The influence of temperature on phase transformations of the minerals present in the red mud: Reduction of hematite to magnetite

Abstract

In this work a technological route was proposed to analyze the behavior of phase transformations of the min-erals present in the red mud during the process of reduction of hematite to magnetite. The fluorescence analy-sis and X-ray diffraction showed that red mud presented approximately 5% titanium oxide as anatase and 28% iron oxide in the forms of hematite and goethite. Experiments involving the reduction of hematite to magnetite using thermal treatment. The material was calcined at temperatures of 500, 600 and 1000 °C for 2 h. Then, X-ray diffraction and Raman spectroscopy analyzes were performed, which showed that the hema-tite was reduced to magnetite in all experimental conditions. For the calcination temperatures of 500 and 600 °C, the titanium oxide remained in anatase free form, but for the calcination performed at 1000 °C, the oxide passed into the form combined with iron (ilmenite). The route proposed in this work allowed to obtain a material with magnetic characteristics, which could be used as source of titanium after extraction of iron compounds by magnetic separation or acid leaching.