Reduction characteristics of carbon-containing REE-Nb-Fe ore pellets

Abstract

To separate and recover the valuable metals from low-grade REE (rare earth elements)-Nb-Fe ore in China, the reduction characteristics of carbon-containing REE-Nb-Fe ore pellets, including mineral phase variation, reduction degree, and reaction kinetics, were observed based on thermogravimetry experiments. The results showed that the reduction and separation efficiency of valuable metals in the carbon-containing pellets were superior to the ones in the previous non-compact mixture. After the reduction roasting of the pellets at 1100 °C and a subsequent magnetic separation, the iron powder with a grade of 91.7 wt % was separated, and in magnetic separation tailings the grades of Nb2O5 and (REE)O were beneficiated to approximately twice the grades in the REE-Nb-Fe ore. The reaction rate of the reduction of the carbon-containing pellets was jointly controlled by the carbon gasification reaction and the diffusion of CO in the product layer with an activation energy of 139.26-152.40 kJ·mol-1. Corresponding measures were proposed to further improve the kinetics condition.