Preparation method of cordierite porous ceramic based on waste magnesia carbon bricks

Abstract

The invention discloses a preparation method of cordierite porous ceramic based on waste magnesia carbon bricks. The preparation method comprises the following steps: taking the following basic raw materials in percentage by mass: 15-25 wt% of waste magnesia carbon bricks, 45-55 wt% of fused quartz and 25-35 wt% of aluminum oxide; silicon nitride and water are added into the basic raw material, the mass of the silicon nitride is 3-5 wt% of the mass of the basic raw material, the mass of the water is 5-8 wt% of the mass of the basic raw material, and the silicon nitride and the water are uniformly mixed; aging for 36-48 hours, molding, drying, and preserving heat at 1320-1370 DEG C for 3-10 hours to obtain a finished product. The production cost is low, and the prepared cordierite porous ceramic based on the waste magnesia carbon bricks is small in volume density, good in compression strength and low in heat conductivity coefficient.

Description

Technical Field

[0001] The invention relates to the field of porous ceramics, and in particular to a method for preparing cordierite porous ceramics based on waste magnesia carbon bricks. Background Art

[0002] China's refractory production accounts for about two-thirds of the world's refractory production. During the service life of refractory materials, when refractory materials reach the end of their service life, they must be replaced with new refractory materials made from raw materials. Initially, due to the low cost of raw materials and processing costs, waste refractory materials were usually disposed of in landfills. In recent years, with the increase in landfill costs and considerations of environmental factors, the recycling of waste refractory materials has received more and more attention.

[0003] In the steel industry, magnesia carbon bricks are the most widely used refractory materials in steelmaking equipment. Their application areas include oxygen-blown converter linings, ladles, electric arc furnace linings, slide plates, etc. Abandoned magnesia carbon bricks account for 60% of waste refractory materials. Magnesia carbon bricks are usually made of more than 96% fused magnesia sand, with a small amount of antioxidants and binders added. They are a kind of refractory material with good quality. Due to the non-wetting characteristics of carbon-containing refractory materials, used MgO-C bricks are less contaminated and basically have no slag penetration. After use, only the surface or local chemical composition and structure of MgO-C bricks will change, and their internal structure and composition will basically not change. Therefore, the abandoned bricks have a high reuse value.

[0004] The patented technology of "A method for preparing periclase insulation material using waste magnesia carbon bricks" (CN110452013A) discloses a method for preparing periclase insulation material using waste magnesia carbon bricks. This method realizes the resource utilization of waste magnesia carbon bricks, but the shortcomings of this method are reflected in: using phenolic resin as a binder, toxic and harmful gases are generated during high-temperature heat treatment. The patented technology of "A method for producing magnesia carbon bricks for refining ladle lining using waste magnesia carbon bricks" (CN109400192A) and "A method for producing magnesia carbon bricks using waste magnesia carbon bricks as the main raw material" (CN101333089) discloses a method for producing refractory materials using waste magnesia carbon bricks as the main raw material. The shortcomings of this patented technology are mainly that a certain amount of pseudo particles are inevitably present in the waste magnesia carbon bricks, and the technical solution disclosed in this patent does not adopt an effective method to avoid the appearance of pseudo particles in the waste magnesia carbon bricks. The patented technology "A regenerated magnesium carbon brick produced from waste magnesium carbon bricks and its preparation method" (CN110342952A) discloses a regenerated magnesium carbon brick produced from waste magnesium carbon bricks and its preparation method. In this patented technology, in order to eliminate the Al4C3 contained in the waste magnesium carbon bricks, the recycled waste magnesium carbon bricks are immersed in water, resulting in a large amount of water resource waste. The patented technology "A method for synthesizing porous cordierite-mullite composite materials using solid waste" (CN200910180637.2) discloses a method for preparing porous cordierite-mullite composite materials using coal gangue as the main raw material and adding waste materials such as spent magnesium carbon bricks. In this patented technology, a small amount of polyvinyl alcohol with a concentration of 0.5mL / 10g is used as a binder. The main disadvantage of this patented technology is that the Al4C3 contained in the spent magnesium carbon bricks is not effectively removed. The patent technology "A method for synthesizing cordierite-mullite composite materials using coal gangue" (ZL 200910078852.1) discloses a method for preparing cordierite-mullite composite materials using coal gangue as the main raw material; the patent technology "A method for synthesizing cordierite using solid waste" (ZL200810239264.7) discloses a method for preparing cordierite using coal gangue as the main raw material and adding waste refractory materials such as used magnesia carbon bricks; the patent technology "A method for synthesizing porous cordierite ceramic materials using coal gangue and waste refractory materials" (ZL 200910082675.4) discloses a method for preparing cordierite porous ceramics using coal gangue as the main raw material and adding waste refractory materials such as used magnesia carbon bricks. The shortcomings of the above patents are: The main shortcomings of the above three patent technologies are: the raw materials are diluted with a large amount of anhydrous ethanol or water for ball milling, resulting in waste. Summary of the invention

