HPGR (High-Pressure Grinding Roll) is a comminution technology that crushes ore between two counter-rotating rolls under very high pressure (50–200 MPa). It produces a finer, partly micro-cracked product more energy-efficiently than conventional cone crushing or SAG/ball milling — improving downstream heap-leach kinetics or reducing mill-circuit power demand.
How It Differs from Crushers
Conventional crushers and mills break ore via impact and attrition. HPGR works by inter-particle compression — every particle in the gap is pressed against its neighbors. The result: more fines, more micro-cracks within particles, and lower specific energy consumption per tonne of size reduction.
Heap Leach Benefit
HPGR product has internal micro-cracks that let cyanide solution penetrate faster. Heap-leach recovery is often 2–8% higher and faster on HPGR product than on cone-crushed product at the same nominal P80. This is the strongest economic case for HPGR in heap leach.
Milling Benefit
Placing HPGR upstream of ball milling reduces ball-mill specific energy (kWh/t) by 15–30%, allowing more throughput from the same mill — or smaller new mills for the same throughput. Increasingly standard in copper and gold mills.
Why Pilot Testing Matters
HPGR economics depend strongly on ore competency and feed moisture, and bench-scale tests cannot replicate inter-particle compression. Pilot data is essential before designing a full-scale HPGR circuit. KCA operates a ThyssenKrupp Polycom PILOTWAL — one of very few pilot HPGRs in North America. See HPGR Pilot Testing.
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