Mineralogy and metallurgical properties of iron ore sinter based on magnetite fines

摘要

This study has shown that sintering is primarily a mineralogical process even though it is traditionally considered as being controlled by chemical analyses. The effect of the mineralogy of the sinter mix on the mineralogy of the finished sinter is, in some extreme cases, quite clear and easily understood. The mineralogy of sinter based on magnetite fines differs completely from that of sinter made of hematite ores, even when they have the same chemical composition. In the author's opinion, this is due to the fact that in the sintering process the material is only partly melted and the first liquid phase to form is then of crucial importance to the mineralogy of the sinter. Magnetite reacts easily with SiO(sub 2) forming a fayalite melt, whereas hematite forms a calcium ferrite melt with CaO. Sinter based on magnetite fines contains 40-60 % magnetite and 10-30 % hematite, the slag phase consisting mainly of vitreous silicate with very little calcium ferrites. Sinters made of hematite ores contain 30-50 % hematite, 10-20 % magnetite and much more calcium ferrites than vitreous slag. The correlation between sinter mineralogy and metallurgical test results has been studied on process sinters made by the Rautaruukki sinter plant at Raahe. In this study, the mineral composition of the sinters has been determined by four different methods, the chemical composition of the minerals has been analyzed in different sinters and the distribution of the main chemical components between different minerals has been calculated