Abstract:Ion adsorption type rare earth ores（IAREO）are a type of weathered ore deposit where rare earth elements are adsorbed on the surface of clay minerals in the form of hydrated or hydrated hydroxyl groups. In this study, it was found for the first time that the rare earth phase state changes in this type of ores under dry grinding conditions, and then through simulation experiments, the effect of mechanical grinding on the changes in the ionic phase rare earth content in the ores and the phase transition path were accurately quantified. The results showed that the reduced Ion exchangeable (F2) in the ore after grinding are mainly converted into Carbonate-bound(F3), and a few are converted into Fe-Mn oxide-bound(F5) and Humic bound (F4). Among them, F2 decreased by 53.48%, while F3 increased by 36.05%. The phenomenon of rare earth phase transition may be related to the influence of grinding on the structure of clay minerals. The evidence from XRD and FTIR indicates that the mechanical grinding process can cause structural damage to clay minerals, and the crystal structure is deformed, causing the lattice damage of clay minerals and the appearance of disordered features. The occurrence of mechanochemical processes accompanying mechanical grinding may be the key reason for the reduction of ion phase rare earths, changes in rare earth occurrence state, and transfer between forms after mechanical grinding; The results of this study have important implications for the development of exploration specifications for ion adsorption type rare earth minerals, ore processing technology, development process of standard materials, analysis and testing, and research on mechanical grinding mechanisms of clay minerals. The reduction of ion phase rare earths caused by mechanical grinding of ion adsorption type rare earth ore is a new and important discovery in the study of this type of ore deposit.