Interaction Between Iron Ore and Magnesium Additives During Pellet Roasting Process

Abstract

To study the interaction between iron ore and magnesium additives, several types of interaction couples were prepared and SEM–EDS was used to measure the diffusion distance of Mg²⁺. Results showed that prolonging the roasting time was beneficial to the diffusion of Mg²⁺ in the iron ore. When the basicity (CaO/SiO₂) of iron ore increased from 0.2 to 1.0, the diffusion distance of Mg²⁺ increased from 15 to 35 μm. Among three magnesium additives, the diffusion distance of Mg²⁺ in dolomite was the longest, while that in serpentine was the shortest. Serpentine contains a large amount of SiO₂, which can hinder the contact between MgO and Fe₂O₃, thus reducing the diffusion distance of Mg²⁺. The roasting experiment of high-magnesium pellets was further carried out to study the influence of basicity on the compressive strength of pellets. Result shows that the compressive strength of pellets decreased from 2701 to 2556 N when 2% dolomite was added. The basicity of high-magnesium pellets was adjusted by adding CaO into the pellets. The compressive strength of pellets with basicity of 1.2 was 2629 N. The compressive strength of pellets with basicity of 1.5 was 2654 N. Adding CaO to high-magnesium pellets can improve the compressive strength.