The role of thermal improvements in indurating machines for pellet production from high-sulfur magnetite concentrate

Mostly, magnetite iron ore mine materials contain significant amounts of sulfur base components. This can cause disturbance in production process of steel. Although high-sulfur magnetite concentrate has not been inciting enough yet to be employed by steel industry, these compounds are potential alternatives for iron ore resources. In this work, oxidation and sulfur removal of magnetite iron ore pellets were studied during the thermal treatment in the pelletizing indurating machine. The oxidation phenomenon and sulfur removal, in the magnetite iron ore pellets, were assessed by determination of appropriate thermal conditions employing thermogravimetric as well as differential scanning calorimetric tests accompanied by heat treatment procedure in a laboratory furnace. The residual sulfur-based compounds were considered as an indicator for the reaction rate; the results showed the reaction progress had a lower rate in the temperature range of 500–750 °C. Furthermore, the high-rate pre-heating and firing processes of pellets caused a higher level of residual magnetite phase within the microstructure, whereas crack initiation and growth were probable within the oxide pellets. The findings did highlight the role of thermal profiling and eventually, led to redesigning the thermal profile for pelletizing indurating machines.