Method for preparing aluminum oxide through hydrochloric acid leaching and two-stage electrolysis of bauxite and comprehensively utilizing aluminum oxide

Abstract

The invention relates to a method for preparing aluminum oxide through hydrochloric acid leaching and two-stage electrolysis of bauxite and comprehensively utilizing aluminum oxide. The method comprises the following steps: carrying out hydrochloric acid leaching, solid-liquid separation and purification on bauxite on bauxite, so as to obtain an iron chloride mixed solution and an aluminum chloride mixed solution; respectively separating and purifying the iron chloride mixed solution and the aluminum chloride mixed solution, so as to obtain scandium chloride, gallium chloride, an aluminum chloride water solution and an iron chloride water solution; setting electrolytic voltage and current density, and respectively carrying out two-stage electrolysis on the aluminum chloride water solution and the iron chloride water solution, so as to respectively obtain aluminum hydroxide, hydrogen and chlorine as well as iron hydroxide, hydrogen and chlorine; preparing a hydrochloric acid solution by using the generated hydrogen and chlorine, and returning the hydrochloric acid solution to a leaching stage for recycling; and roasting aluminum hydroxide, so as to obtain metallurgy level aluminum oxide or chemical aluminum oxide. Compared with a traditional acid method, the electrolysis method for recycling aluminum oxide in the bauxite and processing the bauxite has the advantages that the evaporation step and equipment, the concentration step and equipment are omitted, the operation is simplified, meanwhile, the cost is substantially lowered, and the product has relatively high purity.

Description

[0001] Technical field: [0002] The invention belongs to the technical field of alumina production, and in particular relates to a step-by-step electrolytic preparation of alumina by hydrochloric acid leaching of bauxite and a comprehensive utilization method. [0003] Background technique: [0004] Three bauxites of gibbsite type, boehmite type and diaspore type are the raw materials for the production of aluminum industry, and there are also two or more mixed types of bauxite. my country is rich in bauxite resources, but the vast majority of bauxite resources in my country belong to the diaspore type ore, and the diaspore type bauxite has the characteristics of perfect crystallization and compact structure. Especially difficult. The bauxite with aluminum-silicon ratio between 4-7 accounts for about 80% of the total reserves in my country's proven bauxite reserves. This determines that when my country uses the pure Bayer process to produce alumina, the dissolution conditions...

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Problems solved by technology

[0013] The purpose of the present invention is to solve the technical problems of long flow process, high energy consumption and inability to comprehensively utilize existing technologies. The present invention provides a method for preparing alumina by step-by-step electrolysis of bauxite hydrochloric acid leaching and its comprehensive utilization. By reacting bauxite with hydrochloric acid, the bauxite can be obtained by step-by-step leaching, solid-liquid separation, and purification to obtain ferric chloride mixed solution and aluminum chloride mixed solution. From the mixed solution of aluminum chloride and ferric chloride Separation and extraction of scandium chloride and gallium chloride, after purification, high-purity scandium chloride and gallium chloride products can be obtained; the aluminum chloride aqueous solution and the ferric chloride aqueous solution are subjected to step-by-step electrolysis; the hydrochloric acid produced in the first step of electrolysis is returned to leaching section; the second step is to electrolyze respectively to obtain aluminum hydroxide products, iron hydroxide products, hydrogen and chlorine, wherein hydrogen and chlorine react to prepare hydrochloric acid, which is reused for leaching of bauxite, and effectively recovers alumina in bauxite At the same time, the recycling of hydrogen and chlorine can be realized; the aluminum hydroxide can be roasted to obtain metallurgical grade alumina or chemical alumina

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