Mechanism Research on Niobium Distribution Influenced by Roasting Temperature in the Direct Reduction Roasting Process

Abstract

In this study, the niobium enrichment research of the iron concentrate containing niobium was studied by coal-based direct reduction roasting followed by magnetic separation process. The distribution of niobium element and existence form of mineral bearing-Nb in roasted products were investigated under different roasting temperature which was ranging from 1100°C to 1300°C. X-ray diffraction analysis (XRD) was used to identify the various minerals and compositions of the roasted products. The microstructures of these products were analyzed by the scanning electron microscope (SEM), while the elemental analysis was carried out by using energy dispersive spectrometer (EDS) technique. The results of XRD and EDS analysis showed that most of the niobium minerals were Nb-Fe rutile and ulvospinel which scattered in slag, and only a little was adhered to the surface of metallic iron at 1100°C. And the niobium oxides were partly reduced to Ti-aeschynite and niobocarbide which attached on the surface of metallic iron, and most were still ulvospinel scattering in the slag at 1200°C. The Ti-aeschynite was gradually reduced to Nb adhering to the metallic iron particle forming Nb-Fe soild solution at 1300°C.