Evaluation of VSK separation in the classification of two mineralogically different iron ore fines

With gradually diminishing Fe grade in tandem with the ever-increasing demand for high-grade iron ores, iron ore industries are now focusing on the beneficiation of low-grade iron ore fines, mainly considered waste. Besides, the scarcity of water at many of the mines’ sites and the new water conservation policies of the governments have necessitated research on suitable dry beneficiation routes. In this context, an effort has been made to evaluate the efficacy of a dry classification unit, such as the VSK separator, in upgrading the iron values of two low-grade Indian iron ore fines, named Sample 1 and Sample 2. The mineralogical studies, involving scanning electron microscopy and X-ray diffraction, suggest that Sample 1 is a low-grade blue dust sample (51.2wt% Fe) containing hematite and quartz as the major minerals, while Sample 2 (53.3wt% Fe) shows the presence of goethite in addition to hematite and quartz. The experiments, carried out using Box–Benkhen statistical design, indicate that blower speed, followed by feed rate, is the most influencing operating parameter in obtaining a good product in the VSK separator. At optimum levels of the operating factors, a fines product with ~55wt% Fe at a yield of ~40% can be obtained from Sample 1, while Sample 2 can be upgraded to ~56wt% Fe at a yield of ~85%. The results suggest that the VSK separator can be employed as an efficient intermediate unit operation in a processing circuit to upgrade the iron contents of iron ore fines.