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ABSTRACT
This study presents the beneficiation of coal fines in a Knelson concentrator. With a view to achieving this aim, the bowl speed (250–1250 rpm), fluidization water flow rate (2–4 l/min), solids ratio (10–30%) and feed flow rate (1.5–2.5 l/min) were determined as independent variables. The effects of these variables on the yield of concentrate, the ash content and the combustible matter recovery in concentrate were examined using a central composite design. Quadratic regression models with estimated coefficients were developed to evaluate the responses and three-dimensional plots were presented to evaluate the interactions of independent variables versus responses. It is possible to obtain clean coal with approximately 12% ash content from the coal feed having approximately 24% ash content. Additionally, the optimal results were evaluated by using upgrading curves. The comparison of upgrading curves proved that the Knelson concentrator is quite efficient in cleaning fine coals and it allowed the evaluation which parameters would occur with certain expected quality of concentration.