Consolidation Behaviors of Magnesium Acid Pellet Produced by Serpentine and High-Silicon Iron Ore Concentrate

Magnesium oxide (MgO) is critical for improving the metallurgical properties of magnesium pellets. However, it can reduce the cold compressive strength (CCS) of such pellets; in contrast, moderate SiO2 contents can improve the CCS. In this work, the effect of serpentine mineral on the consolidation behaviors of a magnesium acid pellet under high-silicon iron ore concentrate were investigated. Relevant mechanisms have been clarified using porosity analysis, FactSage 7.0, x-ray diffraction, and scanning electron microscopy. Increasing the serpentine content from 0% to 4% caused the CCS of the pellets to decrease from 2139 N pel(-1) to 1723 N pel(-1), and the porosity to increase from 19.86% to 23.96%. Although an increase in serpentine contents could have a negative impact on the CCS of magnesium pellets, it would restrain the degree of decrease in CCS, caused by the formation of MgSiO3. This MgSiO3 is formed during roasting, due to the decomposition of Fe2O3 to Fe3O4 which reacts with free SiO2 to form low-melting point phases, thereby increasing the liquid phase ratio in the pellet.