This paper presents the results of using positron emission particle tracking to record the trajectories of large (empty set approximate to 1440 mu m) and small (empty set approximate to 58 mu m) particles of hematite (S.G. = 5.3) and quartz (S.G. = 2.7) in a slurry of iron ore (20% solids w/w) flowing in a gravity spiral concentrator. The tracking was undertaken using modular positron emission particle tracking detectors (ECAT 951) assembled and calibrated for this purpose. The tracer particles used were generated by the direct activation of large particle in a cyclotron beam (He-3, 35 MeV), in the Positron Imaging Centre at the University of Birmingham. These larger particles were then broken and sized to isolate small active particle when required. The behaviour of the valuable and gangue particles in the first two turns of the spiral is presented. The formation and interaction of different bands of similar size/density particles is shown. For small particles, these bands are less defined and can be present at dispersion is influenced by the flow of the slurry. Part of the large dense hematite particles are shown concentrating toward the inside of the spiral trough while some others are shown remaining in the high flow-speed outer zone outside of a band of large quartz particles. The behaviour in the feed device and first 0.3 turn of the spiral is related to the later separation of some of the large particles and this highlights the effect of the feed radial distribution of the particles on the trough.