Method for preparing and comprehensively utilizing metal aluminum through coal ash pellet chlorination electrolysis

Abstract

The invention discloses a method for preparing and comprehensively utilizing metal aluminum through coal ash pellet chlorination electrolysis. The method comprises the following steps: uniformly mixing coal ash, a carbon source and kaolin in a mass ratio of 1:(2-6):(0.05-0.3) so as to form a mixed material; adding a binding agent which accounts for 1.0-2.0% of the total mass of the mixed material and water which accounts for 2.0-5.0% of the total mass of the mixed material into the mixed material; uniformly mixing, pelletizing, and drying in air; performing chlorination and separation on pellets so as to respectively obtain anhydrous aluminum chloride, silicon tetrachloride and gallium chloride; directly electrolyzing the anhydrous aluminum chloride so as to obtain the metal aluminum and chlorine; feeding back the chlorine into a chlorination procedure; and further purifying the silicon tetrachloride, thereby obtaining polycrystalline silicon and zinc chloride. The method disclosed by the invention is low in cost, cheap and easy in raw material obtaining, complete in chlorination reaction through pelletization and chlorination, simple in operation process and high in electrolysis automation degree, the prepared metal aluminum is relatively high in purity, and raw materials such as chlorine and zinc can be recycled.

Description

[0001] Technical field: [0002] The invention belongs to the technical field of industrial solid waste reuse, and in particular relates to a method for preparing metallic aluminum by chlorination and electrolysis of fly ash pellets and its comprehensive utilization. [0003] Background technique: [0004] Fly ash is a solid waste after coal combustion. The annual discharge of fly ash from coal-fired thermal power plants is nearly 400 million tons, and there are many oxides (Al 2 o 3 , SiO 2 , Fe 2 o 3 , K 2 O, Na 2 O, TiO 2 , CaO, MgO), in which the alumina content is equivalent to that in my country's medium and low-grade bauxite, and high-alumina fly ash is a potential resource that can replace bauxite in my country's alumina industry. Fly ash is the main source of suspended particulate matter, causing regional air pollution and endangering human health. [0005] High-alumina fly ash refers to fly ash with an alumina content greater than 37%. Its source is high-alumi...

AI Technical Summary

Problems solved by technology

[0014] The purpose of the present invention is to provide a method for the preparation of metal aluminum by chlorination and electrolysis of fly ash pelletizing and its comprehensive utilization in view of the technical problems of long process, high energy consumption and inability to comprehensively utilize existing technologies. Preparation of alumina by chlorination and electrolysis of aluminum fly ash pellets: through batching and pelletizing; the pellets can be chlorinated, separated, and purified to obtain anhydrous aluminum chloride, silicon tetrachloride, and gallium chloride products; Aluminum chloride hydrochloride is directly electrolyzed to obtain metal aluminum and chlorine gas; the chlorine gas produced by electrolysis is returned to the chlorination section; silicon tetrachloride is further purified, and polysilicon can be prepared by reduction with high-purity zinc, and the by-product zinc chloride can be electrolyzed to obtain zinc and chlorine gas. Zinc cyclically reduces silicon tetrachloride, and chlorine returns to the chlorination section to realize the recycling of zinc and chlorine

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