[0005] The object of the present invention is to provide a method for preparing cordierite porous ceramics based on waste magnesia carbon bricks.

[0006] The innovation of the present invention lies in that the production cost is low, and the prepared cordierite porous ceramic based on waste magnesia carbon bricks has small volume density, good compressive strength and low thermal conductivity.

[0007] In order to achieve the above-mentioned object of the invention, the technical solution of the present invention is: A method for preparing cordierite porous ceramics based on waste magnesia carbon bricks, characterized by comprising the following steps: (1) Take the following basic raw materials by mass fraction: 15-25wt% of waste magnesia carbon bricks, 45-55wt% of fused quartz and 25-35wt% of alumina; (2) Add silicon nitride and water to the base raw material, the mass of silicon nitride is 3-5wt% of the mass of the base raw material, and the mass of water is 5-8wt% of the mass of the base raw material, and mix them evenly; (3) The material is trapped for 36 to 48 hours, and after molding and drying, it is kept at 1320 to 1370°C for 3 to 10 hours to obtain the finished product.

[0008] Furthermore, the particle size of the waste magnesia carbon bricks is less than 88 μm.

[0009] Furthermore, the waste magnesia carbon bricks have a MgO content of ≥68wt%, a SiO2 content of ≤10wt%, an Al2O3 content of ≤6wt%, and a C content of ≥13wt%.

[0010] Furthermore, the particle size of the fused quartz is less than 88 μm.

[0011] Furthermore, the SiO2 content of the fused quartz is ≥ 99wt%.

[0012] Furthermore, the particle size of the aluminum oxide is less than 10 μm.

[0013] Furthermore, the content of α-Al2O3 in the alumina is ≥98wt%.

[0014] Furthermore, the particle size of the silicon nitride is 0.1-1 μm.

[0015] Furthermore, the α-Si3N4 content of the silicon nitride is ≥93wt%.

[0016] Furthermore, the molding method is semi-dry vibration pressure molding, and the molding pressure is 5~15MPa.

[0017] The beneficial effects of the present invention are: 1. The main raw material used in the present invention is waste magnesium carbon bricks, which are solid waste with large reserves and low prices. Not only can thermal insulation materials be prepared at low cost, but also the utilization of solid waste can be realized; the carbonaceous components in the waste magnesium carbon bricks are fully utilized, and the carbonaceous components in the waste magnesium carbon bricks are used to burn out and form pores during high-temperature heat treatment, thereby improving the porosity of cordierite porous ceramics, reducing the addition of pore-forming agents, and optimizing the production process; avoiding the appearance of false particles, and using waste magnesium carbon brick fine powder as a raw material to prepare cordierite porous ceramics, thereby avoiding the appearance of false particles; effectively removing Al4C3, and in the process of trapping materials, through long-term trapping, allowing water and Al4C3 in the waste magnesium carbon bricks to fully react, and effectively removing Al4C3 in the waste magnesium carbon bricks; adding silicon nitride, silicon nitride and cordierite have similar thermal expansion coefficients, and the introduction of silicon nitride can improve the mechanical properties of the cordierite porous ceramics based on waste magnesium carbon bricks in the present invention. DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the present invention will be described clearly and completely below.

