Separation of coal with a top size of up to 6 mm in a full-scale REFLUX™ Classifier

A 2 m diameter REFLUX™ Classifier was tested on coal feeds up to 6 mm top size. Solids feed rate was varied from 50 to 160 t/h at suspension concentrations up to 37 wt.% solids. Performance was consistent, with product ashes below 10 wt.% for +1 mm particles and reject ashes usually exceeding 70 wt.%. The density cut point could be freely varied and decreased with particle size to the power −0.114. Ep values less than 0.10 were obtained on the composite +0.5 mm material. Ep varied with particle size to the power −0.963. Hence, beneficiation performance for −4.0 + 0.50 mm material approached that of large dense medium cyclones (DMCs). Hence, REFLUX™ Classifiers could be used to increase the capacity of existing plants with minimal capital expenditure. The primary screen aperture size could be raised to around 4 mm, which should significantly increase screen capacity. The +4.0 mm fraction could be sent to the existing DMC circuit, which with a lower fines loading would have increased capacity and medium recovery. The −4.0 mm fraction could be sent to a REFLUX™ Classifier and if required its overflow could then be sent to a flotation circuit.