Effect of Magnetite Concentrate Particle Size on Pellet Oxidation Roasting Process and Compressive Strength

During the roasting process of pellets, the particle size of the magnetite concentrates affected its component content, which correlated well with the oxidation roasting process and metallurgical properties of the pellets. In this work, using high-silicon iron ore concentrates as raw material, the effect of high-silicon iron ore concentrates with different particle size on the oxidation behavior of pellets was studied. Coats-Redfern data processing model was carried out to calculate the oxidation kinetics parameters of high-silicon iron ore concentrate. The research results showed that the refinement of high-silicon iron ore concentrates could reduce the SiO2 content to 1.96% and increase the pellet grade to 69.84%. At a heating rate of 15 degrees C/min, the refinement of particle size reduced the activation energy to 45.73 kJ.mol(-1), which could greatly improve the degree of oxidation of pellets and increase the consolidation strength to 3 213 N. The iron ore concentrates more than 74 mu m had lower activation energy at a higher heating rate, whereas an opposite trend was identified for the iron ore concentrates less than 74 mu m. Consequently, reducing the particle size range of high-silicon iron ore concentrates can effectively improve the physical and chemical properties and smelting indexes of iron ore concentrates, which indicated the direction of rational utilization of the high-silicon iron ore concentrates.