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CN-122010580-A - High-strength refractory material for VD furnace and preparation process thereof

CN122010580ACN 122010580 ACN122010580 ACN 122010580ACN-122010580-A

Abstract

The invention relates to a high-strength refractory material for a VD furnace and a preparation process thereof, belonging to the technical field of refractory materials. The formula of the refractory material is as follows, 65-75 parts of sintered mullite aggregate, 10-12 parts of flint clay-zirconia composite material, 8-10 parts of alumina micropowder, 4-6 parts of calcium aluminate cement, 2-3 parts of silica micropowder, 0.05-0.1 part of composite pore-forming agent and 0.12-0.25 part of water reducing agent, zirconium oxide dispersion compounding is carried out through flint clay, and a gradient pore-forming agent compounded by pretreated sisal fiber, nano-coated ammonium oxalate and polymer microspheres is utilized to construct a multi-scale gradient pore structure in the material. The finally prepared refractory material has high strength, excellent thermal shock resistance and good slag erosion resistance, and the service life of the material is obviously prolonged.

Inventors

  • XUE NA
  • LAN ZHENHUA
  • Yang ruide

Assignees

  • 上海彭浦特种耐火材料厂有限公司
  • 上海柯瑞冶金炉料有限公司

Dates

Publication Date
20260512
Application Date
20260212

Claims (10)

  1. 1. A high-strength refractory material for a VD furnace is characterized in that the formula of the refractory material is as follows, calculated in parts by weight, 65-75 Parts of sintered mullite aggregate, 10-12 Parts of flint clay-zirconia composite material, 8-10 Parts of aluminum oxide micro powder, 4-6 Parts of calcium aluminate cement, 2-3 Parts of silicon micro powder, 0.05-0.1 Part of composite pore-forming agent, 0.12-0.25 Part of water reducer, Wherein, the preparation method of the flint clay-zirconia composite material is as follows, S1-1, placing superfine flint clay fine powder and zirconia fine powder into a mixer to be mixed for 30-60 min to obtain mixed powder, adding a polyvinyl alcohol solution with the mass concentration of 4-8% into the mixed powder, and granulating in a granulator to obtain wet granules; S1-2, drying the wet particles at 100-120 ℃ for 2-4 hours, heating to 1100-1300 ℃ at a rate of 2-5 ℃ per minute, preserving heat for 1-3 hours, and naturally cooling to room temperature to obtain the flint clay-zirconia composite material.
  2. 2. The high-strength refractory for a VD furnace according to claim 1, wherein the superfine flint clay fine powder and the zirconia fine powder in the S1-1 are mixed according to the mass ratio of (95-97) to (3-5).
  3. 3. The high-strength refractory for a VD furnace according to claim 1, wherein the added amount of the polyvinyl alcohol solution in S1-1 is 4-8% of the mass of the mixed powder.
  4. 4. The high-strength refractory for a VD furnace according to claim 1, wherein the composite pore-forming agent is prepared by the following method, S4-1, immersing sisal fibers in a sodium silicate solution with the concentration of 3-5wt%, stirring for 1-2 hours at 60-80 ℃, washing with deionized water, and drying for 10-12 hours at 60 ℃ to obtain pretreated sisal fibers; s4-2, mixing ammonium oxalate and nano silicon dioxide according to the mass ratio of (97-99) (1-3), and co-grinding in an air flow mill to obtain powder A; s4-3, mixing the pretreated sisal fibers with the powder A for 10-20 min at the mixing speed of 1000-2000 rpm, adding the polystyrene microspheres, mixing for 5-15 min at the mixing speed of 600-800 rpm, adding the liquid paraffin, and continuing mixing for 3-5 min to obtain the composite pore-forming agent.
  5. 5. The high-strength refractory for a VD furnace according to claim 4, wherein the sisal fibers in S4-1 have a length of 0.5 to 2.0 mm and a diameter of 10 to 30 μm.
  6. 6. The high-strength refractory for a VD furnace according to claim 4, wherein the mass ratio of the pretreated sisal fiber, the powder A and the polystyrene microspheres in S4-3 is (30-40): (40-60): (10-15).
  7. 7. The high-strength refractory for a VD furnace according to claim 4, wherein the addition amount of the liquid paraffin in S4-3 is 2-3% of the total mass of the pretreated sisal fiber, the powder A and the polystyrene microspheres.
  8. 8. The high-strength refractory for a VD furnace according to claim 1, wherein the water reducing agent is one or both of sodium tripolyphosphate and sodium hexametaphosphate.
  9. 9. A process for preparing a high-strength refractory for a VD furnace according to any one of claims 1 to 8, wherein the preparation process comprises the following steps of, S9-1, adding sintered mullite aggregate, flint clay-zirconia composite material, alumina micropowder, calcium aluminate cement, silica micropowder, composite pore-forming agent and water reducer into a mixer according to the formula ratio for dry mixing; S9-2, adding deionized water into the dry blend, mixing again to obtain castable, injecting the mixed castable into a mold for molding, curing and demolding, and baking at 450 ℃ for 4h to obtain the high-strength refractory material for the VD furnace.
  10. 10. The process for preparing the high-strength refractory for the VD furnace according to claim 9, wherein the curing temperature in the step S9-2 is 35-45 ℃ and the curing time is 24-36 h.

