CN117881872A

CN117881872A - Horizontal borehole mining method and apparatus

Info

Publication number: CN117881872A
Application number: CN202280058068.8A
Authority: CN
Inventors: C·B·李; P·S·埃斯特胡森; T·T·布瑞兹
Original assignee: Iluka Resources Ltd
Current assignee: Iluka Resources Ltd
Priority date: 2021-08-24
Filing date: 2022-08-24
Publication date: 2024-04-12

Abstract

A mining tool (30) for mining subterranean substantially horizontal mineral seam material includes an eductor module (60) and a fluidization module (62). The fluidization module (62) includes a plenum (66) adapted to receive high pressure fluid from the mining line, and one or more fluid injection nozzles (42, 43, 44) for emitting the high pressure fluid to flow the mineral seam material. The eductor module (60) includes an eductor assembly (69) adapted to recover mined material and return it as a slurry along the pipeline. In use, the tool is connected to a mining pipe or line (35) extending from the surface to supply the ejector arrangement and the fluidising nozzle with said high pressure fluid. An injector assembly is located on the proximal side of the tool and is connected to a mining pipe (35). The fluidising jet nozzle is located closer to the distal side of the tool so that in use the eductor recovers slurry at a proximal position relative to the pipeline. As the mining tool is continuously withdrawn in the direction of the surface along a substantially horizontal borehole, high pressure fluid is supplied to the tool through a fluidising jet nozzle (42, 43, 44) to fluidise the material in the seam and the material is recovered as a slurry by an ejector arrangement "upstream" of the nozzle.

Description

Horizontal borehole mining method and apparatus

Technical Field

The present invention relates generally to underground mining and, more particularly, but not exclusively, to underground mining where access to and/or extraction of a substance is provided with minimal removal of overburden by one or more inclined or horizontal boreholes. Broadly, the present invention provides various mining tools and methods for mining subsurface mineral seam materials.

Background

When a valuable seam in the subsurface is located near the ground or within a reasonable distance, e.g., up to 600 meters or less, a conventional mining method is surface mining, also commonly referred to as surface mining or surface cut mining. However, in many cases, valuable resources are not exploited because the overall economics of surface mining, including extraction and replacement of overburden and subsequent site restoration, do not yield sufficient returns at market price. In other cases, valuable mineral deposits may be narrow and extend for kilometers, or may be submerged or partially submerged below the local groundwater level, and practically impossible to drain.

One proposed solution to these difficulties is hydraulic borehole extraction, which essentially involves drilling and casing a vertical borehole into the seam. Hydraulic mining is then carried out by introducing a high-velocity water jet into the seam to form a slurry, and pumping the slurry through the borehole to the surface. Us patent 4,728,152 discloses the use of this method for recovering bitumen from tar sands.

In extracting hydrocarbon fluids from an oil sands formation, a conventional vertical borehole is drilled and cased, and then a second borehole of a curved path is drilled from a second wellhead into the formation in a horizontal direction. The jet nozzles provided by the corresponding conduits in the two boreholes separate a region of the seam to form a cavity from which material is extracted as a slurry through the horizontal borehole. An example of such an arrangement is disclosed in International patent publication WO 2010/000736.

International patent WO 2013/062871 discloses a borehole mining system in which a borehole is drilled and cased into a seam, the borehole initially being inclined downwardly from the ground and meandering to a horizontal direction. The coaxial mining pipe lowered down the bore defines an annular passageway for delivering high pressure water to operate a set of jet nozzles at the end of the pipe to break down mineral seam material which is recovered into the central passageway by an ejector pump between the nozzle sets. The end of the sleeve or pipe can be rotated to move the water jet laterally, repositioning the nozzle and injector from time to time by withdrawing the pipe along the borehole.

