CN103242051A - Lightweight corundum-mullite castable and preparation method thereof - Google Patents

Abstract

The invention relates to a lightweight corundum-mullite casting material and a preparation method thereof. The technical solution adopted is: 40~70wt% porous corundum-mullite ceramic particles, 10~25wt% porous corundum-mullite ceramic powder, 10~20wt% corundum fine powder, 1~3wt% Silica fine powder, 2~4wt% activated α alumina fine powder, 1~5wt% calcium aluminate cement and 1~5wt% rho alumina fine powder are raw materials, plus 8~20wt% water and 0.02~1wt% water reducer, stir evenly, pour into molding, and dry the molded body naturally for 24 hours, and then dry at 110°C for 8~48 hours. The product prepared by the invention not only has the properties of high apparent porosity, high strength, low thermal conductivity and strong resistance to medium erosion, but also has the advantages of convenient construction, environmental friendliness, controllable apparent porosity and pore size, and small volume change after burning. It is suitable for the working layer or permanent layer of high temperature kiln or container with working temperature lower than 1600℃.

Description

A kind of lightweight corundum-mullite castable and preparation method thereof

technical field

The invention belongs to the technical field of lightweight castables. Specifically relates to a lightweight corundum-mullite castable and a preparation method thereof.

Background technique

Corundum-mullite refractories have the advantages of high load softening temperature, low high-temperature creep rate and good thermal shock stability, and are widely used in high-temperature furnaces or containers in ironworks and glass factories. The traditional corundum-mullite refractory material uses dense corundum or mullite as aggregate, which has high thermal conductivity. When it is applied to the working layer of high-temperature kiln or container, it will cause a large amount of thermal conductivity due to the high thermal conductivity of the entire furnace lining heat loss. Since the closer the insulation material is to the heating surface, the better the insulation effect is (Li Nan et al., Refractory Science, Metallurgical Industry Press, 2010). Therefore, the development of lightweight corundum-mullite refractory materials for the working layer is more conducive to saving energy.

Currently, there have been some studies on lightweight corundum-mullite materials. For example, in the literature on the preparation of mullite-corundum lightweight bricks (Yang Daoyuan et al., Preparation of high-strength and low-thermal conductivity mullite-corundum lightweight bricks, Rare Metal Materials and Engineering, 2009, 38 (2): 1237-1240), Using high-alumina bauxite and silica fume as the main raw materials and polystyrene balls as the pore-forming agent, the lightweight mullite-corundum material was prepared by gel injection molding. The burning of styrene balls causes environmental pollution, and the material has low strength (2.17MPa) and low chemical purity, so it cannot be used in the working layer of high-temperature kilns or containers. Another example is the patented technology of "a corundum-mullite lightweight brick and its preparation method (201110207949.5)", which uses high-alumina bauxite fine powder as the main raw material and polystyrene balls with a particle size of 1-3mm as the pore. The corundum-mullite lightweight refractory material is prepared by using the same agent, but this manufacturing process will also cause environmental pollution, and the refractory material has low chemical purity and large pore size, and is also not suitable for the working layer. Although the patented technology of "a kind of aluminum-silica refractory brick containing lightweight porous aggregate and its preparation method" (200710052470.2) has produced a lightweight corundum-mullite refractory material with high strength and high resistance to medium erosion, it can It is used in the working layer of high-temperature kiln, but its products are stereotyped products, and it cannot prepare refractory materials with complex structures, nor can it be cast on site.

Contents of the invention

The purpose of the present invention is to overcome the defects of the prior art. The purpose is to provide a method for preparing a lightweight corundum-mullite castable with a simple preparation process. The lightweight corundum-mullite castable prepared by this method not only has a significant porosity High, high strength, low thermal conductivity, strong resistance to medium erosion, and controllable apparent porosity and pore size, convenient construction, environmental friendliness and small volume change after burning.

