Method of recovering rare-earth elements

Abstract

Provided is a method of recovering rare-earth elements by performing slight pH adjustment of a leachate, which does not require such significant pH adjustment as in conventional methods, reduces cost and effort, and can efficiently recover rare-earth elements in a bauxite residue in a good yield. The method of recovering rare-earth elements is a method of recovering rare-earth elements, the method including: a leaching step of bringing a raw material bauxite residue, which is produced as a by-product in a Bayer process, into contact with a liquid leaching agent to recover a leachate containing rare-earth elements; an extraction step of bringing the leachate into contact with an extraction treatment liquid containing a phosphoric acid ester-based extractant to recover an extract liquid containing the rare-earth elements; and a back extraction step of bringing the extract liquid into contact with a back extraction treatment liquid to recover the rare-earth elements, the leaching step including recovering a leachate having a pH of 0.5 or more and 1.2 or less by using an acidic liquid leaching agent, the extraction step including adjusting the pH of the leachate to 1.0 or more and 1.7 or less and then bringing the leachate into contact with the extraction treatment liquid.