Selective recovery of heavy rare earth elements from apatite with an adsorbent bearing immobilized tridentate amido ligands

Abstract

Abstract Apatite, which is used in the production of phosphorus fertilizers, contains small amounts of rare earth elements (REEs; 0.1–1%). Apatite deposits occur all over the world and thus have the potential to be a secure source of REEs. We investigated a method for recovery of REEs from an apatite sample; specifically, REEs were leached from the sample with an H2SO4 solution, the acid that is most commonly used for fertilizer production. At high H2SO4 concentrations, most of the REEs in the solution were lost to precipitation as insoluble gypsum (CaSO4·2H2O). However, at H2SO4 concentrations of