Method for chlorinating and electrolyzing bauxite to prepare alumina and comprehensively utilizing bauxite

Abstract

A method for chlorinating and electrolyzing bauxite to prepare alumina and comprehensively utilizing bauxite comprises the following steps: chlorinating and separating chlorite to respectively obtain anhydrous aluminum chloride, anhydrous ferric chloride, silicon tetrachloride, titanium tetrachloride, scandium chloride and gallium chloride; converting the anhydrous aluminum chloride and the anhydrous ferric chloride into an aqueous aluminum chloride solution and an aqueous ferric chloride solution; electrolyzing the corresponding aqueous solutions at a controlled voltage and a controlled current density for a controlled electrolysis time to obtain aluminum hydroxide, ferric hydroxide, hydrogen and chlorine; returning the chlorine to the above chlorination section; calcining the aluminum hydroxide to obtain metallurgical grade / chemical grade alumina; calcining the ferric hydroxide to obtain iron red or other iron-containing products; rectifying and purifying the silicon tetrachloride to generate polysilicon and zinc chloride; refining the titanium tetrachloride to form a sponge titanium raw material; and enriching the scandium chloride in chloride residues to obtain a scandium extraction raw material. The method has the advantages of low cost, cheap and easily available raw materials, simple operating process, high automation degree, high product purity, and realization of recycling of zinc, chlorine and other raw materials.

Description

Technical field: [0001] The invention belongs to the technical field of bauxite utilization, in particular to a method for preparing alumina by chlorination and electrolysis of bauxite and its comprehensive utilization. Background technique: [0002] The vast majority of bauxite in my country (>95%) is diaspore type bauxite, and only the bauxite in some areas such as Hainan is gibbsite type, but it has not been used in industry so far. my country's bauxite is characterized by high aluminum, high silicon and low iron (a small number of exceptions), that is, high alumina content and high silicon oxide content, but relatively low aluminum silicon (mostly between 4-7), aluminum silicon High-quality bauxite resources with a ratio of more than 9 only account for 18.5% of the total reserves. The weighted average aluminum-silicon ratio of bauxite in more than 40 typical mining areas across the country is only about 6. Except for a few mining areas such as Guangxi, the iron oxide...

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Problems solved by technology

[0008] The purpose of the present invention is to provide a method for preparing alumina and its comprehensive utilization by chlorination and electrolysis of bauxite, aiming at the technical problems of long process, high energy consumption and inability to comprehensively utilize existing technology. Through chlorination, separation and purification of bauxite, anhydrous aluminum chloride, anhydrous ferric chloride, silicon tetrachloride, titanium tetrachloride, scandium chloride and gallium chloride can be obtained respectively; Aluminum chloride and ferric chloride are converted into corresponding aqueous chloride solutions and electrolyzed directly to obtain aluminum hydroxide, iron hydroxide products, hydrogen products and chlorine gas; the chlorine gas generated by electrolysis is returned to the chlorination section; aluminum hydroxide can be roasted to obtain metallurgical High-grade alumina or chemical alumina; ferric hydroxide is calcined to obtain iron red or other iron-containing products; silicon tetrachloride is further purified, and polysilicon can be prepared by reduction with high-purity zinc; the by-product zinc chloride can be electrolyzed to obtain zinc and chlorine gas. Zinc cyclically reduces silicon tetrachloride, and chlorine gas returns to the chlorination section to realize the recycling of zinc and chlorine gas; titanium tetrachloride can be used as a raw material for titanium sponge after being refined; scandium is enriched in chloride slag and can be used as a raw material for scandium extraction

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