Method for producing alumina by using pulverized fuel ash

A technology of alumina and fly ash, which is applied in the field of preparing alumina by using fly ash, can solve the problems of equipment and pipeline corrosion, secondary pollution, high cost, etc., and achieve the effect of easy equipment, easy use, and industrialization

Inactive Publication Date: 2012-06-20
SHENYANG ALUMINIUM MAGNESIUM INSTITUTE
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, there are still some problems in the extraction of alumina from fly ash by the alkaline method, mainly ① the calcium silicate slag produced by the sintering method can only be used as cement raw materials, 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; ② The sintering method only extracts the alumina in the fly ash, and the use value of its silica is low
③ The sintering method for processing fly ash equipment requires large investment, high energy consumption and high cost
The acid method (including sulfuric acid method and hydrochloric acid method) is feasible in principle to process fly ash to produce alumina, but due to the strong corrosiveness of acid, the corrosion of equipment and pipelines restricts its large-scale application

Method used

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  • Method for producing alumina by using pulverized fuel ash
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  • Method for producing alumina by using pulverized fuel ash

Examples

Experimental program
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Effect test

Embodiment 1

[0021] 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 fly ash can also use other components, which cannot be used to limit the protection scope of the present invention.

[0022] Take 1000g of fly ash with the above composition, mix the fly ash with ammonium sulfate solution and wet grind to obtain raw meal, wherein the weight ratio of ammonium sulfate to alumina in fly ash is 5:1; heat the raw meal to 450°C , keep warm for 1h, make clinker, exhaust gas for water absorption to make ammonia water, and use for aluminum sulfate decomposition; clinker is dissolved in hot water for 0.5h, aluminum enters the solution in the form of aluminum sulfate, and silicon stays in the residue to form High-silicon slag; after dissolution, the slurry is separated by solid-liquid and countercurrent washed, the liquid is aluminum sulfate solution, and the solid is high-silicon slag; add ammonia g...

Embodiment 2

[0024] Take 1000g of the raw material fly ash composed in Example 1, and wet mix the raw material fly ash and ammonium sulfate circulating fluid to obtain raw meal, wherein the weight ratio of ammonium sulfate to aluminum oxide in the fly ash is 6:1; Heat the raw material to 500°C and keep it warm for 0.5h to make clinker. After the exhaust gas is dried and dedusted, it is sent to the aluminum sulfate decomposition process with a compressor; the clinker is dissolved in hot water for 1 hour, and the aluminum enters in the form of aluminum sulfate. solution, silicon remains in the residue to form high-silicon slag; after dissolution, the slurry undergoes solid-liquid separation and countercurrent washing, the liquid is aluminum sulfate solution, and the solid is high-silicon slag; ammonia gas recovered by adding ammonia to the aluminum sulfate solution is adjusted. When the pH value reaches 2.5, ferric hydroxide is precipitated. After the high-iron slag is separated, ammonia gas ...

Embodiment 3

[0026] In Example 2, the gas produced by clinker burning is absorbed by the high-silicon slag washing liquid to make ammonia water, and ammonia gas is added to the aluminum sulfate solution to recover the ammonia water obtained, and the pH value is adjusted to 3.5 to precipitate ferric hydroxide and separate hydrogen After iron oxide, continue to add ammonia in the solution to obtain aluminum hydroxide and ammonium sulfate solution; Others are the same as in Example 2.

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Abstract

The invention relates to a method for preparing alumina by using pulverized fuel ash. The method comprises the following steps of: (1) preparing raw meal; (2) baking clinker; (3) recovering ammonia gas; (4) dissolving the clinker out; (5) separating and washing high-silicon residues; (6) preparing alumina with an obtained aluminum sulfate solution; and (7) evaporating an ammonia sulfate solution. The method has the advantages and effects that: no aid is added, so that alumina in pulverized fuel ash can be extracted effectively, and the extraction ratio of alumina can be over 85 percent. In the process flow of the method, circulation of ammonia sulfate is realized, so that alumina can be extracted from pulverized fuel ash in batches by circulating; no waste gas or waste liquid is discharged in an entire process; and a major component in residues left by extraction of alumina from pulverized fuel ash is carbon dioxide which is easy to utilize. A reaction system is a weakly acid system, equipment is easy to handle, and industrialization is facilitated.

Description

technical field [0001] The invention relates to a method for producing alumina by utilizing industrial solid waste, in particular to a method for producing alumina by utilizing fly ash. Background technique [0002] Fly ash is a solid waste from coal-fired power plants. In 2010, the annual discharge of fly ash in my country was as high as 350 million tons, and the total stockpile of fly ash in my country was more than 5 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 bauxite resources. According to the current growth rate of alumina production and bauxite mining speed, even considering the prospective reserves, it is difficult for my country's bau...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01F7/02B09B3/00
Inventor 李来时廖新勤刘瑛瑛王剑
Owner SHENYANG ALUMINIUM MAGNESIUM INSTITUTE
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