Method of extracting metal ions from red mud by sonication

A method of extracting metal ions from red mud by sonication, the method comprising the steps of:

• (a) introducing, into a reactor placed in a constant-temperature tank, (1) a neutralized red mud slurry and an acidic solution or (2) red mud slurry, distilled water and an acidic solution, to form a red mud slurry, and heating the constant-temperature tank to allow the red mud slurry in the reactor to react while subjecting the red mud slurry to sonication, thereby extracting metal ions from the red mud;
• and
• (b) filtering a product resulting from step (a) to provide a filtrate and a red mud residue, and separating and recovering the filtrate and the red mud residue,
• wherein the sonication in step (a) is performed using an ultrasonic generator by applying ultrasonic waves to an ultrasonic tip placed in the constant-temperature tank, and
• wherein the neutralized red mud slurry or the red mud slurry and the acidic solution are mixed at a weight ratio of 1:1-1:20, and the acidic solution and distilled water are mixed at a volume ratio of 1:1-1:10.