In order to achieve the above object, the technical solution adopted in the present invention is: with 40~70wt% porous corundum-mullite ceramic particles, 10~25wt% porous corundum-mullite ceramic fine powder, 10~20wt% corundum fine powder Powder, 1~3wt% silica fine powder, 2~4wt% active α alumina fine powder, 1~5wt% calcium aluminate cement and 1~5wt% rho alumina fine powder as raw materials, plus the raw material 8 ~20wt% of water and 0.02~1wt% of water reducing agent are mixed evenly and poured into molding. The molded body is naturally dried in the air for 24 hours, and then dried at 110°C for 8~48 hours.

The described porous corundum-mullite ceramics is: 10~40wt% coal gangue powder and 60~90% Al(OH) ₃ powder are used as a mixture, and 2~10wt% water and 0.05% water of the mixture are added. ~3wt% MgCO ₃ powder, stirred, molded, and the molded body was dried at 110°C for 4-24 hours; then fired at 1450-1600°C or 1600-1650°C, and kept for 1-8 hours, That is, porous corundum-mullite ceramics.

The porous corundum-mullite ceramic particle is that the porous corundum-mullite ceramic is crushed, sieved, and particles with a particle size of 8-0.1mm are selected as the porous corundum-mullite ceramic particle; the porous corundum-mullite ceramic particle is The stone ceramic fine powder is that the porous corundum-mullite ceramic is crushed and sieved; the fine powder with a particle size of less than 88 μm is selected as the corundum-mullite ceramic fine powder.

The corundum fine powder is one or both of fused white corundum fine powder and sintered platy corundum fine powder, and the particle size is less than 88 μm.

The _SiO2 content in the silicon oxide micropowder is greater than 94wt%, and the particle size is less than 3 μm.

The Al ₂ O ₃ content in the activated α-alumina micropowder is greater than 97 wt%, and the particle size is less than 3 μm.

The particle size of the calcium aluminate cement is less than 88 μm.

The _Al2O3 content in the rho alumina _fine powder is greater than 98wt%, and the particle size is less than 88μm.

The water reducer is more than one of sodium tripolyphosphate, sodium hexametaphosphate, dispersible alumina and polycarboxylate water reducer.

Adopting the above-mentioned technical scheme, the present invention adopts the patent technology of "a porous mullite ceramic material and its preparation method (CN 200610019552.2)" applied by the applicant to prepare porous corundum-mullite ceramic particles and porous corundum-mullite ceramic particles. The prepared porous corundum-mullite ceramic particles are used as porous aggregate, and the porous corundum-mullite ceramic fine powder and corundum fine powder are mainly used as substrates to prepare lightweight castables, and the preparation process is simple. The chemical composition of the prepared product is mainly Al ₂ O ₃ and SiO ₂ , and its main crystal phase is corundum and mullite. In addition, because the porous corundum-mullite particles not only have high porosity and small pore size, but also have micropores on the surface of the porous corundum-mullite particles, which have strong compatibility with the matrix, after in-situ reaction at high temperature Mullite bridge can be formed between the aggregate and the matrix, so the prepared material not only has high strength and thermal insulation performance, but also has good resistance to medium erosion.

The lightweight corundum-mullite castable prepared by the present invention is tested: the apparent porosity is 31-53%, the bulk density is 2.25-1.58g/cm ³ , and the flexural strength is 1-8MPa; at 1450-1600°C Bottom firing, holding time is 3~8 hours, after testing: the apparent porosity is 33~55%, the bulk density is 2.23~1.56g/cm ³ , the average pore diameter is 3~15μm, and the flexural strength is 3~16MPa.

Therefore, the preparation process of the present invention is simple, and the prepared lightweight corundum-mullite castable not only has the properties of high apparent porosity, high strength, low thermal conductivity and strong resistance to medium erosion, but also has the advantages of convenient construction and environmental friendliness. , Controllable apparent porosity and pore size, small volume change after firing, etc., suitable for working layer or permanent layer of high-temperature kiln or container with working temperature below 1600°C.

