Abstract: A process and apparatus for recovering metal values from ores is described. Comminuted ores are mixed with a liquid to form a pulp. A plurality of streams of pulp are then projected against one another, thereby causing erosion of ore particles in the pulp. A pair of pulp streams preferably emit through nozzles 68, 70 which are coaxially aligned with each other. The nozzles are located in any impact chamber 66. Gas may be supplied to the impact chamber through a gas inlet 72. The chamber may be kept at an elevated pressure, and the gas may be selected in order to facilitate the reaction of reagents in the pulp with the ore. Pulp from the impact chamber passes into a co-axial vertical tube assembly 78, 80 from where it passes back to a tank 50 for continued treatment.