Process Optimization And Mechanism Study Of Simultaneous Reduction Of High Iron Manganese Oxide Ore

Manganese is widely used in steel,chemical,non-ferrous metallurgy,battery and other fields.Most of the manganese oxide ores in my country are lean ores with high iron and low manganese,with low ratio of manganese to iron,most of them coexist with iron,and the embedded particle size is very fine,which makes the separation of high iron manganese ores difficult,and most of them need beneficiation pretreatment before smelting.In this paper,high iron manganese oxide ore is taken as the research object.Based on the analysis of the chemical composition and phase composition of the original ore,through the research of reduction roasting-magnetic separation process under coal-based and gas-based conditions,a suitable roasting and sorting system is obtained.On the basis of roasting experiments,the kinetics of reduction roasting was studied,and the apparent activation energy and limiting link of iron oxides and manganese oxides in the reduction process under coal-based and gas-based atmospheres were clarified,and it was revealed that high-iron manganese oxide ore is in the process of reduction.Mechanism of simultaneous reduction of manganese oxides and iron oxides.The research showed that under the coal-based reduction roasting condition,from 650℃,Fe₂O₃was gradually converted into Fe₃O₄,and most of Mn₂O₃was reduced to Mn₃O₄.When the temperature was higher than 750℃,the generated magnetite was further increased,and Mn₃O₄was reduced to Mn O.Under the condition of gas-based reduction roasting,Mn₂O₃was directly reduced to Mn O without going through the intermediate product Mn₃O₄.Using gas-based reduction roasting,the iron removal rate of magnetic separation was close to 70%,the grade of manganese concentrate was 49%,the recovery rate of manganese was 72.50%,and the ratio of manganese to iron was increased from 2.5 to 5.92.Kinetic studies showed that the reduction process of Mn₂O₃was controlled by chemical reaction under the condition of coal-based reduction roasting,and the apparent activation energy of reduction reaction was 154.59 k J/mol.The magnetization process of Fe₂O₃was controlled by chemical reaction,and the apparent activation energy of magnetization reduction reaction was 75.11 k J/mol;under the condition of gas-based reduction roasting,the reduction process of Mn₂O₃was controlled by chemical reaction,and the apparent activation energy of reduction reaction was 42.64 k J/mol.The magnetization process of Fe₂O₃was close to mixed control,but the correlation of mixed control was low in the reaction region,the reaction rate was controlled by internal diffusion,and the apparent activation energy of the magnetization reduction reaction was 21.30 k J/mol.Compared with coal-based roasting,the activation energy of the reduction process of Mn₂O₃and Fe₂O₃in the gas-based reduction roasting process was lower,and the reaction was easier to carry out.The direct use of CO as a reducing agent could reduce the difficulty of the reaction.Using CO as a reducing agent was more effective than reducing coal.Compared with coal-based reduction roasting,manganese oxides were directly reduced to Mn O from Mn₂O₃without first being reduced to Mn₃O₄intermediate products.When the volume fraction of CO was 30%,the calcination temperature was 750°C,and the calcination time was 60 min,Mn₂O₃and Fe₂O₃could be simultaneously reduced and converted into Mn O and Fe₃O₄,respectively.