VALUABLE METAL EXTRACTION AGENT AND VALUABLE METAL EXTRACTION METHOD USING SAID EXTRACTION AGENT

The objective of the present invention is to selectively extract light rare earth metals, and by extension, europium, from an acidic solution containing a plurality of types of rare earth metal. This valuable metal extraction agent is represented by the general formula. In the formula: R 1 and R 2 each indicate the same or different alkyl group; R 3 indicates a hydrogen atom or an alkyl group; and R 4 indicates a hydrogen atom or any given group other than an amino group bonded to the ± carbon as an amino acid. Preferably, the general formula has a glycine unit, a histidine unit, a lysine unit, an aspartic acid unit, or an N-methylglycine unit. Preferably, when extracting europium using the extraction agent, the pH is adjusted into the range of 2.0-3.0 inclusive, and when selectively extracting light rare earth metals, the pH is adjusted to 1.7-2.7 inclusive.