International patent publication WO 2015/057657 discloses a borehole extraction method involving four separate fluids being fed through a mining string into a borehole, which may be at any angle from vertical to horizontal. These fluids include high pressure fluid for forming a jet to break down mined material and create a slurry of material, air for encapsulating and accelerating the high pressure fluid jet, low pressure water for mixing with the slurry and transporting the slurry back to the surface, and gas for creating suction to lift the slurry to the surface. Again, the jet is rotated by rotating the tubing and the cavity in the seam becomes larger and longer as the production tool slowly withdraws back from the seam and into the casing string.

It is an object of the present invention, at least in preferred embodiments, to provide alternative or improved arrangements for accessing and/or mining subterranean formation material using drilling techniques.

The reference to any prior art in this specification is not an acknowledgement or suggestion that such prior art forms part of the common general knowledge in any jurisdiction or that such prior art could reasonably be expected to be understood, regarded as relevant and/or combined with other prior art by a person skilled in the art.

Disclosure of Invention

In a first aspect of the present invention there is provided a mining tool for mining subterranean mineral seam material by connection to a conduit structure extending from the surface to the subterranean mineral seam along a borehole, the conduit structure having at least a first passageway, a second passageway and a third passageway for conveying high pressure fluid to the mining tool respectively, the third passageway for recovering slurry containing the mined material, wherein the mining tool comprises:

a plenum connected to the first passage of the piping structure and adapted to receive high pressure fluid from the first passage,

one or more fluidization jet nozzles fluidly connected to the plenum, the fluidization jet nozzles operable to loosen material of the mineral seam adjacent the tool using the high pressure fluid, and

An eductor arrangement adapted to recover and entrain the mined material in the high pressure fluid stream delivered by the second channel to return the material as a slurry along the third channel,

wherein the one or more fluidizing jet nozzles are provided distally with respect to the conduit structure and the ejector arrangement is provided proximally with respect to the conduit structure,

such that in use, the one or more fluidising jet nozzles loosen the material and the eductor is disposed at a proximal position relative to the conduit structure to recover the slurry while the production tool is continuously withdrawn in the surface direction along the borehole.

In one embodiment, one or more fluidization jet nozzles are provided at least between 0 and 3 meters from the ejector arrangement.

In one embodiment, one or more fluidization jet nozzles are provided between 1 and 2 meters from the ejector arrangement.

In another embodiment, the mining tool is disposed along a horizontal or substantially horizontal borehole.

In one embodiment, the one or more openings providing fluid connection between the eductor arrangement and the bore hole comprise a grid or screen structure for controlling slurry pressure therethrough and/or controlling the chip size of the material in the slurry.

In one embodiment, the mining tool includes two openings disposed on opposite sides of the mining tool.

In another embodiment, the two oppositely disposed openings are vertically horizontal in use.

In another embodiment, the grid or screen structure is adapted to hold the slurry at a suction pressure of between 400 and 800 kilopascals.

In one embodiment, the grid or screen structure is adapted to maintain a slurry suction pressure of 600 kilopascals.

In a second aspect of the invention there is provided a method of mining subterranean mineral seam material comprising connecting a mining tool with a conduit structure extending along a borehole from the surface to the seam, the conduit structure having at least first and second channels for delivering high pressure fluid to the mining tool respectively and having a third channel for recovering a slurry containing the mined material, the mining tool having:

a plenum connected to the first channel of the piping structure and receiving high pressure fluid from the channel;

one or more fluidization jet nozzles fluidly connected to the plenum that direct the high pressure fluid to loosen material of the mineral seam adjacent the mining tool; and

an eductor arrangement to recover and entrain the mined material in a high pressure fluid stream provided by the second passage, return the material as a slurry through the third passage,

The one or more fluidizing jet nozzles being disposed distally with respect to the conduit structure, the ejector arrangement being disposed proximally with respect to the conduit structure,

wherein fluid is delivered to the one or more fluidising jet nozzles and the injector arrangement while the production tool is continuously withdrawn along the borehole in the surface direction so that the material becomes mobile from the seam and is recovered as a slurry by the proximally located injector arrangement.

