Classification studies to recover liberated particles of lead and zinc minerals from a ground lead zinc ore were carried out using a 100-mm water-injection cyclone. The effects of variables on the performance of water-injection cyclone are discussed. The results indicated that the injection water rate has a complex interaction with the other variables like spigot opening, feed inlet pressure, and vortex finder opening, A set of empirical equations for slurry throughput. corrected cyclone cut size, minimum distribution point, and reduced efficiency numbers was developed for predicting the performance of water-injection cyclone. Finally, the results obtained in water-injection cyclone are compared with the data obtained oil a similar diameter (100 mm) hydrocyclone. (c) 2005 Elsevier B.V. All fights reserved.