Abstract: A method is disclosed of controlling a hydraulic chuck of a rotary machine tool, the chuck clamping a workpiece to be machined and being actuated by a double-acting clamping/unclamping actuator. A clamping pressure controlled in accordance with a clamping pressure set point is applied to at least one chamber of the actuator and the clamping pressure is maintained in the corresponding chamber if the control pressure upstream of the actuator suddenly falls due to a malfunction. The clamping pressure is controlled by a closed loop and is modified in the chamber to disable the aforementioned maintaining of the pressure for a predetermined time period in response to an operator request to modify the clamping force applied to the workpiece. The disabling is being at least equal to the time necessary for the control system to stabilize.

Abstract: The process comprises injecting into the inlet of a polyphase tubular reactor (6), on one hand, the aqueous solution at such temperature that the oxidation reaction occurs at a temperature between 50.degree. C. and 370.degree. C. and at an absolute pressure Pe of between 2 bars and 210 bars, and, on the other hand, gaseous oxygen at a pressure slightly higher than said pressure Pe. The invention is applicable to the treatment of effluents for the chemical destruction of pollutants.

Abstract: An oxygenated lixiviant is transported down an injection pipe into the leach zone at the bottom of an injection pipe, the lixiviant leaches the ore and the pregnant lixiviant containing metal compounds is recovered through a recovery pipe. The metal compounds are separated from the lixiviant and the lixiviant is regenerated, reoxygenated and recycled. The pressure of the lixiviant at the downstream end of the injection pipe is substantially equal to the pressure of the lixiviant at the upstream end thereby permitting maximum oxygenation without any degassing.