Abstract: Process for the solution mining of minerals from a subterranean formation in which a dilute carbonic acid leaching solution is injected through a first well into the formation and a pregnant liquor containing the dissolved minerals is recovered from a second well. Subsequently the direction of flow through the formation is reversed by injecting the leaching solution through the second well and recovering the pregnant liquor from the first well. Optionally, an oxidizing agent is injected either simultaneously with the leaching solution, or alternately with slugs of the leaching solution.

Abstract: A process is described for maintaining a relatively high and constant concentration in the leachate of an in situ leaching operation as the mineral value in the formation is depleted, and without reducing the daily production, by adjusting the pumping rate of lixiviant proportionally to the depletion of the mineral value. A method for achieving this result by increasing the residence time of the leach solution in the formation is also disclosed.

Abstract: Disclosed is a method permitting above-ground heap leaching of metal bearing ores in below-freezing temperatures by utilizing one or more insulating layers deposited on the principal ore body to be leached. One of said layers is an insulating ore layer covering multiple leach liquor outlets positioned above said principal ore body. Other insulating layers may be comprised of a flexible sheet and a crust of frozen leach liquor.

Abstract: A process is described for improving yields and leaching rates of mineral values in highly reducing uranium-bearing formations, while minimizing deleterious environmental impact, by injecting an oxidant such as gaseous air or O.sub.2 into the formation prior to leaching. The preoxidation may be enhanced by the presence of CO.sub.2 gas in the pre-leaching oxidant. The process is particularly suitable for systems employing a CO.sub.2 /O.sub.2 lixiviant. The presence of sulfate ion further improves the leaching rate of such a system.

Abstract: This process comprises the three successive following steps of:(a) injecting into a formation a solution of sodium or potassium hydroxide during a limited time interval to perform a chemical leaching treatment of the formation,(b) injecting a saline solution, and(c) establishing a circulation of a heat conveying fluid through the formation.

Abstract: A cyclic method for recovering alkali values from subterranean trona deposits. The ore is contacted via solution mining with an aqueous mining solvent containing sodium hydroxide, the resulting Na.sub.2 CO.sub.3 -containing solution is withdrawn and carbonated, and sodium sesquicarbonate and/or sodium bicarbonate is crystallized and separated from the solution. The crystallized solids are calcined in a direct coal-fired calciner, and the resultant anhydrous soda ash is recrystallized in water to form sodium carbonate monohydrate or anhydrous sodium carbonate, which is recovered as a dense alkali product. Aqueous mining solvent is regenerated by causticization of one or more of the various liquor streams, and the recovery cycle is repeated.

Abstract: The present invention relates to in-situ leaching of uranium, particularly employing an acidic leach liquor containing an oxidant, and especially in respect of ores containing significant amounts of transition metals that act as catalysts for peroxidant decomposition. When hydrogen peroxide is used as oxidant under such conditions it decomposes leading to the formation of gas bubbles and exacerbation of ore-blinding, and a reduction in the efficiency of extraction of uranium.The present invention employs peroxymonosulphuric acid as oxidant and thereby ameliorates the problems aforesaid. Preferably, additionally, sulphuric acid is present in the leach liquor and in many preferred embodiments the peroxymonosulphuric acid concentration is from 0.001 to 0.03 moles/liter and the sulphuric acid from 0.025 to 0.075 moles/liter.

Abstract: Process for the in-situ leaching of uranium from a subterranean ore deposit comprising introducing into the deposit an aqueous lixiviant formulated from a dilute sulfuric acid solution which also contains carbon dioxide. The lixiviant has a pH within the range of 1.0-2.5. The lixiviant may also contain an alkali metal sulfate such as sodium sulfate. The process is particularly applicable to subterranean deposits containing uranium associated with carbonaceous material.

Abstract: Process for the in-situ leaching of uranium from a subterranean ore deposit employing a lixiviant containing an oxidizing agent, sulfuric acid, and carbon dioxide. Prior to the injection of the lixiviant, an aqueous solution of sulfuric acid and oxidizing agent is injected into the deposit in an amount of at least 1 pore volume. The initially injected acid solution is substantially free of carbon dioxide. The process is particularly applicable to subterranean deposits containing uranium associated with carbonaceous material.

