A method for reducing the aluminum-silicon ratio of red mud by multi-stage carbonization

Abstract

The invention belongs to the field of bauxite resource utilization, and particularly relates to a method for reducing the alumina-silica ratio of red mud through multistage carbonization. The method comprises the following steps: at first, mixing lime with medium-low-grade aluminum-contained material, stirring in water or a sodium aluminate solution to carry out a calcification conversion reaction, and mixing the obtained calcification conversion slag with clear water or a low-concentration alkaline liquid in a closed container; introducing CO2 in the closed container to carry out calcification conversion to obtain carbide slag; mixing the alkaline liquid with the carbide slag to obtain an aluminum-contained dissolution liquid and solid slag; carrying out carbonization and aluminum dissolving on the solid slag for 1-4 times till the mass ratio of aluminum oxide to silicon oxide in red mud with a novel structure is reduced to 0.2-0.5. Alkali and aluminum are not contained in the red mud with the novel structure, the alumina-silica ratio can be reduced to be below 0.5, the content of sodium oxide in the red mud is lower than 0.6%, and the clean production of the alumina industry and the red mud utilization are realized.

Description

technical field [0001] The invention belongs to the field of utilization of bauxite resources, and in particular relates to a method for reducing the aluminum-silicon ratio of red mud through multi-stage carbonization. Background technique [0002] The Bayer process is the main process for producing alumina. In the process of producing alumina by the Bayer process, the ore undergoes processes such as crushing, high-pressure dissolution, sedimentation separation, and washing to obtain sodium aluminate solution and red mud, and the red mud is discharged as waste. or stockpile. The main phase of Bayer red mud is hydrated sodium aluminosilicate, and its molecular formula is roughly equivalent to Na 2 O·Al 2 o 3 1.7SiO2 2 ·nH 2 O. Since the main phase structure of Bayer red mud is hydrated sodium aluminosilicate, two problems arise: (1) When the ore grade is low and the silica content is high, a large amount of alumina is lost; (2) oxidation in red mud The high sodium cont...

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Problems solved by technology

[0005] Aiming at the current high-grade bauxite mines in my country that are on the verge of depletion, resulting in the low recovery rate of alumina in the existing Bayer process, increased alkali consumption, and large stockpiles of high-alkali red mud, the present invention provides a method for reducing red mud by multi-stage carbonization. The purpose of the method of aluminum-silicon ratio is to change the phase structure of red mud, realize the efficient and clean production of low-grade bauxite in my country, and the comprehensive utilization of a large amount of alkali-containing red mud

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