Morphological Changes Of Nb And P During Magnetic Reduction-separation Of Iron-bearing Minerals

In the Bayan Obo Mine,the Niobium and Phosphorus resources are co-existing with other minerals,and the embedded relationship is close.It is difficult to achieve effective separation of Nb,P and Fe,which affects the utilization of resources.Many scholars at home and abroad have carried out a lot of research on this kind of mineral resources,the methods of selective reduction and magnetic separation can separate phosphorus,niobium and iron to different degrees.However,during the selective reduction process,if the reaction temperature is high,part or all of the Nb phase,P phase enters the Fe phase and cannot be effectively separated from Fe;if the reaction temperature is low,the reaction efficiency is low.In view of the above problems,this paper introduces a steady magnetic field into the selective reduction process,and uses low temperature magnetic reduction-magnetic separation technology to achieve effective separation of Nb,P and Fe.Mixing the pure Tri-calcium phosphate,Fe₂O₃ and columbite in a certain ratio,and then sintered,artificially synthesize iron ore containing niobium and phosphorus,perform isothermal weight loss magnetic reduction in a mixed atmosphere of 80%CO-20%CO₂ and a constant temperature of 800?under normal conditions and magnetic field conditions.The reduced sample was separated Nb,P from Fe by magnetic separation.Analytical detection methods such as ICP,XRD,SEM,EDS,etc.Analysis the morphology changes between Nb phase,P phase and Fe phase during magnetization reduction,determine the distribution ratio of Nb,P and Fe in the slag phase and the metal phase.Established a link between the characteristics of the topography and the separation effect.Conclusion as below:Tri-calcium phosphate and columbite do not undergo chemical reaction during the magnetic reduction in mixed atmosphere of 80%CO-20%CO₂ and a constant temperature of800?,The addition of a steady magnetic field accelerates the reduction process of Fe₂O₃ and improves the reduction efficiency of P,Nb-containing iron oxide.During the magnetization reduction process,the P-containing phase and the Fe-containing phase are broken into fine particles,and the crystal grain size is significantly reduced to 5-10?m,and the particle size of the Nb-containing phase is not significantly changed.The area containing the P phase in closely contact with the Fe-containing phase is reduced to 21.88%,the P phase and the Fe phase are converted into point contact by surface contact,until the two phases are peeled off.The particle size of the Nb-containing phase and the Fe-containing phase are significantly different.The application of a stable magnetic field improves the intercalation relationship between the P,Nb phase and the Fe phase,so that the microscopic morphology of P,Nb and iron oxide conducive to the development of the separation of Fe,P and Nb.The magnetic separation separation shows that the recovery ratio of Fe,P and Nb and the distribution ratio in the slag gold are improved by applying a constant magnetic field during the reduction process.For phosphorus-containing iron oxides,the distribution ratio of P in the slag phase to the metal phase is increased by 62.91%,and the distribution ratio of Fe in the metal phase and the slag phase is increased by 23.49%;For the niobium-containing iron oxide,the distribution ratio of Nb in the slag phase to the metal phase is increased by 23.46%,and the distribution ratio of Fe in the metal phase and the slag phase is increased by 19.90%.This indicates that more Nb,P enters the slag phase,more Fe enters the metal phase,applying a steady magnetic field during the reduction process,the microstructure of the Fe phase and the Nb phase,P phase is more favorable for the separation of Fe,Nb and P.In this study,magnetic field technology is applied to the reduction process in the future,and provides a theoretical basis for dephosphorization and enrichment.