Preparation method of alumina

A technology of alumina and crude alumina, applied in the preparation of alumina/aluminum hydroxide, alumina/hydroxide, etc., can solve the problems of complex alumina process, high energy consumption, environmental and human harm, etc. The effect of sufficient source, simple process and low energy consumption

Active Publication Date: 2007-03-14
SHENHUA ZHUNGER ENERGY
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Problems solved by technology

Alkaline extraction of alumina is a complex process with high energy consumption and a large amount of waste residue
Although the method of extracting alumina by the acid method has the advantages of simple process, low energy consumption, and less waste residue, but because the aluminum in the fly ash of the traditional pulverized coal furnace mainly exists

Method used

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  • Preparation method of alumina

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Effect test

Embodiment 1

[0027] Take 1000 grams of circulating fluidized bed fly ash and place it in a reaction kettle, add 3000 ml of hydrochloric acid with a concentration of 22.5%, heat and stir, control the temperature at 100° C., and react for 2 hours. After the acid-dissolution reaction is completed, the residue liquid is separated, and the filtrate is used for the next step of concentration and crystallization, and the filter residue is washed with water, and the washing liquid is returned to the acid-dissolution reaction for reuse. The aluminum chloride clear liquid after the slag liquid separation is sent to the concentration tank for concentration and crystallization, and the precipitated crystalline aluminum chloride is separated by heap filtration. The obtained crystalline aluminum chloride is heated to 500°C, thermally decomposed to obtain crude alumina, and the hydrogen chloride gas produced by pyrolysis is absorbed by water and returned to the acid solution reaction solution for reuse. ...

Embodiment 2

[0030] Take 1000 grams of circulating fluidized bed fly ash and place it in a reaction kettle, add 2500 ml of hydrochloric acid with a concentration of 30%, heat and stir, control the temperature at 90° C., and react for 2 hours. After the acid-dissolution reaction is completed, the residue liquid is separated, and the filtrate is used for the next step of concentration and crystallization, and the filter residue is washed with water, and the washing liquid is returned to the acid-dissolution reaction for reuse. The aluminum chloride clear liquid after the slag liquid separation is sent to the concentration tank for concentration and crystallization, and the precipitated crystalline aluminum chloride is separated by heap filtration. The obtained crystalline aluminum chloride is heated to 450°C, thermally decomposed to obtain crude alumina, and the hydrogen chloride gas produced by pyrolysis is absorbed by water and returned to the acid solution reaction solution for reuse.

[...

Embodiment 3

[0033] Take 1000 grams of circulating fluidized bed fly ash and place it in a reactor, add 3000 ml of sulfuric acid with a concentration of 40%, heat and stir, control the temperature at 100°C, and react for 1.5 hours. After the acid dissolution reaction, the ore pulp is separated from the slag liquid, and the filtrate is used for the next step of concentration and crystallization. The filter residue is washed with water, and the washing liquid is returned to the acid dissolution reaction for reuse. The aluminum sulfate separated from the slag liquid is sent to the concentration tank at night for concentration and crystallization, and the precipitated crystalline aluminum sulfate is separated by heap filtration. The obtained crystalline aluminum sulfate is heated to 500°C, thermally decomposed to obtain crude alumina, and the sulfur trioxide gas produced by pyrolysis is absorbed by water and returned to the acid solution reaction solution for reuse.

[0034] Grind the coarse a...

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Abstract

The process of preparing alumina includes: the reaction of flyash from circular fluidizing bed and acid to obtain aluminum chloride solution, eliminating silicon impurity, concentrating to crystallize and heating to decompose and to obtain crude alumina product; reaction of crude alumina product and hot alkali solution to obtain sodium aluminate solution; eliminating iron, titanium and other impurity, adding aluminum hydroxide crystal seed into sodium aluminate solution for seed separating decomposition to obtain aluminum hydroxide precipitate; and final calcining aluminum hydroxide to obtain metallurgical alumina. The normal pressure process has no any cosolvent added, and the alumina product has Al2O3 content up to 98 %. The process has small sodium hydroxide consumption, reuse of most of sodium hydroxide, simple operation, low cost, low power consumption, capacity of reducing flyash pollution and other advantages.

Description

Technical field: [0001] The invention relates to a method for producing alumina, in particular to a method for producing alumina by using circulating fluidized bed fly ash as raw material. Background technique: [0002] Fly ash is a waste discharged from thermal power plants. my country uses coal as the main energy source. The fly ash discharged from power plants is as high as hundreds of millions of tons every year, which brings great harm to the ecological environment. How to deal with and utilize fly ash is a very important question. Extracting alumina from fly ash is an effective way to comprehensively utilize fly ash, and has good social and economic benefits. [0003] At present, the methods of extracting alumina from fly ash can be divided into two categories: alkali method and acid method. But all there are some problems in existing technological method. The process of extracting alumina by alkaline method is complicated, consumes a lot of energy, and produces a la...

Claims

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Application Information

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IPC IPC(8): C01F7/02C01F7/30
Inventor 魏存弟杨殿范裴亚利
Owner SHENHUA ZHUNGER ENERGY
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