Abstract: The instant disclosure relates to a method of tracing the flow of a solution for extracting values from an ore, wherein such extraction leaves behind an extracted ore, which method comprises(a) providing a material in said solution which will interact with said extracted ore to form a product, and(b) detecting said product.The instant invention is especially useful for the extraction of copper values from copper oxide ores such as chrysocolla, neotocite, malacite and cuprite. Preferably, the extraction solution is an acidic solution comprising sulfuric acid and said material is a fluorescent surface-active dye which forms an adsorption product with the porous gel-like aluminosilicate network which remains after extracting the copper values from the above ores. A sample of said extracted ore is obtained by drilling and such sample is irradiated with ultra-violet light, e.g. at a wavelength of from about 220 to about 400 nm, depending on the particular dye to detect such adsorption product.

Abstract: A method is disclosed for restoring a clay rich aquifer which has been solution mined with ammonium ions. Calcium carbonate is precipitated from a solution pumped through the aquifer by the addition of calcium oxide, calcium hydroxide, or a mixture thereof in quantities sufficient to raise the pH to at least about 9.5. The precipitated calcium carbonate is separated from the solution and the ammonium ion is then removed from the solution by standard techniques. The solution is recycled through the aquifer and these steps are repeated until the bicarbonate ion concentration has been reduced to such an extent that the addition of at least one soluble salt of calcium, magnesium, or potassium to the solution does not result in precipitation of calcite underground, plugging the aquifer. Recycling with the addition of the soluble salt is continued until the ammonium ion concentration is reduced to a desired level. Finally, residual amounts of the salt are removed from the aquifer using standard techniques.

Abstract: Process for the in-situ leaching of uranium employing an alkaline lixiviant and an alkali metal or alkaline earth metal hypochlorite as an oxidizing agent. The use of the hypochlorite oxidant results in significantly higher uranium recoveries and leaching rates than those attained by the use of conventional oxidants. The invention is particularly suitable for use in subterranean deposits in which the uranium mineral is associated with carbonaceous material which retards access to the uranium by the lixiviant.

Abstract: Mineral values are recovered from underground formations, and pollution of the formation is substantially diminished if not eliminated, by determining the geometry of an ore body and thereafter isolating the body by the formation of an impermeable barrier thereabout which has the capability of retaining leaching fluid therewithin. Leaching fluid remains downhole without substantial dilution by formation fluid, and conversely without pollution of the surrounding formation, until the mineral values are chemically changed into a recoverable substance which is subsequently pumped to the surface of the earth. In one embodiment of the invention, uranium values are recovered by the use of an organic extractant liquid admixed with an acid aqueous leaching fluid by homogenizing the two solutions prior to pumping the mixture downhole into contact with the ore deposit.

Abstract: A method for recovering uranium and/or related values which include means for protecting ion-exchange resins in the recovery operation from oxidative degradation due to contact with hydrogen peroxide. A guard chamber is positioned in the elution circuit so that barren eluant, after it is stripped of its uranium and/or related values by treatment with hydrogen peroxide, will flow through the chamber. The guard chamber contains catalytic material, e.g. activated carbon, which decomposes hydrogen peroxide upon contact into water and oxygen. The barren eluant, after it passes through the catalytic material, is used to make up fresh eluant for reuse in the recovery method without the risk of the fresh eluant causing oxidative degradation of the resins.

Abstract: A method for protecting an ion-exchange resin in a uranium and/or related values recovery operation from poisoning by polythionates contained in the leach solution. A guard chamber containing a catalytic material is positioned in the leaching circuit upstream of the resin so the leach solution will pass through the catalytic material before it contacts the resin. The catalytic material, e.g. activated carbon, converts the polythionates to non-poisoning thiosulfates, sulfites, and water which offer no poisoning threat to the resins. An oxidant, e.g. oxygen, is added to the leach solution before it passes through the catalytic material to speed up the catalytic reaction.

Abstract: Disclosed is a method of economically exploiting deep set porphyry ore bodies of the type containing metal values such as sulfidic copper nickel or uranium minerals and minerals capable of absorbing copper, uranium and nickel ions. The method involves establishing communication with the ore body through access and recovery wells and passing fluids sequentially therethrough. If necessary, thief zones of as low as 25 to 50 md in igneous rock of 1 to 5 md are prevented from distorting flow, by the injection of a polymeric solution of macromolecules with molecular weights of the order of 5 million along the entire wellbore, the higher permeability zones initially accepting the majority of the flow and being impaired at a much faster rate than the less permeable zones.