[0019] Example 1: A method for preparing cordierite porous ceramics based on waste magnesia carbon bricks, comprising the following steps: taking the following basic raw materials in mass fractions: 15wt% of waste magnesia carbon bricks, 50wt% of fused quartz and 35wt% of alumina; the particle size of the waste magnesia carbon bricks is less than 88μm; the MgO content of the waste magnesia carbon bricks is ≥68wt%, the SiO2 content is ≤10wt%, the Al2O3 content is ≤6wt%, and the C content is ≥13wt%; the particle size of the fused quartz is less than 88μm; the SiO2 content of the fused quartz is ≥99wt%; the particle size of the alumina is less than 10μm; the α-Al2O3 content of the alumina is ≥98wt%; the particle size of the silicon nitride is 0.1~1μm, and the α-Si3N4 content of the silicon nitride is ≥93wt%.

[0020] Add silicon nitride and water to the base raw material, the mass of silicon nitride is 3wt% of the mass of the base raw material, the mass of water is 5wt% of the mass of the base raw material, and mix them evenly; The material is trapped for 36 hours, and after molding and drying, it is kept warm at 1320°C for 3 hours to obtain the finished product; the molding method is semi-dry vibration pressure molding, and the molding pressure is 5MPa.

[0021] The volume density of the finished product is 0.99~1.09g / cm 3 The compressive strength is 6.1~6.4MPa and the thermal conductivity is 0.28~0.29w / (m•k) (500℃).

[0022] Example 2: A method for preparing cordierite porous ceramics based on waste magnesia carbon bricks, comprising the following steps: taking the following basic raw materials in mass fractions: 25wt% of waste magnesia carbon bricks, 50wt% of fused quartz and 25wt% of alumina; the particle size of the waste magnesia carbon bricks is less than 88μm; the MgO content of the waste magnesia carbon bricks is ≥68wt%, the SiO2 content is ≤10wt%, the Al2O3 content is ≤6wt%, and the C content is ≥13wt%; the particle size of the fused quartz is less than 88μm; the SiO2 content of the fused quartz is ≥99wt%; the particle size of the alumina is less than 10μm; the α-Al2O3 content of the alumina is ≥98wt%; the particle size of the silicon nitride is 0.1~1μm, and the α-Si3N4 content of the silicon nitride is ≥93wt%.

[0023] Add silicon nitride and water to the base raw material, the mass of silicon nitride is 4wt% of the mass of the base raw material, the mass of water is 6wt% of the mass of the base raw material, and mix them evenly; The material was trapped for 40 hours, and after molding and drying, the finished product was kept at 1330°C for 5 hours; the molding method was semi-dry vibration pressure molding, and the molding pressure was 8MPa.

[0024] The volume density of the finished product is 0.95~1.01g / cm 3 The compressive strength is 5.5~5.9MPa and the thermal conductivity is 0.28~0.29w / (m•k) (500℃).

[0025] Example 3: A method for preparing cordierite porous ceramics based on waste magnesia carbon bricks, comprising the following steps: taking the following basic raw materials in mass fractions: 20wt% of waste magnesia carbon bricks, 55wt% of fused quartz and 25wt% of alumina; the particle size of the waste magnesia carbon bricks is less than 88μm; the MgO content of the waste magnesia carbon bricks is ≥68wt%, the SiO2 content is ≤10wt%, the Al2O3 content is ≤6wt%, and the C content is ≥13wt%; the particle size of the fused quartz is less than 88μm; the SiO2 content of the fused quartz is ≥99wt%; the particle size of alumina is less than 10μm; the α-Al2O3 content of alumina is ≥98wt%; the particle size of silicon nitride is 0.1~1μm, and the α-Si3N4 content of silicon nitride is ≥93wt%.

[0026] Add silicon nitride and water to the base raw material, the mass of silicon nitride is 4.5wt% of the mass of the base raw material, the mass of water is 7wt% of the mass of the base raw material, and mix them evenly; The material is trapped for 44 hours, and after molding and drying, it is kept warm at 1350°C for 8 hours to obtain the finished product; the molding method is semi-dry vibration pressure molding, and the molding pressure is 12MPa.

