Method for producing high-quality superfine aluminum oxide by grafting existing Bayer process system
By grafting the existing Bayer method system, alumina hydroxide is graded and processed in multi-step process, the problems of environmental pollution and high cost in high-purity alumina production are solved, and the low pollution and low cost of high-quality ultra-fine alumina are achieved. Cost production has promoted large-scale promotion.
Patent Information
- Application Number
- CN202411201885.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-29
- Publication Date
- 2024-12-13
AI Technical Summary
The existing high-purity alumina production process has problems such as environmental pollution, high production costs and difficulty in large-scale promotion.
Using the existing Bayer method system, the aluminum hydroxide is graded twice, and the coarse, medium and fine particles are treated respectively, and filtered and washed, roasted, grinded, wet electromagnetization and press-cooking of the autoclave, and finally indirected Calcined in a heating rotary kiln to obtain high-quality ultrafine alumina.
It reduces the environmental pollution in the production process of high-quality ultrafine alumina, reduces production costs, and is conducive to large-scale promotion.
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Figure CN119118173A_ABST
Abstract
Description
Technical Field
[0001] The invention discloses a method for producing high-quality ultrafine alumina by grafting an existing Bayer process system, and belongs to the technical field of electronic ceramics. Background Art
[0002] In the past, the production of high-purity alumina generally adopted the aluminum ammonium sulfate method and the aluminum ammonium carbonate thermal method. This method has a large environmental pollution and high production cost, and has now been eliminated. The current mainstream process is the hydrolysis method of organic aluminum alkoxides. This method has the risk of polluting the environment. The organic alcohol must be recovered, and the hydrogen generated during the production process is dangerous. The production cost of using high-purity aluminum powder to dissolve organic alcohol is high, and large-scale promotion is difficult. In view of this, the present invention grafts the existing Bayer process alumina production system to produce high-quality ultrafine alumina to replace most of the high-purity alumina, which is used in ceramic film coatings, wear-resistant coatings and plasma spraying; electronic ceramics, transparent ceramics, bioceramics; catalysts, catalyst carriers and automobile exhaust purification materials; submicron / nano-level grinding materials, grinding and polishing materials for single crystal silicon wafers; inorganic membrane materials and other fields. Summary of the invention
[0003] The purpose of the present invention is to provide a method for producing high-quality ultrafine alumina by grafting the existing Bayer process system, so as to solve the problems in the prior art that the production of high-quality ultrafine alumina pollutes the environment, has high production costs, and is difficult to promote on a large scale.
[0004] A method for producing high-quality ultrafine alumina by grafting an existing Bayer process system, comprising: classifying the seeds of the Bayer process alumina production system twice, separating the coarse, medium and fine aluminum hydroxide grades to obtain coarse aluminum hydroxide slurry, medium particle seeds and fine particle seeds respectively;
[0005] The coarse aluminum hydroxide slurry is sent to a flat plate for filtration and washing, and the filter cake is sent to a calcining furnace to be fired into sand-like aluminum oxide;
[0006] The medium-sized seed crystals enter the first growing groove;
[0007] The fine particle seeds are divided into two parts. One part enters the agglomeration tank after washing and filtration, and the other part is sent to the flat plate for filtration and washing.
[0008] After the fine particle seed is filtered and washed on a flat plate, the content of fine aluminum hydroxide particles-45μm is ≥40%, the content of attached alkali is ≤0.01%, and the content of Fe2O3 is ≤0.005%.
[0009] The fine particle seed is filtered and washed on a flat plate, and the washed fine aluminum hydroxide particles are mixed with deionized water to form a slurry, which is then ground into a fine particle slurry with a particle size D(50)≤2μm in a sand mill.
[0010] The solid content of the slurry prepared by mixing the washed fine aluminum hydroxide particles with deionized water is between 200 g / l and 300 g / l.
[0011] The fine particle slurry that enters the sand mill for grinding is subjected to wet electromagnetism removal, and then placed in a high-pressure reactor with a polytetrafluoroethylene lining for pressure cooking. After the pressure is released, it enters a sedimentation tank for sedimentation and concentration.
[0012] In the high-pressure reactor, the pressure cooking temperature is between 200°C and 240°C, and the pressure cooking time is between 2h and 10h.
