Inter−particle water infiltration dynamics of iron ore fines during granulation process

Abstract

Inter-particle water infiltration dynamics of iron ore fines and concentrates was investigated using Washburn Capillary Rising method to evaluate the effect of various raw material conditions presented in the iron ore sintering process. The final water content and initial infiltration rate of the ores were determined from the measured infiltration curves and found to be heavily affected by the ore type and the blending, pre-wetting and packing conditions. The final water content of the ores was found to increase with the voidage of the packed ore bed. Ores forming a more permeable bed with a larger voidage is expected to achieve a higher final water content. The final water content of the blended ores showed an intermediate value between the component ores and can be readily predicted from the final water content of the component ores. Like the dry ore, the pre-wetted ore showed a similar infiltration curve. However, compared with the dry ore, the pre-wetted ore picked a considerably less amount of water at the end of infiltration test because some voidages were occupied by initial water. The initial infiltration rate of the ores was found to be greatly governed by the specific surface area, then bed voidage and contact angle. The Canadian magnetite concentrate showed the fastest initial infiltration rate of 3.0 × 10-9 kg2/s likely due to its smallest specific surface area. On the other hand, the Brazilian ores consisting of micro-porous hematite measured the smallest infiltration rate of 3.2 × 10-10 kg2/s due to their largest specific surface area. Unlike the final water content, the initial infiltration rate of the blended ores cannot be readily calculated from the component ores due to the nonlinear relationship between the initial infiltration rate and specific surface area. Pre-wetting was believed to improve the wettability and connection of ores with infiltrated water, leading to a faster completion of infiltration.