| Description |
Because of intensive mining of high-grade manganese ores for a long time while leaving behind the low-grade ores, the utilization of the latter has become necessary. There are several physicochemical differences among the components in manganese ores, which can be used for the enrichment of manganese. In particular, the abundant low-grade manganese ores, which contain iron oxide, may be upgraded by prereduction and magnetic separation. In this study, ferruginous low-grade manganese ore was prereduced by CO, which converted iron oxide to Fe3O4 while manganese oxide was reduced to MnO. Then, the iron-rich component was collected by magnetic separation. The effects of sample particle size and various other reduction parameters on the efficiency of magnetic separation were studied. Under the optimum experimental conditions, the manganese content in the ore increased from around 36% to more than 45%, and almost 50% of iron were removed at a Mn loss of around 5% by this method. For the kinetics study of the reduction of Mn3O4 in the ore, TGA was used to investigate the reduction extent and reduction rate at different reduction conditions. During the reduction, the changes in the phases were examined by XRD. Based on the experimental data as well as the physical features of sample particles used in this work, the nucleation and growth equation was determined to best represent the reduction rate and a complete rate equation was formulated. In addition, the effects of such major impurities as Fe2O3 and SiO2 on the reduction process were also determined in this work. |