Detailed ways

The present invention will be further described below in conjunction with specific embodiment, is not the limitation of its protection scope:

In order to avoid duplication, first the raw materials in this specific embodiment are described as follows, and are not repeated in the examples:

The SiO ₂ content in the silica micropowder is greater than 94wt%, and the particle size is less than 3μm; the Al ₂ O ₃ content in the activated α-alumina micropowder is greater than 97wt%, and the particle size is less than 3μm; the particle size of calcium aluminate cement is less than 88μm; The Al ₂ O ₃ content in the aluminum fine powder is greater than 98wt%, and the particle size is less than 88 μm.

Porous corundum-mullite ceramics are: 10~40wt% coal gangue powder and 60~90% Al(OH) ₃ powder are used as a mixture, and 2~10wt% of water and 0.05~3wt% of the mixture are added MgCO ₃ powder, stirred, molded, and the molded body was dried at 110°C for 4-24 hours; then fired at 1450-1600°C or 1600-1650°C, and kept for 1-8 hours, that is, porous Corundum-mullite ceramics.

The porous corundum-mullite ceramic particle is that the porous corundum-mullite ceramic is pulverized, sieved, and particles with a particle diameter of 8-0.1mm are selected as the porous corundum-mullite ceramic particle; the porous corundum-mullite ceramic particle is The stone ceramic fine powder is that the porous corundum-mullite ceramic is crushed and sieved; the fine powder with a particle size of less than 88 μm is selected as the porous corundum-mullite ceramic fine powder.

Example 1

A lightweight corundum-mullite castable and its preparation method: 50-70wt% porous corundum-mullite ceramic particles, 10-20wt% porous corundum-mullite ceramic fine powder, 10-15wt% Corundum fine powder, 1~2wt% silica fine powder, 3~4wt% active α alumina fine powder, 1~4wt% calcium aluminate cement and 3~5wt% rho alumina fine powder are raw materials, and the The raw materials are 8-12wt% water, 0.1-0.3wt% sodium tripolyphosphate and 0.1-0.3wt% sodium hexametaphosphate, stirred evenly, and poured into molding; the formed green body is naturally dried for 24 hours, and then heated at 110°C Dry under the same conditions for 8~18 hours.

In this embodiment: the particle gradation ratio of porous corundum-mullite ceramic particles is: 8~5mm accounts for 8~12wt% of raw materials, 5~3mm accounts for 18~24wt% of raw materials, 3~1mm accounts for 18~24wt% of raw materials, 1~0.1mm accounts for 6~10wt% of the raw material; the corundum fine powder is fused white corundum fine powder, and the particle size is less than 88 μm.

The lightweight corundum-mullite castable prepared in this example is tested: the apparent porosity is 31-41%, the bulk density is 2.25-1.93g/cm ³ , and the flexural strength is 3-8MPa; at 1450-1600 Firing at ℃, the holding time is 3~8 hours, after testing: the apparent porosity is 33~43%, the bulk density is 2.23~1.91g/cm ³ , the average pore diameter is 5~15μm, and the flexural strength is 8~ 16 MPa.

Example 2

A light corundum-mullite castable and its preparation method: 40~60wt% porous corundum-mullite ceramic particles, 15~25wt% porous corundum-mullite ceramic fine powder, 15~20wt% Corundum fine powder, 2~3wt% silicon oxide fine powder, 2~3wt% active α alumina fine powder, 3~5wt% calcium aluminate cement and 2~4wt% rho alumina fine powder are raw materials, plus the The raw materials are 12-16wt% water and 0.02-0.4wt% sodium tripolyphosphate, stirred evenly, and poured into molding; the molded body is naturally dried for 24 hours, and then dried at 110°C for 16-32 hours.

In this embodiment: the particle gradation ratio of porous corundum-mullite ceramic particles is: 5~3mm accounts for 15~22wt% of raw materials, 3~1mm accounts for 15~22wt% of raw materials, and 1~0.1mm accounts for 10~16wt% of raw materials ; Corundum fine powder is sintered plate-shaped corundum fine powder with a particle size of less than 88 μm.