[0013] The overflow of the sedimentation tank washes fine-particle aluminum hydroxide, the underflow enters the centrifuge for dehydration, the centrifuge filtrate and the overflow of the sedimentation tank wash the fine-particle aluminum hydroxide together, and the filter cake enters the indirect heating rotary kiln for calcination.
[0014] In an indirectly heated rotary kiln, the heating temperature is between 700°C and 900°C, and the heating time is between 1h and 2h.
[0015] The heat source of the indirect heating rotary kiln is electricity or natural gas, and the material is 310S.
[0016] After being cooled by the cooler, the alumina enters the bin and enters the air flow mill to be broken up into high-quality ultrafine alumina with D(50) between 0.4μm and 1.2μm, Al2O3 content ≥99.9%, Na2O content ≤0.03%, and Fe2O3 content ≤0.008%, and then the high-quality ultrafine alumina for finished product packaging is produced.
[0017] Compared with the prior art, the present invention has the following beneficial effects: the process design and the raw materials used are novel and creatively grafted with the existing Bayer process alumina production system to produce high-quality ultrafine alumina, which reduces the pollution to the environment during the production of high-quality ultrafine alumina, reduces the production cost, and is conducive to large-scale promotion. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Figure 1 It is a technical flow chart of the present invention. DETAILED DESCRIPTION
[0019] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention is described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the 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.
[0020] A method for producing high-quality ultrafine alumina by grafting an existing Bayer process system, comprising: classifying the seeds of the Bayer process alumina production system twice, separating the coarse, medium and fine aluminum hydroxide grades to obtain coarse aluminum hydroxide slurry, medium particle seeds and fine particle seeds respectively;
[0021] The coarse aluminum hydroxide slurry is sent to a flat plate for filtration and washing, and the filter cake is sent to a calcining furnace to be fired into sand-like aluminum oxide;
[0022] The medium-sized seed crystals enter the first growing groove;
[0023] The fine particle seeds are divided into two parts. One part enters the agglomeration tank after washing and filtration, and the other part is sent to the flat plate for filtration and washing.
[0024] After the fine particle seed is filtered and washed on a flat plate, the content of fine aluminum hydroxide particles-45μm is ≥40%, the content of attached alkali is ≤0.01%, and the content of Fe2O3 is ≤0.005%.
[0025] The fine particle seed is filtered and washed on a flat plate, and the washed fine aluminum hydroxide particles are mixed with deionized water to form a slurry, which is then ground into a fine particle slurry with a particle size D(50)≤2μm in a sand mill.
[0026] The solid content of the slurry prepared by mixing the washed fine aluminum hydroxide particles with deionized water is between 200 g / l and 300 g / l.
[0027] The fine particle slurry that enters the sand mill for grinding is subjected to wet electromagnetism removal, and then placed in a high-pressure reactor with a polytetrafluoroethylene lining for pressure cooking. After the pressure is released, it enters a sedimentation tank for sedimentation and concentration.
[0028] In the high-pressure reactor, the pressure cooking temperature is between 200°C and 240°C, and the pressure cooking time is between 2h and 10h.
[0029] The overflow of the sedimentation tank washes fine-particle aluminum hydroxide, the underflow enters the centrifuge for dehydration, the centrifuge filtrate and the overflow of the sedimentation tank wash the fine-particle aluminum hydroxide together, and the filter cake enters the indirect heating rotary kiln for calcination.
[0030] In an indirectly heated rotary kiln, the heating temperature is between 700°C and 900°C, and the heating time is between 1h and 2h.
[0031] The heat source of the indirect heating rotary kiln is electricity or natural gas, and the material is 310S.
[0032] After cooling in the cooler, the aluminum oxide in the bin enters the air flow mill and is broken into high-quality ultrafine aluminum oxide with D(50) between 0.4μm and 1.2μm, Al2O3 content ≥99.9%, Na2O content ≤0.03%, and Fe2O3 content ≤0.008%, and then the high-quality ultrafine aluminum oxide for finished product packaging is produced. The technical flow chart of the present invention is as follows: Figure 1 shown.
