US-12618308-B2 - Method and device for horizontal bore mining

US12618308B2US 12618308 B2US12618308 B2US 12618308B2US-12618308-B2

Abstract

The invention provides a mining tool ( 30 ) for mining an underground substantially horizontal seam of material comprising an eductor module ( 60 ) and a fluidising module ( 62 ). The fluidising module ( 62 ) includes a plenum ( 66 ) adapted to receive high pressure fluid from a mining string, and one or more fluid jet nozzles ( 42,43,44 ) for emitting the high pressure fluid to mobilise material of the seam. The eductor module ( 60 ) includes an eductor assembly ( 69 ) adapted to recover the mined material to return it as a slurry along the string. In use, the tool is connected to a mining pipe or string ( 35 ) extending from the surface to supplying said high pressure fluid to the eductor arrangement and fluidising nozzles. The eductor assembly is positioned toward the proximal side of the tool which is connected to mining pipe ( 35 ). The fluidising jet nozzles are positioned more towards the distal end of the tool, such that when in use, eductor recovers the slurry at said proximal position relative to the string. While the mining tool is continuously withdrawn towards the ground surface along the substantially horizontal borehole, high pressure fluid is fed to the tool to fluidise the material in the seam via the fluidising jet nozzles ( 42,43,44 ), and recover the material as a slurry via the eductor arrangement positioned “upstream” from the jet nozzles.

Inventors

Christopher Brian Lee
Pieter Stephanus Esterhuysen
Tertius Theunis Brits

Assignees

ILUKA RESOURCES LIMITED

Dates

Publication Date: 20260505
Application Date: 20220824
Priority Date: 20210825

Claims (18)

1 . A mining tool for mining an underground seam of material, the mining tool configured to be coupled to a pipe structure that extends along a borehole from a ground surface to the seam, which pipe structure delivering a first and a second high pressure fluid to the mining tool, and having a passage for recovering a slurry containing mined material, wherein the mining tool comprises: a plenum being connected to and adapted to receive the first high pressure fluid from the pipe structure, one or more fluidising jet nozzles fluidly connected to said plenum and operable with said first high pressure fluid to mobilise material of the seam adjacent to the tool, and an eductor arrangement adapted to recover and entrain said mined material in the second high pressure fluid flow delivered by the pipe structure, to return said material as a slurry through said passage, wherein the first and the second high pressure fluids are fluidly isolated such that the first high pressure fluid received by the plenum is distinct from the second high pressure fluid at the eductor arrangement, wherein said one or more fluidising jet nozzles are distally disposed relative to said pipe structure, and said eductor arrangement is disposed proximally relative to said pipe structure, such that when in use, said one or more fluidising jet nozzles mobilise said material and said eductor arrangement recovers said slurry at said proximal position relative to the pipe structure, while said mining tool is continuously withdrawn towards the ground surface along said borehole.
2 . A mining tool according to claim 1 , wherein said one or more fluidising jet nozzles are disposed at least between 0 and 3 m from said eductor arrangement.
3 . A mining tool according to claim 2 , wherein said one or more fluidising jet nozzles are disposed between 1 to 2 m from said eductor arrangement.
4 . A mining tool according to claim 1 , wherein said mining tool is disposed along a horizontal or substantially horizontal borehole.
5 . A mining tool according to claim 1 , wherein one or more openings providing fluid connection between said eductor arrangement and said borehole include grille or strainer structures for controlling slurry pressure therethrough and/or controlling fragment sizes of said material in said slurry.
6 . A mining tool according to claim 5 , wherein said mining tool comprises two said openings disposed on opposing faces of the mining tool.
7 . A mining tool according to claim 6 , wherein said two opposingly disposed openings are vertically level when in use.
8 . A mining tool according to claim 5 , wherein said grille or strainer structures are adapted to maintain a slurry suction pressure of between 400 and 800 kPa.
9 . A mining tool according to claim 8 , wherein said grille or strainer structures are adapted to maintain a slurry suction pressure of 600 kPa.
10 . A method for mining an underground seam of material comprising coupling a mining tool to a pipe structure that extends along a borehole from a ground surface to the seam, which pipe structure separately delivering a first high pressure fluid and a second high pressure fluid to said mining tool, and having a passage for recovering a slurry containing mined material, said mining tool having: a plenum connected to and receiving the first high pressure fluid from the pipe structure; one or more fluidising jet nozzles fluidly connected to said plenum and directing said first high pressure fluid to mobilise material of the seam adjacent to said mining tool; and an eductor arrangement recovering and entraining said mined material in said second high pressure fluid flow delivered by the pipe structure, returning said material as a slurry along said passage, wherein the first high pressure fluid and the second high pressure fluid are fluidly isolated such that the first high pressure fluid received by the plenum is distinct from the second high pressure fluid at the eductor arrangement, said one or more fluidising jet nozzles being distally disposed relative to said pipe structure, and said eductor arrangement being proximally disposed relative to said pipe structure, wherein said mining tool is continuously withdrawn towards the ground surface along said borehole while fluid is fed to said one or more fluidising jet nozzles and said eductor arrangement such that said material is mobilised from said seam and recovered as said slurry through said proximally located eductor arrangement.
11 . A method according to claim 10 , wherein said material adjacent to said tool is mobilised by the first high pressure fluid directed by said one or more fluidising jet nozzles disposed at least between 0 and 3 m from said eductor arrangement.
12 . A method according to claim 11 , wherein said one or more fluidising jet nozzles are disposed between 1 and 2 m from said eductor arrangement.
13 . A method according to claim 10 , wherein said underground seam of material is mined by said mining tool disposed along a horizontal or substantially horizontal borehole.
14 . A method according to claim 10 , wherein slurry pressure and/or fragment sizes of said material recovered in said eductor arrangement is controlled by grille or strainer structures comprising one or more openings providing fluid connection between said eductor arrangement and said borehole.
15 . A method according to claim 14 , wherein said slurry is recovered through two said openings disposed on opposing faces of said mining tool.
16 . A method according to claim 15 , wherein said mining tool is oriented such that said two opposingly disposed openings are vertically level.
17 . A method according to claim 14 , wherein said grille or strainer structures maintain said slurry suction pressure to between 400 and 800 kPa.
18 . A method according to claim 17 , wherein said grille or strainer structures maintain said slurry suction pressure at 600 kPa.

