Method used for producing alumina from fly ash

Abstract

The invention provides a method used for producing alumina from fly ash. The method comprises following steps: high aluminum fly ash is subjected to dissolving out with hydrochloric acid at a high temperature, obtained aluminium chloride dissolving out solution and white clay are separated, and evaporation is carried out to obtain impurity containing AlCl<3>*6H<2>O crystal; the impurity containingAlCl<3>*6H<2>O crystal is subjected to hydrolysis at water vapour atmosphere at a hydrolysis temperature is controlled to be 200 to 850 DEG C to obtain an amorphous substance taking alumina as the main component; the amorphous substance is subjected to dissolving out with an alkali solution at normal pressure at a dissolving out temperature of 70 to 100 DEG C, or is subjected to dissolving out with an alkali solution at an increased pressure at a dissolving out temperature of 100 to 300 DEG C, a slag phase is removed through filtering, and a sodium aluminate solution is obtained at last; thesodium aluminate solution is filtered, diluted, and cooled for seed precipitation to obtain aluminium hydroxide. The methd is capable of reducing production cost of alumina from fly ash effectively, improving alumina quality, realizing utilization of large amount of solid waste, alleviating the shortage problem of bauxite resource of our state, and is suitable for application popularization in industrial production.

Description

technical field [0001] The invention relates to the technical field of industrial alumina extraction, in particular to a new method for producing alumina by using fly ash. Background technique [0002] With the rapid development of my country's aluminum industry, a large amount of bauxite resources are consumed. At present, high-grade bauxite is scarce, and a large number of low-grade bauxite has been mined and used. However, the development of my country's aluminum industry still faces the problem of resource shortage. At this stage, the import of bauxite resources has exceeded 50%, and the import ratio is still expanding. my country's aluminum industry may face the problem of "stuck neck" at any time. At the same time, we produce a large amount of fly ash solid waste every year. The treatment of these fly ash solid wastes is also a problem that needs to be solved urgently. Therefore, using fly ash as an aluminum source and extracting the aluminum element for production can ...

AI Technical Summary

Problems solved by technology

[0002] With the rapid development of my country's aluminum industry, a large amount of bauxite resources are consumed. At present, high-grade bauxite is scarce, and a large number of low-grade bauxite has been mined and used. However, the development of my country's aluminum industry still faces the problem of resource shortage. At this stage, the import of bauxite resources has exceeded 50%, and the import ratio is still expanding. my country's aluminum industry may face the problem of "stuck neck" at any time

At the same time, we produce a large amount of fly ash solid waste every year. The treatment of these fly ash solid wastes is also a problem that needs to be solved urgently. Therefore, using fly ash as an aluminum source and extracting the aluminum element for production can effectively solve the problem. For the above problems, there are currently some industrial methods for producing alumina from fly ash, but there are a series of problems to be solved in these methods, such as: for the alkali method, it is necessary to improve the technology to achieve solid waste reduction treatment; for the acid method Generally speaking, the cost of removing impurities in acidic solution is too high, and the quality of alumina is difficult to guarantee. To solve the above problems, a new method for producing alumina by using fly ash is needed