Method for extracting aluminum oxide from high-alumina coal ash

Abstract

The invention provides a method for extracting aluminum oxide from high-alumina coal ash. The method comprises the following steps: activating the high-alumina coal ash, and performing solid-liquid separation to obtain pretreated coal ash and activated mother liquid; performing pre-desiliconization treatment on the pretreated coal ash, and performing solid-liquid separation to obtain desiliconizedcoal ash and desiliconized liquid; performing Bayer dissolution on the desiliconized coal ash, and performing solid-liquid separation on dissolved slurry to obtain a sodium aluminate solution and Bayer dissolved slag; performing hydrothermal reaction on the Bayer dissolved slag and lime milk, and performing solid-liquid separation to obtain silicon-calcium slag and a recycled alkaline solution; performing seed precipitation decomposition on the sodium aluminate solution to obtain aluminum hydroxide and seed precipitation decomposition mother liquid; and calcining the aluminum hydroxide to obtain aluminum oxide. According to the method disclosed by the invention, after the high-alumina coal ash is activated and desiliconized, the aluminum oxide is extracted by adopting a Bayer process, sothat a high-quality metallurgy-level aluminum oxide product can be obtained, and alkali in the Bayer dissolved slag can be recycled; and the method has the process characteristics of low cost, low energy consumption and the like and has the advantage of simplicity in operation.

Description

technical field [0001] The invention relates to resource utilization of high-alumina fly ash, in particular to a method for extracting alumina from high-alumina fly ash. Background technique [0002] Alumina is the main raw material for the production of aluminum ingots. More than 95% of the world's alumina is produced through bauxite. my country is the world's largest producer of alumina, and currently produces more than 30 million tons of alumina per year. But at the same time, my country's bauxite resources are relatively scarce, and the bauxite reserves only account for about 7% of the world's total reserves, and most of them are difficult-to-handle diaspore ores. Due to insufficient bauxite resources, currently about 60% of bauxite depends on imports from abroad. [0003] However, the reserves of high-aluminum fly ash produced by coal power generation in central and western Inner Mongolia and northern Shanxi in my country are abundant. The potential reserves of high-...

AI Technical Summary

Problems solved by technology

However, more than 90% of the world's alumina is currently produced by the Bayer process, and the sintering process focuses on the production of various types of alumina, so the pre-desilication-soda lime sintering process is difficult to be widely used to produce metallurgical grade alumina

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