A method for preparing a foam ceramic filter using waste chrome corundum

Abstract

This application provides a method for preparing a foam ceramic filter using waste chromium corundum, relating to the field of foam ceramics. The method includes: grinding the waste chromium corundum and then sieving it through a 200-mesh sieve to obtain the undersize; mixing a first raw material, sintering it, and then cooling and pulverizing it to obtain a first powder; the first raw material includes 95-97% undersize, 1-2% nano-lanthanum oxide, 1-2% nano-cerium oxide, 0.5-1% sodium dodecylbenzenesulfonate, and K... 4 Sb 2 O 7 0.1-0.5%; the second raw material is mixed with water and stirred to obtain a slurry; the second raw material includes 50-70% of the first powder, 20-40% of alumina, 5-10% of zirconium oxide, 1-5% of isothiazolinone derivative, and 1-5% of ammonium carbonate; the slurry is impregnated with a carrier, then extruded and dried to obtain a blank; the blank is sintered and cooled to obtain a foam ceramic filter. The method provided in this application can prepare foam ceramic filters using waste chromium corundum.

Description

A method for preparing foam ceramic filters using waste chromium corundum Technical Field

[0001] This application relates to the field of foam ceramics, and more particularly to a method for preparing foam ceramic filters using waste chromium corundum. Background Technology

[0002] The main mineral composition of chromium corundum is α-Al₂O₃-Cr₂O₃ solid solution. Waste chromium corundum mainly comes from glass kiln linings, molten glass flow hole cover bricks, and waste refractory materials used in molten iron pretreatment devices, waste incinerators, and pressurized coal-water slurry gasification furnaces.

[0003] The main raw material for foam ceramics is alumina. Waste chromium corundum contains a large amount of alumina. Therefore, recycling waste chromium corundum to prepare foam ceramics is one way to reuse it as a resource.

[0004] However, waste chromium corundum cannot be directly used to prepare foam ceramics. Even if it is added to the raw materials, it often results in small addition amounts, poor filtration effect, easy introduction of impurities such as chromium, and short service life.

[0005] Therefore, it is necessary to study a method to solve the above problems and achieve the effective utilization of waste chromium corundum. Summary of the Invention

[0006] The purpose of this application is to provide a method for preparing foam ceramic filters using waste chromium corundum, so as to solve the above-mentioned problems.

[0007] To achieve the above objectives, this application adopts the following technical solution:

[0008] A method for preparing a foam ceramic filter using waste chromium corundum includes:

[0009] Waste chromium corundum is ground and then sieved through a 200-mesh sieve to obtain the undersize material;

[0010] The first raw material is mixed, subjected to first sintering, and then subjected to first cooling and first pulverization to obtain the first powder; the first raw material, calculated based on its total mass of 100%, includes: 95-97% of the sieve undersize, 1-2% of nano lanthanum oxide, 1-2% of nano cerium oxide, 0.5-1% of sodium dodecylbenzenesulfonate, and 0.1-0.5% of K4Sb2O7;

[0011] Sodium dodecylbenzenesulfonate is usually used as a surfactant, but in this application, it is mainly used as a catalyst to promote the formation of complex oxides from waste chromium corundum, lanthanum oxide, cerium oxide, and K4Sb2O7, thereby solidifying the chromium element and preventing it from melting out of the filter during subsequent sintering and use, thus preventing contamination of the filter material.

[0012] Optionally, the amount of the sieve residue can be any value between 95%, 96%, 97%, or 95-97%, calculated based on the total mass of the first raw material as 100%; the amount of nano-lanthanum oxide can be any value between 1%, 1.5%, 2%, or 1-2%; the amount of nano-cerium oxide can be any value between 1%, 1.5%, 2%, or 1-2%; the amount of sodium dodecylbenzenesulfonate can be any value between 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, or 0.5-1%; and the amount of K4Sb2O7 can be any value between 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, or 0.1-0.5%.

[0013] The second raw material is mixed and water is added to prepare a slurry. The second raw material, calculated as 100% of its total mass, includes: 50-70% of the first powder, 20-40% of alumina, 5-10% of zirconium oxide, 1-5% of an isothiazolinone derivative, and 1-5% of ammonium carbonate. The structural formula of the isothiazolinone derivative is:

[0014]

[0015] The slurry is impregnated with flexible polyurethane foam as a carrier, and then extruded and dried to obtain a blank.

