Effect of impurity additions on the remanence and coercivity of reduced hematite ores

Abstract

AbstractSynthetic ores of pure ferric oxide, and ferric oxide with additions of CaO, SiO2, MnO2 and TiO2 were made up by sintering the mixtures at 1100°C. Subsequent crushing, grinding and screening yielded ores with particle between 149 and 208 microns. The ores were reduced to mainetite between 500°C and 1000°C in a CO-CO2 atmosphere.The coercive force and remanence of the reduced ores were determined using a 60 cps hysteresis loop tracer. The addition of CaO decreased the coercive force and remanence of the reduced ore as compared to pure magnetite, whereas the effects of the other additions were not significant. Explanations for the findings are offered. Resume Des minerais synthetiques d'oxide ferrique pur et d'oxyde ferrique additionne de CaO, SiO2, MnO2 et TiO2 ont ete elabore par frittage a 1100°C. Apres broyage et tamisage, la tail1e des particules de minerai s' echelonnait de 149 a 208 microns. Ces minerais etaient ensuit reduits en magnetite a des temperatures variant de 500 a 1000°C en atmosph...