The characteristic differences between open- and closed-circuit grinding systems were examined via the use of a continuous vibration ball mill and a blade type classifier. For the same median diameter of the product, the rate of powder production in the closed-circuit is about 5% higher than that of the open-circuit. The median diameter of classified coarse particles for the closed-circuit is smaller than that for the open-circuit. The power requirement per unit mass production increases with decreasing mean diameter of the product. For the same mean diameter of the product, the power requirement for the closed-circuit process is about 5% smaller than that of the open-circuit process. This value corresponds to the difference in the rate of powder production between the two systems. (C) 2003 Elsevier B.V. All rights reserved.