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

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 degrees C. Once the reduction roasting temperature reached 1150 degrees 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 similar to 79.1% of Fe was separated, and the grade of total Fe in the magnetic materials was 88.2 wt.% when the ores were reduced first at the optimum temperature of 1100 degrees 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 degrees C. The results showed that similar to 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. (C) 2016 Elsevier B.V. All rights reserved.