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Preparation method of boehmite

A boehmite and preparation process technology, applied in the direction of alumina/aluminum hydroxide, etc., can solve the problems of affecting product performance, easy growth of original crystals, high raw material cost, and achieve low production cost, easy availability of raw materials, Simple production process

Inactive Publication Date: 2011-06-15
GUIZHOU BRANCH CHINA ALUMINUM IND
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Although ultra-low-sodium alumina products can be produced by using aluminum ammonium carbonate pyrolysis method, aluminum alcohol salt hydrolysis method, spark discharge method, spray pyrolysis method, sol-gel method, etc., there are high raw material costs, complicated processes, and production problems. However, the production of low-sodium alumina by using metallurgical-grade aluminum hydroxide as raw material by pickling and purifying after roasting and adding a sodium-removing agent during high-temperature calcination has problems such as environmental pollution and easy growth of the original crystal, which affect the quality of the product. Performance

Method used

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preparation example Construction

[0019] A method for preparing boehmite, comprising first putting aluminum hydroxide and water into a hydrothermal container such as an autoclave, and adding a certain amount of acidic electrolyte additives to further reduce the content of sodium oxide impurities in the boehmite; After heating, the temperature of the hydrothermal system is raised, and the precipitation of aluminum hydroxide particles in the system can be prevented by stirring. After a certain period of hydrothermal reaction, the temperature of the hydrothermal system is reduced by heat exchange. When the temperature drops below 100 ° C , filter the slurry after the hydrothermal reaction, wash the filter cake with pure water for about two times, and then dry the filter cake to obtain ultra-low sodium boehmite with a sodium oxide content of less than 300ppm.

[0020] In the hydrothermal system, the solid content of aluminum hydroxide in the water-based slurry is 10-800g / L. The smaller the solid content, the better...

Embodiment 1

[0026] Add 300 grams of industrial aluminum hydroxide (average particle size of 65 microns) into a 5L autoclave, add 3L of pure water, and then conduct a hydrothermal reaction in the autoclave at 220°C for 3 hours, in order to ensure that the aluminum hydroxide is in the slurry Fully suspended in the medium, mechanical stirring is required to stir the slurry, and the stirring speed after the mechanical stirring is not less than 80 rpm. After the reaction, turn off the heating power of the reactor, continue to stir until the temperature drops below 95°C, open the high-pressure reactor, take out the slurry, filter it, and wash about 3 liters with 80°C hot pure water for 3 times. Afterwards, the filter cake was dried at 110° C., and the impurity sodium oxide content in the obtained boehmite was 320 ppm, the original grain size was about 2.5 microns, and the crystal shape was rhomboid.

Embodiment 2

[0028] Add 300 grams of industrial aluminum hydroxide (average particle size of 65 microns) into a 5L autoclave, add 3L of pure water, add 6 grams of acetic acid at a concentration of 2g / L, and then conduct a hydrothermal reaction in the autoclave at 220°C 3 hours, in order to ensure that the aluminum hydroxide is fully suspended in the slurry, mechanical stirring is required to stir the slurry, and the stirring speed after the mechanical stirring is not less than 80 rpm. After the reaction, turn off the heating power of the reactor, continue to stir until the temperature drops below 95°C, open the high-pressure reactor, take out the slurry, filter it, and wash about 3 liters with 80°C hot pure water for 3 times. Afterwards, the filter cake was dried at 110° C., and the impurity sodium oxide content in the obtained boehmite was 60 ppm, the original grain size was about 2.0 μm, and the crystal shape was rhomboid.

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Abstract

The invention relates to a preparation method of boehmite, particularly a preparation method of ultralow-sodium boehmite. In the preparation process, aluminum hydroxide is used as the raw material. The preparation method is characterized by comprising the following steps: adding water into the raw material aluminum hydroxide to obtain a pulp, and carrying out hydrothermal treatment, wherein in the hydrothermal treatment process, boehmite and the like are added as seed crystals to control the granular form of the boehmite, and acid or acidic electrolyte is added to enable the pulp to be weakly acidic, thereby further reducing the sodium content in the boehmite; and filtering, washing and drying to obtain the boehmite. The method provided by the invention has the advantages of simple production technique, wide material source, low production cost and the like, and is an ideal method for preparing ultralow-sodium boehmite and aluminum oxide.

Description

technical field [0001] A preparation method of boehmite, in particular to a preparation method of ultra-low sodium boehmite. Background technique [0002] Boehmite is a kind of preparation active alumina, catalyst carrier and calcined α-Al 2 o 3 The physical and chemical properties of the precursor boehmite directly affect the performance of activated alumina and calcined alumina. Na 2 O is one of the most harmful impurities in chemical alumina. Strict control is required when making temperature-resistant and voltage-resistant insulating devices, high-frequency ceramics, integrated circuit ceramic substrates, resistor ceramics, high-speed cutting ceramic tools, and sodium lamps. Impurity Na in alumina 2 O content. [0003] The content of impurity sodium oxide in boehmite is high, and the γ-Al formed after roasting 2 o 3 The smaller pore volume affects the reactivity of the catalyst. Na in alumina hydrate 2 O exists in the form of adsorbed alkali, intercrystalline al...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01F7/02
Inventor 王建立樊大林姚长江兰文兰耿红娟马艳红韩冬战
Owner GUIZHOU BRANCH CHINA ALUMINUM IND
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