Red mud dealkalization method at normal pressure by Bayer process

Abstract

The invention discloses a red mud dealkalization method at normal pressure by Bayer process, wherein the dealkalizing step consists of, washing and filtering the red mud, charging lime cream into the red mud filter cake, mixing for dealkalizing reaction, subjecting the reaction slip to washing, filtering, drying and discharging.

Description

technical field [0001] The invention relates to a Bayer method red mud dealkalization method under normal pressure, which relates to the treatment of red mud in the process of producing alumina by Bayer method or mixed method. technical background [0002] my country's alumina production mainly uses insoluble diaspore bauxite as raw material. According to statistics, the ore with A / S>10 accounts for 10%, the ore with A / S of 7-10 accounts for 20%, and the ore with A / S>10 accounts for 20%. The ore whose S is 4-7 accounts for more than 60%, and the ore whose A / S is 2.6-4 accounts for 10%. Due to the use of bauxite with high aluminum, high silicon, and low aluminum-silicon ratio as raw materials, most alumina plants mostly adopt the hybrid production process, and the sintering part provides the Bayer process system with seed steaming mother liquor to make up alkali, and the Bayer process part Red mud is also provided as raw material to the sintering system. The two systems...

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Problems solved by technology

[0003] At present, after the dissolution slurry in the Bayer process system of Shanxi Branch is diluted and separated by settling, the bottom flow of the settling tank is washed with red mud by the second reverse washing process. Under the existing production conditions, the water content in the filter cake of the red mud filter It is about 40% and contains a large amount of alkali components, which are divided into bound alkali and attached alkali. The bound alkali exists in the form of hydrated sodium aluminosilicate. After the red mud is fully washed, the N / S is kept in the range of 0.3-0.9 , unable to meet the requirement of red mud discharge N / S<0.2, which affects the effect of the process

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