The effect of ball size on the energy efficiency of hybrid high-pressure roll mill/ball mill grinding

To find ways to reduce energy consumption in comminution, dolomite was ground in a hybrid grinding system, involving the operation of a laboratory-scale high-pressure roll mill and ball mill in series. The work presented here has demonstrated the energy efficiency of the hybrid system can be increased by reducing ball size, provided the roll mill product contains sufficient internal damage to allow for the use of the smaller balls. There is an optimum range of energy partitioning between the high-pressure roll mill and the ball mill in the hybrid system. The increased efficiency of hybrid grinding is related to the particle damage imparted by the roll mill, as evidenced by the increased breakage rates of high-pressure roll, mill product relative to particles that had not been roll milled. (C) 1999 Elsevier Science S.A. All rights reserved.