Method for the production of a foam ceramic filter using spent chrome corundum
By graded mixing and multiple calcinations of waste chromium corundum, combined with special solvents and stirring methods, foam ceramic filters were prepared, solving the problems of poor filtration effect and short service life of waste chromium corundum in foam ceramics, and achieving efficient resource utilization and good filtration performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- JIANGXI HONGKE SPECIAL ALLOYS
- Filing Date
- 2024-08-20
- Publication Date
- 2026-06-23
AI Technical Summary
Waste chromium corundum cannot be directly used to prepare foam ceramics because it contains Cr2O3, resulting in poor filtration effect, short service life, and limited addition amount, making it impossible to effectively utilize resources.
Waste chromium corundum was ground and graded, then mixed with cerium oxide, lanthanum oxide, zirconium oxide, and alumina respectively, and calcined multiple times. Glycerol and solvent oil were used as solvents, and a special stirring method was used to prepare a slurry. A foam ceramic filter was prepared using soft polyurethane foam as a carrier.
With high doping levels, the foam ceramic filter achieved good filtration performance and extended service life, solved the chromium contamination problem, and improved resource utilization efficiency.
Smart Images
Figure BDA0005000769320000091 
Figure BDA0005000769320000101
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of solid waste utilization, and particularly relates to a method for preparing a foam ceramic filter using waste chrome corundum. BACKGROUND
[0002] Waste chrome corundum widely exists in many waste refractory materials, and the main mineral composition of the raw material chrome corundum is an alpha-Al2O3-Cr2O3 solid solution. It is of great significance to digest solid waste and reduce costs by fully recycling the aluminum oxide therein.
[0003] The main raw material of foam ceramic is aluminum oxide, and therefore, recycling waste chrome corundum to prepare foam ceramic is one of the ways to recycle the waste chrome corundum.
[0004] However, the waste chrome corundum cannot be directly used to prepare foam ceramic because it contains Cr2O3. In order to avoid introducing chromium impurities and ensure the filtering effect, only a small amount of waste chrome corundum can be added, which may cause poor filtering effect and short service life.
[0005] Therefore, it is necessary to study a method to solve the above problems and effectively utilize the waste chrome corundum. SUMMARY
[0006] The present application aims to provide a method for preparing a foam ceramic filter using waste chrome corundum to solve the above problems.
[0007] To achieve the above purpose, the present application adopts the following technical scheme:
[0008] A method for preparing a foam ceramic filter using waste chrome corundum, comprising:
[0009] grinding the waste chrome corundum to obtain fine particles smaller than 0.15 mm, medium particles of 0.15-0.3 mm, and coarse particles larger than 0.3 mm and smaller than or equal to 1 mm through sieving;
[0010] mixing the fine particles with cerium oxide and lanthanum oxide of the same particle size range to obtain a first mixture, mixing the medium particles with zirconium oxide of the same particle size range to obtain a second mixture, and mixing the coarse particles with aluminum oxide of the same particle size range to obtain a third mixture;
[0011] calcining the first mixture, the second mixture, and the third mixture 2-4 times at 1000-1300 DEG C, respectively, and then grinding and mixing to obtain a fourth mixture;
[0012] mixing the fourth mixture with glycerol and solvent oil, stirring the mixture by using a double planetary stirrer to obtain a slurry, impregnating the slurry in a soft polyurethane foam carrier, and then extruding and drying to obtain a blank.
[0013] sintering and cooling the blank to obtain the foam ceramic filter.
[0014] The requirements of the fine particles, the medium particles and the coarse particles for the solidification of chromium are different, the fine particles are more likely to escape into the filtered metal solution in the subsequent preparation process, the medium particles are less likely, and the coarse particles are the least likely, therefore, the fine particles are mixed with cerium oxide and lanthanum oxide for calcination, the medium particles are mixed with zirconium oxide for calcination, and the coarse particles are mixed with aluminum oxide for calcination; the complex oxide formed between chromium and chromium oxide is most stable in the presence of lanthanum oxide and cerium oxide, the ability of zirconium oxide is less, and aluminum oxide is used as the most conventional filter raw material for the coarse particles. The purpose of multiple calcination is to further strengthen the above-mentioned effects.
