A method for preparing metal aluminum from bauxite through microwave chlorination specifically includes the following steps that carbon is added in the bauxite to be evenly mixed, chlorine is pumped in, heating is conducted through a microwave fluidized bed for 5 min to 50 min, the temperature ranging from 300 DEG C to 900 DEG C is achieved, the temperature keeps constant for 10 min to 60 min, the bauxite is sufficiently decomposed, various types of chlorination mixed gas containing aluminum chloride is obtained, and then anhydrous aluminum chloride with the purity larger than 99% is prepared through impurity removal and purification; a sodium hydroxide solution is added in the anhydrous aluminum chloride, an intermediate product is prepared, and aluminum hydroxide precipitate and a sodium chloride solution are obtained through precipitation, filtration and solid-liquid separation; the aluminum hydroxide precipitate is calcined at a temperature ranging from 800 DEG C to 1200 DEG C and decomposed to generate aluminum oxide; and the aluminum oxide is subjected to electrolysis to obtain the metal aluminum. The method is a clean process which is simple in technological process and low in energy consumption, all chlorine gas and sodium hydroxide which are generated by the system are used in a cyclic manner, all elements can be effectively separated and utilized, the whole system is free of emission of waste water, waste acid and waste alkali liquid, and zero emission of 'three wastes' is basically achieved.

Method for preparing metal aluminum from bauxite through microwave chlorination

The invention is applicable to the field of compound preparation and provides a preparation method of aluminum hydroxide. The method comprises steps as follows: coal gangue is crushed into fine particles which react with a hydrochloric acid solution in a mass ratio of 1:2.15 in a corrosion-resistant container; a produced chloride mixed solution is filtered, a filter cake and filtrate are obtained, the filtrate is purified with aluminum hydroxide, and aluminum chloride and hydroxide precipitates are produced; the purified filtrate is filtered, and a filter cake containing hydroxide and a clear aluminum chloride solution are obtained; the clear aluminum chloride solution and sodium hydroxide react in the corrosion-resistant container in a mass ratio of 1:0.899, and aluminum hydroxide precipitates and a sodium chloride solution which are produced by the clear aluminum chloride solution and sodium hydroxide are filtered; the filtered aluminum hydroxide precipitates are washed, filter-pressed, dried and crushed, and aluminum hydroxide is obtained. Coal gangue pollution is effectively eliminated, the social benefit is obtained, the production cost of aluminum hydroxide and sodium chloride is reduced, and the economic benefit is improved.

Preparation method of aluminum hydroxide

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.

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

The invention discloses a method for producing aluminum oxide by virtue of acid treatment of a low-aluminum mineral. The method comprises the following steps: (1) milling the low-aluminum mineral until the particle size is 200 meshes to obtain aluminum mineral powder; (2) adding acid to dissolve the aluminum mineral powder to obtain an aluminum salt solution; (3) adding a hexafluoro-aluminate crystal into the aluminum salt solution to perform impurity removal, thereby obtaining a purified aluminum salt solution; (4) adding alkali metal fluoride into the purified aluminum salt solution, filtering and washing to obtain a crystal and a crystal mother solution; (5) adding alkali into the crystal to perform reaction, filtering and washing after the reaction to obtain crystal aluminum hydroxide and alkali metal fluoride, and returning the alkali metal fluoride to the step (4); and (6) filtering, washing, drying and calcining crystallized aluminum hydroxide to obtain aluminum oxide. The purity of the aluminum oxide prepared by the process provided by the invention reaches more than 98.5%, and the aluminum oxide contains extremely less impurities. The process provided by the invention can ensure that a lot of low-aluminum non-bauxite resources can be utilized.

Method for producing aluminum oxide by virtue of acid method treatment of low-aluminum mineral

The invention relates to a comprehensive utilization method for bauxite and particularly relates to a comprehensive utilization method for low-grade bauxite. The method includes following steps of: (1) mixing the low-grade bauxite with hydrochloric acid after ore grinding; (2) performing solid liquid separation and washing after the reaction is cooled; (3) adding the solution obtained in the step (2) into a sodium hydroxide solution to obtain an aluminium hydroxide precipitate, an iron hydroxide precipitate and a sodium chloride solution, performing solid liquid separation, and washing; (4) preparing the aluminium hydroxide and iron hydroxide solid obtained in the step (3) into metallurgy-level aluminum oxide and high-iron slag through a simple Bayer process; (5) subjecting the sodium chloride solution obtained in the step (3) to electrolysis by an ionic exchange membrane electrolytic cell to obtain hydrogen, chlorine and a sodium hydroxide solution; and (6) returning the sodium hydroxide solution that is discharged from an ionic membrane cathode zone in the step (5) into the step (3) and recycling. The method is obvious in environment protection effects, and effectively separates aluminum, iron and silicon in the low-grade bauxite to achieve comprehensive utilization.

Li Laishi

Papers

A comprehensive utilization method for low-grade bauxite