Abstract: Disclosed is a method of connecting two or more subterranean cavities in a deposit having a potassium chloride-rich stratum which contains sodium chloride and which is disposed above a potassium chloride-lean, sodium chloride-rich stratum. The method comprises drilling at least two adjacent wells into the sodium chloride-rich stratum, establishing a chimney filled with insulating fluid at the bottom of at least one of the wells, extracting ore from the potassium chloride-lean stratum with solvent, raising the roof of the cavities by incrementally raising the insulating fluid level and allowing the cavities to grow laterally until the cavities connect.

Abstract: A relatively nonvolatile, high molecular weight sulfur solvent produced by activating a dialkyl disulfide oil by the addition of a relatively high molecular weight predominantly aliphatic amine (e.g., a N-alkyl-1,3-propane diamine) and optionally further increasing the molecular weight by the addition of elemental sulfur. Such a sulfur solvent is particularly useful in sustaining a liquid phase at bottomhole conditions for high temperature, high pressure sour gas.

Abstract: The present invention comprises a method of mining a solid substance, such as coal, minerals, or the like, from an underground deposit in one of a plurality of earth strata. Void areas are created in the deposit so as to generally define an area within the deposit which is to be enclosed. Plugging material is injected into the void areas to form a relatively impervious barrier enclosing the aforementioned area of the deposit and isolating it from the remainder of the earth strata in which it is located. Conversion media, such as solvents or oxidation supporting media, are then injected into the enclosed area to convert the substance therein into flowable form. Finally, the substance as so converted is withdrawn from the enclosed area.

Abstract: An underground method for in situ leaching of mineral resource bodies is used to recover the mineral. The method comprises running a drift close to the resource body in such a manner as to minimize any effect on subsurface water; drilling long holes from the drift into the resource body at intervals which are determined by the character of the resource body; perforating the long holes and capping the long holes at the drift end with valves; injecting a recovery solution into a portion of the long holes and recovering the recovery solution from another portion of the long holes. The entire development of the drifts and long holes and the conduction of the recovery solution are done in such a manner as to minimize any effect on the subsurface water table or hydrostatic pressure. The spacing of the long holes is selected so as to maximize the exposure of the resource body to the recovery solution.

Abstract: The invention disclosed herein relates to solution mining soluble ore deposits by creating a cavity substantially entirely filled with a deep bed of rubble. Solvent introduced at the top of the cavity is permitted to percolate downwardly through the rubble and is withdrawn near the bottom of the cavity. More specifically, the invention relates to selective solution mining generally horizontal beds of sylvinite, i.e., a mixture of crystals of halite (NaCl) and sylvite (KCl) wherein water or salt brine is washed down a generally vertical bore hole into the deposits and recovered enriched with dissolved KCl.

Abstract: The present invention relates to an improved method for the solution mining of a mineral from a subterranean formation. More specifically, the invention relates to an improved method which enhances significantly the recovery of the mineral from a mature subterranean formation via solution mining. The improvement comprises increasing the flow rate of leachant into the formation by at least a factor of two.

Abstract: An improved method of in situ mining of a mineral bearing stratum. The method comprises drilling alternating rows of vertical injection and recovery wells to the depth of an aquiferrous mineral bearing stratum. Two horizontal branches are drilled at the bottom of each injection and recovery well. The horizontal branches are substantially parallel to one another and lie within the mineral bearing stratum. Leachant fluid is pumped under pressure into the injection wells to dissolve the minerals contained in the stratum. Leachant fluid containing the dissolved minerals is pumped out through the recovery wells. The method of the present invention requires substantially less drilling and pipe for extracting minerals from a given volume of a mineral bearing stratum and results in more constant mineral extraction rates than conventional techniques.

Abstract: A method of mining sulphur from an underground deposit overlying a soluble salt layer, wherein spaced parallel rows of repression boreholes and depression boreholes are drilled to penetrate into the salt layer, production boreholes are provided in a row intermediate the repression and depression boreholes, hot water or brine is introduced to the salt layer through the repression boreholes to create a superheated salt solution which is directed into the sulphur deposit, brine is pumped out through the depression boreholes thereby causing a flow of hot brine through the sulphur deposit from the repression to the depression boreholes which melts and entrains sulphur, and this molten sulphur is pumped up through the production boreholes. Hot water or brine is also introduced through the production boreholes to keep sulphur filters at the lower ends of the production boreholes clear.

