Method for preparing alumina by using fly ash

A technology of fly ash and alumina, applied in the preparation of alumina/aluminum hydroxide, alumina/hydroxide, etc., can solve the problems of secondary pollution, hidden safety hazards for operators, and high cost, and achieves the benefits of industrialization, Easy equipment, energy saving effect

Inactive Publication Date: 2009-04-01
SHENYANG ALUMINIUM MAGNESIUM INSTITUTE
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, there are still some problems in the extraction of alumina from fly ash by alkaline method, mainly ① the calcium-silicate slag produced by sintering method can only be used as cement raw material, and the production of 1 ton of alumina will produce several times the silicon content of fly ash Calcium slag, while cement has its corresponding sales radius, if there is no large-scale cement industry support in the local area, it will cause secondary pollution; ②The sintering method only extracts the alumina in the fly ash, and the use value of its silica is low
③ The sinte

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  • Method for preparing alumina by using fly ash

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Comparison scheme
Effect test

Embodiment 1

[0022] The composition of raw fly ash is: Al 2 o 3 : 41%, SiO 2 : 48%, Fe 2 o 3 : 3.3%, CaO: 3.3%, TiO 2 : 1.3%, MgO: 0.2%. The composition of the raw coal fly ash can also adopt other components and specific dosages, any conventional fly ash can be used, which cannot be used to limit the protection scope of the present invention.

[0023] Mechanically activate the fly ash, grind it to 200 mesh with a vibrating mill, mix it with water at a ratio of 1:1 and place it in an acid-resistant high-pressure reactor, and place concentrated sulfuric acid with a weight ratio of 1.5 in another pressure-resistant container connected to the reactor Inside, after the high-pressure system is closed, concentrated sulfuric acid flows into the reaction kettle where fly ash and water are mixed. The reaction kettle is lined with acid-resistant ceramic tiles, heated to 180°C, the pressure is 0.29MPa, the reaction time is 2h, and the solid-liquid separation after the reaction cools down , to o...

Embodiment 2

[0026] The raw material fly ash in Example 1 is mechanically activated, ground to 300 mesh in a vertical mill, mixed with water at a ratio of 1:1.5 and placed in an acid-resistant high-pressure reactor, and concentrated sulfuric acid with a weight ratio of 2 is placed in the reaction with In another pressure vessel connected to the kettle, after the high-pressure system is closed, the concentrated sulfuric acid flows into the reaction kettle mixed with fly ash and water. 1.5h, solid-liquid separation after the reaction cools down to obtain aluminum sulfate liquid, the solid-liquid separation equipment of aluminum sulfate solution and slag adopts pressure filtration, evaporates and concentrates, then cools, and precipitates aluminum sulfate crystals, and the liquid aluminum sulfate is evaporated and concentrated by vacuum evaporation, The lining of the evaporation equipment is made of organic materials, and a part of the leached slag is washed to neutrality, and the Al 2 o 3 a...

Embodiment 3

[0029] Mechanically activate the fly ash as the raw material in Example 1, grind it to 150 mesh in a planetary mill, mix it with water at a ratio of 1:0.5 and place it in an acid-resistant high-pressure reactor, and place concentrated sulfuric acid with a weight ratio of 1 in the reactor In another pressure-resistant container connected, after the high-pressure system is closed, the concentrated sulfuric acid flows into the reaction kettle where the fly ash and water are mixed. . After the reaction cools down, the solid-liquid is separated to obtain aluminum sulfate liquid. The solid-liquid separation equipment for aluminum sulfate solution and slag is filtered under reduced pressure. After evaporation and concentration, it is cooled to precipitate aluminum sulfate crystals. The evaporation and concentration of liquid aluminum sulfate adopts atmospheric pressure evaporation. The evaporation equipment is lined for organic materials. Take a part of the leached slag and wash it ...

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Abstract

The invention discloses a method for producing alumina by disposing and utilizing industrial solid wastes, in particular to a method for preparing alumina by fly ash, comprising the steps as follows: the fly ash is mechanically activated; the activated fly ash, water and concentrated sulfuric acid react in a reaction kettle under the conditions of heating and pressurizing; the solid is separated from the liquid after the temperature of the reaction is reduced so as to gain aluminium sulfate liquid; the aluminium sulfate liquid is evaporated, concentrated and cooled so as to precipitate aluminium sulphate crystals; the aluminium sulphate crystals are dehydrated and decomposed to gain gama-Al2O3 and SO3; coarse gama-Al2O3 is dissolved in alkaline solution; after the solid is separated from the liquid, the pure sodium aluminate solution is gained; aluminum hydroxide crystal seed is added to the sodium aluminate solution so as to precipitate the aluminum hydroxide; the coarse gama-Al2O3 can be prepared by circularly dissolving the seed-precipitated alkaline solution after vaporization-concentration; the metallurgical alumina can be gained by baking the prepared aluminum hydroxide. The method adds no additive, can lead the alumina in the fly ash to be effectively leached out with the leaching rate more than 90% and saves the energy resource.

Description

technical field [0001] The invention relates to a method for producing alumina by treating and utilizing industrial solid waste, in particular to a method for preparing alumina by using fly ash. Background technique [0002] Fly ash is a solid waste from coal-fired power plants. At present, my country's annual discharge of fly ash is hundreds of millions of tons, and the total stockpiles of fly ash in my country are more than one billion tons. The discharge of a large amount of fly ash not only occupies a large amount of land, but also seriously pollutes the environment, which constitutes a double damage to the ecology and the environment. Therefore, the comprehensive utilization of fly ash has great practical and long-term strategic significance. Similarly, my country is a country that is not rich in aluminum resources. It is reported that 45 major minerals in my country can guarantee the demand in 2010. There are 10 minerals that cannot be guaranteed, including bauxite. ...

Claims

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Application Information

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IPC IPC(8): C01F7/02C01F7/30
Inventor 李来时刘瑛瑛周凤禄翟玉春
Owner SHENYANG ALUMINIUM MAGNESIUM INSTITUTE
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