Fundametal Research On The Comprehensive Utilization Technology Of Nb-Bearing Tailings

Bayan Obo ore in Inner Mongolia of China is a world-renowed RE-Nb-Fe deposit, in which the rare earth reserves ranks first and niobium reserves ranks second in the world. The iron resourse has long dominated the mineral resourse exploitation and utilization of Ban Obo ore, and the comprehensive utilization rate of rare earth resourse is less than10%. However, the niobium resourse has not been efficient utilized up to now. Much research has been done on the separation, extraction and utilization of niobium resourse in Bayan Obo ore. Many niobium extraction technologies from Bayan Obo ore have been developed. But all of them have not been applied in industrial production.Based on the previous research work, two new technologies for recovering and utilizing Nb-bearing tailings were proposed according to the composition and mineral phase characteristic of Nb-bearing tailings in this paper. The research work can effectly improve the level of comprehensive utilization of Bayan Obo ore and ease the dependence of our country on foreign niobium resourse imports. Therefore, the research work has the impotant academic value and strategic significant. The main resrach results of this paper are as follows.(1) In accordance to the coexistence theory of slag structure, the calculation model of activity for slag system of CaO-SiO2-Al2O3-FeO-CaF2-RE2O3-Nb2O5-TiO2was established. The results show that the activity calculated by the model is in good accordance with experimental data. The activity change of components in Nb-bearing slags can be calculated and analysed.(2) The preliminary separation of niobium and iron from the Nb-bearing tailings can be realized by the technology process of reductive roasting and magnetic separation.In magnetic tailings, the mass fraction of Nb2O5is7.35%, and the mass fraction of RE oxides is6.98%. The yield ratios of niobium and rare earth both reach above97%. The main mineral phase of niobium in tailings change to NbC from (Ce,Nd)NbTiO5by reductive roasting at1150℃.(3) A new preparation technology of Nb-Fe alloys with Nb-bearing tailings was proposed. The mass fraction of niobium in the Nb-Fe alloys prepared with the new technology is12.29%, and the yield ratio of niobium is85.3%. Meanwhile, RE-enriched slags can be obtained, in which the mass fraction of rare earth is8.60%. Relative to other preparation technologies of Nb-Fe alloys, the new technology has some significant advantages, such as reducing energy consumption and improving production efficiency.(4) A new hydrometallurgical processing technology for Nb-bearing tailings was proposed. The separation, extraction and utilization of niobium, rare earth and iron resourses can be realized with the new technology. The mass fraction of Nb2O5is60.67%in the crude Nb2O5product, and the mass fraction of RE oxides is88.65%in the composite RE oxides product. The yield ratios of Nb, RE and Fe are72.4%,78.5, and77.4%respectively. Relative to traditional technologies, the equipment of the new technology is simple, meanwhile the energy consumption and the cost of processing technology are low.