[0015] Optionally, the temperature of calcination can be 1000℃, 1100℃, 1200℃, 1300℃ or any value between 1000-1300℃, and the number of calcination can be any value between 2, 3, 4 times.
[0016] Preferably, the mass ratio of the fine particles, the cerium oxide and the lanthanum oxide is 1:(0.01-0.05):(0.01-0.05), the mass ratio of the medium particles and the zirconium oxide is 1:(0.1-0.5), and the mass ratio of the coarse particles and the aluminum oxide is 1:(0.1-0.5).
[0017] Optionally, the mass ratio of the fine particles, the cerium oxide and the lanthanum oxide can be 1:0.01:0.01, 1:0.01:0.03, 1:0.01:0.05, 1:0.03:0.01, 1:0.03:0.03, 1:0.03:0.05, 1:0.05:0.01, 1:0.05:0.03, 1:0.05:0.05 or any value between 1:(0.01-0.05):(0.01-0.05), the mass ratio of the medium particles and the zirconium oxide can be 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5 or any value between 1:(0.1-0.5), and the mass ratio of the coarse particles and the aluminum oxide can be 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5 or any value between 1:(0.1-0.5).
[0018] Preferably, the mass ratio of the first mixture, the second mixture and the third mixture is 1:(1-3):(1-3).
[0019] Optionally, the mass ratio of the first mixture, the second mixture, and the third mixture can be any value between 1:1:1, 1:2:1, 1:3:1, 1:2:1, 1:2:2, 1:2:3, 1:3:1, 1:3:2, 1:3:3, or 1:(1-3):(1-3).
[0020] Preferably, the calcination time is 1-5 hours for each individual.
[0021] Optionally, the calcination time can be independently 1h, 2h, 3h, 4h, 5h or any value between 1-5h.
[0022] Preferably, the particle size of the fourth mixture is less than 200 mesh.
[0023] Preferably, the volume ratio of the glycerol to the solvent oil is 1:(1-5).
[0024] Glycerin and solvent oil are combined to form a solvent system with a viscosity suitable for the mixture of the three calcined particles in the fourth mixture.
[0025] Optionally, the volume ratio of glycerol to solvent oil can be any value between 1:1, 1:2, 1:3, 1:4, 1:5 or 1:(1-5).
[0026] Preferably, the solid content of the slurry is 20-40%.
[0027] Optionally, the solid content of the slurry can be any value between 20%, 25%, 30%, 35%, 40%, or 20-40%.
[0028] Preferably, the stirring includes:
[0029] Stir at a revolution speed of 500-1000 rpm and a rotation speed of 1500-2000 rpm for 1-2 hours, then let stand for 12-24 hours, and then stir at a revolution speed of 100-300 rpm and a rotation speed of 500-1000 rpm for 12-24 hours.
[0030] First, mix the particles at high speed, then let them stand. In the presence of glycerin and solvent oil, the particles will not separate into layers as they would in water. Instead, the uneven and uniform parts will become visible. Then, stir for a long time at a lower speed to form a uniform slurry, thus avoiding local defects during subsequent impregnation and sintering.
[0031] Optionally, the initial stirring can be performed at a revolution speed of 500 rpm, 600 rpm, 700 rpm, 800 rpm, 900 rpm, 1000 rpm, or any value between 500 and 1000 rpm, and a rotation speed of 1500 rpm, 1600 rpm, 1700 rpm, 1800 rpm, 1900 rpm, 2000 rpm, or any value between 1500 and 2000 rpm, for a duration of 1 hour, 1.5 hours, 2 hours, or any value between 1 and 2 hours. The settling time can be any value between 12h, 18h, 24h, or 12-24h; the subsequent stirring can be performed with a revolution speed of any value between 100 rpm, 200 rpm, 300 rpm, or 100-300 rpm, and a rotation speed of any value between 500 rpm, 600 rpm, 700 rpm, 800 rpm, 900 rpm, 1000 rpm, or 500-1000 rpm, for a duration of any value between 12h, 18h, 24h, or 12-24h.