In one embodiment, the material in the vicinity of the tool is moved by means of a high-pressure fluid directed by one or more fluidizing jet nozzles arranged at least between 0 and 3 meters from the ejector arrangement.

In another embodiment, one or more fluidization jet nozzles are provided between 1 and 2 meters from the ejector arrangement.

In one embodiment, the subsurface mineral seam material is mined by a mining tool disposed along a horizontal or substantially horizontal borehole.

In one embodiment, slurry pressure and/or the size of the chips of recovered material is controlled by a grid or screen structure contained by one or more openings providing fluid connection between the injector arrangement and the borehole.

In another embodiment, the slurry is recovered through two openings provided on opposite sides of the mining tool.

In a further embodiment, the mining tool is positioned such that two openings disposed opposite one another are vertically horizontal.

In one embodiment, the grid or screen structure maintains the slurry suction pressure between 400 and 800 kilopascals.

In one embodiment, the slurry suction pressure of the grid or screen structure is maintained at 600 kilopascals.

In vertical borehole production, a jet is provided to flush the borehole wall, from where the produced material falls under gravity to a location below the jet, is extracted and returned to the surface. In horizontal or near horizontal drilling, the mining equipment with jet nozzles is usually located at or near the bottom of the ore body (0 to 1 meter from the bottom), the jet nozzles pointing generally upwards to release valuable minerals. However, unlike vertical borehole extraction, horizontal boreholes do not have the assistance of gravity to direct the released material to the extraction system and back to the surface.

The extraction system for returning mined material as a slurry is typically located at the free or distal end of the apparatus. This is designed to allow the operator to recover mined material near the free end of the apparatus. In some cases, this arrangement is combined with movement of the production equipment so that the extraction system can be moved over the borehole to recover the produced material. However, this has a number of difficulties. In particular, the distal or free end of the device is most susceptible to damage when the device is inserted and moved, and the opening for the extraction system through which slurry enters may be blocked or damaged by contact with surrounding rock or minerals.

Further, in typical horizontal or near horizontal borehole production, each nozzle is provided with a separate hydraulic line, which are substantially identical in equipment. In some cases, additional directional jet nozzles are also provided to direct mined material released by the mining jet nozzles toward the inlet of the extraction system. These directional jets require additional pressure and fluid connections, etc. Furthermore, these additional directional jet nozzles are directed away from the extraction equipment of the ore body. This may be a waste of energy in the extraction system, simply to force the extracted material to the extraction apparatus.

On the other hand, the present invention, contrary to intuition, places the jet nozzle at the free or distal end (with respect to the ground) and the extraction device or ejector arrangement closer to the proximal end of the device.

The arrangement of the present invention provides a number of significant advantages over conventional systems. First, the placement of the extraction system/eductor inlet at the proximal end of the device reduces the likelihood of damage to the extraction system, eductor arrangement, and inlet thereof during insertion. Surprisingly, however, this does not significantly reduce the operating efficiency. While the extraction system is now actually "upstream" of the jet nozzle, recovery of the mined material by the extraction system operates at least as well as conventional systems.

Further, the applicant has found that placing the eductor inlet/extraction apparatus closer to the proximal end of the apparatus and the mining jet nozzle closer to the distal or free end provides many other unexpected advantages, including more efficient and reliable operation, and reduced clogging and damage.

Although the reason for this is not fully understood, the inventors have found that the mined material is reliably recovered as a slurry despite the ejector inlet being located substantially "upstream" of the mine face formed by the jet nozzle. It is assumed that the bore itself acts as a confining substance enabling it to be reliably drawn into the ejector arrangement from the jet through the proximally facing inlet.

While the apparatus is moved or withdrawn toward the surface, thus essentially removing the extraction/eductor inlet from the open portion of the borehole, the apparatus and method of the present invention is at least as effective and reliable in recovering mined material as conventional systems that place the extractor at or near the free end.