[0016] The blank is subjected to a second sintering and a second cooling to obtain a foam ceramic filter.

[0017] It should be noted that the preparation method of this isothiazolinone derivative is based on existing literature, specifically including: reacting NaH, N,N-dimethylformamide and isothiazolin-3-one under a protective atmosphere, adding γ-chloropropyltriethoxysilane, reacting under ice bath conditions for 20-40 min, then reacting at 70-100℃ for 2-4 h, and then separating the solvent to obtain the target substance.

[0018] The purpose of ammonium carbonate is to compensate for the decrease in filtration efficiency after using isothiazolinone derivatives.

[0019] Optionally, the second raw material is calculated based on its total mass as 100%, and the amount of the first powder can be any value between 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, or 50-70%; the amount of alumina can be 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, etc. The dosage of zirconium oxide can be any value between 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, or 20-40%; the dosage of zirconium oxide can be any value between 5%, 6%, 7%, 8%, 9%, 10%, or 5-10%; the dosage of isothiazolinone derivatives can be any value between 1%, 2%, 3%, 4%, 5%, or 1-5%; the dosage of ammonium carbonate can be any value between 1%, 2%, 3%, 4%, 5%, or 1-5%.

[0020] Preferably, the first sintering temperature is 1100-1300℃ and the time is 3-6h.

[0021] Optionally, the temperature of the first sintering can be any value between 1100℃, 1200℃, 1300℃ or 1100-1300℃, and the time can be any value between 3h, 4h, 5h, 6h or 3-6h.

[0022] Preferably, the second sintering temperature is 1200-1400℃ and the time is 1-5h.

[0023] Optionally, the second sintering temperature can be any value between 1200℃, 1300℃, 1400℃ or 1200-1400℃, and the time can be any value between 1h, 2h, 3h, 4h, 5h or 1-5h.

[0024] Preferably, the amount of the isothiazolinone derivative is 2-3%.

[0025] Optionally, the amount of the isothiazolinone derivative can be any value between 2%, 2.5%, 3%, or 2-3%.

[0026] Preferably, the solid content of the slurry is 50-70 wt%.

[0027] Optionally, the solid content of the slurry can be any value between 50wt%, 55wt%, 60wt%, 65wt%, 70wt%, or 50-70wt%.

[0028] Preferably, the flexible polyurethane foam has a pore size of 10-30 PPI.

[0029] Optionally, the flexible polyurethane foam has a pore size of 10 PPI, 20 PPI, 30 PPI, or any value between 10 and 30 PPI.

[0030] Preferably, the drying temperature is 20-100℃.

[0031] Optionally, the drying temperature can be any value between 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, or 20-100°C.

[0032] Preferably, both the first sintering and the second sintering are carried out in an air atmosphere.

[0033] Preferably, the first cooling and the second cooling are natural cooling to room temperature.

[0034] Preferably, the stirring speed is 500-1000 rpm.

[0035] Optionally, the stirring speed can be any value between 500 rpm, 600 rpm, 700 rpm, 800 rpm, 900 rpm, 1000 rpm, or 500-1000 rpm.

[0036] Compared with the prior art, the beneficial effects of this application include:

[0037] The method for preparing foam ceramic filters using waste chromium corundum provided in this application avoids defects caused by large particles during foam ceramic preparation, which would affect the filtration effect and service life. The waste chromium corundum is pre-ground and sieved, and the small particles undersize are used. The undersize is mixed with nano-lanthanum oxide, nano-cerium oxide, and K4Sb2O7 and sintered in the presence of sodium dodecylbenzenesulfonate as an additive to form a complex oxide of chromium, lanthanum, cerium, and antimony, thus solving the problems of chromium contamination and poor filtration effect during the utilization of waste chromium corundum. The first powder obtained from sintering is then mixed with alumina and zirconium oxide and water to prepare a slurry in the presence of isothiazolinone derivatives and ammonium carbonate as additives. This solves the problems of poor compatibility between the first powder and alumina and zirconium oxide, poor structural stability of the resulting filter after sintering, and short service life. Detailed Implementation

[0038] 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.

