Method for removing fluoride in aluminum ash by external field strengthening means

The invention provides a method for removing fluoride in aluminum ash by an external field strengthening means. The method comprises the following steps that (1), dried raw material aluminum ash is ball-milled to below 100 microns; (2), a sodium hydroxide solution is taken as a leaching solution, and the leaching solution is uniformly mixed with the fine aluminum ash obtained in the step (1) to obtain mixed alkaline slurry; (3), leaching reaction is carried out on the mixed alkaline slurry obtained in the step (2) under microwave and/or ultrasonic conditions; (4), the slurry obtained in the step (3) is dehydrated and filtered to obtain a leaching solution and leaching slag; and (5), lime is added into the leaching solution obtained in the step (4) to precipitate the fluorine. According tothe method for removing the fluoride in the aluminum ash by the external field strengthening means, the structure of the micro/indissolvable fluoride is destroyed by utilizing the ultrasonic wave andmicrowave assisted strengt