Pergamon Minerals Engineering, Vol. 10, No. 4, pp. 401-419, 1997 © 1997 Elsevier Science Ltd Printed in Great Britain. All rights reserved PIhS0892--6875(97)00017--4 0892-6875/97 $17.00+0.00 THE EFFECT OF ROLLS SPEED AND ROLLS SURFACE PATTERN ON HIGH PRESSURE GRINDING ROLLS PERFORMANCE W.I.L. LIM§, J.J. CAMPBELL§ and L.A. TONDOt § CSIRO Division of Minerals and Centre for Mining Technology and Equipment, Pinjarra Hills, Brisbane, Qld. 4069, Australia t JKMRC and Centre for Mining Technology and Equipment, Indooroopilly, Brisbane, Qld. 4070, Australia (Received 30 October 1996; accepted 6 January 1997) ABSTRACT An important aspect in the performance of the high pressure grinding rolls (HPGR) is its throughput. The HPGR throughput can be changed by varying the speed of the rolls, but, it is important to determine the effects of changes in the rolls speed together with other variations such as grinding force and feed size, on the overall performance of the HPGR. To that end, the CSIRO laboratory-scale HPGR has recently been modified to extend its circumferential speed up to 3.6 m/s. This paper reports on a study examining the effects of rolls speed variations on the CSIRO HPGR from 0.38 m/s up to 3.1 m/s on a number of ores. It was complemented by some studies performed on pilot-scale machines with different surfaces. It was generally found that with increasing rolls speed, the working gap becomes smaller as does the specific throughput. Higher rolls speed tended to produce a steeper product size distribution curve and in some cases size reduction for less energy consumption compared with lower speed. The rolls surface pattern was found to significantly affect the performance of the HPGR. This paper concludes with some possible implications of the results on application of the HPGR. ©1997 Elsevier Science Ltd Keywords Comminution, grinding INTRODUCTION The high pressure rolls developed by Professor Schoenert of Clausthal has been offered as a promising new comminution technology with claims of improved performance relative to conventional grinding technology especially rod and ball mills. In particular, it has been claimed that the advantage of the HPGR is its lower specific energy consumption for a given size reduction. Indeed, it has been demonstrated that the HPGR can lead to considerable savings over conventional ball mills [1]. In addition, it has been claimed that micro-cracking associated with the damaged product particles, can significantly improve downstream processing performance such as fine grinding or leaching [2]. HPGR are now widely used in the cement industry. However, apart from the diamond mines, acceptance of these machines in the minerals industry have been considerably slower although there are strong signs of increasing interest, particularly in copper and iron ore processing. Presented at MineralsEngineering "96. Brisbane,Australia,August 26-28, 1996 401