[0033] In Example 1 of the present invention, the crystal seeds of the Bayer process alumina production system are classified twice, and the coarse, medium and fine particle sizes of aluminum hydroxide are separated. The coarse particle aluminum hydroxide slurry is sent to a flat plate for filtering and washing, and the filter cake enters a roasting furnace to be fired into sand-like aluminum oxide. The medium particle crystal seeds enter the growth first tank, and a part of the fine particle crystal seeds enters the agglomeration first tank after washing and filtering, and a part of the fine particle crystal seeds are sent to a flat plate for filtering and washing. After washing, the fine aluminum hydroxide particles-45μm content is 52%, the alkali content is 0.0082%, and the Fe2O3 content is 0.0036%. The washed fine aluminum hydroxide particles and deionized water are mixed into a 266g / l solid content slurry and then enter a sand mill to grind into a D(50)=1.82μm fine particle slurry. The slurry is subjected to After wet electromagnetism removal, it is placed in a high-pressure reactor with a polytetrafluoroethylene lining and boiled at 225°C for 2h. After depressurization, it enters the sedimentation tank for sedimentation and concentration. The overflow of the sedimentation tank washes fine-grained aluminum hydroxide, and the bottom flow enters the centrifuge for dehydration. The centrifuge filtrate and the overflow of the sedimentation tank wash the fine-grained aluminum hydroxide together. The filter cake enters the indirect heating rotary kiln and is calcined at 810°C for 1 hour (the heat source of the rotary kiln is natural gas, and the material is 310S). After cooling in the cooler, it enters the warehouse. The alumina in the warehouse enters the air flow mill and is broken into high-quality ultrafine alumina with D(50)=1.12μm, Al2O3 content of 99.93%, Na2O content of 0.028%, and Fe2O3 content of 0.0059%, and the high-quality ultrafine alumina production process for finished product packaging is carried out.
[0034] In Example 2 of the present invention, the crystal seeds of the Bayer process alumina production system are classified twice, and the coarse, medium and fine particle sizes of aluminum hydroxide are separated. The coarse particle aluminum hydroxide slurry is sent to a flat plate for filtering and washing, and the filter cake enters a roasting furnace to be fired into sand-like aluminum oxide. The medium particle crystal seeds enter the growth first tank, and a part of the fine particle crystal seeds enters the agglomeration first tank after washing and filtering, and a part of the fine particle crystal seeds are sent to a flat plate for filtering and washing. After washing, the fine aluminum hydroxide particles-45μm content is 48%, the alkali content is 0.0076%, and the Fe2O3 content is 0.0043%. The washed fine aluminum hydroxide particles and deionized water are mixed into a 238g / l solid content slurry and then enter a sand mill to grind into a D(50)=1.56μm fine particle slurry. The slurry is wet After the electromagnetism removal, it is placed in a high-pressure reactor with a polytetrafluoroethylene lining and boiled at 230°C for 6 hours. After the pressure is released, it enters the sedimentation tank for sedimentation and concentration. The overflow of the sedimentation tank washes fine-grained aluminum hydroxide, and the bottom flow enters the centrifuge for dehydration. The centrifuge filtrate and the overflow of the sedimentation tank wash the fine-grained aluminum hydroxide together. The filter cake enters the indirect heating rotary kiln for calcination at 830°C for 1 hour and 15 minutes (the heat source of the rotary kiln is natural gas, and the material is 310S). After cooling in the cooler, it enters the warehouse. The aluminum oxide in the warehouse enters the air flow mill and is broken into high-quality ultrafine aluminum oxide with D(50)=0.82μm, Al2O3 content of 99.92%, Na2O content of 0.026%, and Fe2O3 content of 0.0056%, and is packaged as a finished product. High-quality ultrafine aluminum oxide production process.
