiment of the present invention, the composite micro powder is a mixture of α-alumina and spinel in a mass ratio of 35-45:55-65.

[0009] As a further embodiment of the present invention, the composite binder is a mixture of pure calcium aluminate cement, MgO micro powder, organic acid, p-Al2O3 and SiO2 micro powder, with a mass ratio of 40-50:5-15:0.5-10:10-20:5-15.

[0010] As a further aspect of the present invention, the organic acid is at least one selected from boric acid, oxalic acid, citric acid, tartaric acid, and sodium gluconate.

[0011] As a further aspect of the present invention, the organic carboxylic acid water-reducing agent is at least one of FS-type polycarboxylic acid water-reducing agent or FW-type polycarboxylic acid water-reducing agent.

[0012] As a further aspect of the present invention, the organic fiber is at least one of polypropylene fiber, polyvinyl alcohol fiber, or aramid fiber.

[0013] In the above technical solution, by precisely controlling the amount of each raw material added, each raw material can give full play to its own advantages.

[0014] Specifically, adding appropriate amounts of 90% alumina and recycled material without altered layers can increase the microporosity of the castable, generating microcracks and a very small amount of liquid phase during use, thus improving the thermal shock resistance of the castable. Using composite micro-powder of α-alumina and spinel helps reduce the water content of the castable, improving its fluidity and slag resistance. Utilizing a mixture of several binders to create a composite binder can produce complementary advantages, reducing the water content of the castable, improving fluidity, extending the initial setting time, and also generating microporosity in the castable, improving slag resistance and thermal shock resistance; however, adding too much will shorten the workability time, reduce explosion-proof and slag-resistant properties, increase thermal stress during use, leading to large cracks and severe spalling. Appropriate water-reducing agents and organic fibers are key to reducing water content, increasing fluidity, and improving explosion-proof performance.

[0015] A method for producing RH-impregnated pipe castable includes the following steps: Step 1: Raw Material Preparation 90% alumina, recycled material without metamorphic layer, and fused magnesia are processed into granular materials of the required particle size through crushing and screening equipment. The particle size of 90% alumina and recycled material without metamorphic layer is controlled at 10-15mm, and the particle size of fused magnesia is controlled at 0-1mm. The composite micro powder is ball-milled to a particle size of <5μm, and the composite binder is ball-milled to a particle size of <325 mesh. The particle sizes of fused white corundum particles, sintered corundum, and fused white corundum powder are 10-15mm, 0-5mm, and 120-325 mesh, respectively. Step 2: Ingredient Preparation Weigh and prepare all ingredients according to their weight proportions; Step 3: Particle premixing The granular material is obtained by mixing fused white corundum particles, 90 alumina, recycled material without metamorphic layer, fused magnesia, and sintered corundum. Step 4: Premixing fine powders First, add fused white corundum powder, then add composite binder and water-reducing agent to the middle layer, and add composite micro powder to the top layer. Mix and grind for 15-20 minutes to obtain fine powder. Step 5: Preparation of RH-impregnated pipe casting material First, mix and grind the granular material with organic fiber for 1-2 minutes, then add fine powder and mix and grind for 1-2 minutes, and finally add steel fiber and continue mixing and grinding for 1-2 minutes before discharging and packaging.

[0016] The beneficial effects of this invention are: The RH-impregnated pipe casting material produced by this invention has the characteristics of balanced performance, namely, suitable demolding strength, convenient transportation during production, and a certain number of nano-scale micropores in both aggregate and matrix during use, resulting in small and few cracks, which can be appropriately slag-coated and crack-bridging. It also has the characteristics of high-temperature flexural strength, good thermal shock resistance, erosion resistance and corrosion resistance, which significantly improves the service life of RH-impregnated pipes.

[0017] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Detailed Implementation

[0018] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] In the following examples, the recycled material without alteration layer is selected as a mixture of precast steel ladle bricks, steel ladle seat bricks and permeable bricks in a mass ratio of 65:20:15. The composite micro powder is a mixture of α-alumina and spinel in a mass ratio of 40:60; The composite binder is a mixture of pure calcium aluminate cement, MgO powder, organic acid, ρ-Al2O3 and SiO2 powder in a mass ratio of 50:10:5:20:15. The organic acid is boric acid; Choose FS type polycarboxylate superplasticizer as the organic carboxylate superplasticizer; The organic fiber is aramid fiber.

[0020] Example 1 An RH-impregnated pipe casting refractory comprises the following raw materials in parts by weight: 15 parts of fused white fused alumina particles, 20 parts of sintered fused alumina, 5 parts of 90 alumina, 20 parts of recycled material without altered layer, 1 part of fused magnesia, 10 parts of composite micro powder, 5 parts of fused white fused alumina powder, 1.5 parts of composite binder, 0.1 parts of organic carboxylic acid water-reducing agent, 0.5 parts of steel fiber, and 0.05 parts of organic fiber.