The light corundum-mullite castable prepared in this example is tested: the light corundum-mullite castable with an apparent porosity of 39-47%, a bulk density of 2.00-1.82g/ ^cm3 and a flexural strength of 2-4MPa Mullite castable; fired at 1450~1600℃, holding time 3~8 hours, after testing: the apparent porosity is 41~49%, the bulk density is 1.98~1.81g/cm ³ , and the average pore diameter is 3~12μm, the flexural strength is 4~9MPa.

Example 3

A lightweight corundum-mullite castable and its preparation method: 40-70wt% porous corundum-mullite ceramic particles, 10-25wt% porous corundum-mullite ceramic fine powder, 10-20wt% Corundum fine powder, 2~3wt% silicon oxide fine powder, 2~4wt% active α alumina fine powder, 3~5wt% calcium aluminate cement and 3~5wt% rho alumina fine powder are raw materials, plus the The raw materials are 15-20wt% water and 0.5-1wt% dispersible alumina, stirred evenly, and poured into molding; the molded green body is naturally dried for 24 hours, and then dried at 110°C for 30-48 hours.

In this embodiment: the particle gradation ratio of porous corundum-mullite ceramic particles is: 3~1mm accounts for 15~30wt% of raw materials, 1~0.1mm accounts for 25~40wt% of raw materials; the composition of corundum fine powder is: electric fusion White corundum fine powder accounts for 6~9wt% of the raw material, sintered tabular corundum fine powder accounts for 6~9wt% of the raw material, and the particle size is less than 88μm.

The lightweight corundum-mullite castable prepared in this example is tested: the apparent porosity is 43~53%, the bulk density is 1.92~1.58g/cm ³ , and the flexural strength is 1~3MPa; at 1450~1600 Firing at ℃, the holding time is 3~8 hours, after testing: the apparent porosity is 44~55%, the bulk density is 1.92~1.56g/cm ³ , the average pore diameter is 5~15μm, and the flexural strength is 3~ 6MPa.

Example 4

A light corundum-mullite castable and its preparation method: 40~60wt% porous corundum-mullite ceramic particles, 15~25wt% porous corundum-mullite ceramic fine powder, 15~20wt% Corundum fine powder, 2~3wt% silicon oxide fine powder, 2~3wt% active α alumina fine powder, 3~5wt% calcium aluminate cement and 1~5wt% rho alumina fine powder are raw materials, plus the The raw materials are 13~17wt% water, 0.2~0.8wt% dispersible alumina and 0.05~0.15wt% polycarboxylate water reducer, stir evenly, and pour into molding; the molded green body is naturally dried for 24 hours, Then dry at 110°C for 16-32 hours.

In this embodiment: the particle gradation ratio of porous corundum-mullite ceramic particles is: 5~3mm accounts for 15~22wt% of raw materials, 3~1mm accounts for 15~22wt% of raw materials, and 1~0.1mm accounts for 10~16wt% of raw materials ; Corundum fine powder is fused white corundum fine powder, the particle size is less than 44μm.

The lightweight corundum-mullite castable prepared in this example is tested: the apparent porosity is 38-46%, the bulk density is 2.04-1.86g/cm ³ , and the flexural strength is 2-6MPa; at 1450-1600 Firing at ℃, the holding time is 3~8 hours, after testing: the apparent porosity is 39~48%, the bulk density is 2.03~1.85g/cm ³ , the average pore diameter is 5~15μm, and the flexural strength is 5~ 12 MPa.

