Hpgr—Revolution In Platinum

Paper 23_Rule:text

9/26/08

1:54 PM

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RULE, C.M., MINNAAR, D.M., and SAUERMANN, G.M. HPGR—revolution in platinum? Third International Platinum Conference ‘Platinum in Transformation’, The Southern African Institute of Mining and Metallurgy, 2008.

HPGR—revolution in Platinum?
C.M. RULE*, D.M. MINNAAR†, and G.M. SAUERMANN‡
*Anglo Platinum Management Services †Northam Platinum‡Polysius, a Division of ThyssenKrupp Engineering

High pressure grinding rolls (HPGR) technology has come a long way in its application for comminution duty in hard rock mineral processing in the last three years. Several major projects in copper, nickel, gold, molybdenum, platinum, and iron ore have opted for this technology. Advances in wear abatement technology have established the HPGR as areliable machine with the required high utilization and availability. The HPGR captures the imagination as the next step change improvement in ore processing, based on the following benefits: • Energy efficiency (potentially 10–30% more efficient)—very topical in an increasingly ‘green’ society, and in times of rapidly increasing energy costs and availability concerns. 2008 has shown this to beespecially important in Southern Africa • High (and stable) throughput with a relatively small footprint • Lower operation cost • Liberation benefits • Creative ‘mine-to-metal’ system improvements made possible by HPGR. The platinum industry, renowned for its historically conservative approach, has not been left behind with two significant new HPGR installations, one in Platreef application and onein UG2 application, commissioned in 2008. While the decision for the Platreef application was driven primarily by comminution circuit capacity and design imperatives, the UG2 application seeks to develop a flowsheet that will have a significant recovery benefit in addition to capacity increase and reduced operating cost. The Platreef application of HPGR also provides the opportunity to introduce anovel comminution flow sheet and to demonstrate exceptionally low wear rates treating very hard, abrasive and variable ore types. The HPGR lends itself for inclusion in existing SABC circuits to increase the capacity of the plant and mills. With current PGM prices many operations are attracted to the HPGR technology benefits. The HPGR clearly has the potential to transform entrenched opinion andprovide decision makers with significant alternative comminution options. This paper aims to provide an overview of the current applications and to speculate on the transforming stimulus that the HPGR exerts on industry.

Introduction
‘Acceptance of the HPGR in the hard rock sector has been slow and cautious, but has come to maturity in the successful commissioning of the Cerro Verde project’.(Morley C, 2008) High pressure grinding roll (HPGR) technology has been the subject of many technical presentations in the minerals comminution fraternity ever since the technology was first introduced as an energy efficient comminution device that revolutionized cement grinding plants. HPGR was quickly accepted in the minerals realm for diamond processing in various flowsheet positions. Since thefirst installation in 1986 HPGR also revolutionized kimberlite treatment plants. Avoiding the breakage of large diamonds in the size reduction process provides very persuasive driving force. From the mid-nineties HPGR revolutionized iron ore concentrate and pellet feed filter cake treatment plants to the point that it is now considered standard equipment.

Twenty-one years after the firstinstallation, the Polycom HPGR has come of age, having developed appropriate roll wear abatement technology (Figure 1), and proved itself as an alternative comminution device for ‘hard rock’ applications offering (amongst others) reduced operating cost (energy and wear efficiency). The Cerro Verde (copper/molybdenum), Freeport Indonesia (copper) and Boddington (gold/copper) projects selected HPGR as...