Development of a Mathematical Model for Prediction of Washery Performance

Optimization of operating parameters for achieving maximum clean coal yield at the desired clean coal ash level is a major problem for all coal washeries. The problem is aggravated when the washeries receive raw coal from different seams/collieries with frequent variations in proportions and characteristics of individual coals. The problem is more severe in countries like India which have predominant reserves of difficult-to-wash coals. As a result, the yield of clean coal drops to a lower level compared to what can be achieved if necessary corrections are incorporated in the operating conditions. Hence, the present study involves development of a mathematical model, which would identify the enablers for optimizing the operating conditions and also to predict the actual yield based on the variations in proportion and characteristics of raw coal used. The model calculates theoretical yield and predicted yield of composite clean coal. The theoretical yield is calculated from the washability data of blended coarse coal and the ideal flotation response of blended fine coal. The predicted yield of coarse clean coal was calculated from the theoretical yield of coarse clean coal using a designed Ep value for a dense media (DM) cyclone. Similarly the predicted yield of fine clean coal was calculated from the theoretical yield of fine clean coal considering the designed process performance of a flotation plant. The predicted yield of composite clean coal was calculated from the predicted yield of coarse and fine clean coal. The developed model was validated and implemented in the Jamadoba washery.