It was initially thought that the arrangement of the present invention may lead to difficulties in that it was thought that placing the extraction or eductor inlet distally would be more effective as it was the last point of contact when the production equipment was withdrawn to the surface. However, this appears to be sufficient to effectively entrain the jet nozzles and mined minerals due to their continuous fluidization and flow within the borehole. This may also be due to rapid collapse of the open portion of the borehole.

In a third aspect of the invention, there is provided a mining tool for mining subterranean mineral seam material comprising a plurality of fluidising jet nozzles arranged in one or more of the following configurations:

wherein a central fluidizing jet nozzle (a) and one or more side fluidizing jet nozzles (B) are disposed about the mining tool such that they each direct a motive fluid flow at an angle of no more than 100 degrees relative to each other;

wherein one or more side fluidizing jet nozzles (B) are located at a longitudinal distal or proximal position along the mining tool relative to the central fluidizing jet nozzle (a);

wherein each of the plurality of fluidization jet nozzles is configured to direct the flow of motive fluid toward a material longitudinally forward and aft adjacent the production tool; and

wherein the central fluidizing jet nozzle (A) and the one or more side fluidizing jet nozzles (B) comprise different nozzle outlet diameters,

such that, in use, the plurality of fluidising jet nozzles loosen and break down subterranean mineral seam material adjacent the mining tool.

In one embodiment, two side fluidization jet nozzles (B) are disposed about the mining tool such that they each direct the motive fluid flow at an angle of 70 degrees relative to the directed fluid flow directed by the central fluidization nozzle (a).

In another embodiment, two side fluidizing jet nozzles (B) are disposed about the central fluidizing jet nozzle (A) such that they together form a longitudinally spaced diagonal nozzle array adapted to direct the flow of mobilizing fluid within 180 degrees of the circumference of the mining tool.

In another embodiment, the nozzle outlet diameter of the central fluidizing jet nozzle (a) is smaller relative to the one or more side fluidizing jet nozzles (B).

Vertical or horizontal borehole mining is an extremely harsh environment and equipment failure is not uncommon. Typically, equipment for vertical or horizontal borehole extraction includes a plurality of substantially identical nozzles that are supplied with mining fluid to break up or loosen valuable minerals from the ore body. These jet nozzles are typically fed through separate direct lines in an effort to maintain a reliable pressure for each nozzle. Furthermore, such systems typically provide substantially identical nozzles and fluid supply lines.

However, so many fluid supply lines bring about many points of failure and increased initial expense and maintenance costs. These systems are also very inflexible and difficult to customize to the needs of a particular ore body. In practice, these systems are "one-shot" devices, the only variable being essentially the fluid pressure applied to the nozzle.

Applicants have determined that conventional supply systems and nozzle arrangements are neither flexible nor prone to failure.

The differential nozzle system of the present invention allows an operator to provide different fluid pressures, volumes, etc. to ore bodies in different directions. Furthermore, the use of a plenum to supply the nozzles greatly reduces the cost and potential failure points of prior art direct supply systems, while providing a more uniform fluid pressure distribution. In addition to improving performance and reducing unnecessary wear, these characteristics in turn allow the mining tool to be modified or "customized" to suit the particular needs of the ore body at hand.

For example, innovative equipment can be used to access and retrieve ore bodies of significantly different shapes and sizes. For example, because of the differential nozzle configuration, either narrow and tall ore bodies or shallow and flat ore bodies can be recovered using the present invention. Expensive and continuous changes in hardware and control systems are not possible using conventional systems.

In a fourth aspect, the present invention provides a mining tool for mining subterranean mineral seam material by connection to a conduit structure extending from the surface to the subterranean mineral seam along a borehole, wherein the mining tool comprises:

The outer shell of the shell is provided with a plurality of grooves,

a plenum within the housing, connected to the first channel of the piping structure and adapted to receive mining fluid from the first channel,

one or more fluidization jet nozzles in fluid communication with the plenum and operable with the mining fluid to loosen mineral seam material in the vicinity of the tool, an

