Method for preparing aluminum oxide by using hydrochloric acid treatment coal ash

A fly ash, alumina technology, applied in the removal of alumina/aluminum hydroxide, solid waste, etc., can solve the problems of high energy consumption, hidden safety hazards for operators, secondary pollution, etc., to ensure the concentration of hydrochloric acid, avoid Corrosion hazard, beneficial effect on industrialization

Active Publication Date: 2014-03-26
SHENYANG ALUMINIUM MAGNESIUM INSTITUTE
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  • Description
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Problems solved by technology

However, there are still some problems in the extraction of alumina from fly ash by alkaline method, mainly ① the silicon-calcium slag produced by the sintering method can only be used as cement raw material, and the production of 1 ton of alumina will produce several times the silicon content of fly ash Calcium slag, and 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 method reported in the current data is to add fluoride to aid dissolution in the acid leaching reaction, so that silico

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  • Method for preparing aluminum oxide by using hydrochloric acid treatment coal ash

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Comparison scheme
Effect test

Embodiment 1

[0026] The fly ash is mechanically activated by a vibrating mill, and 5% concentration of supplementary hydrochloric acid and washing liquid are mixed with fly ash to form a slurry, which is indirectly heated to 160°C with saturated steam in an indirect heat exchanger and then sent to the lining for acid resistance The ceramic tile reactor is filled with hydrogen chloride gas recovered by drying concentrated sulfuric acid. The molar ratio of hydrogen chloride and the sum of HCl in the supplemental hydrochloric acid to the sum of alumina and iron oxide in the fly ash is 6.5, and the reaction time is 2 hours. Liquid separation to obtain aluminum chloride liquid. The solid-liquid separation of aluminum chloride solution and high silicon slag uses flocculation sedimentation. The aluminum chloride liquid is spray-dried to obtain crystalline aluminum chloride, and aluminum chloride crystals are decomposed at 400°C to obtain crude γ -Al 2 O 3 And hydrogen chloride gas, hydrogen chlorid...

Embodiment 2

[0028] The raw material fly ash in Example 1 is mechanically activated by a vertical mill, and 10% concentration of supplementary hydrochloric acid and washing liquid are mixed with fly ash to form a slurry, which is indirectly heated to 190°C with superheated steam in an indirect heat exchanger Then it is sent to the reactor lined with enamel, and the hydrogen chloride gas recovered by the drying of concentrated sulfuric acid is passed. The molar ratio of hydrogen chloride and the above supplementary hydrochloric acid to the sum of alumina and iron oxide in the fly ash is 7.5, and the reaction time 3h, after the reaction is cooled, solid-liquid separation is obtained to obtain aluminum chloride liquid. The solid-liquid separation of aluminum chloride solution and high silicon slag adopts flocculation sedimentation, and the aluminum chloride liquid is dried by drum to obtain crystalline aluminum chloride. Decompose at 500℃ to obtain crude γ-Al 2 O 3 And hydrogen chloride gas, hy...

Embodiment 3

[0030] The raw material fly ash in Example 1 is mechanically activated by a planetary mill, and 8% concentration of supplementary hydrochloric acid and the lotion are mixed with fly ash to form a slurry, which is indirectly heated to 200°C with heat transfer oil in an indirect heat exchanger and then sent Into a glass-lined reactor, pass the hydrogen chloride gas recovered by drying with concentrated sulfuric acid. The molar ratio of hydrogen chloride and the sum of HCl in the supplementary hydrochloric acid to the sum of alumina and iron oxide in the fly ash is 9, and the reaction time is 1h. After the reaction is cooled down, the solid-liquid is separated to obtain aluminum chloride liquid. The solid-liquid separation of the aluminum chloride solution and the high silicon slag adopts flocculation and sedimentation. The aluminum chloride liquid adopts forced circulation evaporation and crystallization to obtain crystalline aluminum chloride. The aluminum chloride crystal is 600 ...

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Abstract

The invention discloses a method for preparing aluminum oxide by using hydrochloric acid treatment coal ash. The method comprises the steps: activating coal ash; mixing the activated coal ash with hydrochloric acid with the concentration of 5-10 percent; feeding mixed slurries into a heat exchanger to be heated to be between 90 and 200 DEG C; feeding the heated slurries into a reactor; adding hydrogen chloride gas into the reactor and reacting for 1-8 hours; separating solid from the liquid after reaction is finished and the temperature is reduced to obtain aluminum chloride and ferric chloride solution and high silicon slag; evaporating and condensing or drying to obtain crystallized aluminum chloride and ferric chloride; heating and decomposing the crystallized aluminum chloride to obtain coarse gamma-Al2O3 containing a large number of impurities and hydrogen chloride gas; and treating coarse gamma-Al2O3 by using the Bayer process to prepare metallurgical-level aluminum oxide, wherein residual slag is high iron slag and can be used an iron-making raw material. According to the method, the problem of severe corrosion of the equipment can be avoided, aluminum oxide in the coal ash is effectively leached, and the produced aluminum oxide can meet the industrial requirement of electrolytic aluminum.

Description

technical field [0001] The invention relates to a method for producing alumina by treating and utilizing industrial solid waste, in particular to a method for preparing alumina by treating fly ash with hydrochloric acid. Background technique [0002] Fly ash is a solid waste from coal-fired power plants. At present, my country's annual discharge of fly ash is hundreds of millions of tons, and the total stockpiles of fly ash in my country are more than one 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 aluminum resources. It is reported that 45 major minerals in my country can guarantee the demand in 2010. There are 10 minerals that cannot be guara...

Claims

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Application Information

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IPC IPC(8): C01F7/02B09B3/00
Inventor 李来时刘瑛瑛廖伟
Owner SHENYANG ALUMINIUM MAGNESIUM INSTITUTE
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