Solution mining process
AssigneeUnion Oil Company of California
InventorWilliam E. Showalter
Life of this patent
Estimating the term…
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.
Claims19
In a method for the solution mining of a substance which in an oxidizing state is soluble in an aqueous leaching solution, said method comprising the steps of (1) introducing an aqueous leaching solution through a first well into a subterranean formation containing said substance, thereby to solubilize said substance in situ to form a pregnant liquor, (2) recovering said pregnant liquor from said formation through a second well, and (3) separating said substance from said pregnant liquor, the improvement comprising:
- utilizing as said aqueous leaching solution a solution comprising a dilute aqueous carbonic acid solution;
- and
- reversing the direction of flow through said formation after a first preselected period of time by injecting said aqueous leaching solution through said second well and recovering said pregnant liquor from said first well.
A method for the solutiom mining of metal values selected from the group consisting of uranium, thorium, vanadium, copper, nickel, molybdenum, rhenium and selenium, from a subterranean formation containing said metal values, comprising the steps of:
- (a) penetrating said formation with a first well and a second well in spaced relation with said first well;
- (b) during a first time period, (1) introducing a leaching solution through said first well into said formation to in situ leach said metal values thereby forming a pregnant liquor, and (2) recovering said pregnant liquor from said second well, said leaching solution comprising a dilute aqueous carbonic acid solution having a pH less than about 7 and a bicarbonate ion concentration between about 380 ppm and about 1000 ppm;
- (c) during a subsequent second time period, (1) introducing said leaching solution through said second well into said formation, and (2) recovering said pregnant liquor from said first well, thereby reversing the direction of flow through said formation;
- (d) forming a barren liquor by separating said metal values from said pregnant liquor;
- (e) introducing gaseous carbon dioxide into at least a portion of said barren liquor, thereby to form a dilute carbonic acid solution;
- and
- (f) recycling at least a portion of the solution formed in step (e) for reintroduction into said formation in step (b) or step (c).
A method for the solution mining of uranium values from a subterranean formation containing said uranium values, comprising the steps of:
- (a) penetrating said formation with a first well and a second well in spaced relation with said first well;
- (b) during a first time period of between about one week and about one year, (1) introducing a leaching solution through said first well into said formation to in situ leach said uranium values thereby forming a pregnant liquor, and (2) recovering said pregnant liquor from said second well, said leaching solution comprising a dilute aqueous carbonic acid solution and an oxidant selected from the group consisting of hydrogen peroxide, oxygen and oxygen-containing gases, said leaching solution having a pH less than about 7 and a bicarbonate ion concentration between about 380 ppm and about 1000 ppm and the concentration of said oxidant in said leaching solution being between about 100 ppm and about 300 ppm on a free oxygen basis;
- (c) during a subsequent second time period of between about one week and one year, (1) introducing said leaching solution through said second well into said formation, and (2) recovering said pregnant liquor from said first well, thereby reversing the direction of flow through said formation;
- (d) forming a barren liquor by separating said uranium values from said pregnant liquor;
- (e) introducing gaseous carbon dioxide and said oxidant into at least a portion of said barren liquor, thereby to form an oxidant-containing dilute carbonic acid solution;
- and
- (f) recycling at least a portion of the solution formed in step (e) for reintroduction into said formation in step (b) or step (c).
Dependencies are inferred from the claim text.