Modeling of free and hindered settling conditions for fine coal beneficiation through a falcon concentrator

In this study, the free and hindered settling conditions for coal-shale-clay separation through a Falcon concentrator were determined experimentally using response surface methodology. The model parameters consisted of the separation efficiency and ash content of the concentrate and tailings. Based on the model with the highest response, free settling conditions dominated at centrifugal forces below 100 g and at solid concentrations of up to 30%-35%, especially for coarser particle sizes of 300 μm. These results revealed that, for effective fine coal beneficiation through a Falcon concentrator, the solid concentration should be maintained higher than 30%-35% (with a maximum of 45%-50%) to create hindered settling conditions because separation under these conditions is achieved based on specific gravity. The best results were obtained at a solid concentration of 50%. This finding was interesting because separations through enhanced gravity separators were achieved under conditions similar to separations performed in autogenous media.