METHOD FOR RECOVERING RARE EARTH ELEMENT

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PROBLEM TO BE SOLVED : To provide a method for recovering rare earth elements capable of recovering rare earth elements in the bauxite residue at a high yield while reducing cost and time and labor by performing the slight pH regulation of a leach liquid without performing remarkable pH regulation in the conventional method. SOLUTION : There is provided a method for recovering rare earth elements, comprising : a leaching step where raw material bauxite residue creating a by-product in a Bayer step is contacted with a leaching treatment liquid to recover a leach liquid including rare earth elements; an extraction step where the leach liquid is contacted with an extraction treatment liquid including a phosphate based ester extraction agent to recover the extraction liquid including the rare earth elements; and a back extraction step where the extraction liquid is contacted with a back extraction treatment liquid to recover the rare earth elements. In the leaching step, the leach liquid with a pH of 0.5 to 1.2 is recovered using an acidic leaching treatment liquid, and further, in the extraction step, after the pH of the leach liquid is controlled to 1.0 to 1.7, it is contacted with the extraction treatment liquid. SELECTED DRAWING : None COPYRIGHT : (C)2016, JPO&INPIT