The recovery of rare earth elements from coal combustion products by ionic liquids

Rare earth elements (REEs) are essential for hundreds of applications in the fields of permanent magnets, batteries, fluorescent materials, laser crystals, alloys, ceramics, catalysts, superconductors, etc. With the need of environmental protection increasing, the novel resource utilization and separation technology for REEs have caused widespread concerns. The reclamation of REEs from coal combustion products (CCPs) were proposed as a way to supply rare earth mining. However, the effective REEs extraction technology from CCPs has still been less reported. In this article, the REE contents of some Chinese CCPs from Jiangxi, Guizhou and a power plant were investigated. Then the ionic liquid type extractants of [N-1888]Cl, [P-6,P-6,P-6,P-14]Cl, [P-6,P-6,P-6,P-14] [SOPAA] and [P-6,P-6,P-6,P-14] [SOPAA] were studied for the purification of REEs from the leaching solutions of CCPs. Using the purification and recovery procedures, the purification multiples of Al, Fe, Ca arrived at 94, 40,588 and 8.7 times, and the recovery rate of REE was 37.4%. The development of recovery technology in this study contributes to the REEs resource utilization from CCPs.