Example 5

A lightweight corundum-mullite castable and its preparation method: 50-70wt% porous corundum-mullite ceramic particles, 10-20wt% porous corundum-mullite ceramic fine powder, 10-15wt% Corundum fine powder, 1~2wt% silica fine powder, 3~4wt% activated α alumina fine powder, 1~5wt% calcium aluminate cement and 3~5wt% rho alumina fine powder as raw materials, plus the above raw materials 13~18wt% of water, 0.1~0.3wt% of sodium tripolyphosphate, 0.1~0.3wt% of sodium hexametaphosphate and 0.1~0.3wt% of polycarboxylate water reducing agent, stir evenly, pouring molding; molding The finished green body is dried naturally for 24 hours, and then dried at 110°C for 16-32 hours.

In this embodiment: the particle gradation ratio of porous corundum-mullite ceramic particles is: 8~5mm accounts for 8~12wt% of raw materials, 5~3mm accounts for 18~24wt% of raw materials, 3~1mm accounts for 18~24wt% of raw materials, 1~0.1mm accounts for 6~10wt% of raw materials; the composition of corundum fine powder is: fused white corundum fine powder with a particle size of less than 44μm accounts for 4~6wt% of raw materials, and sintered tabular corundum fine powder with a particle size of less than 88μm accounts for 6% of raw materials ~9wt%.

The lightweight corundum-mullite castable prepared in this example is tested: the apparent porosity is 39-47%, the bulk density is 2.03-1.85g/cm ³ , and the flexural strength is 1-4MPa; at 1450-1600 Firing at ℃, the holding time is 3~8 hours, after testing: the apparent porosity is 40~48%, the bulk density is 2.02~1.84g/cm ³ , the average pore diameter is 5~15μm, and the flexural strength is 4~ 9MPa.

Example 6

A lightweight corundum-mullite castable and its preparation method: 40-70wt% porous corundum-mullite ceramic particles, 10-25wt% porous corundum-mullite ceramic fine powder, 10-20wt% Corundum fine powder, 2~3wt% silicon oxide fine powder, 2~4wt% active α alumina fine powder, 3~5wt% calcium aluminate cement and 3~5wt% rho alumina fine powder are raw materials, plus the Raw materials 8~13wt% water, 0.3~0.5wt% dispersible alumina, 0.1~0.2wt% sodium tripolyphosphate, 0.1~0.2wt% sodium hexametaphosphate and 0.05~0.15wt% polycarboxylic acid It is a water-reducing agent, stirred evenly, and poured into molding; the molded body is naturally dried for 24 hours, and then dried at 110°C for 10-20 hours.

In this embodiment: the particle gradation ratio of porous corundum-mullite ceramic particles is: 3~1mm accounts for 15~30wt% of raw materials, 1~0.1mm accounts for 25~40wt% of raw materials; corundum fine powder is sintered plate-shaped corundum fine powder Powder, particle size less than 88μm.

The lightweight corundum-mullite castable prepared in this example is tested: the apparent porosity is 34~42%, the bulk density is 2.11~1.91g/cm ³ , and the flexural strength is 4~8MPa; at 1450~1600 Firing at ℃, the holding time is 3~8 hours, after testing: the apparent porosity is 36~44%, the bulk density is 2.10~1.90g/cm ³ , the average pore diameter is 5~15μm, and the flexural strength is 6~ 15MPa.

the

This specific embodiment uses the patented technology of "a porous mullite ceramic material and its preparation method (CN 200610019552.2)" applied by the applicant to prepare porous corundum-mullite ceramic particles and porous corundum-mullite ceramic fine powder, to The prepared porous corundum-mullite ceramic particles are porous aggregates, the corundum-mullite ceramic fine powder and corundum fine powder are mainly used as substrates to prepare lightweight castables, and the preparation process is simple. The chemical composition of the prepared product is mainly Al ₂ O ₃ and SiO ₂ , and its main crystal phase is corundum and mullite. In addition, because the porous corundum-mullite particles not only have high porosity and small pore size, but also have micropores on the surface of the porous corundum-mullite particles, which have strong compatibility with the matrix, after in-situ reaction at high temperature Mullite bridge can be formed between the aggregate and the matrix, so the prepared material not only has high strength and thermal insulation performance, but also has good resistance to medium erosion.