[0021] The preparation method of the castable includes the following steps: Step 1: Raw Material Preparation 90% alumina, recycled material without metamorphic layer, and fused magnesia are processed into granular materials of the required particle size through crushing and screening equipment. The particle size of 90% alumina and recycled material without metamorphic layer is controlled at 15mm, and the particle size of fused magnesia is controlled at 1mm. The composite micro powder is ball-milled to a particle size of <5μm, and the composite binder is ball-milled to a particle size of <325 mesh. The particle sizes of fused white corundum particles, sintered corundum, and fused white corundum powder are 15mm, 5mm, and 325 mesh, respectively. Step 2: Ingredient Preparation Weigh and prepare all ingredients according to their weight proportions; Step 3: Particle premixing The granular material is obtained by mixing fused white corundum particles, 90 alumina, recycled material without metamorphic layer, fused magnesia, and sintered corundum. Step 4: Premixing fine powders First, add fused white corundum powder, then add composite binder and water-reducing agent to the middle layer, and add composite micro powder to the top layer. Mix and grind for 20 minutes to obtain fine powder. Step 5: Preparation of RH-impregnated pipe casting material First, mix the granular material with organic fiber for 2 minutes, then add fine powder and mix for 2 minutes, and finally add steel fiber and continue mixing for 2 minutes before discharging and packaging.

[0022] Example 2 An RH-impregnated pipe casting refractory comprises the following raw materials in parts by weight: 20 parts of fused white fused alumina particles, 25 parts of sintered fused alumina, 10 parts of 90% bauxite, 25 parts of recycled material without altered layer, 1.5 parts of fused magnesia, 15 parts of composite micro powder, 12 parts of fused white fused alumina powder, 4 parts of composite binder, 0.2 parts of organic carboxylic acid water-reducing agent, 1.5 parts of steel fiber, and 0.08 parts of organic fiber.

[0023] The preparation method of the castable includes the following steps: Step 1: Raw Material Preparation 90% alumina, recycled material without metamorphic layer, and fused magnesia are processed into granular materials of the required particle size through crushing and screening equipment. The particle size of 90% alumina and recycled material without metamorphic layer is controlled at 15mm, and the particle size of fused magnesia is controlled at 1mm. The composite micro powder is ball-milled to a particle size of <5μm, and the composite binder is ball-milled to a particle size of <325 mesh. The particle sizes of fused white corundum particles, sintered corundum, and fused white corundum powder are 15mm, 5mm, and 325 mesh, respectively. Step 2: Ingredient Preparation Weigh and prepare all ingredients according to their weight proportions; Step 3: Particle premixing The granular material is obtained by mixing fused white corundum particles, 90 alumina, recycled material without metamorphic layer, fused magnesia, and sintered corundum. Step 4: Premixing fine powders First, add fused white corundum powder, then add composite binder and water-reducing agent to the middle layer, and add composite micro powder to the top layer. Mix and grind for 20 minutes to obtain fine powder. Step 5: Preparation of RH-impregnated pipe casting material First, mix the granular material with organic fiber for 2 minutes, then add fine powder and mix for 2 minutes, and finally add steel fiber and continue mixing for 2 minutes before discharging and packaging.

[0024] Example 3 An RH-impregnated pipe casting refractory comprises the following raw materials in parts by weight: 25 parts of fused white fused alumina particles, 30 parts of sintered fused alumina, 15 parts of 90% bauxite, 30 parts of recycled material without altered layer, 2 parts of fused magnesia, 20 parts of composite micro powder, 15 parts of fused white fused alumina powder, 4.5 parts of composite binder, 0.3 parts of organic carboxylic acid water-reducing agent, 2.0 parts of steel fiber, and 0.10 parts of organic fiber.

[0025] The preparation method of the castable includes the following steps: Step 1: Raw Material Preparation 90% alumina, recycled material without metamorphic layer, and fused magnesia are processed into granular materials of the required particle size through crushing and screening equipment. The particle size of 90% alumina and recycled material without metamorphic layer is controlled at 15mm, and the particle size of fused magnesia is controlled at 1mm. The composite micro powder is ball-milled to a particle size of <5μm, and the composite binder is ball-milled to a particle size of <325 mesh. The particle sizes of fused white corundum particles, sintered corundum, and fused white corundum powder are 15mm, 5mm, and 325 mesh, respectively. Step 2: Ingredient Preparation Weigh and prepare all ingredients according to their weight proportions; Step 3: Particle premixing The granular material is obtained by mixing fused white corundum particles, 90 alumina, recycled material without metamorphic layer, fused magnesia, and sintered corundum. Step 4: Premixing fine powders First, add fused white corundum powder, then add composite binder and water-reducing agent to the middle layer, and add composite micro powder to the top layer. Mix and grind for 20 minutes to obtain fine powder. Step 5: Preparation of RH-impregnated pipe casting material First, mix the granular material with organic fiber for 2 minutes, then add fine powder and mix for 2 minutes, and finally add steel fiber and continue mixing for 2 minutes before discharging and packaging.

