Performance evaluation of a conventional closed circuit process at different cement productions

Performance of a conventional Polysius® two-compartment ball mill and a OSepa® high efficiency dynamic air classifier (FLSmidth) closed circuit process was investigated at the steady state conditions at CEM II type Portland cement productions. Two sampling surveys were performed around the circuit. CEM II type Portland calcareous and composite cements were produced in sampling survey-1 and survey-2 respectively. Mass balance of circuits were performed by using the JKSimMet Mineral Processing Simulator. Size reduction performance of the ball mill with dimensions of Ø4xL12.4m was evaluated in different feed conditions. Size reduction performance of the ball mill was determined to be improved at CEM II Portland composite cement production mode. Air classifier rotor speed (%) was decreased in order to achieve required fineness specifications of the final product in CEM II Portland composite cement production. Separation efficiency of the dynamic air classifier in the circuit was determined on the basis of efficiency curve approach (Munn et.al., 2005). Approximately 9% circuit capacity increase was achieved in CEM II Portland composite cement production by changing the type and amount of grinding aid in addition to operating the air classifier at its optimum conditions.