Inventors:
John B. Cheung - Kent WA
Earll M. Murman - Kent WA
Assignee:
The United States of America as represented by the Secretary of the
Interior - Washington DC
International Classification:
E21B 3900
E21B 2100
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. To prevent clogging or blocking of the screens such as can occur when particles accumulate thereon, a backflush or backwash valve is provided which, when actuated, blocks and deflects the water from the jet nozzle and thus causes the water flow to reverse itself and pass out through the screens to thereby provide cleaning of the screens.