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Method for preparing superfine alumina by solid-phase reaction

A technology of ultra-fine alumina and solid-state reaction, which is applied in the preparation of alkali metal aluminate/alumina/hydroxide, etc., which can solve the problems of releasing a large amount of nitrogen oxides, carbon oxides, manpower and material resources for filtration and washing, etc.

Inactive Publication Date: 2012-02-08
SHANDONG AOPENG NEW MATERIAL TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

But we know that superfine hydrated alumina precipitates are generally flocculent colloids, and their filtration and washing are very labor-intensive.
[0004] Many reports such as Wei Kunxia's master thesis "Preparation of α-Al by low-temperature combustion synthesis technology 2 o 3 Micropowder" (Kunming: Kunming University of Science and Technology, 2002), Wang Zhiqiang's research paper "Ultrafine α-Al 2 o 3 The study on low-temperature combustion synthesis and sintering characteristics (Silicate Bulletin, 2000, No. 5), adopted a low-temperature combustion synthesis method: using aluminum nitrate and organic matter to burn to produce alumina; but the combustion process released a large amount of nitrogen oxides and carbon oxides and other harmful gases

Method used

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preparation example Construction

[0008] The above-mentioned step (1) operation is not included in the original preparation method with basic aluminum salt as the main aluminum-containing raw material, that is, the innovation of the present invention; the step (2) operation belongs to the conventional steps of the prior art.

[0009] The ratio of basic aluminum salt to acidic raw material (according to the OH that can be generated after complete reaction - moles / H + The number of moles) is (0.3-3) / 1, if (0.3-0.99) / 1 is taken, it is an excess of acidic raw materials, and if (1.01-3) / 1 is taken, it is an excess of basic raw materials. The preferred ratio is (0.6-1.5) / 1.

[0010] In order to avoid the generation of harmful gases in the solid-phase reaction stage to pollute the environment, the present invention determines that the temperature of this step of the solid-phase reaction should be lower than the temperature at which the reactants decompose harmful gases such as nitrogen oxides, sulfur oxides, and car...

Embodiment 1

[0013] Add 66.7g (0.6mol of hydrogen ions can be generated after complete reaction) aluminum sulfate powder and 100g (1.0mol of hydroxyl ions can be generated) sodium aluminate into the experimental kneader in turn, heat to 230°C while kneading, keep the reaction for 1h, When cooled to 70°C, transfer the material into a beaker, add 200ml of water, stir to form a uniform and fine thick suspension, suction filter, add 40ml of water to wash the filter cake, and suction filter to a non-fluid liquid on the filter cake; repeat this way Washed 3 times for 19 minutes and 120 ml of water, dried in an oven at 70 °C for 6 hours, and calcined at 500 °C for 1 hour to obtain 49.6 g of alumina. X-ray diffraction analysis showed that the obtained powder was γ-AL 2 O 3 , the particle size is 11.3 nanometers; the mortar is ground for 30 minutes, and then D is measured by a laser particle size analyzer. 50 = 1.36 microns.

Embodiment 2

[0017] Add 73g (can generate 0.6mol hydrogen ion) aluminum nitrate powder and 50g (can generate 0.5mol hydroxyl ion) sodium aluminate into the experimental kneader in turn, heat to 170 ℃ while kneading, keep the reaction for 1h, cool to 65 ℃ Transfer the material into a beaker, add 160ml of water, stir to form a uniform and fine thick suspension, suction filter, add 40ml of water to wash the filter cake, repeat the washing 3 times, share 26 minutes and 120ml of water, in an oven at 70 ℃ After drying for 6 hours, calcined at 500 °C for 1 hour, 29.3 g of alumina was obtained. X-ray diffraction analysis showed that the obtained powder was γ-AL 2 O 3 , the particle size is 15.7; the nano mortar is ground for 30 minutes, and then D is measured with a laser particle size analyzer. 50 = 1.41 microns.

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Abstract

The invention discloses a method for preparing superfine alumina by reacting alkaline aluminum salt powder (such as sodium aluminate, potassium aluminate and the like) and acid powder raw materials (aluminum chloride, aluminum sulfate, aluminum nitrate, oxalic acid, citric acid, trichloroacetic acid, ammonium chloride, ammonium sulfate and the like) to overcome the defect of difficulty in filtering and washing in a liquid-phase precipitation method. The method is characterized by comprising the following steps of: (1) performing solid-phase reaction, namely mixing the acid powder raw materials and alkaline aluminum salt powder, heating to over 60 DEG C to evaporate water generated by reaction, and keeping materials in a basically dried solid state; and (2) filtering and washing and drying, namely after cooling, mixing the materials and water to obtain suspension, filtering, washing and drying. The temperature of the solid-phase reaction is lower than temperature of harmful gas such as nitrogen oxide, sulfur oxide, carbon monoxide and the like decomposed by a reactant system; and if the temperature of the solid-phase reaction is lower than temperature when the required crystal is formed, calcining is performed at the temperature of 500 to 1,200 DEG C after filtering, washing and drying so as to prepare the required crystal.

Description

technical field [0001] The invention relates to a method for preparing nanometer and submicron alumina by using basic aluminum salt through solid-phase reaction, and belongs to the field of preparation of special alumina products. Background technique [0002] Ultrafine alumina has the advantages of high melting point, high strength, wear resistance, corrosion resistance, oxidation resistance, good insulation, and large surface area, and is widely used in modern technical ceramics, aerospace, electronic circuits, catalysts and biological materials. At present, there are many preparation methods for ultrafine alumina, such as mechanical pulverization method, ammonium aluminum sulfate pyrolysis method, ammonium aluminum carbonate pyrolysis method, modified Bayer method, sol-gel method, gas phase method, etc. The preparation process of the mechanical pulverization method is easy to mix with impurities; although the sol-gel method can prepare ultra-fine alumina powder with high ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01F7/14
Inventor 李军远李金生丁子华严泉才
Owner SHANDONG AOPENG NEW MATERIAL TECH
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