This study aimed at optimizing both the energy efficiency and the quality of the end product by modifying the existing flowsheet of the cement grinding circuit. As a general application, mill filter stream is sent to the air classifier owing to its coarser size distribution than the desired product. However, the study proved that some further evaluations i.e., quality tests and chemical assays, could make it possible to treat this stream as a final product. Consequently, directing this stream to the final product silo could be considered. Within the study, sampling survey was undertaken initially that was followed by the modelling and simulation works. The calculations implied that the production rate increased by 4.45% that corresponded to energy saving of 4.26%. As the plant decided to change the flow sheet, another sampling campaign was arranged to validate the outputs of the simulation studies. In that case, the real data showed that the increase in production rate was 3.68% and 28-Days strength of the cement improved by 2.9%. As a result, the simulation outputs were found to be in agreement with the real data hence the efficiency of the cement production, both quality and energy, for a given circuit was improved. (C) 2018 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.