1 Observation of Iron Ore Beneficiation within a Spiral Concentrator by Positron Emission Particle Tracking of Large (Ø≈1440 μm) and Small (Ø≈58 μm) Hematite and Quartz Tracers D. Boucher a*, Z. Deng, T. Leadbeaterb, R. Langlois, K.Watersa aDepartment of Mining and Materials Engineering, McGill University, 3610 University Street, Montreal, Quebec, H3A 0C5, Canada