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:(2-5):(0.1-0.5) so as to form a mixed material; adding a binding agent and water; pelletizing, and drying in air; performing chlorination, separation and purification so as to respectively obtain anhydrous aluminum chloride, silicon tetrachloride and gallium chloride; converting the anhydrous aluminum chloride into an aluminum chloride solution, controlling voltage and current density, implementing electrolysis so as to obtain aluminum hydroxide, hydrogen and chlorine, and feeding back the chlorine to a chlorination procedure; roasting the aluminum hydroxide so as to obtain metallurgy-level / chemical aluminum oxide; and purifying the silicon tetrachloride. 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, high in automation degree and high in product 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 alumina 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-alumina coal, w...

AI Technical Summary

Problems solved by technology

[0014] The purpose of the present invention is to provide a method for preparing alumina and its comprehensive utilization by chlorination and electrolysis of fly ash pelletizing in order to solve 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; chlorine Aluminum hydroxide solution is directly electrolyzed to obtain aluminum hydroxide, hydrogen product and chlorine gas; the chlorine gas produced by electrolysis is returned to the chlorination section; aluminum hydroxide can be roasted to obtain metallurgical grade alumina or chemical alumina; silicon tetrachloride is further purified, 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 is cyclically reduced to silicon tetrachloride, and chlorine gas returns to the chlorination section to realize the recycling of zinc and chlorine gas.

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