Method for preparing high-purity aluminum oxide from fly ash

A high-purity alumina and fly ash technology, applied in the chemical industry, can solve problems such as high cost, volume expansion, and unsatisfactory product purity, and achieve the effects of low production cost, low loss, and easy industrialization

Active Publication Date: 2014-04-02
CHINA SHENHUA ENERGY CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The alumina prepared by this process has a high purity, which can reach more than 99.999%, but the cost is very high, at least 10,000 yuan per ton
[0006] The improved Bayer method prepares high-purity aluminum hydroxide by performing several desiliconization, de-ironization, and crystallization decomposition processes on the bauxite alkali eluate (sodium metaaluminate solution), and high-purity aluminum hydroxide is obtained by high-temperature roasting, but the purity of the product Not ideal; the ammonium aluminum sulfate pyrolysis method is to dissolve aluminum hydroxide with sulfuric acid first, react with ammonium sulfate to obtain ammonium alum, and after repeated recrystallization and refining, then pyrolyze the refined ammonium alum to obtain high-purity alumina, but sulfuric acid Aluminum ammonium has disadvantages such as thermal decomposition, volume expansion of dehydrated alum, and generation of polluting gases such as sulfur trioxide and ammonia.

Method used

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  • Method for preparing high-purity aluminum oxide from fly ash

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0063] Add the high-alumina fly ash in Table 1 to hydrochloric acid for acid leaching reaction to obtain acid-soluble slurry. The mass ratio of fly ash to hydrochloric acid solution is 1:2, the mass fraction of hydrochloric acid solution is 25%, and the reaction temperature is 150 °C , the reaction time is 2h, and the reaction pressure is 0.5MPa. The acid-soluble slurry is passed through a plate-and-frame filter press (Zhongda Belight), and the pressure of the plate and frame is 300kPa; two plate-frames are selected in series for secondary filtration; the filter aid is α-cellulose. A crude aluminum salt solution is obtained after filtration. Pass the crude aluminum salt solution through the column of cation exchange resin Amberlite IR-116 (Dow resin in the United States) to remove iron, the temperature is 80°C, the speed of the solution passing through the column is 3 times the resin volume / h, and the way of passing through the column is from bottom to top The resin column ad...

Embodiment 2

[0065] Add the high-alumina fly ash in Table 1 to hydrochloric acid for acid leaching reaction to obtain acid-soluble slurry. The mass ratio of fly ash to hydrochloric acid solution is 1:3, the mass fraction of hydrochloric acid solution is 25%, and the reaction temperature is 150 °C , the reaction time is 2h, and the reaction pressure is 2MPa. The acid-soluble slurry is passed through a plate and frame filter press (Zhongda Belight), the pressure of the plate and frame is 450kPa; three plates and frames are selected in series for three-stage filtration; the filter aid is activated carbon. A crude aluminum salt solution is obtained after filtration. The thick aluminum salt solution adopts the extraction method to remove iron, the extractant is N235, the diluent is kerosene, the volume ratio of the extractant to the diluent=1:2, the volume ratio of the organic phase to the water phase=1:3, and the chlorinated Aluminum Refining Liquid. Detect the concentration of iron ions in ...

Embodiment 3

[0067]Add sulfuric acid to high alumina fly ash for acid leaching reaction to obtain acid soluble slurry, the mass ratio of fly ash to sulfuric acid solution is 1:2, the mass fraction of sulfuric acid solution is 25%, the reaction temperature is 130°C, and the reaction time is 2h , the reaction pressure is 0.5MPa. The acid-soluble slurry is passed through a plate and frame filter press (Zhongda Belight), the pressure of the plate and frame is 550kPa, and four plates and frames are selected in series for four-stage filtration, and the filter aid is diatomaceous earth. After filtration, coarse aluminum saline solution. Send the crude aluminum salt solution to the settling system with a settling temperature of 95°C and a settling time of 50 minutes to obtain crude aluminum sulfate semen; the settled slurry enters the washing device for washing at a washing temperature of 80°C. The aluminum sulfate crude semen is removed by extraction method, the extraction agent is P204, the dil...

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Abstract

The invention belongs to the field of chemical industry and relates to a method for preparing chemical-grade high-purity aluminum oxide from fly ash. The method comprises the steps of dissolving with acid, carrying out controlled filtering, carrying out deep iron removal, concentrating for crystallizing, roasting at low temperature, dissolving with alkali, carrying out deep filtering, removing calcium and magnesium with resin, decomposing seed crystals, carrying out hydrothermal synthesis to remove sodium, atomizing to produce powder, and the like. The method disclosed by the invention has the advantages that the energy consumption is low, the raw materials are reused, the loss is little, the production cost is low, the technical conditions of a process are broad, the industrialization is easy to realize, and the like.

Description

technical field [0001] The invention belongs to the field of chemical industry and relates to a preparation method of high-purity alumina. Background technique [0002] Fly ash is the main solid waste discharged from coal-fired power plants. Statistics show that the accumulated amount of fly ash in my country is as high as one billion tons. Globally, in 2006 alone, the total emissions of fly ash reached 1.2 billion tons. If a large amount of fly ash is not handled in time or handled properly, it will cause serious harm and impact on the environment and even the survival of human beings. At present, countries all over the world are actively exploring ways to develop high value-added recycling of fly ash in order to further increase its comprehensive utilization value. [0003] From the 1940s to the present, the comprehensive utilization technology of high aluminum fly ash has been a research hotspot. High-aluminum fly ash is a new type of fly ash that has appeared in the ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01F7/30
Inventor 郭昭华池君洲王永旺董宏姬学良吴永峰邹萍钞晓光
Owner CHINA SHENHUA ENERGY CO LTD
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