[0026] Test case The comprehensive performance of each castable in the examples was tested, and the results are recorded in Table 1: Table 1 - Test Results

[0027] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of these embodiments are merely to aid in understanding the method and core ideas of the present invention, including the best mode, and to enable any person skilled in the art to practice the present invention, including manufacturing and using any device or system, and implementing any combined method. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from its principles, and these improvements and modifications also fall within the scope of protection of the claims. The scope of protection of this patent is defined by the claims and may include other embodiments that can be conceived by those skilled in the art. If these other embodiments have structural elements similar to those expressed in the claims, or if they include equivalent structural elements that are not substantially different from those expressed in the claims, then these other embodiments should also be included within the scope of the claims.

[0028] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A type of RH-impregnated pipe casting refractory, characterized in that, The raw materials include the following by weight: 15-25 parts of fused white corundum granules, 20-30 parts of sintered corundum, 5-15 parts of 90% bauxite, 20-30 parts of recycled material without metamorphic layer, 1-2 parts of fused magnesia, 10-20 parts of composite micro powder, 5-15 parts of fused white corundum powder, 1.5-4.5 parts of composite binder, 0.1-0.3 parts of organic carboxylic acid water-reducing agent, 0.5-2.0 parts of steel fiber, and 0.05-0.10 parts of organic fiber.

2. The RH-impregnated pipe casting refractory according to claim 1, characterized in that, The recycled material without altered layers is a mixture of precast steel ladle bricks, steel ladle seat bricks, and permeable bricks in a mass ratio of 55-65:15-25:15-25.

3. The RH-impregnated pipe casting refractory according to claim 1, characterized in that, The composite micro powder is a mixture of α-alumina and spinel in a mass ratio of 35-45:55-65.

4. The RH-impregnated pipe casting refractory according to claim 1, characterized in that, The composite binder is a mixture of pure calcium aluminate cement, MgO micro powder, organic acid, p-Al2O3 and SiO2 micro powder, with a mass ratio of 40-50:5-15:0.5-10:10-20:5-15.

5. The RH-impregnated pipe casting refractory according to claim 4, characterized in that, The organic acid is at least one of boric acid, oxalic acid, citric acid, tartaric acid, and sodium gluconate.

6. The RH-impregnated pipe casting refractory according to claim 1, characterized in that, The organic carboxylic acid water-reducing agent is at least one of FS-type polycarboxylic acid water-reducing agent or FW-type polycarboxylic acid water-reducing agent.

7. The RH-impregnated pipe casting refractory according to claim 1, characterized in that, The organic fiber is at least one of polypropylene fiber, polyvinyl alcohol fiber, or aramid fiber.

8. A method for producing the RH-impregnated pipe castable as described in claim 1, characterized in that, Includes the following steps: Step 1: Raw Material Preparation 90% alumina, recycled material without metamorphic layer, and fused magnesia are processed into granular materials of the required particle size through crushing and screening equipment. The particle size of 90% alumina and recycled material without metamorphic layer is controlled at 10-15mm, and the particle size of fused magnesia is controlled at 0-1mm. The composite micro powder is ball-milled to a particle size of <5μm, and the composite binder is ball-milled to a particle size of <325 mesh. The particle sizes of fused white corundum particles, sintered corundum, and fused white corundum powder are 10-15mm, 0-5mm, and 120-325 mesh, respectively. Step 2: Ingredient Preparation Weigh and prepare all ingredients according to their weight proportions; Step 3: Particle premixing The granular material is obtained by mixing fused white corundum particles, 90 alumina, recycled material without metamorphic layer, fused magnesia, and sintered corundum. Step 4: Premixing fine powders First, add fused white corundum powder, then add composite binder and water-reducing agent to the middle layer, and add composite micro powder to the top layer. Mix and grind for 15-20 minutes to obtain fine powder. Step 5: Preparation of RH-impregnated pipe casting material First, mix and grind the granular material with organic fiber for 1-2 minutes, then add fine powder and mix and grind for 1-2 minutes, and finally add steel fiber and continue mixing and grinding for 1-2 minutes before discharging and packaging.

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