Method for comprehensive utilization of low-iron red mud

Abstract

The invention relates to a method for comprehensive utilization of low-iron red mud, wherein the method includes the following steps: S1, mixing and batching low-iron red mud, a small amount of lime,an alkali and circulating mother liquor, preparing slurry, and drying outside a kiln; S2, carrying out sintering reaction of the dried raw material at low temperature to obtain a sintered clinker after the reaction is finished; S3, carrying out leaching reaction of the sintered clinker, and carrying out liquid-solid separation to obtain a leached residue and a leached solution; S4, treating the leached solution, selecting crystal seed decomposition, carbonation decomposition or evaporative crystallization process according to product needs, or freely combining, requiring to adjust a solution obtained from the reaction, and allowing the solution to return to the mixing process; and S5, carrying out dealkalization reaction of the leached residue under the action of a sodium hydroxide solution, and carrying out liquid-solid separation, to obtain calcium silicate powder and a dealkalization solution, wherein a part of the dealkalization solution is used as the products, and a part of the dealkalization solution returns for dealkalization. By the method, the low-iron red mud is completely recovered, and a series of products containing aluminum and the calcium silicate powder material are prepared. The method can largely decompose the low-iron red mud, realizes the recovery and value-added utilization of the low-iron red mud, and achieves the effect of green utilization of resources.

Description

technical field [0001] The invention relates to a method for comprehensive utilization of low-iron red mud, and belongs to the technical field of comprehensive utilization of red mud. Background technique [0002] Red mud is the waste residue produced during the production of alumina. 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 more than 400 million tons, which has become a major environmental hazard. [0003] In recent years, many scientific research units have devoted themselves to the de...

AI Technical Summary

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 Only for Na in red mud 2 O·Al 2 o 3 、Na 2 SiO 3 and Na 2 CO 3 works, but for Na 2 O·Al 2 o 3 1.7SiO2 2 ·nH 2 O does not work, and most of the sodium in red mud is in the form of Na 2 O·Al 2 o 3 1.7SiO2 2 ·nH 2 The form of O exists, so the removal efficiency of this method is not high; in the lime-sulfuric acid combined dealkalization method, the acid method and the alkali method coexist, and it is easy to waste raw materials.

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