Comparison of the mineralogy of iron ore sinters using a range of techniques

Many different approaches have been used in the past to characterise iron ore sinter mineralogy to predict sinter quality and elucidate the impacts of iron ore characteristics and process variables on the mechanisms of sintering. This paper compares the mineralogy of three sinter samples with binary basicities (mass ratio of CaO/SiO₂) between 1.7 and 2.0. The measurement techniques used were optical image analysis and point counting (PC), quantitative X-ray diffraction (QXRD) and two different scanning electron microscopy systems, namely, Quantitative Evaluation of Materials by Scanning Electron Microscopy (QEMSCAN) and TESCAN Integrated Mineral Analyser (TIMA). Each technique has its advantages and disadvantages depending on the objectives of the measurement, with the quantification of crystalline phases, textural relationships between minerals and chemical compositions of the phases covered by the combined results. Some key differences were found between QXRD and the microscopy techniques. QXRD results imply that not all of the silico-ferrite of calcium and aluminium (SFCA types) are being identified on the basis of morphology in the microscopy results. The amorphous concentration determined by QXRD was higher than the glass content identified in the microscopy results, whereas the magnetite and total SFCA concentration was lower. The scanning electron microscopy techniques were able to provide chemical analysis of the phases; however, exact correspondence with textural types was not always possible and future work is required in this area, particularly for differentiation of SFCA and SFCA-I phases. The results from the various techniques are compared and the relationships between the measurement results are discussed.