The group of SUN Xiaoqi from CAS Fujian Institute of Research on the Structure of Matter has developed a new method for the isolation of rare earth metals from softening ammonia sulfate wastewater produced during bastnasite ammonia sulfate roasting. Based on alkyl phenoxy carboxylic acid derivatives [4,4′-isopropylidenebis (phenoxyacetate)]as a cation exchanger, Ca²⁺and Mg²⁺are precipitated from the wastewater within 10 min, forming particles which can be easily separated. The ion exchanger was repeatedly used 5 times with little loss, contributing to a process with low cost and little pollution. 

CAS news release, May 31, 2019