Combined with Fig. , the relationship between leaching agent concentration and conductivity changes shows that the conductivity is the largest in Dinan, the second largest in Anyuan and the smallest in From Fig. Zeta potential versus rare earth ion content variation graph, it can be seen that during the titration of 0.15 mol/L MgSO4 leaching agent, its Zeta potential is linearly related to the leaching amount of rare earth ions, the larger the leaching amount of rare earth ions, the larger the absolute value of Zeta potential and the more negative the Zeta potential. The Zeta potential corresponds to the slip surface potential, where the rare earth ions are exchanged out of the slip surface by the leaching agent, and the positive charge inside the slip surface decreases and the negative charge increases due to the lower valence of the exchanged ions, the presence of anions or poor bonding and rediffusion, etc. The linear relationship between the Zeta potential and the rare earth ion content indicates that the overall Zeta potential is negative. The linear relationship between Zeta potential and ion content indicates that the internal structural changes of the slip surface of clay minerals caused by the leaching of rare-earth ions are the main reason for the change of Zeta potential throughout the exchange process.