[0032] Preferably, the maximum sintering temperature is 1200-1400℃, and the time is 6-8h.
[0033] Preferably, the flexible polyurethane foam has a pore size of 10-30 PPI.
[0034] Compared with the prior art, the beneficial effects of this application include:
[0035] The method for preparing foam ceramic filters using waste chromium corundum provided in this application first grinds and classifies the waste chromium corundum, then mixes it with cerium oxide, lanthanum oxide, zirconium oxide, and alumina according to different particle sizes, and then calcines each mixture multiple times. This solves the problem of uneven oxide distribution caused by uneven mixing of waste chromium corundum with various oxides during use, thereby solving the problem of chromium contamination during the use of foam ceramic filters. It changes the traditional method of using water as a solvent to prepare slurry, using glycerol and solvent oil as solvents, and further solves the problem of uneven mixing of slurry caused by different densities of the materials in the fourth mixture, resulting in many defects after sintering. Thus, it is possible to obtain foam ceramic filters with good filtration effect and long service life even with high doping of waste chromium corundum. Detailed Implementation
[0036] The implementation schemes of this application will be described in detail below with reference to specific embodiments. However, those skilled in the art will understand that the following embodiments are only for illustrating this application and should not be regarded as limiting the scope of this application. Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments used without specified manufacturers are all conventional products that can be purchased commercially.
[0037] Example 1
[0038] This embodiment provides a method for preparing a foam ceramic filter using waste chromium corundum, specifically including the following steps:
[0039] Waste chromium corundum is ground and sieved to obtain fine particles smaller than 0.15 mm, medium particles of 0.15-0.3 mm, and coarse particles larger than 0.3 mm and smaller than or equal to 1 mm.
[0040] A first mixture is obtained by mixing fine particles with cerium oxide and lanthanum oxide of the same particle size range; a second mixture is obtained by mixing medium particles with zirconium oxide of the same particle size range; and a third mixture is obtained by mixing coarse particles with alumina of the same particle size range. The mass ratio of fine particles, cerium oxide and lanthanum oxide is 1:0.01:0.02, the mass ratio of medium particles to zirconium oxide is 1:0.1, and the mass ratio of coarse particles to alumina is 1:0.1.
[0041] The first mixture, the second mixture, and the third mixture were calcined four times at 1000℃, with each calcination lasting 4 hours. After each calcination, they were naturally cooled to room temperature. Then, they were ground and mixed to obtain a fourth mixture with a particle size of less than 200 mesh. The mass ratio of the first mixture, the second mixture, and the third mixture was 1:1:1.
[0042] The fourth mixture was mixed with glycerin and No. 70 solvent oil, and stirred with a double planetary stirrer to obtain a slurry with a solid content of 20%. The stirring included: stirring at a revolution speed of 500 rpm and a rotation speed of 1500 rpm for 2 hours, then letting it stand for 24 hours, and then stirring at a revolution speed of 100 rpm and a rotation speed of 500 rpm for 24 hours.
[0043] The slurry is impregnated with flexible polyurethane foam as a carrier, and then the excess slurry is squeezed out and dried at 120°C to obtain a blank; the flexible polyurethane foam has a pore size of 10 PPI;
[0044] The blank is sintered and cooled to obtain a foam ceramic filter; the sintering process involves uniform heating, with the highest sintering temperature being 1200℃ and the time being 8 hours.
[0045] Example 2
[0046] This embodiment provides a method for preparing a foam ceramic filter using waste chromium corundum, specifically including the following steps:
[0047] Waste chromium corundum is ground and sieved to obtain fine particles smaller than 0.15 mm, medium particles of 0.15-0.3 mm, and coarse particles larger than 0.3 mm and smaller than or equal to 1 mm.
