Pre-classification of flotation feed

Pre-classification concept was developed by the University of Minnesota researchers. The concept was later improved for plant implementation. A simplified flow sheet of pre-classification circuit is shown in the figure. It involves separation of coarse and fine fraction prior to flotation. While magnetic separation is applied to the fine fraction, the coarse fraction was treated by flotation. Since the feed rate to the flotation circuit would be approximately halved, substantial savings could be achieved through reduced reagent consumption. This concept of processing was implemented in an iron ore processing plant and a 5% increase in magnetic iron recovery and 24% decrease in reagent consumption were reported. The lab recently carried out simulation based studies to quantify benefits from the application of this concept to other flotation circuits. Simulations produced favorable results for the implementation of this concept to other plants.