Material Grinding by Water Jets—Feasibility and Limits

Disintegration of the brittle material particles by water jet takes place during generation of the injection abrasive water jet just in the mixing process inside the mixing chamber and the focusing tube. The physical limits of these processes are the topic of the theoretical investigation the results of which are presented in this paper. The mean particle size resulting from the mixing process can be evaluated from the mean particle size of the input material particles and basic water jet parameters using the theoretical equation. The equation is used for explanation of the basic problems of particle grinding by water jet. Some propositions are made for improvement of the water jet grinding process. The primary disintegration process, taking place in the mixing chamber and focusing tube, can be followed up by subsequent intensifying processes—interaction with rigid target or collision with opposite jet of the same type. The second mentioned is just investigated and the basic theoretical postulations of its efficiency are formulated. The theoretical studies are supported by results of experiments aimed at the disintegration processes inside the mixing chamber and the focusing tube and then at the opposite jet collision. All theoretical and experimental conclusions are analyzed from the economical point of view and the most important conditions for both the laboratory and the industrial use of this type of mineral comminution and pulverization are submitted.