Method for recycling aluminum oxide from red mud

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...

AI Technical Summary

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.

Images