Selective Precipitation And Super Gravity Separation Of Rare Earth Phases In Rare Earth Slag

Bayan Obo ore deposit is a unique multi-element symbiotic deposit in China,and its rare earth reserves rank first in the world.However,the complex mineral phase structures and chemical compositions bring great difficulty to the recovery and utilization of rare earth resources.At present,the lack of high temperature phase diagrams and the basic data of rare earth minerals leads to the limited study of the metallurgical process of rare earth systems.Therefore,this paper systematically carried out the high temperature phase diagrams of multiple rare earth slag systems,the phase balance and crystallization growth dynamics of typical rare earth phases,the super gravity selective separation and characterization of different rare earth phases in the rare earth slag systems,and obtained the following results.Based on the differences of smelting process and compositions of typical rare earth slag in Bayan Obo,the phase equilibria relationships of four kinds of rare earth basic slag systems(CaO-SiO2-Ce2O3、CaO-SiO2-CaF2-Ce2O3、CaO-SiO2-CaF2-P2O5-Ce2O3、CaO-SiO2-CaF2-P2O5-FexOy-RE2O3)are explored.The corresponding isotemperature phase equilibria diagrams are constructed according to the basic construction rules of phase diagrams,and the phase diagrams and thermodynamics data of the rare earth slag systems are supplemented.The phase equilibria and crystallization growth dynamics of rare earth phases are studied in the equilibrium region of liquid phase and rare earth phase,which provides necessary theoretical basis for the separation and extraction of rare earth resources from multiple rare earth slag systems.Based on the optimum conditions of selective precipitation and growth of rare earth phases,the super gravity field is applied in the melting crystallization zone of each rare earth phase.With the help of its characteristics of strengthening the phase separation,the selective separations of different rare earth phases in the multiple rare earth slag systems are realized.At the same time,the obtained high purity rare earth phases are analyzed and characterized,and the basic information of rare earth chemical formulas,XRD standard patterns and crystal structures are supplemented,and the basic physical and chemical data of different rare earth phases are improved.The selective separations of rare earth phases in rare earth concentrate and rare earth blast furnace slag are studied with the support of obtained thermodynamic data and crystallization kinetics.According to the step crystallization law of Ce,La,Pr and Nd in rare earth concentrate,the step separation of different rare earth phases is realized.The kilogram scale experiment of super gravity separation of rare earth phase in blast furnace slag is carried out,and the practical effect of super gravity selective separation has been confirmed,which provides a reliable basis for the engineering application of this technical route.This paper provides a novel method for the separation of rare earth components in rare earth ores and slag in China.The research results provide some basic data for the physical and chemical properties of slag containing rare earths,which has certain theoretical and application value for the utilization of rare earth ore and slag resources in China.