Method for preparing aluminum oxide through treatment of coal ashes with hydrochloric acid

A technology of fly ash and alumina, which is applied in the direction of alumina/hydroxide, etc., can solve problems such as high cost, secondary pollution, and environmental pollution, and achieve the effect of easy equipment solution and favorable industrialization

Active Publication Date: 2014-03-26
SHENYANG ALUMINIUM MAGNESIUM INSTITUTE
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  • Abstract
  • 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 silicon and fluorine can be combined to achieve the purpose of releasing alumina in it. However, harmful gases such as HF may be produced during the process of aiding dissolution. During the process, fluorine-containing waste liquid and waste residue will be discharged, which will not only pollute the environment, but also cause safety hazards to operators

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  • Method for preparing aluminum oxide through treatment of coal ashes with hydrochloric acid

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Experimental program
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Effect test

Embodiment 1

[0020] Activate the fly ash mechanically, grind it to 800 mesh with a vibrating mill, and add 36% hydrochloric acid to the acid-resistant high-pressure reactor according to 1:6.5 (the molar ratio of the sum of alumina and iron oxide in fly ash to HCl in hydrochloric acid) Mix it with fly ash, the reactor is lined with acid-resistant tiles, heated to 160 ° C, the reaction time is 2 hours, the solid-liquid separation after the reaction cools down, and the aluminum chloride liquid is obtained, and the solid-liquid separation of the aluminum chloride solution and the high-silicon slag Using flocculation and sedimentation, the aluminum chloride liquid is spray-dried to obtain crystalline aluminum chloride, and the aluminum chloride crystal is decomposed at 400°C to obtain crude γ-Al 2 o 3 And hydrogen chloride gas, hydrogen chloride is absorbed by high silicon slag washing liquid to prepare hydrochloric acid, so as to realize the recycling of acid. Calcined crude γ-Al 2 o 3 Meta...

Embodiment 2

[0022] The raw material fly ash in Example 1 is mechanically activated, ground to 300 mesh in a vertical mill, and 25% hydrochloric acid is mixed according to the ratio of 1:7.5 (the sum of aluminum oxide and iron oxide in fly ash and the mole of HCl in hydrochloric acid ratio) into an acid-resistant high-pressure reactor and mix it with fly ash. The reactor is lined with enamel, heated to 190 ° C, and the reaction time is 3 hours. The solid-liquid separation of high-silicon slag adopts pressure filtration, and the aluminum chloride liquid is dried by drum to obtain crystalline aluminum chloride, and the aluminum chloride crystal is decomposed at 500°C to obtain crude γ-Al 2 o 3 And hydrogen chloride gas, hydrogen chloride is absorbed by water to prepare hydrochloric acid, so as to realize the recycling of acid. Calcined crude γ-Al 2 o 3 Metallurgical-grade alumina and high-iron slag that meet the standards are obtained through the Bayer process. High-silicon slag is used ...

Embodiment 3

[0024] Mechanically activate the raw coal fly ash in Example 1, use a planetary mill to grind to 100 mesh, and mix 15% hydrochloric acid at a ratio of 1:9 (the molar ratio of the sum of alumina and iron oxide in fly ash to HCl in hydrochloric acid) Add it into an acid-resistant high-pressure reactor and mix it with fly ash. The reactor is lined with glass, heated to 230 ° C, and the reaction time is 8 hours. The solid-liquid separation of slag adopts vacuum filtration, and the aluminum chloride liquid adopts multi-effect falling film evaporation to obtain crystalline aluminum chloride, and the aluminum chloride crystal is decomposed at 600°C to obtain crude γ-Al 2 o 3 And hydrogen chloride gas, hydrogen chloride is absorbed with dilute hydrochloric acid to prepare hydrochloric acid, so as to realize the recycling of acid. Calcined crude γ-Al 2 o 3 Metallurgical-grade alumina and high-iron slag that meet the standards are obtained through the Bayer process. High-silicon sla...

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Abstract

The invention discloses a method for producing aluminum oxide through treatment and utilization of industrial solid wastes and particularly relates to a method for preparing aluminum oxide through treatment of coal ashes with hydrochloric acid. The method comprises the following steps: activating coal ashes; mixing the activated coal ashes with 15%-36% hydrochloric acid, wherein a molar ratio of HCl in the hydrochloric acid to aluminum oxide and iron oxide in the coal ashes is 4-9; feeding mixed serous fluid into a reactor, heating to 90 DEG C-230 DEG C, wherein reaction time is 1 hour-8 hours; carrying out solid-liquid separation after reacting and cooling to obtain aluminum chloride liquid and high-silicon residue, and evaporating, concentrating or drying to obtain crystallized aluminum chloride; decomposing the crystallize aluminum chloride to obtain crude gamma-Al2O3 and a hydrogen chloride gas; and preparing metallurgical-level aluminum oxide by gamma-Al2O3 through a Bayer process, wherein the residue is high-iron residue and can be used as a steelmaking material. According to the method, any auxiliary agent is not added, so that aluminum oxide in the coal ashes can be effectively leached out, and the leaching rate of the aluminum oxide can reach over 85%.

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 guar...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01F7/02
Inventor 李来时刘瑛瑛王鹏周凤禄
Owner SHENYANG ALUMINIUM MAGNESIUM INSTITUTE
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