[0027] The volume density of the finished product is 0.95~1.09.g / cm 3The compressive strength is 5.5~6.4MPa and the thermal conductivity is 0.28~0.29w / (m•k) (500℃).

[0028] Example 4: A method for preparing cordierite porous ceramics based on waste magnesia carbon bricks, comprising the following steps: taking the following basic raw materials in mass fractions: 23wt% of waste magnesia carbon bricks, 45wt% of fused quartz and 32wt% of alumina; the particle size of the waste magnesia carbon bricks is less than 88μm; the MgO content of the waste magnesia carbon bricks is ≥68wt%, the SiO2 content is ≤10wt%, the Al2O3 content is ≤6wt%, and the C content is ≥13wt%; the particle size of the fused quartz is less than 88μm; the SiO2 content of the fused quartz is ≥99wt%; the particle size of the alumina is less than 10μm; the α-Al2O3 content of the alumina is ≥98wt%; the particle size of the silicon nitride is 0.1~1μm, and the α-Si3N4 content of the silicon nitride is ≥93wt%.

[0029] Add silicon nitride and water to the base raw material, the mass of silicon nitride is 5wt% of the mass of the base raw material, the mass of water is 8wt% of the mass of the base raw material, and mix them evenly; The material is trapped for 48 hours, and after molding and drying, it is kept warm at 1370°C for 10 hours to obtain the finished product; the molding method is semi-dry vibration pressure molding, and the molding pressure is 15MPa.

[0030] The bulk density of the finished product is 0.96~1.02.g / cm 3 The compressive strength is 5.7~6.1MPa and the thermal conductivity is 0.28~0.29w / (m•k) (500℃).

[0031] The described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

Claims

1. A method for preparing cordierite porous ceramics based on waste magnesia carbon bricks, characterized in that: The following steps are involved: (1) Take the following basic raw materials by mass fraction: 15-25wt% of waste magnesia carbon bricks, 45-55wt% of fused quartz and 25-35wt% of alumina; (2) Add silicon nitride and water to the base raw material, the mass of silicon nitride is 3-5wt% of the mass of the base raw material, and the mass of water is 5-8wt% of the mass of the base raw material, and mix them evenly; (3) The material is trapped for 36 to 48 hours, and after molding and drying, it is kept at 1320 to 1370°C for 3 to 10 hours to obtain the finished product.

2. The method for preparing cordierite porous ceramics based on waste magnesia carbon bricks according to claim 1, characterized in that: The particle size of the waste magnesia carbon bricks is less than 88 μm.

3. The method for preparing cordierite porous ceramics based on waste magnesia carbon bricks according to claim 1, characterized in that: The waste magnesia carbon bricks have a MgO content of ≥68wt%, a SiO2 content of ≤10wt%, an Al2O3 content of ≤6wt%, and a C content of ≥13wt%.

4. The method for preparing cordierite porous ceramics based on waste magnesia carbon bricks according to claim 1, characterized in that: The particle size of the fused quartz is less than 88 μm.

5. The method for preparing cordierite porous ceramics based on waste magnesia carbon bricks according to claim 1, characterized in that: The SiO2 content of the fused quartz is ≥ 99wt%.

6. The method for preparing cordierite porous ceramics based on waste magnesia carbon bricks according to claim 1, characterized in that: The particle size of the aluminum oxide is less than 10 μm.

7. The method for preparing cordierite porous ceramics based on waste magnesia carbon bricks according to claim 1, characterized in that: The content of α-Al2O3 in the alumina is ≥98wt%.

8. The method for preparing cordierite porous ceramics based on waste magnesia carbon bricks according to claim 1, characterized in that: The particle size of the silicon nitride is 0.1-1 μm.

9. The method for preparing cordierite porous ceramics based on waste magnesia carbon bricks according to claim 1, characterized in that: The α-Si3N4 content of the silicon nitride is ≥93wt%.

10. The method for preparing cordierite porous ceramics based on waste magnesia carbon bricks according to claim 1, characterized in that: The molding method is semi-dry vibration pressure molding, and the molding pressure is 5~15MPa.