Abstract: A method for optimal placement and orientation of a well field for solution mining comprises first determining the direction and magnitude of the major and minor axes of transmissivity of the ore body. Then, determining the location of the injection and recovery wells based on the magnitude and orientation of the major and minor axes of transmissivity.

Abstract: A relatively nonvolatile, high molecular weight sulfur solvent produced by adding at least 40 parts by weight of elemental sulfur per 100 parts by weight dialkyl disulfide to an amine activated dialkyl disulfide oil. Such a sulfur solvent is particularly useful in sustaining a liquid phase at bottomhole conditions for high temperature, high pressure wells.

Abstract: A fragmented permeable mass of formation particles containing oil shale and carbonates of calcium and magnesium is formed in an in situ oil shale retort. A combustion zone is advanced through the fragmented mass, whereby kerogen in oil shale in the fragmented mass is decomposed in a retorting zone on the advancing side of the combustion zone to produce gaseous and liquid products including shale oil. The combustion zone also converts the magnesium values in the particles of retorted oil shale to a more leachable form such as magnesium oxide. Magnesium values are selectively leached from the combusted particles, with respect to calcium compounds, with an aqueous solution of a purgeable, acid-forming gas such as carbon dioxide and a minor amount of a polyelectrolyte such as polyacrylic acid, polysulfonic acid, polyphosphonic acid, or the salts thereof. An enriched solution containing magnesium values is withdrawn from the fragmented mass and magnesia is recovered from such enriched solution.

Abstract: A novel system is disclosed for utilizing, in the mining of subterranean sulfur by the Frasch process, the heat of water that has accumulated underground above at least a portion of the subterranean sulfur deposit from previous mining operations wherein the underground water is brought to the surface, mixed with fresh heated water, and returned underground to melt the subterranean sulfur via a return pipeline which is separate and distinct from the pipeline through which the molten sulfur is brought to the surface. In one embodiment the return pipeline is in the same well casing as the sulfur pipeline, but displaced laterally from it. In a second embodiment, the return pipeline extends through a separate well casing.

Abstract: A method for dissolving a deposit of elemental sulfur by contacting the deposit with dialkyl disulfides catalyzed with an aliphatic amine in which a small amount of sulfur is added to the disulfide amine mixture before it is used as a sulfur solvent. The small percentage of sulfur added increases the rate at which the disulfide dissolves such sulfur deposit.

Abstract: Disclosed is an improved method of solution mining a mineral from a subterranean deposit thereof, where an aqueous solvent is introduced into the deposit and a solution enriched in the mineral is withdrawn from the deposit through a conduit which traverses a water bearing formation which overlies the deposit. The improvement comprises establishing through the wall of the conduit communication between the water bearing formation and the conduit to effect dilution of the enriched withdrawn solution thereby avoiding plugging of the conduit caused by crystallization of the mineral.

Abstract: Producing a fracture network in deep rock, e.g., in an ore body, by detonating explosive charges sequentially in separate cavities therein, the detonations producing a cluster of overlapping fracture zones and each detonation occurring after liquid has entered the fraction zones produced by previous adjacent detonations. High permeability is maintained in an explosively fractured segment of rock by flushing the fractured rock with liquid, i.e., by sweeping liquid through the fracture zones with high-pressure gas, between sequential detonations therein so as to entrain and remove fines therefrom. Ore bodies prepared by the blast/flush process with the blasting carried out in substantially vertical, optionally chambered, drilled shot holes can be leached in situ via a number of holes previously used as injection holes in the flushing procedure and a number of holes which are preserved upper portions of the shot holes used in the detonation process.

Abstract: Disclosed is a method of increasing the solution mining rate of potassium chloride from a cavity in a subterranean ore deposit containing potassium chloride and sodium chloride, in which cavity ore has been rubblized to effect a large contact surface area, by (1) solution mining the ore rubble at a first temperature for a time sufficient to determine the mining rate at that temperature; (2) increasing the temperature of the cavity solution to a temperature determined to be near the highest temperature at which the invariant composition is achievable at the solvent dissolving rate; and (3) solution mining the ore at the higher temperature.