[0039] The waste chromium corundum used in the embodiments of this application is the lining of a waste glass kiln.

[0040] Example 1

[0041] This embodiment provides a method for preparing a foam ceramic filter using waste chromium corundum, specifically including the following steps:

[0042] Waste chromium corundum is ground and then sieved through a 200-mesh sieve to obtain the undersize material;

[0043] The following mixture was prepared: 95% of the sieved material, 2% of nano-lanthanum oxide, 2% of nano-cerium oxide, 0.5% of sodium dodecylbenzenesulfonate, and 0.5% of K4Sb2O7 were mixed and sintered in air. The mixture was then naturally cooled to room temperature and pulverized to obtain the first powder. The first sintering temperature was 1100℃ and the time was 6 hours.

[0044] The following mixture was prepared by mixing 70% of the first powder, 20% of alumina, 5% of zirconium oxide, 1% of isothiazolinone derivative, and 4% of ammonium carbonate, adding water, and stirring at 500 rpm to obtain a slurry with a solid content of 50 wt%. The structural formula of the isothiazolinone derivative is:

[0045]

[0046] The slurry is impregnated with a soft polyurethane foam with a pore size of 10 PPI, and then extruded and dried to obtain the blank.

[0047] The blank was subjected to a second sintering in air and naturally cooled to room temperature to obtain a foam ceramic filter; the second sintering temperature was 1200℃ and the time was 5h; the drying temperature was 25℃.

[0048] Example 2

[0049] This embodiment provides a method for preparing a foam ceramic filter using waste chromium corundum, specifically including the following steps:

[0050] Waste chromium corundum is ground and then sieved through a 200-mesh sieve to obtain the undersize material;

[0051] The following mixture was prepared: 97% of the sieved material, 1% of nano-lanthanum oxide, 1% of nano-cerium oxide, 0.9% of sodium dodecylbenzenesulfonate, and 0.1% of K4Sb2O7 were mixed and subjected to a first sintering in air atmosphere, followed by natural cooling to room temperature. The first powder was obtained by first pulverization. The first sintering temperature was 1300℃ and the time was 3 hours.

[0052] The following mixture was prepared by mixing 50% of the first powder, 40% of alumina, 7% of zirconium oxide, 2% of isothiazolinone derivative, and 1% of ammonium carbonate, adding water, and stirring at 1000 rpm to obtain a slurry with a solid content of 70 wt%. The structural formula of the isothiazolinone derivative is:

[0053]

[0054] The slurry is impregnated with a flexible polyurethane foam with a pore size of 20 PPI, and then extruded and dried to obtain the blank.

[0055] The blank was subjected to a second sintering in air and naturally cooled to room temperature to obtain a foam ceramic filter; the second sintering temperature was 1400℃ and the time was 1h; the drying temperature was 50℃.

[0056] Example 3

[0057] This embodiment provides a method for preparing a foam ceramic filter using waste chromium corundum, specifically including the following steps:

[0058] Waste chromium corundum is ground and then sieved through a 200-mesh sieve to obtain the undersize material;

[0059] The following mixture was prepared: 96% of the sieved material, 1.3% of nano-lanthanum oxide, 1.3% of nano-cerium oxide, 1% of sodium dodecylbenzenesulfonate, and 0.4% of K4Sb2O7 were mixed and subjected to a first sintering in air atmosphere, followed by natural cooling to room temperature. The first powder was obtained by first pulverization. The first sintering temperature was 1200℃ and the time was 5 hours.

[0060] The following mixture was prepared by mixing 55% of the first powder, 25% of alumina, 10% of zirconium oxide, 5% of isothiazolinone derivative, and 5% of ammonium carbonate, adding water, and stirring at 800 rpm to obtain a slurry with a solid content of 60 wt%. The structural formula of the isothiazolinone derivative is:

[0061]

[0062] The slurry is impregnated with a flexible polyurethane foam with a pore size of 30 PPI, and then extruded and dried to obtain the blank.

[0063] The blank was subjected to a second sintering in air and naturally cooled to room temperature to obtain a foam ceramic filter; the second sintering temperature was 1300℃ and the time was 3h; the drying temperature was 100℃.

[0064] Comparative Example 1

[0065] Unlike Example 3, the waste chromium corundum is not graded and is used directly after grinding.

