Abstract: A fluid jet drilling nozzle and associated drilling method. The nozzle is adapted to be connected to a source of high pressure fluid and to be rotated about a rotation axis, and comprises a body formed so that it partially encloses a cavity, which cavity is in fluid communication with the source of high pressure fluid when the nozzle is connected to such source. The nozzle further comprises means for allowing high pressure fluid in the cavity to exit the nozzle in the form of a high velocity fluid jet which intersects the axis of rotation of the nozzle. Such a nozzle may be mounted in any drilling apparatus capable of supplying high pressure fluid to the cavity and of rotating or oscillating the nozzle about its rotation axis.

Abstract: By the action of water jetted against the concrete in systematically controlled manner under ultra-high pressures (i.e. above 25,000 psi) areas of structural concrete are removed to required depths through the one or more levels of aggregate involved efficiently and with safety to the basic structure and to attendant personnel. With this method and apparatus employing an array of such jets scanned progressively back and forth over a work area, the rates at which requisite volumes of hardened concrete can be removed, regardless of condition or state of the concrete and the presence of reinforcing bars, are much greater than those customarily achieved with conventional methods. Moreover the operation can be performed without danger of cutting into and weakening embedded reinforcing bars, without damaging the concrete in adjoining regions, without dust pollution and with minimum noise levels that are also readily shieldable.

Abstract: A hydraulic borehole mining device is provided of the type wherein a pair of high pressure water jets located along the length of the device are used to cut the mineral to be mined and a slurry pick-up system used to transport the particles cut away by the jets back to the ground surface. The slurry pick-up may include a slurry jet pump which is also supplied with water under pressure. The jet pump includes a jet nozzle which is directed so as to draw particles through screens that cover inlets for the particles located about the circumference of the device, and which thus entrains the particles in a slurry with the water, this slurry of water and mineral particles being pumped back to the surface.