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A method of recovering alumina from red mud

A technology of alumina and aluminum hydroxide, which is applied in the direction of alumina/hydroxide, etc., can solve the problems of low recovery rate, high recovery cost, and low raw material price, with simple methods, small residues, and easy particle size range Effect

Active Publication Date: 2016-02-10
北京世纪地和控股有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0003] At present, the comprehensive utilization of red mud mainly includes two aspects of work: one is to extract useful components in red mud and recover rare metals. The disadvantage is that the recovery cost is high and the recovery rate is low; the other is to use red mud as a bulk material. Raw materials should be comprehensively utilized as a whole. The disadvantage is that the price of raw materials is low and it is difficult to create higher added value.

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  • A method of recovering alumina from red mud

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Effect test

Embodiment 1

[0052] Dry the red mud containing 18% alumina and grind it to 200 meshes. The mass ratio of red mud and ammonium sulfate is 1:0.5. The ground mixture is weighed and sintered. The sintering temperature is 280°C and the sintering time is 0.5 hours. Dissolve the sintered clinker with water at 75°C under normal pressure, and the dissolution rate of aluminum oxide in the obtained crude aluminum ammonium solution is 75%. The aluminum ammonium sulfate solution is cooled to 10°C to crystallize, and the crude aluminum ammonium solution is recrystallized to remove iron. , titanium and other impurities to obtain refined aluminum ammonium crystals, and then dissolve the obtained refined aluminum ammonium crystals to prepare a 0.1mol / L aluminum ammonium sulfate solution, and then pass through ammonia water to decompose, NH 3 The molar ratio to aluminum ammonium sulfate is 3.2:1, the reaction temperature is 30°C, and after 0.5h of reaction, the aluminum hydroxide solid is obtained after was...

Embodiment 2

[0054] Dry the red mud containing 22% alumina and grind it to 600 meshes. The mass ratio of red mud and ammonium sulfate is 1:3. The ground mixture is weighed and sintered. The sintering temperature is 420°C and the sintering time is 2.5 hours. Dissolve the sintered clinker with water at 98°C under normal pressure, and the dissolution rate of aluminum oxide in the obtained crude aluminum ammonium solution is 85%. The aluminum ammonium sulfate solution is cooled to 10°C to crystallize, and the crude aluminum ammonium solution is recrystallized to remove iron. , titanium and other impurities to obtain refined aluminum ammonium crystals, and then dissolve the obtained refined aluminum ammonium crystals to prepare a 0.22mol / L aluminum ammonium sulfate solution, and then pass through ammonia water to decompose, NH 3 The molar ratio to ammonium aluminum sulfate is 4:1, and the reaction temperature is 55°C. After reacting for 2 hours, the aluminum hydroxide solid is obtained after wa...

Embodiment 3

[0056] The red mud containing 25% alumina was dried and ground to 1000 mesh, and the ground mixture was weighed according to the mass ratio of red mud and ammonium sulfate as 1:5 for sintering. The sintering temperature was 580°C and the sintering time was 6 hours. Water the sintered clinker at 5kgf / cm 2 Dissolution at 140°C, the dissolution rate of alumina in the obtained crude aluminum ammonium solution is 90%, the aluminum ammonium sulfate solution is cooled to 5°C to crystallize, the crude aluminum ammonium solution is recrystallized to remove impurities such as iron and titanium to obtain refined aluminum ammonium crystal, and then the obtained crude aluminum ammonium crystals were dissolved and prepared into a 0.5mol / L ammonium aluminum sulfate solution, and ammonia water was introduced to decompose it, NH 3 The molar ratio to ammonium aluminum sulfate is 4:1, the reaction temperature is 60°C, and after 3 hours of reaction, the aluminum hydroxide solid is obtained after...

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Abstract

The invention relates to a method for recycling aluminum oxide from red mud. The method comprises the following steps: filtering the red mud by pressing, drying by heating, and grinding the red mud into fine powder; mixing the ground red mud with ammonium sulfate, and sintering to obtain a solid mixture and ammonia gas; pouring the solid mixture into water so as to dissolve out by heating, and separating by filtering to obtain a solution containing ammonium aluminum sulfate; dedusting and desulfurizing the ammonia gas, and absorbing the ammonia gas by water to obtain ammonia water; crystallizing the salt solution containing ammonium aluminum sulfate to obtain crude ammonium aluminum sulfate; dissolving the solid ammonium aluminum sulfate into hot water, cooling, crystallizing, and removing impurity; dissolving the fine ammonium aluminum sulfate obtained after secondary crystallization into water, and reacting with the ammonia water to obtain aluminum hydroxide and ammonium sulfate; calcinating the aluminum hydroxide to obtain the aluminum oxide. In the method for recycling the aluminum oxide from the red mud, the ammonia gas and the ammonium sulfate are recycled, therefore, the cost and byproducts are reduced greatly.

Description

technical field [0001] The invention relates to a method for recycling red mud, in particular to a method for extracting alumina from red mud. Background technique [0002] Red mud mainly comes from the by-products of alumina production. An alumina plant has to discharge tens to millions of tons of red mud (dry weight) every year. The huge volume and corrosiveness of red mud slurry is a problem for red mud stacking. The environmental impact caused by mud stacking, in addition to occupying a large amount of land, the infiltration of alkali and sulfate in the attached liquid may also pollute the groundwater and soil, change the nature and structure of the soil, cause a large area of ​​soil salinization, and make the soil harden. With the gradual shortage of bauxite resources and land resources in our country, the technology of recovering alumina from red mud conforms to the principle of reduction and resource utilization. [0003] At present, the comprehensive utilization of...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01F7/02
Inventor 张开元王洪高延强赵宏彬
Owner 北京世纪地和控股有限公司