Method by using andradite one-step alkaline heat process to treat Bayer process red mud to produce metallurgical aluminum oxide

Abstract

The invention relates to a method by using andradite one-step alkaline heat process to treat Bayer process red mud to produce metallurgical aluminum oxide. The method comprises the following steps of S1, mixing red mud, sodium ferrite or calcium ferrite, active lime and circulating mother liquid, so as to prepare raw material ore pulp; S2, performing alkaline heat dissolving-out reaction on the raw material ore pulp, so as to obtain dissolved-out ore pulp; S3, thinning the dissolved-out ore pulp, and separating liquid and solid of the thinned liquid, so as to obtain dissolved-out slag and dissolved-out liquid; S4, introducing carbon dioxide gas into the dissolved-out liquid, and decomposing carbon, so as to obtain crude aluminum hydroxide and carbon decomposing mother liquid; S5, treating the crude aluminum hydroxide by Bayer process, so as to obtain the metallurgical aluminum oxide; S6, causticizing the carbon decomposing mother liquid by lime milk, obtaining a sodium aluminate solution with high molecular ratio, and adjusting into the circulating mother liquid for dissolving out. The method provided by the invention has the advantages that the aluminum oxide in the red mud is recycled, the alkaline content in the red mud is reduced, the solid wastes are recycled, and the green utilization effect of resources is realized.

Description

technical field [0001] The invention belongs to the technical field of alumina production, and in particular relates to a method for producing metallurgical grade alumina by processing red mud of a Bayer process by one-step alkali-thermal treatment of andandroid. Background technique [0002] Red mud is the waste residue produced during the production of alumina. It is red because it contains a large amount of iron oxide, so it is called red mud. The output of red mud varies with ore grade, production method and technical level. Every time 1 ton of alumina is produced in my country, 1.0 to 1.7 tons of red mud will be produced. At present, the cumulative accumulation of red mud exceeds 300 million tons. A large amount of red mud cannot be effectively used and can only be stacked in a large area, which not only takes up a lot of land, but also causes serious pollution to the environment due to the high alkalinity of the red mud. As of 2016, the cumulative stockpiles reached ...

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Problems solved by technology

However, the above-mentioned dealkalization methods all have problems in varying degrees. The effect of the lime dealkalization method under normal pressure is unsatisfactory and the cost is high under high pressure; Alkali is ineffective; chloride ions in magnesium chloride and ammonium chloride dealkalization will corrode equipment and is not conducive to the subsequent application of red mud; CO 2 Suspension dealkalization, in which CO 2

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