[0035] In Example 3 of the present invention, the crystal seeds of the Bayer process alumina production system are classified twice, and the coarse, medium and fine particle sizes of aluminum hydroxide are separated. The coarse particle aluminum hydroxide slurry is sent to a flat plate for filtering and washing, and the filter cake enters a roasting furnace to be fired into sand-like aluminum oxide. The medium particle crystal seeds enter the growth first tank, and a part of the fine particle crystal seeds enters the agglomeration first tank after washing and filtering, and a part of the fine particle crystal seeds are sent to a flat plate for filtering and washing. After washing, the fine aluminum hydroxide particles-45μm content is 42%, the alkali content is 0.0062%, and the Fe2O3 content is 0.0035%. The washed fine aluminum hydroxide particles and deionized water are mixed into a 282g / l solid content slurry and then enter a sand mill to grind into a D(50)=1.63μm fine particle slurry. The slurry is wet processed After the electromagnetism removal, it is placed in a high-pressure reactor with a polytetrafluoroethylene lining and boiled at 210°C for 10 hours. After the pressure is released, it enters the sedimentation tank for sedimentation and concentration. The overflow of the sedimentation tank washes fine-grained aluminum hydroxide, and the bottom flow enters the centrifuge for dehydration. The centrifuge filtrate and the overflow of the sedimentation tank wash the fine-grained aluminum hydroxide together. The filter cake enters the indirect heating rotary kiln for calcination at 850°C for 1 hour and 20 minutes (the heat source of the rotary kiln is natural gas, and the material is 310S). After cooling in the cooler, it enters the warehouse. The aluminum oxide in the warehouse enters the air flow mill to be broken into high-quality ultrafine aluminum oxide with D(50)=0.65μm, Al2O3 content of 99.95%, Na2O content of 0.022%, and Fe2O3 content of 0.0052%, and the high-quality ultrafine aluminum oxide production process of finished product packaging is carried out.
[0036] In Example 4 of the present invention, the crystal seeds of the Bayer process alumina production system are classified twice, and the coarse, medium and fine particle sizes of aluminum hydroxide are separated. The coarse particle aluminum hydroxide slurry is sent to a flat plate for filtering and washing, and the filter cake enters a roasting furnace to be fired into sand-like aluminum oxide. The medium particle crystal seeds enter the growth first tank, and a part of the fine particle crystal seeds enters the agglomeration first tank after washing and filtering, and a part of the fine particle crystal seeds are sent to a flat plate for filtering and washing. After washing, the fine aluminum hydroxide particles-45μm content is 46%, the alkali content is 0.0073%, and the Fe2O3 content is 0.0042%. The washed fine aluminum hydroxide particles and deionized water are mixed into a 276g / l solid content slurry and then enter a sand mill to grind into a D(50)=1.77μm fine particle slurry. The slurry is wet After the electromagnetism removal, it is placed in a high-pressure reactor with a polytetrafluoroethylene lining and boiled at 240°C for 3 hours. After the pressure is released, it enters the sedimentation tank for sedimentation and concentration. The overflow of the sedimentation tank washes fine-grained aluminum hydroxide, and the bottom flow enters the centrifuge for dehydration. The centrifuge filtrate and the sedimentation tank overflow wash together to wash the fine-grained aluminum hydroxide. The filter cake enters the indirect heating rotary kiln for calcination at 860°C for 1 hour and 36 minutes (the heat source of the rotary kiln is natural gas, and the material is 310S). After cooling in the cooler, it enters the warehouse. The alumina in the warehouse enters the air flow mill and is broken into high-quality ultrafine alumina with D(50)=0.92μm, Al2O3 content of 99.94%, Na2O content of 0.029%, and Fe2O3 content of 0.0068%, and is packaged as a finished product. High-quality ultrafine alumina production process.
[0037] In Example 5 of the present invention, the crystal seeds of the Bayer process alumina production system are classified twice, and the coarse, medium and fine particle sizes of aluminum hydroxide are separated. The coarse particle aluminum hydroxide slurry is sent to a flat plate for filtering and washing, and the filter cake enters a roasting furnace to be fired into sand-like aluminum oxide. The medium particle crystal seeds enter the growth first tank, and a part of the fine particle crystal seeds enters the agglomeration first tank after washing and filtering, and a part of the fine particle crystal seeds are sent to a flat plate for filtering and washing. After washing, the fine aluminum hydroxide particles-45μm content is 52%, the alkali content is 0.0096%, and the Fe2O3 content is 0.0046%. The washed fine aluminum hydroxide particles and deionized water are mixed into a 292g / l solid content slurry and then enter a sand mill to grind into a D(50)=1.91μm fine particle slurry. The slurry is subjected to After wet electromagnetism removal, it is placed in a high-pressure reactor with a polytetrafluoroethylene lining and boiled at 230°C for 5 hours. After depressurization, it enters a sedimentation tank for sedimentation and concentration. The overflow of the sedimentation tank washes fine-grained aluminum hydroxide, and the bottom flow enters a centrifuge for dehydration. The centrifuge filtrate and the overflow of the sedimentation tank wash the fine-grained aluminum hydroxide together. The filter cake enters an indirect heating rotary kiln and is calcined at 880°C for 1 hour and 5 minutes (the heat source of the rotary kiln is natural gas, and the material is 310S). After cooling in a cooler, it enters a warehouse. The aluminum oxide in the warehouse enters an air flow mill and is broken into high-quality ultrafine aluminum oxide with D(50)=0.88μm, Al2O3 content of 99.9%, Na2O content of 0.021%, and Fe2O3 content of 0.0072%, and is then packaged as a finished product. High-quality ultrafine aluminum oxide production process.
