Kennecott Copper Corporation

Kennecott Corporation

Ray V Huff

Donald H Davidson

Limin Hsueh

Robert A Hard

Daniel J Moynihan

Method and apparatus for introducing finely divided gas bubbles into a lixiviant used for in-situ mining of minerals containing metal values, such as copper values. The lixiviant is supplied to a plurality of porous tubes formed of sintered powdered metal while a gas is supplied under pressure about the tubes to cause the gas to penetrate into the interior of the tubes in the form of fine bubbles which are wiped from the interior of the tubes by the lixiviant passing therethrough. The method and apparatus can be advantageously employed in situations where it is desirable to perform in-situ mining with an oxidizing lixiviant. In these cases oxygen is supplied under pressure about the tubes.

In-situ method and apparatus for sparging gas bubbles

Methods for increasing the permeability of a subterranean igneous rock formation penetrated by at least one well where a hydraulic fluid is injected into the formation at a pressure sufficient to cause diffusion into the natural fractures thereof and thus increase the cross-sectional area thereof, maintaining the pressure and injecting a second fluid which results, by the use thereof, in substantially maintaining the increased cross-sectional area after the pressure is reduced.

Well stimulation for solution mining

A circulation tubing string is disposed about the lixiviant return tubing string in the production hole of an in situ minefield. The circulation string extends from the surface to a point near a packer which defines the top of the leaching interval. A fluid coupler provides a fluid flow path between the annular cross-section regions between the production hole casing and the circulation string, and between the circulation string and the lixiviant return string. A flow of cooling fluid is maintained from the surface through the circuital path defined by the annular cross-section regions and the fluid coupler, particularly including the exterior surface of the production tubing string. The fluid is maintained at a temperature and flow rate so that the pregnant leach liquor flows in the production tubing string between the leaching interval and the surface is characterized by a predetermined temperature drop.

Method for in situ minefields

An environmentally compatible, industrially safe, and potentially economic means for recovering copper and/or nickel from deep-seated deposits without resorting to extensive underground development. A two-phase ammoniacal leach solution containing oxygen bubbles is forced under high pressure through an injection hole several thousand feet deep into a leaching interval of a deep lying deposit containing copper or nickel or copper and nickel. The two-phase leach solution travels through the leaching interval of the deep lying deposit and is pumped out of withdrawal holes spaced apart from the injection hole. The two-phase leach solution under high pressure (more than 500 psi) penetrates the deposit through cracks, fissures and fractures, leaching copper and/or nickel along the way. Under a controlled pressure gradient, the leaching solution migrates over a period of time to receiving holes from which the pregnant leaching solution is withdrawn. The pregnant solution is then processed for recovery of copper or nickel or copper and nickel before it is returned to an injection hole. A method and apparatus for producing the two-phase leach solution and for maintaining a system in which the gas bubbles are able to penetrate the deposit is disclosed. Also disclosed are various parameters, such as hole spacing techniques, hole completion techniques and stimulation techniques.

In-situ mining method and apparatus

A downhole recirculator for injecting two-phase lixiviant from a tubing string into a leaching interval of an in situ mine field injection hole, and for circulating the injected lixiviant within the leaching interval. The recirculator includes a core device which is adapted to be readily inserted or removed from its operating position in a fixture defining the upper limit of the leaching interval. The core device includes an induction valve arrangement whereby a primary flow of two-phase lixiviant supplied from the minefield surface by way of the tubing string induces a secondary flow of lixiviant from regions of the injection hole near the top of the leaching interval. The primary flow two-phase lixiviant is combined with the secondary flow lixiviant and injected to a region near the bottom of the leaching interval to establish a circulatory motion of lixiviant within the leaching interval.

Lixiviant recirculator for in situ mining

A process is disclosed for in-situ mining of copper from a subterranean ore body characterized, at least in part, by the presence of a sulfidic ore and by natural, microscopic fracture openings. The process comprises forcing a stable, two-phase lixiviant comprising an aqueous phase, a multiplicity of gaseous, oxygen-containing bubbles having a size sufficient to pass through the natural fracture openings in the ore body, and a surfactant for enhancing the formation of the bubbles and for minimizing bubble coalescence through the ore body to leach copper. The aqueous and gaseous phases of the lixiviant are mixed at the surface and injected into the leaching interval through an injection hole, or preferably, are mixed in a subterranean sparger within the hole above the leaching interval. The pregnant liquor is recovered through one or more production holes and, after the copper is recovered, the lixiviant may be reconstituted and recirculated.

Growing community of inventors

Acton, MA, United States of America

Ray V Huff