The properties of rare earth elements are very similar. There are generally about 15 kinds of rare earth elements coexisting in rare earth minerals. It is difficult to separate and purify them, and the consumption of chemical materials is high.
Firstly, the main extraction and separation systems and separation processes of rare earths used in industry were reviewed, and the characteristics of several current extraction and purification processes were compared and analyzed; The new methods and technologies of rare earth separation and purification developed in recent years are introduced.
1.Material recycling technology in rare earth separation and purification process
A comprehensive utilization method of wastewater containing MgCl2 or CaCl2 in the rare earth smelting and separation process has been proposed in the rare earth research, that is, the MgCl2 containing wastewater generated in the rare earth extraction and separation, precipitation and crystallization process is concentrated and dehydrated for pretreatment, and then pyrolyzed to obtain MgO solid and HCl containing gas; The gas containing HCl is absorbed by water to prepare hydrochloric acid, which is returned to the rare earth separation and purification process.
2.A new method for separation and purification of rare earth
In view of the problems that chloride wastewater in the existing rare earth separation and purification process is difficult to be recycled and targeted deep removal of specific impurities, optimizing, upgrading and iteratively developing new methods of rare earth separation and purification are also one of the effective ways to achieve green extraction of rare earth.
The current research focuses mainly include ion imprinting, ionic liquid extraction, Rapid SXTM separation, rare earth chloride pyrolysis, rare earth chloride electrolysis, etc., which are expected to be used in the field of rare earth separation and purification in the future.
Conclusion and Prospect
(1) Encourage the R&D, optimization, upgrading and promotion of green process technology;
(2) Iterative development of new green smelting and rare earth separation technology;
(3) Establish systematic evaluation system for green manufacturing of rare earth;
Chinese Journal of Rare Earth, 2021, Issue 3
Authors: Feng Zongyu, Wang Meng, Zhao Longsheng, etc
(1) Youyan Technology Group Co., Ltd., National Engineering Research Center for Rare Earth Materials, Youyan Rare Earth New Materials Co., Ltd;
(2) Hebei xiongan Rare Earth Functional Material Innovation Center Co., Ltd