Separation and recovery of valuable metals from low-grade REE–Nb–Fe ore

Abstract

To recover valuable metals from Bayan Obo tailings, thermodynamic analysis and experiments were conducted to extract Fe, Nb, and rare earth elements (REE) from low-grade REE–Nb–Fe ore by reduction roasting, magnetic separation, and sulfuric acid (H2SO4) leaching. The separation efficiency of Fe increased with the increase in reduction roasting temperature to 1100°C. Once the reduction roasting temperature reached 1150°C, the aeschynite ((Ce,Nd)NbTiO6) as the main mineral phase of Nb was reduced to NbC. After a magnetic treatment, it was observed that ~79.1% of Fe was separated, and the grade of total Fe in the magnetic materials was 88.2wt.% when the ores were reduced first at the optimum temperature of 1100°C. As the Fe was removed, the content of Nb2O5 and REE oxides ((REE)O) in magnetic separation tailings also increased. A H2SO4 solution was used to separate Nb and REE from the magnetic separation tailings at 160°C. The results showed that ~98.2% of Nb and 99.0% of REE were extracted; they could be used to obtain Nb or REE-bearing products by further purification.