An eductor arrangement within the housing spaced from and fluidly isolated from the one or more fluidizing jet nozzles, the eductor arrangement being adapted to receive mobilized fluid from the second channel of the piping structure and recover mined material and return in slurry form through the third channel of the piping structure;

the housing defining respective first, second and third generally longitudinally extending fluid passages fluidly connecting respective passages of the conduit structure to the one or more fluidization jet nozzles and the ejector arrangement,

whereby the housing provides a first passageway to supply mining fluid to the one or more fluidising jet nozzles, a second passageway to supply mobilization fluid to the ejector arrangement, and a third passageway to return mined material to the pipeline structure in slurry form,

Wherein the housing is arranged to fluidly isolate mining and mobilization fluids prior to delivery to the plenum and injector arrangement.

In a preferred embodiment, at least the first and second channels are provided by annular channels extending along at least a portion of the length of the housing. More preferably, the annular channels are formed in a nested array, the first and second annular channels being substantially coaxial and having different radii, nested within each other, and a third substantially tubular channel being provided coaxially and radially inwardly of the first and second channels. The ejector arrangement is also preferably located and substantially coaxial within said third passage.

In another embodiment, the housing is provided in two parts, a nozzle part defining the plenum and housing the one or more nozzles, and an ejector part housing the ejector arrangement and defining an ejector inlet to retrieve the slurry and supply the slurry to the ejector arrangement, the first, second and third channels being formed in the ejector part and at least the first channel being formed in the nozzle part, the ejector and nozzle parts being connectable to align the respective first channels in the ejector arrangement and nozzle housing parts.

The first and second annular channels may be continuous or formed as an annular array of tubular ports.

It is a significant advantage of the current apparatus that it is able to supply fluid to the nozzle and eductor arrangements separately through nested annular channels without the need for additional separate fluid lines, as compared to conventional systems. The use of a 3-core housing that mates with a 3-core (3C) tubing system allows for a reliable fluid supply system and efficient return of produced slurry without increasing costs. The complexity and potential failure points of the prior art are largely eliminated.

The elegant design of the present invention allows for different fluid pressures to be applied to the nozzle and eductor arrangement as they remain fluidly isolated. Further, in a preferred embodiment, the eductor arrangement is located at the proximal end of the apparatus near the 3C tube connection end and the nozzle is located at the free or distal end of the apparatus, the design of the invention being such that the first passage is an array of outermost passages extending from the 3C tube connection, bypassing the eductor arrangement exterior and bypassing to the plenum to supply fluid to the fluidization nozzle.

The next innermost channel is the second channel, supplying fluid to the ejector arrangement. This second passage terminates substantially adjacent the ejector arrangement to supply fluid to the ejector arrangement. The third channel is the innermost channel extending from the 3C tube to the injector arrangement (or vice versa in the direction of fluid flow) where it retrieves the mined material released from the ore body back to the surface as a slurry. The use of the housing as a fluid supply and return system provides a reliable and efficient system that integrates multiple functions into a elegant device without the need for additional and separate fluid conduits and the like. The connection to the 3C tubing and the replacement and repair of the various components is relatively simple compared to conventional systems.

In a fifth aspect, the present invention provides an apparatus for mining subterranean mineral seam material, the apparatus being adapted for connection to a conduit structure extending from the surface to the seam along a borehole, wherein the apparatus comprises:

two interconnect modules, comprising:

an eductor module releasably connected at a proximal end thereof to the conduit structure and housing a diffuser assembly adapted to receive motive fluid from the conduit structure,

a fluidization module releasably connected to the distal end of the eductor module and defining a plenum housing a plurality of fluidization nozzles adapted to receive fluidizing fluid from the conduit structure and through the eductor module, an

One or more eductor inlets on the eductor module for receiving and delivering a slurry of minerals and fluids to the surface along the conduit structure,

wherein the diffuser assembly and the fluidization nozzle are releasably mounted within respective modules, and

wherein the modules have substantially the same outer diameter and are adapted to be coaxially connected in use.

In a preferred embodiment, at least two of said inlets are provided on opposite sides of said ejector module.

