Method for extracting high-purity ultra-fine alumina from coal ash

A technology of ultra-fine alumina and fly ash, applied in chemical instruments and methods, alumina/aluminum hydroxide, inorganic chemistry, etc., can solve the problems of complicated process, secondary pollution, low alumina extraction rate, etc.

Inactive Publication Date: 2008-06-18
TIANJIN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In order to obtain high-purity alumina, it is necessary to add special process steps to remove it, which complicates the process and is not conducive to actual production
[0005] (2) Acid / alkali direct dissolution method: Alumina is extracted from fly ash by acid / alkali direct dissolution method, which requires a high concentration of acid / alkali, which requires high equipment and is prone to secondary pollution; and oxidation The extraction rate of aluminum is very low
Due to the existence of these negative factors, the development of the alumina extraction industry from fly ash is limited
Relevant aluminum factories in my country have conducted trial production in this area, but due to serious problems in technology and efficiency, they had to stop production in the end

Method used

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  • Method for extracting high-purity ultra-fine alumina from coal ash
  • Method for extracting high-purity ultra-fine alumina from coal ash
  • Method for extracting high-purity ultra-fine alumina from coal ash

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0062] 1. Fly ash calcination activation process

[0063] Na 2 CO 3 Na by weight ratio with fly ash 2 CO 3 / Al 2 o 3 (Contained in fly ash) = 1:1 uniform mixing, after grinding through a 100-mesh sieve, place in a muffle furnace and calcinate at 900°C for 2h.

[0064] 2. Active fly ash dissolution, purification and refinement process

[0065] 1.0mol / L of H 2 SO 4 Mix with the activated fly ash at a volume ratio of 5:1, stir evenly, and heat up to 70°C for 2 hours to dissolve. The aluminum in the activated fly ash is transferred into the solution. After filtering, the remaining waste residue and the eluate containing aluminum are obtained.

[0066] During the dissolution process, a part of the iron salt in the activated fly ash participates in the reaction and enters the dissolution solution, so the dissolution solution contains a small amount of Fe 3+ , which was removed by complexometric titration. Adding concentration is 0.003mol / L ethylenediaminetetraacetic acid...

Embodiment 2

[0072] The preparation process steps are the same as in Example 1, except that the final heat treatment temperature is different during the heat treatment process. In this example, the activation temperature of step 1 in a muffle furnace will be changed to 900°C for calcination for 2 hours.

Embodiment 3

[0074] The preparation process steps are the same as in Example 1, except that the final heat treatment temperature is different during the heat treatment process. In this example, the activation temperature of step 1 in a muffle furnace will be changed to 950°C for calcination for 2 hours.

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Abstract

The invention relates to a method of extracting pure ultrafine alumina from powder coal ash, which comprises the following: 1 sintering and activating process: Na2CO3 is used as activating agent during sintering; 2. aluminum salt extraction process: in the activated power coal, low-concentration sulfuric acid is selected to perform aluminum salt extraction; 3. leaching and sedimentation process: the solution after sulfuric acid is extracted is leached, the aluminum salt filtrate is added with dispersant, ammonia is used as precipitator so that the aluminum ion is separated out in the form of aluminum hydroxide; 4. heat treatment process: the aluminum hydroxide is cleaned with water and then dried, under different temperature, the heat treatment of the aluminum hydroxide is performed so that the aluminum hydroxide is dehydrated, decomposed, and crystallized, so as to obtain different crystal type alumina powder. The invention has the advantages of simple process, good synthetic benefit and high extraction ratio of alumina.

Description

technical field [0001] The invention belongs to waste utilization engineering, in particular to a method for extracting high-purity superfine alumina from fly ash. Background technique [0002] Fly ash is an industrial coal-fired fly ash solid waste mainly composed of silicon and aluminum, which contains a large amount of alumina, which generally accounts for about 30% of the total composition of fly ash. High-purity ultra-fine alumina is one of the important raw materials in the fine ceramic industry. With the development of modern industry, its demand has increased sharply. Due to the limitations of the nature of bauxite in my country, the production cost of alumina is relatively high, and its output is far from meeting the needs of domestic and foreign markets. Therefore, the extraction of high-purity ultra-fine alumina from fly ash has become a focus of attention. [0003] From the current research reports, there are roughly the following me...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01F7/02C01F7/26
Inventor 季惠明徐明霞卢会湘
Owner TIANJIN UNIV
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