New Process For Comprehensive Recovery Of Rare Earth,Fluorite,Niobium And Thorium In Bayan Ebo Tailings

Bayan Obo deposit is an iron-rare earth-niobium polymetallic symbiotic deposit,which has been mainly mined as iron ore for many years.The recovery rates of rare earth,niobium,scandium and fluorite are very low.A large number of useful minerals have been dumped into tailings for stockpiling,which has caused a huge waste of resources and adverse impact on the surrounding environment.Therefore,it is of great significance for the recovery and utilization of valuable components in rare earth tailings in Bayan Obo.In this paper,With Bayan Obo tailings as the research object,the combined process of“magnetic separation-superconducting magnetic separation-flotation–leaching”is adopted to recover valuable elements to develop a new process with high recovery and short flow.The process mineralogy analysis results show that the tailings contained a large number of Fe,SiO₂,CaF₂ and a small number of valuable components such as REO,Nb₂O₅ and Sc₂O₃,and it is very hard to separate for the parcels minerals much more than the adjacent minerals in the continuous generation minerals.Therefore,the removing iron process is firstly adopted by permanent magnetic separation,and then the weakly magnetic iron minerals such as rare earth,niobium,scandium are separated from non-magnetic minerals such as fluorite,quartz gangue mineral in removing iron minerals by the superconducting high gradient magnetic separation.It is found that in minerals samples by the superconducting magnetic separation,more than90%valuable components such as rare earth,niobium,scandium gather in weak magnetic minerals,but the gangue minerals such as fluorite,quartz gather in non-magnetic minerals,which shows that the superconducting high gradient magnetic separation has obvious the effects in the weak magnetic minerals separation from non-magnetic minerals.The different flotation processes are adopted to separate gangue minerals such as fluorite and quartz from non-magnetic minerals and the minerals contain rare earth,niobium and scandium from weakly magnetic minerals.Firstly,the fluorite concentrate with a grade of 91.80%was obtained by the closed-circuit flotation process of“one roughing a-six cleanings-middling returning”,and then the grade of fluorite increases to 97.58%and the recovery is 72.45%by superconducting magnetic separation.After that,the rare earth concentrate with the grade of60.83%and the recovery of 77.65%is obtained by the closed-circuit flotation process of“one roughing a-two cleanings-middling returning”.The rare earth tailings after flotation were recovered with the closed-circuit process of“one roughing a-three cleanings-middling returning”,and the niobium concentrate with the niobium grade of 2.71%and the recovery of85.78%is obtained,but scandium is concentrated in niobium tailings,and the leaching liquid with scandium content of 330.18 ppm is obtained by acid leaching,the leaching rate reached to97.51%.In conclusion,superconducting magnetic separation exhibits high selectivity for Bayan Obo tailing,and the weak magnetic minerals can be well separated from non-magnetic minerals in Bayan Obo tailing,which lowers the effect of easy floating gangue minerals on the flotation of many kinds of valuable minerals,and then decreases reagent dosages,shorten the flotation process,reduces the production cost.This process provides a new way for the high value utilization of Bayan Obo rare earth tailings and can be used in the actual production.