Abstract
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.
Highlights
Iron ore sinter remains an important feed for the production of iron and steel, and research continues into the improvement of sinter quality for economic and environmental reasons [1,2].In the authors’ previous paper [3], the mineralogy of an industrial sinter sample was analysed using a combination of reflected light microscopy point counting (PC), automated image analysis (AIA), quantitative X-ray diffraction (QXRD) and electron probe microanalysis (EPMA)
The total iron oxide concentration measured by TESCAN Integrated Mineral Analyser (TIMA) agreed well with the total iron oxide measured by PC
QXRD with the difference less than 5%; the total silico-ferrite of calcium and aluminium (SFCA) amounts determined by TIMA were all relatively lower than the PC results, lending some weight to the hypothesis that some amorphous SFCA phases may exist in the sinter samples
Summary
Iron ore sinter remains an important feed for the production of iron and steel, and research continues into the improvement of sinter quality for economic and environmental reasons [1,2]. In the authors’ previous paper [3], the mineralogy of an industrial sinter sample was analysed using a combination of reflected light microscopy point counting (PC), automated image analysis (AIA), quantitative X-ray diffraction (QXRD) and electron probe microanalysis (EPMA). SFCA-I and SFCA are stable in discrete compositional ranges and have distinct crystallographic structures, which are presumed to correspond to the platy and prismatic morphologies observed using reflected light microscopy, respectively. Electron Microscopy (QEMSCAN) analysis to exploit this difference in chemistry and were able to delineate SFCA-I from SFCA. Given the ongoing uncertainty about the correspondence of morphological and chemical definitions of SFCA and SFCA-I and QXRD results, a round robin test was undertaken using additional sinter samples with a range of binary basicities. The PC, AIA and QXRD were complemented with analysis using the automated scanning electron microscopy (SEM) techniques QEMSCAN and TESCAN
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