Poor results are generally achieved in the treatment of coal slimes using conventional methods. Since fine size fractions below 0.5 mm can together represent a significant portion of the plant’s feed, the development of suitable technologies for an efficient recovery of their fuel content can add a considerable contribution to the economic balance of the beneficiation process. Together with oil agglomeration, froth flotation can be regarded as the most attractive technique for treating such slimes. In order to create the most favourable conditions for the full development of collection and separation mechanisms, a new approach has been devised and tested, according to which agitation is produced using high velocity water jets generated through a suitable nozzle configuration. The paper illustrates the features of the prototype installed at the Waterjet Laboratory of the University of Cagliari and describes the results obtained in the cleaning of coal fines. In particular the influence on technical results of the various operational variables, like water pressure and flowrate, collector and frother dosage and residence time, is illustrated and discussed.