The fifth aspect of the invention is particularly useful in terms of equipment adapted to different conditions and ease of maintenance, while still maintaining the eductor at the proximal end and the fluidising nozzle at the distal end relative to the ground. As will be explained more fully below, having a separately releasably attachable fluidization nozzle and eductor arrangement facilitates repair and replacement of the various components. If the nozzle or eductor needs modification, repair or replacement, the module can be disconnected and related actions taken. For example, the nozzles in the fluidization module may be easily accessed by simply separating the fluidization module from the eductor module. The nozzle can then be modified, moved, repaired or replaced in a quick and efficient manner. There is no need to unwind multiple fluid lines to each nozzle or the like.

Such distally placed fluidization nozzles were not possible prior to the present invention. Without the innovative modular arrangement described above, maintenance and modification of the equipment would result in significant downtime.

Also, if it is desired to adjust or modify the eductor arrangement, once the modules are separated, in a preferred embodiment the eductor assembly may simply be removed from its housing and appropriate action taken. The inventive eductor module not only performs its function of capturing and returning valuable mined material to the surface as a slurry, but also provides the necessary fluidizing material (e.g., water) to a remotely located fluidizing nozzle. Such a modular arrangement has significant advantages over conventional systems.

The invention includes one or more of the above aspects, alone or in any and all combinations thereof.

Drawings

The invention will now be described, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a cross-sectional view, not to scale, including a partial enlarged view of a mining configuration of a valuable seam into the subsurface, with a mining tool at the far end of the seam, ready to begin mining;

FIG. 2 is a plan view of the field showing the direction of longitudinal alignment of the borehole relative to the seam;

FIG. 3 is an isometric view of the mining tool of FIG. 1, shown in a translucent state for illustrative purposes;

FIG. 4 is a non-transparent isometric view of the injector module of the mining tool shown in FIG. 3;

FIG. 5 is an exploded view of the components comprising the ejector module of FIG. 4;

FIG. 6 is an axial cross-sectional plan view of the ejector module taken along section A-A of FIG. 4;

FIG. 7 is a cross-sectional view of the ejector module taken along the radial section B-B in FIG. 6;

FIG. 8 is a non-transparent isometric view of the fluidization jet module of the mining tool shown in FIG. 3;

FIG. 9 is an axial cross-sectional plan view of the fluidization jet module taken along section A-A of FIG. 8;

FIG. 10 is a simplified transparent cross-sectional plan view of a nozzle arrangement in a fluidization jet module; and

FIG. 11 is a schematic illustration of the operation of the mining tool in a stope.

Detailed Description

It should be understood that the invention disclosed and defined in this specification extends to all alternative combinations of two or more of the individual features mentioned or evident from the text or drawings. All of these different combinations constitute various alternative aspects of the invention.

Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise", "comprising", and the like, are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is, it is understood in the sense of "including but not limited to".

In discussing the features that make up the mining tool, relative positions may be used to reference their positions, such as distal or proximal positions relative to each other or to a particular feature. Thus, the mining tool, relative to the surface-oriented mining pipe to which it is attached, includes a "proximal end" and a "distal end". Thus, the proximal end is defined as the end of the mining tool relatively close to the mining pipe and will thus be close to the ground, while the distal end is the end relatively far from the mining tool and thus inserted farther into the borehole in operation. "front" and "back" are used in a similar context and are defined as the same general direction as "distal" and "proximal".

Likewise, the production tool and its constituent features may be defined in terms of the direction of the directed fluid flow. In this regard, the "upstream" or "downstream" position and/or direction is defined with respect to the fluidization and mobilization fluid flow (described below), both of which are directed from the surface toward the mining tool for loosening target seam material or mobilization fluid as an eductor, respectively. Thus, "upstream" is defined as a location or direction through the mining pipe toward or closer to the ground facility. Conversely, "downstream" is defined as a position or direction toward or closer to the furthest position of the borehole as viewed from the ground level origin of the borehole.

