Improved method for producing aluminium oxide by medium-low-grade bauxite

Abstract

The invention relates to an improved method for producing aluminium oxide by medium-low-grade bauxite, which is characterized in that the production process comprises two-time dissolution processes, i.e. (1) dealuminizing slag is added into the bauxite for carrying out Bayer-process dissolution, and carrying out Bayer-process production of the aluminium oxide; and (2) adding Bayer-process dissolved red mud obtained in the step (1) into alkali liquor, carrying out wet-process dissolution treatment, recovering alkali and aluminium oxide in the Bayer-process red mud. In the method disclosed by the invention, the process of the Bayer process mainly recovers the aluminium oxide in the bauxite, and a wet-process red mud treatment system mainly recovers alkali in the Bayer-process red mud. Dissolved liquor obtained in the Bayer-process part is diluted and purified to remove seed crystal for decomposition, lime is added into the dissolved liquor by wet-process treatment of the Bayer-process red mud to dealuminize, the obtained high-molecular-proportion dealuminized mother liquor is then used for dissolving the Bayer-process red mud, solid-phase dealuminizing slag replacing the lime is added into a Bayer-process system. In the method disclosed by the invention, the process is simple, the energy consumption is low, alkali consumption is low, the recovery ratio of the aluminium oxide is high, the method is suitable for treating the medium-low-grade bauxite mainly in China, the resource utilization ratio is high, the discharged red mud amount is less, and the red mud is easy to be utilized comprehensively.

Description

technical field [0001] An improved method for producing alumina from middle and low-grade bauxite relates to a method for Bayer red mud wet treatment and dissolution in the process of producing alumina from middle and low-grade bauxite. Background technique [0002] my country's bauxite resources are mostly high-alumina, high-silicon, low-iron, and low-to-medium grade diaspore-type bauxite. Alumina is mainly produced by the hybrid method with high energy consumption and complicated process. In order to reduce alkali consumption, energy consumption and more effective use of bauxite resources, new production processes such as beneficiation Bayer method, lime Bayer method, and series method have been gradually developed and applied. However, there are still some problems in the above-mentioned production processes, such as the low alumina recovery rate of the beneficiation Bayer process and the lime Bayer process; although the resource utilization rate of the series process is...

AI Technical Summary

Problems solved by technology

high alpha k Solution reverse washing Bayer process red mud will increase the molecular ratio of the red mud dissolution system, but the process is complicated and there is still room for optimization

The technological conditions of the Bayer dissolution process in this patent are: the aluminum-silicon ratio A/S of the middle and low-grade bauxite is 3-9, and the amount of dea...

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