The lightweight corundum-mullite castable prepared in this specific embodiment is tested: the apparent porosity is 31-53%, the bulk density is 2.25-1.58g/cm ³ , and the flexural strength is 1-8MPa; at 1450-1600 Firing at ℃, the holding time is 3~8 hours, after testing: the apparent porosity is 33~55%, the bulk density is 2.23~1.56g/cm ³ , the average pore diameter is 3~15μm, and the flexural strength is 3~ 16 MPa.

Therefore, the preparation process of this specific embodiment is simple, and the prepared lightweight corundum-mullite castable not only has the properties of high apparent porosity, high strength, low thermal conductivity and strong resistance to medium erosion, but also has the advantages of convenient construction, Environmentally friendly, controllable apparent porosity and pore size, and small volume change after firing, it is suitable for the working layer or permanent layer of high-temperature kilns or containers with operating temperatures below 1600 °C.

Claims (9)

1. a preparation method of light corundum-mullite castable, is characterized in that with the porous corundum-mullite ceramic particle of 40～70wt%, the porous corundum-mullite ceramic fine powder of 10～25wt%, 10~20wt% corundum fine powder, 1~3wt% silica fine powder, 2~4wt% active α alumina fine powder, 1~5wt% calcium aluminate cement and 1~5wt% rho alumina fine powder are Raw materials, plus 8~20wt% water and 0.02~1wt% water reducing agent of the raw materials, stirred evenly, poured and molded, the molded green body was naturally dried in the air for 24 hours, and then dried at 110°C for 8~ 48 hours. 2. the preparation method of lightweight corundum-mullite castable according to claim 1, is characterized in that described porous corundum-mullite ceramics is: With 10~40wt% coal gangue powder and 60~90% Al(OH) powder as a mixture _, add 2~10wt% water and 0.05~ _3wt % MgCO powder of the mixture, stir, form, The formed body is dried at 110°C for 4-24 hours; then fired at 1450-1600°C or 1600-1650°C, and kept for 1-8 hours to obtain porous corundum-mullite ceramics; The porous corundum-mullite ceramic particle is that the porous corundum-mullite ceramic is crushed, sieved, and particles with a particle size of 8 to 0.1 mm are selected as the porous corundum-mullite ceramic particle; The porous corundum-mullite ceramic powder is that the porous corundum-mullite ceramic powder is crushed and sieved; the fine powder with a particle size of less than 88 μm is selected as the porous corundum-mullite ceramic powder. 3. the preparation method of lightweight corundum-mullite castable according to claim 1, is characterized in that described corundum fine powder is a kind of in fused white corundum fine powder and sintered tabular corundum fine powder or Two kinds, the particle size is less than 88μm. 4. The preparation method of lightweight corundum-mullite castable according to claim 1, characterized in that the _SiO2 content in the described silicon oxide micropowder is greater than 94wt%, and the particle size is less than 3 μm. 5. The preparation method of lightweight corundum-mullite castable according to claim 1, characterized in that the content of Al ₂ O ₃ in the activated α-alumina micropowder is greater than 97wt%, and the particle size is less than 3 μm. 6. The preparation method of lightweight corundum-mullite castable according to claim 1, characterized in that the particle size of the calcium aluminate cement is less than 88 μm. 7. The preparation method of lightweight corundum-mullite castable according to claim 1, characterized in that the _Al2O3 content in the described rho alumina fine powder is greater than 98wt%, and the particle size is _less than 88 μm. 8. the preparation method of lightweight corundum-mullite castable according to claim 1, is characterized in that described water reducer is sodium tripolyphosphate, sodium hexametaphosphate, dispersible alumina and polycarboxylic acid It is more than one type of water reducing agent. 9. A light corundum-mullite castable, characterized in that said castable is produced according to the preparation method of the light corundum-mullite castable according to any one of claims 1 to 8 Prepared lightweight corundum-mullite castables.