[0048] A first mixture is obtained by mixing fine particles with cerium oxide and lanthanum oxide of the same particle size range; a second mixture is obtained by mixing medium particles with zirconium oxide of the same particle size range; and a third mixture is obtained by mixing coarse particles with alumina of the same particle size range. The mass ratio of fine particles, cerium oxide and lanthanum oxide is 1:0.05:0.01, the mass ratio of medium particles to zirconium oxide is 1:0.5, and the mass ratio of coarse particles to alumina is 1:0.3.
[0049] The first mixture, the second mixture, and the third mixture were calcined twice at 1300℃, each for 1 hour. After each calcination, they were naturally cooled to room temperature. Then, they were ground and mixed to obtain a fourth mixture with a particle size of less than 200 mesh. The mass ratio of the first mixture, the second mixture, and the third mixture was 1:2:3.
[0050] The fourth mixture was mixed with glycerol and No. 70 solvent oil, and stirred using a double planetary stirrer to obtain a slurry with a solid content of 30%. The stirring process included: stirring at a revolution speed of 1000 rpm and a rotation speed of 2000 rpm for 1 hour, then letting it stand for 12 hours, and then stirring at a revolution speed of 300 rpm and a rotation speed of 1000 rpm for 12 hours. The volume ratio of glycerol to solvent oil was 1:5.
[0051] The slurry is impregnated with flexible polyurethane foam as a carrier, and then the excess slurry is squeezed out and dried at 120°C to obtain a blank; the flexible polyurethane foam has a pore size of 20 PPI;
[0052] The blank is sintered and cooled to obtain a foam ceramic filter; the sintering process involves uniform heating, with the highest sintering temperature being 1400℃ and the time being 6 hours.
[0053] Example 3
[0054] This embodiment provides a method for preparing a foam ceramic filter using waste chromium corundum, specifically including the following steps:
[0055] Waste chromium corundum is ground and sieved to obtain fine particles smaller than 0.15 mm, medium particles of 0.15-0.3 mm, and coarse particles larger than 0.3 mm and smaller than or equal to 1 mm.
[0056] A first mixture is obtained by mixing fine particles with cerium oxide and lanthanum oxide of the same particle size range; a second mixture is obtained by mixing medium particles with zirconium oxide of the same particle size range; and a third mixture is obtained by mixing coarse particles with alumina of the same particle size range. The mass ratio of fine particles, cerium oxide and lanthanum oxide is 1:(0.03):0.05, the mass ratio of medium particles to zirconium oxide is 1:0.4, and the mass ratio of coarse particles to alumina is 1:0.5.
[0057] The first mixture, the second mixture, and the third mixture were calcined three times at 1200℃, each for 2 hours. After each calcination, they were naturally cooled to room temperature. Then, they were ground and mixed to obtain a fourth mixture with a particle size of less than 200 mesh. The mass ratio of the first mixture, the second mixture, and the third mixture was 1:3:2.
[0058] The fourth mixture was mixed with glycerin and No. 70 solvent oil, and stirred with a double planetary stirrer to obtain a slurry with a solid content of 40%. The stirring included: stirring at a revolution speed of 800 rpm and a rotation speed of 1600 rpm for 2 hours, then letting it stand for 15 hours, and then stirring at a revolution speed of 200 rpm and a rotation speed of 700 rpm for 20 hours.
[0059] The slurry is impregnated with flexible polyurethane foam as a carrier, and then the excess slurry is squeezed out and dried at 120°C to obtain a blank; the volume ratio of glycerol to solvent oil is 1:3; the flexible polyurethane foam has a pore size of 30 PPI;
[0060] The blank is sintered and cooled to obtain a foam ceramic filter; the sintering process involves uniform heating, with the highest sintering temperature being 1300℃ and the time being 7 hours.
