IN SITU ORE LEACHING USING FREEZE BARRIERS
A method is provided herein for performing a leaching process on a substrate ( 113 ). In accordance with the method, a freeze wall ( 115 ) is created which isolates a portion ( 117 ) of a substrate, and the isolated portion of the substrate is subjected to a leaching process.
1 . A method for performing a leaching process on a substrate, comprising:
creating a freeze wall which isolates a portion of the substrate; and
subjecting the isolated portion of the substrate to the leaching process.
2 . The method of claim 1 , wherein creating a freeze barrier comprises:
creating a plurality of holes in the substrate; and
circulating a working fluid through said plurality of holes such that said working fluid absorbs heat from the substrate.
3 . The method of claim 2 , further comprising:
extracting the heat from the working fluid by passing the working fluid through a heat exchanger.
4 . The method of claim 3 , further comprising:
recirculating the working fluid through said plurality of holes after the working fluid is passed through the heat exchanger.
5 . The method of claim 2 , further comprising:
after the working fluid absorbs heat from the substrate, venting the heated working fluid to the atmosphere.
6 . The method of claim 5 , wherein the working fluid comprises a material selected from the group consisting of nitrogen and carbon dioxide.
7 . The method of claim 5 , wherein the working fluid undergoes a phase transition from a liquid to a gas when it absorbs heat from the substrate.
8 . The method of claim 2 , wherein the working fluid is circulated through the plurality of holes in series.
9 . The method of claim 2 , wherein the working fluid is circulated through the plurality of holes in parallel.
10 . The method of claim 2 , wherein the working fluid is a brine.
11 . The method of claim 10 , wherein the working fluid comprises calcium chloride.
12 . The method of claim 2 , wherein the working fluid is selected from the group consisting of nitrogen, ammonia and carbon dioxide.
13 . The method of claim 12 wherein, after the freeze wall is created, maintaining the freeze wall with a device selected from the group consisting of thermosyphons and heat pipes.
14 . The method of claim 1 , wherein the freeze wall consists of at least one essentially vertical wall and at least one essentially horizontal wall.
15 . The method of claim 1 , further comprising:
subjecting the isolated portion of the substrate to a remediation process after the leaching process; and
removing a portion of the freeze wall after the remediation process.
16 . The method of claim 15 , wherein the remediation process comprises treating the isolated portion of the substrate with an alkaline solution.
17 . The method of claim 1 , further comprising:
subjecting the isolated portion of the substrate to a remediation process after the leaching process; and
removing the entire freeze wall after the remediation process.
18 . A method for performing a leaching process on a substrate, comprising:
performing the method of claim 1 on a first portion of a substrate; and
performing the method of claim 1 on a second portion of the substrate which is adjacent to the first portion of the substrate;
wherein a portion of the freeze wall used to isolate the first portion of the substrate is reused to isolate the second portion of the substrate.
19 . The method of claim 1 , wherein the leaching process comprises treating the isolated portion with a metal leaching solution.
20 . The method of claim 19 , wherein the metal is selected from the group consisting of nickel, gold, copper, uranium and zinc.
21 . The method of claim 19 , wherein the metal is nickel.
22 . The method of claim 1 , wherein the leaching process comprises treating the isolated portion with an acidic leaching solution.
23 . The method of claim 1 , wherein the leaching process comprises treating the isolated portion with a biological leaching solution.
24 . The method of claim 1 , wherein the leaching process comprises treating the isolated portion with a bacterial leaching solution.
25 . The method of claim 1 , wherein said freeze wall hydrodynamically isolates a portion of the substrate.
26 . A method for extracting nickel from a porous substrate containing a nickel bearing ore, comprising:
creating a freeze wall in the substrate such that a portion of the substrate is hydrodynamically isolated from the rest of the substrate; and
treating the isolated portion of the substrate with an acidic leaching solution which dissolves a portion of the nickel content in the substrate.
27 . A mining construct, comprising:
an ore bearing substrate;
a freeze wall which hydrodynamically isolates a portion of the substrate; and
a leaching solution disposed in the isolated portion of the substrate.
28 . The mining construct of claim 27 , further comprising:
a heat exchange system adapted to maintain said freeze wall.
29 . The mining construct of claim 28 , wherein said heat exchange system comprises a thermosyphon.
30 . The mining construct of claim 28 , wherein said heat exchange system comprises a heat pipe.
31 . The mining construct of claim 28 , wherein said heat exchange system comprises a plurality of downpipes and a plurality of freeze pipes.
32 . The mining construct of claim 31 , wherein said heat exchange system comprises a working fluid, and wherein said working fluid is a brine.
33 . The mining construct of claim 32 , wherein said brine comprises calcium chloride.
34 . The mining construct of claim 31 , wherein said heat exchange system comprises a working fluid, and wherein said working fluid is selected from the group consisting of nitrogen, ammonia and carbon dioxide.
35 . The mining construct of claim 31 , wherein said heat exchange system comprises a working fluid, and wherein the working fluid undergoes a phase transition from a liquid to a gas when it absorbs heat from the substrate.
36 . The mining construct of claim 31 , wherein the working fluid is circulated through the plurality of downpipes in series.
37 . The mining construct of claim 31 , wherein the working fluid is circulated through the plurality of downpipes in parallel.
38 . The mining construct of claim 27 , wherein the freeze wall consists of at least one essentially vertical wall and at least one essentially horizontal wall.
39 . The mining construct of claim 27 , wherein the leaching solution is a metal leaching solution.
40 . The mining construct of claim 39 , wherein the metal is selected from the group consisting of nickel, gold, copper, uranium and zinc.
41 . The mining construct of claim 39 , wherein the metal is nickel.
42 . The mining construct of claim 27 , wherein the leaching solution is an acidic leaching solution.
43 . The mining construct of claim 27 , wherein the leaching solution is a biological leaching solution.
44 . The mining construct of claim 43 , wherein the leaching solution is a bacterial leaching solution.