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Preparation method of low-sodium fine grain alumina

A technology of fine-crystalline alumina and aluminum hydroxide, which is applied in the field of preparation of low-sodium fine-crystalline alumina, can solve the problems of difficulty in filtering, washing, drying, complicated salting-out purification process, and high requirements on corrosion resistance, and achieves production cost. Low, wide source of raw materials, the effect of simplifying the production process

Inactive Publication Date: 2012-01-18
GUIZHOU BRANCH CHINA ALUMINUM IND
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

CN1565975A discloses a method for preparing submicron alumina by improving the salting-out method. The hydrochloric acid method is used to produce submicron alumina, and low-sodium alumina can be prepared by salting out. However, the acid method requires high corrosion resistance of the equipment, and The salting-out purification process is complicated and the production cost is high
CN1342609A discloses a preparation technology for loose submicron and nano-alumina. Aluminum and alcohol are used as raw materials to prepare organic alkoxide aluminum salt, which is then hydrolyzed to obtain high-purity alumina hydrate, which is further calcined to obtain superfine alumina powder body, the method has the problem of high cost of raw materials
Although the method provided by this patent can be used to prepare fine-grained alumina powder, the patent must first prepare submicron boehmite. Due to the small size of the particles, there are filtration, washing, and drying processes in the wet production process. Difficulties and other problems, resulting in higher production costs of products

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  • Preparation method of low-sodium fine grain alumina
  • Preparation method of low-sodium fine grain alumina

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preparation example Construction

[0021] A method for preparing low-sodium fine-grained alumina, which involves fully mixing industrial aluminum hydroxide and pseudo-boehmite (or boehmite) seed crystals to form a slurry, which is carried out at a certain temperature in a hydrothermal reaction device. Hydrothermal reaction, after which the slurry is filtered, washed, and dried to obtain low-sodium fine-grained alumina monohydrate, and then the alumina monohydrate is pressed into bricks or balls by a brick press or ball making machine, and placed in a flint kiln The powder is calcined at a certain temperature in a shuttle kiln or other calcining kilns to prepare low-sodium fine-grained alumina. After further grinding and classification, low-sodium submicron alumina powder can be obtained.

[0022] The process is as follows: firstly, industrial aluminum hydroxide and pure water or tap water are prepared into a slurry with a certain solid content, and seeds can be added and the pH value of the slurry can be adjuste...

Embodiment 1

[0024] Add 10 tons of industrial aluminum hydroxide (average particle size of 65 microns) into the batching tank, add 50 cubic meters of tap water, stir the slurry to fully mix, and then transport the slurry to the pipeline device by a diaphragm pump. After the slurry is gradually preheated to 220°C in the pipeline, it enters the high-pressure reactor for hydrothermal reaction. The slurry stays in the high-pressure reactor for 60 minutes, and then the slurry is flashed and cooled to 98 by flash tank. ℃. After the reaction, the slurry enters the buffer tank, and the slurry is transported to the vacuum belt filter by the slurry pump for filtration and washing. The obtained alumina monohydrate is pressed and formed by a brick press, and then placed on the SiC shed plate, and then placed on the shuttle-type Calcined in the kiln at 1250°C and kept at 1250°C for 6 hours to obtain high-temperature alumina with an α-phase transformation rate greater than 95%. Observation by scanning e...

Embodiment 2

[0026] Add 10 tons of industrial aluminum hydroxide (average particle size of 65 microns) into the batching tank, add 50 cubic meters of tap water, stir the slurry to fully mix, and then transport the slurry to the pipeline device by a diaphragm pump. After the slurry is gradually preheated to 240°C in the pipeline, it enters the high-pressure reactor for hydrothermal reaction. The slurry stays in the high-pressure reactor for 30 minutes, and then the slurry is flashed and cooled to 98 by flash tank. ℃. After the reaction, the slurry enters the buffer tank, and the slurry is transported to the vacuum belt filter by the slurry pump for filtration and washing. The obtained alumina monohydrate is pressed and formed by a brick press, and then placed on the SiC shed plate, and then placed on the shuttle-type Calcined in a kiln at 1250°C and held at 1350°C for 6 hours to obtain high-temperature alumina with an α-phase conversion rate greater than 95%. Observation by a scanning elect...

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Abstract

The invention relates to a preparation method of low-sodium fine grain alumina, in particular to a preparation method of low-sodium submicro grain alumina used for electronic ceramics, microcrystalline ceramics, fine polishing, catalyst carriers and the like. The preparation method is characterized by taking industrial aluminium hydroxide as a raw material in the preparation process and comprising the following steps of: firstly carrying out hydrothermal phase inversion processing on aluminium hydroxide to obtain low-sodium fine grain alumina monohydrate with sodium oxide content being less than 500ppm; briquetting the obtained low-sodium fine grain alumina monohydrate, and then roasting to obtain low-sodium fine grain alumina; and finally grinding and grading, thus obtaining low-sodium submicro alumina. The preparation method of low-sodium fine grain alumina has the advantages of simple production process, wide raw material sources, low production cost, environment friendliness and the like, and can combine with the existing alumina production process and equipment to carry out hydrothermal processing, thus effectively simplifying the production process and lowering the production cost. The method is ideal for preparing ultra-low-sodium boehmite and alumina.

Description

technical field [0001] The invention discloses a method for preparing low-sodium fine-grained alumina, which relates to a method for preparing low-sodium submicron-crystalline alumina used for electronic ceramics, microcrystalline ceramics, fine polishing, catalysts and carriers thereof. Background technique [0002] Low-sodium fine-grained (primary grain size less than 2 microns) alumina has the characteristics of wear resistance, corrosion resistance, high insulation, and easy sintering. It has been used in microcrystalline ceramics, precision ceramics, foam ceramics, integrated circuit chips, aviation It has been widely used in fine polishing of light source devices, electronic ceramics, semiconductor substrates, hard disk substrates and sapphire substrates for LEDs. [0003] Although low-sodium fine-grained alumina products with high conversion rates can be produced by adopting processes such as ammonium aluminum carbonate pyrolysis method, aluminum salt hydrolysis metho...

Claims

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Application Information

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IPC IPC(8): C01F7/30
Inventor 樊大林王建立车洪生姚长江余峰涛耿红娟马艳红宋为聪姜雪芹
Owner GUIZHOU BRANCH CHINA ALUMINUM IND
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