Positron emission particle tracking (PEPT) is a method of detecting the position of particles in vessels over a period of time. It has been used effectively in a number of mixing applications, and this work introduces the concept to the froth flotation process. Using PEPT, it was possible to map the position of a pyrite particle as it mixed in the pulp phase of a Denver Cell batch flotation experiment. Once the air flow was switched on, it was then possible to observe the particle entering the froth after attaching to an air bubble, and observing the detachment from the froth, re-entry into the pulp phase and then re-attachment to another bubble leading to the particle entering the froth once again. From this work, PEPT has the potential to become a powerful tool in order to understand exactly what happens in flotation practice, and to enable more accurate mathematical models to be developed. (C) 2008 Elsevier Ltd. All rights reserved.