An investigation of the performance of the hpgr used in heap leach crushing circuit

Within the scope of this thesis, the performance of high pressure grinding roller (HPGR), used as tertiary crusher in heap leaching operation, has been evaluated by using the operational parameters and the size distributions of the samples taken from the HPGR circuit. Functioning as a tertiary crusher, HPGR has been configured as a closed circuit together with two tertiary screens. The fresh ore feed to this circuit is provided at -45 mm from a two-stage crushing and screening circuit. The samples have been collected for the variable specific grinding pressure conditions and sieve analyses have been performed. Considering the obtained particle size distributions, specific grinding pressure charts, and consumed energy data, it has been concluded that the ideal specific grinding pressure is 3750kN/m2 and the size distribution of the -1.18 mm material in the under screen product is 50% at this pressure. It has been calculated that the circulating load in the closed system is 47.6%. Moreover, it has been observed that the ideal feed size distribution has been achieved from the blending of this circulating load and fresh feed. Thus, it has been concluded that the circulating load should be kept more than 45% in order to maintain high crusher performance. On the other hand, it has been observed that operating at higher specific grinding pressure than the ideal one, would result in increased power consumption per ton and high vibration causing a low efficiency of the equipment.