Description

High-strength refractory material for VD furnace and preparation process thereof Technical Field The invention belongs to the technical field of refractory materials, and relates to a high-strength refractory material for a VD furnace and a preparation process thereof. Background VD refining is an important method in modern steel refining technology, and is characterized in that molten steel which is preliminarily melted in an electric furnace or a converter is placed in a closed vacuum tank, and impurities and gases in the molten steel are removed through vacuumizing treatment and stirring by bottom blowing argon, so that the purity of the molten steel is improved, and the quality of steel is improved. In the VD refining process, the furnace cover plays a key role, on one hand, other equipment in the furnace is protected from being damaged by high-temperature radiation of molten steel and steel slag splashing, on the other hand, heat loss is required to be reduced, the temperature in the furnace is kept stable, and excessive drop of the temperature of the molten steel in the degassing process is avoided. However, the conventional refractory material for the VD furnace has various problems, such as thermal shock damage to the furnace cover castable lining caused by thermal stress change when the conventional refractory material frequently fluctuates at high temperature and low temperature, influence on the long-term stability of the furnace cover castable lining, and insufficient heat preservation performance, so that a large amount of heat energy is wasted, unstable temperature in the furnace is aggravated, energy consumption is increased, and the temperature of molten steel is uneven, the components fluctuate, and the quality of the final steel is influenced. In addition, the strength of part of refractory materials is insufficient, when the furnace is subjected to complex working environments such as high-temperature airflow flushing, high-temperature slag splashing, chemical gas erosion, mechanical vibration and the like, phenomena such as steel shell deformation, falling of internal refractory materials, falling of blocks and the like are easy to occur, the service life of the furnace cover is shortened, the downtime of the VD furnace is long, and the utilization rate is reduced. Therefore, development of a high-strength refractory material for a VD furnace and a process for preparing the same are desired. Disclosure of Invention The invention aims to provide a high-strength refractory material for a VD furnace and a preparation process thereof, and the high-strength refractory material has the characteristics of high strength, excellent thermal shock resistance and good slag erosion resistance. The aim of the invention can be achieved by the following technical scheme: a high-strength refractory material for a VD furnace comprises the following components in parts by weight, 65-75 Parts of sintered mullite aggregate, 10-12 Parts of flint clay-zirconia composite material, 8-10 Parts of aluminum oxide micro powder, 4-6 Parts of calcium aluminate cement, 2-3 Parts of silicon micro powder, 0.05-0.1 Part of composite pore-forming agent, 0.12-0.25 Part of water reducer, Wherein, the preparation method of the flint clay-zirconia composite material is as follows, S1-1, placing superfine flint clay fine powder and zirconia fine powder into a mixer to be mixed for 30-60 min to obtain mixed powder, adding a polyvinyl alcohol solution with the mass concentration of 4-8% into the mixed powder, and granulating in a granulator to obtain wet granules; S1-2, drying the wet particles at 100-120 ℃ for 2-4 hours, heating to 1100-1300 ℃ at a rate of 2-5 ℃ per minute, preserving heat for 1-3 hours, and naturally cooling to room temperature to obtain the flint clay-zirconia composite material. As a preferable technical scheme of the invention, the superfine flint clay fine powder and the zirconia micro powder in the S1-1 are mixed according to the mass ratio of (95-97) to (3-5). As a preferable technical scheme of the invention, the addition amount of the polyvinyl alcohol solution in the S1-1 is 4-8% of the mass of the mixed powder. As a preferable technical scheme of the invention, the preparation method of the composite pore-forming agent is as follows, S4-1, immersing sisal fibers in a sodium silicate solution with the concentration of 3-5wt%, stirring for 1-2 hours at 60-80 ℃, washing with deionized water, and drying for 10-12 hours at 60 ℃ to obtain pretreated sisal fibers; s4-2, mixing ammonium oxalate and nano silicon dioxide according to the mass ratio of (97-99) (1-3), and co-grinding in an air flow mill to obtain powder A; s4-3, mixing the pretreated sisal fibers with the powder A for 10-20 min at the mixing speed of 1000-2000 rpm, adding the polystyrene microspheres, mixing for 5-15 min at the mixing speed of 600-800 rpm, adding the liquid paraffin, and continuing mixing for 3-5 min to obtain the composite pore-