Particle-laden plumes are ubiquitous in many industrial environments, including cement manufacturing, metallurgical processes and fossil-fuel-based power plants. Once a plume is emitted into the atmosphere, the size of the particles plays a crucial role on their sedimentation patterns and on the risk they pose to terrestrial ecosystems and to humans. It is therefore of great interest to consider and compare the behaviour of particles of different sizes emitted from an industrial chimney. In this paper, we present a model that describes the dynamics and deposition pattern from gravity currents generated by axisymmetric particle-laden plumes composed of polydispersed particles. Predictions of the deposition patterns of particles of different sizes are successfully compared with new laboratory measurements. We also present experimental and theoretical predictions for the mean particle diameter in the deposit at the floor as a function of radial position. We consider environments of both infinite and finite lateral extent. Finally, we illustrate and discuss the application of the model to the emission of chromium particles from a commercial chromium plating plant.