초록 ▼

A method and apparatus is provided for recovering deep subterranean ore deposits using conventional dual conduit pipe in the tool string. The drill cuttings and ore are returned to the surface by reverse circulation. A combination drilling and mining head is disclosed which permits the outer casing

A method and apparatus is provided for recovering deep subterranean ore deposits using conventional dual conduit pipe in the tool string. The drill cuttings and ore are returned to the surface by reverse circulation. A combination drilling and mining head is disclosed which permits the outer casing to be driven by the power swivel during both the drilling and mining operations. A hydraulic eductor pump located at the suction entrance to the inner conduit is used to raise drill cuttings to the surface; a separate slurry eductor pump within the inner conduit located only sufficiently below the slurry discharge of the tool to prevent cavitation at the jet is used to pump the ore slurry to the surface. Another embodiment of this invention employs both eductors to raise the drill cuttings and ore slurry to the surface. Valves controlling the flow of fluid to the drill bit, the mining jet and the slurry discharge eductor pump are located within the inner conduit and a novel valve actuating means is disclosed which employs the pressure within the annular space between the conduits to convert the tool from the drilling to the mining mode. Surface mounted flow control valves and flowmeters in the fluid feed line and in the slurry discharge line control the volume of fluid entering and discharging from the tool. These valves may be controlled by instrumentation to balance the flows, adjusted to control the mining cavity pressure or to compensate for the influx of ground water.

대표청구항 ▼

A method of hydraulic borehole mining by drilling into a subterranean ore deposit, reducing the ore to a slurry and pumping the ore to the surface with an apparatus which includes a mobile platform having a drilling mast with a vertical hoist for handling the drill string, power slips and wrenching

A method of hydraulic borehole mining by drilling into a subterranean ore deposit, reducing the ore to a slurry and pumping the ore to the surface with an apparatus which includes a mobile platform having a drilling mast with a vertical hoist for handling the drill string, power slips and wrenching means for assembling the drill string sections intermittently during drilling until the ore strata is reached, a swivel head on the uppermost section of the drill string with the fluid supply connection entering the annular space between the conduits and a slurry discharge connection connected through a swivel to the inner conduit, a dual conduit tool string having a drill bit as its drilling head, drilling fluid controlled by a valve that is normally open during drilling and closed during mining, two hydraulic eductor pumps within the discharge conduit, the first or lower eductor is located at the suction entrance at the base of the tool and is controlled by a valve that is normally open during drilling and closed during mining, the second or slurry eductor is located intermediate of the mining section and below the fluid level in the borehole with fluid jetting from the eductor nozzle during the drilling and mining mode to pump drill cuttings and/or slurry to the surface, a mining nozzle adjacent to the slurry entrance to the tool to erode the ore matrix to form an ore-bearing slurry and controlled by a valve that is normally closed in the drilling mode and open during the mining mode, a flow measuring element and a flow control valve in the fluid supply pipe to the drill string, a flow measuring element and a flow control valve in the discharge conduit from the mining tool; the method comprising the steps of drilling a borehole from the surface to the ore deposit while pumping drilling fluid at drilling system capacity and pressure into the supply conduit and directing the fluid down the annulus between the conduits through a normally open valve to the drill bit and through a normally open control valve supplying fluid to the eductor at the suction entrance and also through the second or slurry eductor nozzle which is open during drilling and mining to pump the drill cuttings to the surface, increasing the capacity and pressure of the supply fluid to mining system conditions, pumping the mining fluid down the annulus between the conduits with the increased fluid pressure actuating the down-hole control valve actuators to convert the tool from the drilling to the mining mode by closing the valve and stopping the flow of fluid to the drill bit and to the lower eductor nozzle while opening the mining nozzle control valve and directing mining fluid through the mining nozzle to reduce the ore to a slurry, rotating the tool string continuously or intermittently during mining, pumping the slurry to the surface by the slurry eductor located within the inner conduit intermediate of the mining section and the discharge of the tool, throttling the flow of fluid from the tool string by the flow control valve in the discharge piping to maintain the fluid level in the borehole sufficient to prevent cavitation in the slurry eductor pump.