[0061] Example 4
[0062] This embodiment provides a method for preparing a foam ceramic filter using waste chromium corundum, specifically including the following steps:
[0063] Waste chromium corundum is ground and sieved to obtain fine particles smaller than 0.15 mm, medium particles of 0.15-0.3 mm, and coarse particles larger than 0.3 mm and smaller than or equal to 1 mm.
[0064] A first mixture is obtained by mixing fine particles with cerium oxide and lanthanum oxide of the same particle size range; a second mixture is obtained by mixing medium particles with zirconium oxide of the same particle size range; and a third mixture is obtained by mixing coarse particles with alumina of the same particle size range. The mass ratio of fine particles, cerium oxide and lanthanum oxide is 1:0.03:0.03, the mass ratio of medium particles to zirconium oxide is 1:0.35, and the mass ratio of coarse particles to alumina is 1:0.25.
[0065] The first mixture, the second mixture, and the third mixture were calcined four times at 1200℃, each for 3 hours. After each calcination, they were naturally cooled to room temperature. Then, they were ground and mixed to obtain a fourth mixture with a particle size of less than 200 mesh. The mass ratio of the first mixture, the second mixture, and the third mixture was 1:2:2.
[0066] The fourth mixture was mixed with glycerin and No. 70 solvent oil, and stirred with a double planetary stirrer to obtain a slurry with a solid content of 40%. The stirring included: stirring at a revolution speed of 800 rpm and a rotation speed of 1800 rpm for 2 hours, then letting it stand for 24 hours, and then stirring at a revolution speed of 200 rpm and a rotation speed of 800 rpm for 24 hours.
[0067] The slurry is impregnated with flexible polyurethane foam as a carrier, and then the excess slurry is squeezed out and dried at 120°C to obtain a blank; the volume ratio of glycerol to solvent oil is 1:3; the flexible polyurethane foam has a pore size of 20 PPI;
[0068] The blank is sintered and cooled to obtain a foam ceramic filter; the sintering process involves uniform heating, with the highest sintering temperature being 1300℃ and the time being 6 hours.
[0069] Comparative Example 1
[0070] Unlike Example 4, the waste chromium corundum was not graded after grinding, but directly mixed with cerium oxide, lanthanum oxide, zirconium oxide and aluminum oxide, and calcined 4 times at 1200°C, with each calcination time being 3 hours.
[0071] Comparative Example 2
[0072] Unlike Example 4, the waste chromium corundum was not graded after grinding, but was mixed with cerium oxide, lanthanum oxide, zirconium oxide and aluminum oxide respectively in the same mass ratio as in Example 4 to obtain the first mixture, the second mixture and the third mixture.
[0073] Comparative Example 3
[0074] Unlike Example 4, it was calcined only once.
[0075] Comparative Example 4
[0076] Unlike Example 4, an equal amount of water was used instead of glycerin and solvent oil.
[0077] Comparative Example 5
[0078] Unlike Example 4, a conventional stirring method was used, with stirring at 1600 rpm for 26 hours.
[0079] Comparative Example 6
[0080] Unlike Example 4, cerium oxide, lanthanum oxide, and zirconium oxide were not used; instead, they were replaced with an equal amount of aluminum oxide.
