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Method for producing metallurgical grade alumina by using fly ash

A technology for the production of metallurgy and fly ash, applied in the direction of alumina/aluminum hydroxide, etc., can solve the problems of huge investment, doubled discharge of residual slag, and harsh equipment material requirements.

Inactive Publication Date: 2014-12-03
NORTH UNITED POWER CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In the alkaline process, whether it is the limestone sintering method or the soda lime sintering method, there are problems of high energy consumption and double discharge of residual slag
In the acid process, the formed aluminum salt-aluminum chloride or aluminum sulfate needs to be calcined at a high temperature of 800°C for a long time to discharge the acid radical-hydrogen chloride or sulfur trioxide. In order to cope with the corrosion of strong acid at high temperature, the equipment material Strict requirements, huge investment, high energy consumption in the calcination process, and many difficulties in acid recovery
In the existing ammonium sulfate process, there are disadvantages such as relatively low alumina extraction rate and long roasting time during the roasting process.

Method used

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  • Method for producing metallurgical grade alumina by using fly ash
  • Method for producing metallurgical grade alumina by using fly ash

Examples

Experimental program
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Effect test

Embodiment 1

[0035] The fly ash is ground to 325 mesh, and the molar ratio of alumina and ammonium bisulfate contained in the fly ash is Al 2 o 3 : NH 4 HSO 4 =1:5.3 ingredients, 390°C roasting for 2.5h, the calcined clinker is dissolved in a closed autoclave, the amount of water added is 5 times the clinker mass, the dissolution pressure is 0.3Mpa, and the dissolution time is 1h. The ammonium concentration is 0.47mol / L, and the aluminum content in the eluate is 86.7% of the total aluminum contained in the fly ash. After the dissolution, the obtained filtrate was slowly added dropwise to 7.5mol / L ammonia water at 50°C and 100r / min stirring conditions to pH = 8 to obtain aluminum hydroxide precipitate, which was washed and filtered to obtain crude aluminum hydroxide and ammonium sulfate solution, crude hydrogen Alkali-dissolved impurity removal, carbon content, and roasting are used to obtain metallurgical-grade alumina. The ammonium sulfate solution is evaporated and concentrated to obt...

Embodiment 2

[0037] The fly ash is ground to 400 mesh, according to the molar ratio of alumina and ammonium bisulfate in the fly ash 2 o 3 : NH 4 HSO 4 = 1: 6.1 ingredients, 440 ° C roasting 1.5h, the fired clinker is dissolved in a closed autoclave, the amount of water added is 4 times the clinker mass, the dissolution pressure is 0.25Mpa, and the dissolution time is 50min. The ammonium concentration is 0.52mol / L, and the aluminum content in the eluate is 84.7% of the total aluminum contained in the fly ash. In the above examples, the filtrate obtained after the fly ash and ammonium bisulfate roasted clinker was dissolved was slowly added dropwise with 11 mol / L ammonia water to pH=8.5 under 45°C and 260r / min stirring conditions to obtain aluminum hydroxide precipitate, which was washed Filtrate to obtain crude aluminum hydroxide and ammonium sulfate solution. The crude aluminum hydroxide is subjected to alkali dissolution to remove impurities, carbon content, and roasting to obtain met...

Embodiment 3

[0039] The fly ash is ground to 300 mesh, according to the molar ratio of alumina and ammonium bisulfate in the fly ash 2 o 3 : NH 4 HSO 4 = 1:4 ingredients, 420 ° C roasting for 2 hours, the calcined clinker is dissolved in a closed pressure vessel, the amount of water added is 3 times the clinker mass, the dissolution pressure is 1Mpa, and the dissolution time is 0.5h. The measured dissolution filtrate aluminum ammonium sulfate The concentration is 0.92mol / L, and the aluminum content in the stripping solution is 85.2% of the total aluminum content in the fly ash. In the above-mentioned examples, after the fly ash and ammonium bisulfate roasted clinker are dissolved, the filtrate obtained is slowly dripped with 4.5mol / L ammonia water at 55°C under stirring conditions of 350r / min to pH=9 to obtain aluminum hydroxide precipitation, which is passed through Wash and filter to obtain crude aluminum hydroxide and ammonium sulfate solution. The crude aluminum hydroxide is dissolv...

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Abstract

The invention relates to a method for producing metallurgical grade alumina by using fly ash. The method is characterized by comprising the following steps: uniformly mixing and roasting a raw material fly ash and a circulating medium ammonium hydrogen sulfate; dissolving out an obtained clinker to prepare an aluminium ammonium sulfate solution; subjecting the solution with ammonia or ammonia liquid to liquid-liquid or liquid-gas replacement reaction to obtain a product of a mixture containing aluminium hydroxide and ammonium sulfate; washing and filtering the mixture to obtain coarse aluminum hydroxide; subjecting the ammonium sulfate in the washing liquid to evaporative crystallization and pyrolysis deamination to generate ammonium hydrogen sulfate; returning the ammonium hydrogen sulfate to a roasting process; and subjecting the coarse aluminum hydroxide to impurity removal by alkali dissolution, carbon separation or grade separation to prepare metallurgical grade alumina. Compared with the existing method, the method using ammonium hydrogen sulfate as the circulating medium to produce aluminum alumina has the advantages of extraction rate of aluminum increased by 8%-15% in the roasting process, short roasting time, low roasting temperature and improved efficiency, and is easy for scale production.

Description

technical field [0001] The invention relates to a method for producing metallurgical-grade alumina by using fly ash, in particular to a method for producing metallurgical-grade alumina by using ammonium bisulfate as a circulating medium. Background technique [0002] The most important ore resource in alumina production is bauxite. my country's bauxite resources are relatively poor. According to the current growth rate of alumina production, even considering the prospective reserves, the guarantee period of my country's bauxite is very short. Therefore, it is urgent to find resources to replace bauxite to ensure the sustainable development of my country's aluminum industry. [0003] The fly ash burned at high temperature contains a large amount of active minerals that can be directly dissolved in acid or alkali. The main substances contained are silica, alumina and iron oxide. The content of alumina in high-alumina fly ash is 30 %above. In some areas of Shanxi and Inner Mo...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01F7/02
Inventor 吴景龙薛惠民王自宽王少勋刘晓明陈金燕葛海鹏
Owner NORTH UNITED POWER CO LTD
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