Abstract: A method for restoring a formation which has undergone an in situ leaching operation wherein minerals oxidized during the leach operation pose a contamination threat to the formation water. In the present invention, the formation is flushed with a restoration fluid which contains a reducing agent capable of reducing the oxidized minerals to their reduced, insoluble state so that they are redeposited into the formation. Examples of suitable reducing agents are hydrogen gas, hydrogen sulfide, sulfur dioxide, carbon monoxide, and ferrous iron solutions.

Abstract: Subterranean formations of water soluble salt deposits are solution mined by introducing into the formation an aqueous solvent having a temperature substantially above the temperature of the deposit thereby heating the deposit and dissolving the soluble salts, and withdrawing from the deposit an aqueous solution enriched in the dissolved salts. An aqueous solvent having a temperature lower than the temperature of the first solvent is subsequently introduced into the deposit thereby recapturing heat given up to the deposit and dissolving the soluble salt utilizing greater solubility characteristics of the soluble salts owing to the increased deposit temperature, and withdrawing from the deposit a substantially increased amount of dissolved salt.

Abstract: The process of the present invention involves the following steps:producing, as by hydrofracing, a substantially horizontal fracture in the subterranean rock mass to be processed;emplacing an explosive charge in the mass in spaced juxtaposed position to the fracture;enlarging the fracture to create a void space thereat, an initial lifting of the overburden, and to provide a free face juxtaposed to and arranged to cooperate with the emplaced explosive charge; andexploding the charge against the free face for fragmenting the rock and to distribute the space, thus providing fractured, pervious, rubble-ized rock in an enclosed subterranean chamber.Firing of the charge provides a further lifting of the overburden, an enlargement of the chamber and a larger void space to distribute throughout the rubble-ized rock within the chamber.

Abstract: The present invention relates to an improved method for the solution mining of a mineral from a subterranean formation. More specifically, the invention relates to an improved method which enhances significantly the recovery of the mineral from a subterranean formation via solution mining by reducing the oxidant consuming reactions which compete with the mineral for the oxidant injected therein.

Abstract: A method and apparatus for in-situ leach mining which utilizes multiple dhole branch wells whipstocked off a single main generally vertical well. Initially the vertical well is drilled into the earth so that it may intersect the ore zone of material to be recovered. The vertical well may be cased and cemented after drilling. Thereafter from this same well a plurality of branch wells are whipstocked or drilled which intersect the vertical well at an angle from about 2 degrees to 60 degrees. These branch wells extend into the ore zone. A submersible pump and drop pipe are placed in the main well and at some point below the intersection of the main well with the branch wells a packer is placed around the drop pipe. The drop pipe carries solutions to the surface from the pump.

Abstract: An improved in-situ ore body chemical-mining system and method are disclosed, whereby it is practicable to mine an ore body of substantially horizontally extended configuration which would otherwise be uneconomical because of adverse overhead or overburden conditions. Beginning adjacent the distal ends of two or more generally horizontally drilled and substantially parallel bore holes which are drilled into the ore body from an elevation substantially similar to that of the ore body, a combination of permeabilizing and mining processes are applied to the body of ore circumjacent the horizontal penetration. The permeabilizing and mining processes are retrogressively applied to successive blocks of the ore body retreating by stages from the distal region of the penetration towards the entry region thereof.

Abstract: For the purpose of in-situ recovery of coal a borehole is driven from the surface in the plane of the coal over at least a large part of its travel, as far as conditions permit. At or near its end this borehole is widened over such a length and to such a width as corresponds with at least twice the deviation to be expected in the horizontal projection of a second borehole which is driven so far as to connect the widened section described above. The widened section is preferably made with the aid of mechanical means.After the boreholes have been linked, the coal is recovered by gasification, dissolution or extraction, whether or not under supercritical conditions and whether or not with attendant chemical/physical disintegration. The method according to the invention is particularly suited for use in the `in-line` gasification technique.

Abstract: The present invention relates to an improved method for the solution mining of a mineral from a subterranean formation. More specifically, the invention relates to an improved method which enhances significantly the recovery of a mineral from a subterranean formation via solution mining by increasing the rate of reactant flow through the formation via improved formation permeability and thereby reducing the time necessary to recover the mineral values therefrom.

