Vertical drainage system for heap leach piles

1. In combination with a pre-existing heap leach system comprising a controlled percolation system mounted atop a heap of crushed metal-laden ore to percolate leach solution from atop the heap down through the heap to recover a valuable fraction, the ore heap being deposited on a collection pad having a granulated collection layer and one or more substantially horizontal collection pipes embedded in the collection layer, a drainage system, comprising:

a plurality of substantially vertical wicking conduits spaced in a parallel array throughout the ore heap, each wicking conduit being driven by a mandrel downward through and substantially traversing said pre-existing ore heap from an upper-exposed surface thereof to the collection pad, and operating during percolation and consolidation loading of said ore about said plurality of wicking conduits, to collect and drain standing fluid vertically downward throughout the heap, thereby consolidating and maintaining geotechnical stability of the heap.

2. The drainage system according to claim 1 , wherein each of said wicking conduits is in fluid communication from a top of said ore heap to said one or more collection pipes for draining trapped and avoiding slope or geotechnical failure.

3. The drainage system according to claim 1 , wherein each of said wicking conduits further comprises an elongate rigid support member and a porous filter media surrounding the support member.

4. The drainage system according to claim 3 , wherein said rigid support member comprises an elongate central core having a cross-section defined by a latticework of intersecting walls.

5. The drainage system according to claim 4 , wherein said latticework of intersecting walls comprises a straight lateral wall and a plurality of shorter walls projecting perpendicularly from the lateral wall at uniform intervals.

6. The drainage system according to claim 1 , wherein each of said wicking conduits further comprises an elongate support member having tubular perforated walls and a porous filter media inside the support member.

7. The drainage system according to claim 3 , wherein said rigid support member is plastic.

8. The drainage system according to claim 3 , wherein said rigid support member comprises a elongate central core having a corrugated cross-section.

9. In combination with a pre-existing heap leach system comprising a controlled percolation system mounted atop a heap of crushed metal-laden ore to percolate leach solution from atop the heap down through the heap to recover a valuable fraction, the ore heap being deposited in cascading tiers on a collection pad having a granulated collection layer and one or more substantially horizontal collection pipes embedded in the collection layer, a drainage system, comprising:

a plurality of substantially vertical wicking conduits being driven by a mandrel downward through said pre-existing ore heap from an upper-exposed surface thereof to the collection pad in a parallel array throughout the ore heap, said wicking conduits being of different lengths so as to substantially traverse all of the tiers of the ore heap within which said wicking conduits are inserted, and operating during percolation and consolidation loading of said ore about said plurality of wicking conduits to thereby collect and drain standing fluid vertically at any level of the heap, thereby consolidating and maintaining geotechnical stability of the heap.

10. The drainage system according to claim 9 , wherein each of said wicking conduits is in fluid communication from a top of said ore heap to said one or more collection pipes for draining trapped and avoiding slope or geotechnical failure.

11. The drainage system according to claim 9 , wherein each of said wicking conduits further comprises an elongate rigid support member and a porous filter media surrounding the support member.

12. The drainage system according to claim 9 , wherein each of said wicking conduits further comprises an elongate support member having tubular perforated walls and a porous filter media inside the support member.

13. The drainage system according to claim 11 , wherein said rigid support member comprises an elongate central core having a cross-section defined by a flexible latticework of intersecting walls.

14. The drainage system according to claim 13 , wherein said flexible latticework of intersecting walls comprises a straight lateral wall and a plurality of short evenly-spaced walls projecting perpendicularly from the lateral wall.

15. The drainage system according to claim 11 , wherein said rigid support member is plastic.

16. The drainage system according to claim 11 , wherein said rigid support member comprises an elongate central core having a corrugated cross-section.

17. A method for constructing a heap leach pile having a vertical drainage system comprising the steps of:

grading a collection foundation;

covering said collection foundation with an impermeable sheet;

placing one or more collection conduits lengthwise atop said sheet;

depositing a granulated collection layer onto said plastic sheet so as to embed said one or more collection conduits;

depositing pre-crushed ore in one or more tiers atop the collection layer to form a heap;

installing a plurality of substantially vertical wicking conduits in a parallel array throughout the ore heap by driving each wicking conduit downward through the ore heap with a mandrel from an upper-exposed surface thereof to the collection pad, and removing the mandrel such that each wicking conduit substantially traverses said ore heap;

installing a controlled percolation system on the upper surface of said ore heap;

percolating fluid downward through said ore heap, thereby consolidating and loading said ore about said plurality of wicking conduits;

whereby said plurality of wicking conduits to collect and drain standing fluid vertically throughout the heap, thereby consolidating and maintaining geotechnical stability of the heap.

18. The method of claim 17 , wherein said step of installing a plurality of substantially vertical wicking conduits comprises installing each of said wicking conduits in fluid communication from a top of said ore heap to said one or more collection pipes for draining trapped and avoiding slope or geotechnical failure.

19. The method of claim 17 , wherein said plurality of substantially vertical wicking conduits each comprises an elongate rigid support member and a porous filter media surrounding the support member.

20. The method of claim 17 , wherein said plurality of substantially vertical wicking conduits each comprises an elongate support member having tubular perforated walls and a porous filter media inside the support member.