**5. Conclusions and outlook**

Based on the introduction of solution chemistry and extraction chemistry of cerium(IV) and preparation of cerium products, the mechanism, methods, and objectives of extraction and recovery of cerium from rare earth ore are described in detail in this chapter. It is of great significance to make use of the changeable valence properties and the strong complexation and coordination ability of Ce4+ in REs separation. The cerium in rare earth ores can be efficiently oxidized to Ce(IV) and can be separated and recovered by solvent extraction easily. According to these studies, Li and our group established an important process to recover Ce(IV) by Cyanex 923 from rare earth ore. The Ce(III) in rare earth ore can be effectively oxidized into Ce(IV) by oxidizing roasting Baotou mixed rare earth ore. The complexation property between Ce(IV) with F and/or P in acidic solution can help to separate and recover Ce(IV), F, and P by solvent extraction. This invention can realize the comprehensive utilization of resources and avoid resource waste and environmental pollution by utilizing the associated resources of the Baotou rare earth ore to recover the Ce. It also provides a convenient condition for the subsequent separation of Th and other RE(III). More efforts on the studies of mechanism, process intensification, and equipment will be needed in the future.