[0038] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some or all of the technical features may be replaced by equivalents, and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.
Claims
1. A method for producing high-quality ultrafine alumina by grafting an existing Bayer process system, characterized in that: include: The crystal seeds of the Bayer process alumina production system are classified twice, and the coarse, medium and fine aluminum hydroxides are separated to obtain coarse particle aluminum hydroxide slurry, medium particle crystal seeds and fine particle crystal seeds respectively; The coarse aluminum hydroxide slurry is sent to a flat plate for filtration and washing, and the filter cake is sent to a calcining furnace to be fired into sand-like aluminum oxide; The medium-sized seed crystals enter the first growing groove; The fine particle seeds are divided into two parts. One part enters the agglomeration tank after washing and filtration, and the other part is sent to the flat plate for filtration and washing.
2. The method for producing high-quality ultrafine alumina by grafting an existing Bayer process system according to claim 1, characterized in that: After the fine particle seed is filtered and washed on a flat plate, the content of fine aluminum hydroxide particles-45μm is ≥40%, the content of attached alkali is ≤0.01%, and the content of Fe2O3 is ≤0.005%.
3. The method for producing high-quality ultrafine alumina by grafting an existing Bayer process system according to claim 2, characterized in that: The fine particle seed is filtered and washed on a flat plate, and the washed fine aluminum hydroxide particles are mixed with deionized water to form a slurry, which is then ground into a fine particle slurry with a particle size D(50)≤2μm in a sand mill.
4. The method for producing high-quality ultrafine alumina by grafting an existing Bayer process system according to claim 3, characterized in that: The solid content of the slurry prepared by mixing the washed fine aluminum hydroxide particles with deionized water is between 200 g / l and 300 g / l.
5. The method for producing high-quality ultrafine alumina by grafting an existing Bayer process system according to claim 4, characterized in that: The fine particle slurry that enters the sand mill for grinding is subjected to wet electromagnetism removal, and then placed in a high-pressure reactor with a polytetrafluoroethylene lining for pressure cooking. After the pressure is released, it enters a sedimentation tank for sedimentation and concentration.
6. The method for producing high-quality ultrafine alumina by grafting an existing Bayer process system according to claim 5, characterized in that: In the high-pressure reactor, the pressure cooking temperature is between 200°C and 240°C, and the pressure cooking time is between 2h and 10h.
7. The method for producing high-quality ultrafine alumina by grafting an existing Bayer process system according to claim 6, characterized in that: The overflow of the sedimentation tank washes fine-particle aluminum hydroxide, the underflow enters the centrifuge for dehydration, the centrifuge filtrate and the overflow of the sedimentation tank wash the fine-particle aluminum hydroxide together, and the filter cake enters the indirect heating rotary kiln for calcination.
8. The method for producing high-quality ultrafine alumina by grafting an existing Bayer process system according to claim 7, characterized in that: In an indirectly heated rotary kiln, the heating temperature is between 700°C and 900°C, and the heating time is between 1h and 2h.
9. The method for producing high-quality ultrafine alumina by grafting an existing Bayer process system according to claim 8, characterized in that: The heat source of the indirect heating rotary kiln is electricity or natural gas, and the material is 310S.
10. The method for producing high-quality ultrafine alumina by grafting an existing Bayer process system according to claim 9, characterized in that: After being cooled by the cooler, the alumina enters the bin and enters the air flow mill to be broken up into high-quality ultrafine alumina with D(50) between 0.4μm and 1.2μm, Al2O3 content ≥99.9%, Na2O content ≤0.03%, and Fe2O3 content ≤0.008%, and then the high-quality ultrafine alumina for finished product packaging is produced.