Method for recycling alkali and aluminum in process of treating bayer red mud by calcification-carbonization method

Abstract

The invention relates to the field of environment protection, and in particular relates to a method for recycling alkali and aluminum in a process of treating bayer red mud by a calcification-carbonization method. The method comprises the steps of mixing the bayer red mud with calcium aluminate or lime and the calcium aluminate to obtain a mixture, performing calcification dealkalization transformation on the mixture in high-concentration alkali liquid with the caustic alkali concentration being 100-300g / L, totally converting silicon-containing phases in the red mud into calcified slag generated in a dealkalization process in the form of hydrate garnet, carbonizing the calcified slag to obtain carbonized slag, then o carrying out low-temperature aluminum smelting and aluminum precipitation to obtain a calcium aluminate product, and recycling the calcium aluminate product in the red mud calcification dealkalization transformation process. Part of alkali and aluminum-containing liquid phases subjected to calcification dealkalization transformation can be reused as supplement alkali in a bayer production process. The method disclosed by the invention can realize recycling of alkali and aluminum in the red mud and harmless treatment of the bayer red mud, and is an energy-saving and environment-friendly red mud utilization method.

Description

technical field [0001] The invention relates to the field of environmental protection, in particular to a method for recovering alkali and aluminum in the process of processing Bayer process red mud. technical background [0002] Aluminum is a pillar industry in my country's non-ferrous metallurgical industry. As of 2013, my country's primary aluminum production capacity reached 18 million tons, and its alumina production capacity was close to 40 million tons, ranking first in the world. At present, more than 80% of alumina in my country is produced by the Bayer process, and the silicon-containing phase in bauxite will be converted into hydrated sodium aluminosilicate (Na 2 O·Al 2 o 3 1.7SiO2 2 ·nH 2 O), that is, 1 kg of silica in the mineral will cause 1 kg of alumina to be taken away in the red mud, and cause 0.608 kg of alkali loss. The presence of alkali and aluminum in red mud has caused two problems: first, the alkali content is too high, making red mud unusable i...

AI Technical Summary

Problems solved by technology

At present, more than 80% of alumina in my country is produced by the Bayer process, and the silicon-containing phase in bauxite will be converted into hydrated sodium aluminosilicate (Na 2 O·Al 2 o 3 1.7SiO2 2 ·nH 2 O), that is, 1 kg of silica in the mineral will cause 1 kg of alumina to be taken away from the red mud and cause a loss of 0.608 kg of alkali

The presence of alkali and aluminum in red mud has caused two problems: first, the alkali content is too high, making red mud unusable in bulk industries such as cement; second, when processing low-grade bauxite, the alumina is lost too much Large, low overall yield

Although some alumina production enterprises dealkalize red mud and use it in cement and other industries, there are still two problems in the direct dealkalization process: first, using lime to dealkalize red mud can only recycle the red mud Sodium oxide, although the alkali content in red mud can be reduced to the requirements of the cement industry, but due to the single product, the overall income is small; second, dealkalization in low-concentration alkali solution or clear water, the red mud produced after dealkalization The low-concentration alkaline solution cannot be used directly, and needs to be concentrated by evaporation, which consumes a lot of energy

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