Method for extracting aluminium oxide from coal ash

Abstract

The invention relates to a method for extracting aluminium oxide from coal ash. The method comprises the following steps: (1), mixing coal ash with ammonium sulphate and granulating; (2), roasting particles through a two-section type fluidized roasting system; (3), adding dilute sulphuric acid into a clinker, and dissolving out and filtering materials, wherein filtrate is a crude NH4Al(SO4)2 solution; (4), filtering after removing impurities from the solution by adopting a combination method to obtain a fine NH4Al(SO4)2 solution; (5), absorbing ammonia gas released in the roasting reaction process by the purified and separated fine NH4Al(SO4)2 solution, and carrying out ammonia settlement reaction of ammonia gas and the fine NH4Al(SO4)2 solution so as to generate Al(OH)3; and (6), calcining Al(OH)3 sediment at 1100 DEG C so as to obtain Al2O3. By adopting the two-section type fluidized roasting system including roasting of coal ash and ammonium sulphate, impurity removing through the combination method and oxygen-enriched combustion, the problems of being high in corrosion, sticky to roast, cake and coke of equipment in the background technology are solved.

Description

technical field [0001] The invention relates to a method for extracting alumina from fly ash. Background technique [0002] Thermal power generation occupies a dominant position in my country's power generation structure, and coal-fired thermal power generation occupies an absolute proportion in thermal power generation. Fly ash is a solid waste discharged from coal-fired power plants. [0003] In recent years, with the development of the power industry, the emission of fly ash has increased sharply. According to the report of China Coal Industry Association in January 2009, the total coal production in my country in 2008 was 2.716 billion tons, most of which were used for power generation , the annual discharge of fly ash in my country has exceeded 200 million tons, and the cumulative stockpiles have exceeded 2.5 billion tons, occupying a large amount of arable land and polluting the environment on a large scale. Therefore, carrying out research on the comprehensive utiliza...

AI Technical Summary

Problems solved by technology

[0008] In the process of extracting alumina by acid leaching or sintering alkali fusion, in order to remove impurities in the solution, the Bayer method in the alumina industry is basically used to remove impurities, resulting in a long process chain, large equipment investment, and energy consumption. At the same time, whether it is the mixing of fly ash and activating material at high temperature and heating or the calcination of aluminum salt to produce alumina, it needs to be roasted. During the roasting process, the energy consumption is high and the amount of flue gas is large, which brings difficulties to the subsequent flue gas treatment. , and during the roasting process, it is very easy for the material to melt and stick to the wall, agglomerate or ring.

Therefore, due to the above-mentioned reasons such as high cost and difficult operation of the process, the extraction of alumina from fly ash cannot be truly industrialized.

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