[0081] The foam ceramic filters obtained in the examples and comparative examples were all prepared with dimensions of 30*30*20mm. They were tested using molten aluminum at a temperature of 700-750℃, with each filter capable of filtering 20kg of molten aluminum per test. The following were measured: the detection rate of chromium in the molten aluminum after one filtration, the maximum number of uses (regardless of filtration efficiency, only observing for cracking; data are averages from multiple tests, rounded to the nearest whole number), and the percentage increase in tensile strength and elongation of the molten aluminum after one filtration. The test results are as follows:
[0082] Table 1 Test Results
[0083]
[0084]
[0085] As shown in Table 1 above, classifying the ground waste chromium corundum and then mixing it with cerium oxide, lanthanum oxide, zirconium oxide, and alumina respectively plays a crucial role in effectively improving filtration efficiency, inhibiting chromium contamination of molten aluminum during use, and extending the filter's service life. Multiple calcinations can improve the filter's service life and filtration efficiency to a certain extent. The combination of glycerol and solvent oil forms a solvent system with a viscosity suitable for the mixture of the three calcined particles in the fourth mixture, which helps improve filtration efficiency and also has a certain impact on the filter's service life. A special stirring method can avoid localized defects during subsequent impregnation and sintering processes, significantly extending the service life. The use of cerium oxide, lanthanum oxide, and zirconium oxide is one of the fundamental factors in achieving the desired filtration efficiency, inhibiting chromium contamination of molten aluminum during use, and extending the filter's service life.
[0086] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application 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 or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.
[0087] Furthermore, those skilled in the art will understand that although some embodiments herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of this application and form different embodiments. For example, in the foregoing claims, any of the claimed embodiments can be used in any combination. The information disclosed in this background section is intended only to enhance the understanding of the general background of this application and should not be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.
Claims
1. A method for preparing a foam ceramic filter using waste chromium corundum, characterized in that, include: The waste chromium corundum was ground and sieved to obtain fine particles smaller than 0.15 mm, medium particles of 0.15-0.3 mm, and coarse particles larger than 0.3 mm and smaller than or equal to 1 mm. The fine particles are mixed with cerium oxide and lanthanum oxide of the same particle size range to obtain a first mixture; the medium particles are mixed with zirconium oxide of the same particle size range to obtain a second mixture; and the coarse particles are mixed with alumina of the same particle size range to obtain a third mixture. The first mixture, the second mixture, and the third mixture are calcined 2-4 times at 1000-1300℃, and then ground and mixed to obtain the fourth mixture. The fourth mixture is mixed with glycerin and solvent oil, and stirred using a double planetary stirrer to obtain a slurry. The slurry is impregnated with a soft polyurethane foam carrier, and then extruded and dried to obtain a blank. The stirring includes: stirring at a revolution speed of 500-1000 rpm and a rotation speed of 1500-2000 rpm for 1-2 hours, then letting it stand for 12-24 hours, and then stirring at a revolution speed of 100-300 rpm and a rotation speed of 500-1000 rpm for 12-24 hours. The blank is sintered and cooled to obtain a foam ceramic filter.
2. The method for preparing a foam ceramic filter using waste chromium corundum according to claim 1, characterized in that, The mass ratio of the fine particles, the cerium oxide, and the lanthanum oxide is 1:(0.01-0.05):(0.01-0.05), the mass ratio of the medium particles to the zirconium oxide is 1:(0.1-0.5), and the mass ratio of the coarse particles to the alumina is 1:(0.1-0.5).
3. The method for preparing a foam ceramic filter using waste chromium corundum according to claim 2, characterized in that, The mass ratio of the first mixture, the second mixture, and the third mixture is 1:(1-3):(1-3).
4. The method for preparing a foam ceramic filter using waste chromium corundum according to claim 1, characterized in that, The calcination time for each is 1-5 hours.
5. The method for preparing a foam ceramic filter using waste chromium corundum according to claim 1, characterized in that, The particle size of the fourth mixture is less than 200 mesh.
6. The method for preparing a foam ceramic filter using waste chromium corundum according to claim 1, characterized in that, The volume ratio of the glycerol to the solvent oil is 1:(1-5).
7. The method for preparing a foam ceramic filter using waste chromium corundum according to claim 6, characterized in that, The solid content of the slurry is 20-40%.
8. The method for preparing a foam ceramic filter using waste chromium corundum according to claim 1, characterized in that, The maximum sintering temperature is 1200-1400℃, and the time is 6-8 hours.
9. The method for preparing a foam ceramic filter using waste chromium corundum according to any one of claims 1-8, characterized in that, The flexible polyurethane foam has a pore size of 10-30 PPI.