Study on Material Composition and Particles Characteristics of Red Mud from the Sintering Alumina Process

Red mud can be derived from the processing of bauxite using different methods. The chemical composition of red mud varies greatly with respect to the types of bauxite ore and processing parameters. The characterization of red mud with sintering alumina process from Guizhou, China, was investigated using X-ray Fluorescence Spectrometry (XRF), Inductively Coupled Plasma-Mass Spectrometry (ICP-MS), X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and Malvern Mastersizer 2000 laser scattering particle size distribution analyzer in this study. The results show that red mud consists of eight main chemical compositions of CaO, Al₂O₃, SiO₂, Fe₂O₃, TiO₂, Na₂O, K₂O and MgO, and multiple trace elements. Calcium silicate, tricalcium aluminate, perovskite, calcite, amorphous mass and other phases such as iron-bearing minerals and clay minerals were identified in red mud by XRD. TEM analysis showed that mineral phases in Guizhou red mud used in this paper had different micro shapes: thin sheets and aggregation of small particles; regular shapes such as flake, column, and grain; aggregation of filamentous or trichoid shapes. The small size of red mud particles related to comprehensive utilization of red mud and was one of its distinctive characteristics or attributes revealed by a Mastersizer 2000 laser scattering particle size distribution analyzer. The purpose of this investigation is to establish the relationship between the properties of red mud from sintering alumina process and its usage, so as to provide necessary data and a scientific base for its comprehensive utilization.