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 specifically relates to a method for reducing the aluminum-silicon ratio of red mud through multi-stage carbonization. In the present invention, lime is first mixed with low- and medium-grade aluminum-containing materials, stirred in water or sodium aluminate solution to carry out calcification transformation reaction, and the calcification transformation slag obtained is mixed with clean water or low-concentration alkali liquid in a closed container, and then poured into the closed container. Introduce CO2 and perform carbonization transformation to obtain carbonized slag. Mix the alkali solution and carbonized slag to obtain aluminum-containing leachate and solid slag. The solid slag is carbonized and dissolved aluminum for 1 to 4 times until the final red mud with a new structure is obtained. The mass ratio of alumina and silicon oxide drops to 0.2~0.5. The new structure red mud processed by the invention theoretically does not contain alkali and aluminum, the aluminum-silicon ratio can be reduced to less than 0.5, and the sodium oxide content in the red mud is less than 0.6%, realizing the clean production of alumina industry and the utilization of red mud. .

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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