[0066] Comparative Example 2

[0067] Unlike Example 3, the first raw material does not include sodium dodecylbenzenesulfonate.

[0068] Comparative Example 3

[0069] Unlike Example 3, the first raw material does not include K4Sb2O7.

[0070] Comparative Example 4

[0071] Unlike Example 3, the first raw material does not include sodium dodecylbenzenesulfonate and K4Sb2O7.

[0072] Comparative Example 5

[0073] Unlike Example 3, the first raw material does not include nano-lanthanum oxide.

[0074] Comparative Example 6

[0075] Unlike Example 3, the first raw material does not include nano-cerium oxide.

[0076] Comparative Example 7

[0077] Unlike Example 3, the first raw material does not include nano-lanthanum oxide and nano-cerium oxide.

[0078] Comparative Example 8

[0079] Unlike Example 3, the second raw material does not include isothiazolinone derivatives.

[0080] Comparative Example 9

[0081] Unlike Example 3, the second raw material does not include ammonium carbonate.

[0082] Comparative Example 10

[0083] Unlike Example 3, the second raw material does not include isothiazolinone derivatives and ammonium carbonate.

[0084] 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: chromium content detected in the molten aluminum after one filtration; maximum number of uses (regardless of filtration efficiency, only observing for cracking; data are rounded averages from multiple tests); filter porosity; and the percentage increase in tensile strength and elongation of the molten aluminum after one filtration. The test results are as follows:

[0085] Table 1 Test Results

[0086]

[0087]

[0088] As shown in Table 1 above, classifying waste chromium corundum and selecting small-particle materials helps to improve service life and filtration effect; using sodium dodecylbenzenesulfonate, K4Sb2O7, nano lanthanum oxide, and nano cerium oxide can solve the problems of chromium pollution and poor filtration effect when utilizing waste chromium corundum; using isothiazolinone derivatives and ammonium carbonate can solve the problems of poor compatibility between the first powder and alumina and zirconium oxide, poor structural stability of the filter obtained after sintering, and short service life.

[0089] 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.

[0090] 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: Waste chromium corundum is ground and then sieved through a 200-mesh sieve to obtain the undersize material; The first raw material is mixed, sintered, cooled and pulverized to obtain the first powder. The first raw material, calculated by its total mass as 100%, includes: 95-97% of the sieve undersize, 1-2% of nano-lanthanum oxide, 1-2% of nano-cerium oxide, 0.5-1% of sodium dodecylbenzenesulfonate, and 0.1-0.5% of K4Sb2O7; the second raw material is mixed and water is added to prepare a slurry; the second raw material, calculated by its total mass as 100%, includes: 50-70% of the first powder, 20-40% of alumina, 5-10% of zirconium oxide, 1-5% of isothiazolinone derivative, and 1-5% of ammonium carbonate; the structural formula of the isothiazolinone derivative is: The slurry is impregnated with flexible polyurethane foam as a carrier, and then extruded and dried to obtain a blank. The blank is then subjected to a second sintering and a second cooling to obtain a foam ceramic filter. The temperature of the first sintering is 1100-1300℃ and the time is 3-6h. The temperature of the second sintering is 1200-1400℃ and the time is 1-5h. Both the first sintering and the second sintering are carried out in an air atmosphere.

2. The method for preparing a foam ceramic filter using waste chromium corundum according to claim 1, characterized in that, The amount of the isothiazolinone derivative used is 2-3%.

3. The method for preparing a foam ceramic filter using waste chromium corundum according to claim 1, characterized in that, The solid content of the slurry is 50-70 wt%.

4. The method for preparing a foam ceramic filter using waste chromium corundum according to claim 1, characterized in that, The flexible polyurethane foam has a pore size of 10-30 PPI.

5. The method for preparing a foam ceramic filter using waste chromium corundum according to claim 1, characterized in that, The drying temperature is 20-100℃.

6. The method for preparing a foam ceramic filter using waste chromium corundum according to claim 1, characterized in that, The first and second cooling methods involve natural cooling to room temperature.

7. The method for preparing a foam ceramic filter using waste chromium corundum according to any one of claims 1-6, characterized in that, The stirring speed is 500-1000 rpm.

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