LAUSR

Abstract Nowadays, ball mills are used widely in cement plants to grind clinker and gypsum to produce cement. In this work, the energy and exergy analyses of a cement ball mill (CBM) were performed and some measurements were carried out in an existing CBM in a cement plant to improve the efficiency of the grinding process. The first and second laws efficiency of the CBM was specified to be 80.5% and 19.9%, respectively. The electrical energy consumption of the CBM unit was specified to be 37.9 kWh/t. The effects of ball charge pattern, cement fineness and two additive materials (limestone and pozzolan) on the performance of the CBM unit and the quality of cement were investigated. The first and second laws efficiency of the CBM increased (81.8% and 20.6%) and the electrical energy consumption of CBM unit decreased (36.5 kWh/t) after modifying the ball charge pattern. Also, the results demonstrated that cement production rate increases (185–224 t/h) and the electrical consumption decreases (41.1–33.1 kWh/t) when cement fineness decreases (3250 –2820 cm2/g). However, the cement compressive strength (3, 7 and 28 days) decreases and the cement setting time (initial and final) increases by reducing the cement fineness. Besides, when the clinker was replaced by limestone or pozzolan, on the one side, the efficiency of the first and second laws of the CBM unit was increased, but on the other side the cement compressive strength was decreased and the cement setting time was increased.