Abstract: A process for creating a hot dry rock oven for the extraction of heat energy is disclosed wherein the geothermal fluid injection and withdrawal wells are brought into positive hydraulic communication during the creation of the hot dry rock oven. The oven complex is produced by fracturing the formation from a plurality of bore holes simultaneously.

Abstract: Disclosed is a method of disposing solid sodium chloride while selectively solution mining potassium chloride from a subterranean deposit containing potassium chloride and sodium chloride. In this novel method an aqueous solvent saturated with respect to sodium chloride, unsaturated with respect to potassium chloride and slurried with solid sodium chloride, is fed into the deposit having a cavity wherein there is face on which rich and lean potassium chloride ore is exposed. Potassium chloride is thereby dissolved while sodium chloride is deposited from the solvent slurry and the resultant solution withdrawn from the cavity enriched in potassium chloride.

Abstract: Process for the in-situ leaching of uranium from a subterranean ore deposit comprising introducing into the deposit an aqueous lixiviant having a pH of at least 6.0 and containing an alkali metal sulfate leaching agent. The alkali metal sulfate may be employed in combination with an alkali metal carbonate or bicarbonate with the sulfate comprising the predominant leaching agent. The lixiviant may be at a pH of at least 7.5 and contain an alkali metal sulfate leaching agent and a hypochlorite oxidizing agent.

Abstract: A method for leaching mineral values from an underground ore body in situ comprises introducing an oxygen-bearing gas into a pressurized saturation-disengagement chamber located above ground of the ore body where the oxygen-bearing gas becomes dissolved in a leach solution. The leach solution with dissolved oxygen therein is then pumped into the well and through the ore body where the leach solution oxidizes the mineral values in the ore body permitting their solubilization and transport by the leach solution to a recovery well where the pregnant leach solution is pumped above ground. The pregnant leach solution is then treated to remove the mineral values therefrom. Insuring that the oxygen-bearing gas is completely dissolved in the leach solution above ground in the saturation-disengagement chamber prevents gas bubbles from being pumped into the ore formation, thereby preventing loss of injectivity.

Abstract: A fragmented permeable mass of formation particles containing oil shale and carbonates of calcium and magnesium is formed in an in situ oil shale retort. A combustion zone is advanced through the fragmented mass, whereby kerogen in oil shale in the fragmented mass is decomposed in a retorting zone on the advancing side of the combustion zone to produce gaseous and liquid products including shale oil, and particles containing retorted oil shale are combusted for converting magnesium values to more leachable form such as magnesium oxide. Magnesium values are leached from the combusted particles selectively with respect to calcium compounds and silicates with aqueous solutions of a purgeable, acid-forming gas such as carbon dioxide or sulfur dioxide. An enriched solution containing magnesium values is withdrawn from the fragmented mass and magnesia is recovered from such enriched solution.

Abstract: Uranium ore deposits which contain certain proportions of other metals and elemental components, such as are present in redox roll front ore deposits, are selectively leached in situ by passing therethrough relatively dilute aqueous leach solutions comprising essentially from about 0.5 to 5 grams per liter of ammonium bicarbonate and from about 0.1 to 3 grams per liter of peroxide, preferably introduced as aqueous H.sub.2 O.sub.2, and sufficient ammonia to bring the solution to a pH of from about 7.4 to 9, and preferably from 7.5 to 8.5, thereafter withdrawing from the ore deposit the aqueous leach solution enriched in uranium which it preferentially extracts along with a generally lower proportion of other metals and elements as compared to their respective ratios in the ore deposit, and contacting the enriched leach solution with a strong base anion exchange material to strip the uranium from the leach solution.

Abstract: The present invention relates to a method for the restoring of an underground reservoir subsequent to the solution mining of a mineral from a subterranean formation. More specifically, the invention relates to the cycling of clean water through a subterranean formation to decrease the total dissolved solids level of the reservoir present therein.

Abstract: The present invention relates to a method for the solution mining of a mineral from a subterranean formation. More specifically, the invention relates to a method which enhances significantly the recovery of a mineral from a subterranean formation via solution mining utilizing an oxidant and leach solution with an injection and production well. The method comprises ceasing oxidant injection via the injection well and measuring the change in mineral concentration in the pregnant solution recovered via the production well.

Abstract: 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.

Abstract: 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.