Description

FIELD OF THE INVENTION This invention relates generally to underground mining and particularly but not only with accessing and/or mining an underground seam of a material with minimal removal of the overburden, by way of one or more inclined or horizontal boreholes. In a broad aspect, the invention provides various mining tools and methods for mining an underground seam of material. BACKGROUND OF THE INVENTION Where an underground seam of valuable material is located close to or within a reasonable distance of the ground surface, e.g. up to 600 m below the surface, the usual method of recovery is via open pit mining, also commonly known as open cast or open cut mining. There are however many instances where valuable resources are not being recovered because the overall economics of open pit mining including extraction and replacement of the overburden and subsequent site restoration do not allow sufficient return at market prices. In other instances, the valuable seam may be narrow and extend over many kilometres or may be submerged or partly submerged below a local water table and be impractical to dewater. One proposed solution to these difficulties has been hydraulic borehole mining, which essentially involves drilling and casing a vertical borehole to the seam. The ore is then hydraulically mined by directing high velocity water jets into the seam to form a slurry, and pumping the slurry to the surface via the borehole. U.S. Pat. No. 4,728,152 discloses the use of this method for the recovery of bitumen from tar sands. In a variation for extracting hydrocarbon fluid from a layer of oil sand, the usual vertical borehole is drilled and cased, and a second borehole is drilled in a curved path from a second well head to access the seam in a horizontal direction. Jet nozzles supplied by respective conduits in the two boreholes disaggregate a zone of the seam to form a cavity from which the material is extracted as a slurry via the horizontal borehole. An example of this arrangement is disclosed in International patent publication WO 2010/000736. International patent publication WO 2013/062871 discloses a borehole mining system in which the seam is accessed via a drilled and cased borehole that is initially directed at an inclination from the surface and curves into a horizontal direction. A coaxial mining pipe run down the borehole defines an annular passage for delivering high pressure water to operate sets of jet nozzles at the end of the pipe for disaggregating the seam material, which is recovered into the central passage via an eductor pump between the sets of nozzles. The casing or the end of the pipe can be rotated to traverse the water jets, and the nozzles and eductor are repositioned from time to time by retraction of the pipe along the borehole. International patent publication WO 2015/057657 discloses a borehole mining method that entails delivering four separate fluid streams down a mining string run into the borehole, which may be at any angle from vertical to horizontal. These fluids comprise a high pressure fluid to form jets for disaggregating the material being mined and creating a slurry of the material, air for a shroud to encapsulate and accelerate the high pressure fluid jets, low pressure water to mix with and transport the slurry back to the surface, and gas for an airlift sub to create suction for lifting the slurry to the surface. Again, the pipe is rotated to rotate the jets, and the cavity in the seam grows larger and longer as the mining tool is slowly retracted across the seam and into the casing string. It is an object of at least preferred embodiments of the invention to provide alternative or improved arrangements for accessing and/or mining an underground seam of material utilising borehole techniques. Reference to any prior art in the specification is not an acknowledgment or suggestion that this prior art forms part of the common general knowledge in any jurisdiction or that this prior art could reasonably be expected to be understood, regarded as relevant, and/or combined with other pieces of prior art by a skilled person in the art. SUMMARY OF THE INVENTION In the first aspect of the present invention, there is provided a mining tool for mining an underground seam of material by being coupled to a pipe structure that extends along a borehole from a ground surface to the seam, which pipe structure having at least a first and second passage for separately delivering high pressure fluid to the mining tool, and a third passage for recovering a slurry containing mined material, wherein the mining tool comprises: a plenum being connected to and adapted to receive high pressure fluid from the first passage of the pipe structure,one or more fluidising jet nozzles fluidly connected to said plenum and operable with said high pressure fluid to mobilise material of the seam adjacent to the tool, andan eductor arrangement adapted to recover and entrain said mined material in said hig