Various aspects of the invention will now be described in the context of the entry and exploitation of an underground seam 10 of ore resources such as rutile, ilmenite and/or zircon, the geological conditions of which are shown in figures 1 and 2. For purposes of illustration, the seam 10 is a longitudinal seam having a length that is substantially greater than a width or depth. For example, the seam 10 may be located about 70 meters below the ground 12, a few kilometers long, an average width of 300 meters, and a height of 5 meters, for purposes of illustration. It is immersed in a body of water that extends to a water level 14 of about 20 meters below the ground 12.

According to a preferred embodiment of the present invention, the subsurface ore layer 10 is accessed through the following sequence of operations. In a first step, a borehole 20 is drilled along the side of the seam 10 from a location 18 on the surface 12 to a second location 19 on the other side of the seam 10 using a surface drilling tool such as a drilling rig. For example, the diameter of the borehole 20 may be in the range of 400 to 450 millimeters. The directional drilling tool and its trailing drill string are directed to begin drilling 20 at a substantial inclination relative to the horizontal (at least 15 °), but then bend through the ground material 90 surrounding the seam 10, into the proximal boundary 11a of the seam 10, and then horizontally through and beyond the seam 10 to the opposite distal boundary 11b. The arrangement is such that the distal section 20b of the borehole passes horizontally or substantially horizontally through the seam 10 at a location on average of about 0.5 meters from the seam bottom 11c to minimize dilution from the bottom. Of course, in other cases, if the bottom of the seam is inclined, the borehole will pass through the seam at a corresponding inclination.

As shown in fig. 2, the alignment of the bore holes 20 is such that the distal section 20b extends obliquely to the longitudinal alignment relative to the seam 10, typically at an angle of about 13 °. As a result, the section extends up to 600 meters in the seam. The total length of the borehole from entry location 18 to location 19 may be 1 km or more.

If desired, the initial section 20a of the borehole 20 will be cased: in this embodiment, a sleeve has been installed and is shown at 13. The casing 13 is typically installed during the drilling process: when the drilling tool reaches the seam 10 for the first time, the drilling is stopped and the casing 13 is flushed on the drill string to a boundary 11a near the seam side. The drilling is then restarted.

Once the borehole is completed and casing is required, the mining tool 30 at the head of the trailing mining pipe 35 is pushed into the borehole by a suitable drill rig which has been converted to process the mining pipe 35. The conversion mainly involves providing a mining rotator and a mining foot grip to handle the mining pipe 35, the mining pipe 35 being larger than the pipe normally driven by the drilling machine. The mining tool 30 and the mining pipe assembly are pushed into the borehole until the mining tool 30 reaches the location 19 distal 11b of the seam 10.

In a first embodiment of the invention, the mining pipe 35 is a known "three-core" (3C) mining pipe having a coaxial structure with a central passageway 32 and two surrounding annular passageways 33 and 34. The mining pipe is provided in sections of length, for example 6 to 12 metres, which are added continuously as the pipe is pushed into the borehole. The segment connections are threaded, i.e., threaded tubular connections, designed to minimize energy loss and promote gentle curvature of the pipe as it passes through the curved borehole.

The surface facility is typically configured to deliver high pressure fluid, typically water, to the intermediate and outer annular pipe channels 33 and 34 and to recover a slurry of mined material from the central channel 32. The mining tool 30 is initially positioned with its distal or free end proximate to but offset from the distal seam boundary 11b in preparation for starting mining. The size of the central passage 32 is used to maintain the minimum slurry transport speed required to minimize particle deposition in the pipeline.

The mining tool 30 configured as the first embodiment of the invention will now be described with reference to fig. 3 to 10.

As shown in fig. 3, the mining tool is in modular form, including at least one pair of coupled modules 60, 62. The injector module 60 is adapted to be coupled at one end to the end of the mining pipe 35 and at its opposite end to the rear end of the fluidization or mining module 62 by a low profile adapter module 35 a. One or more fluidization jet nozzles 42, 43, 44 located on the fluidization jet module 62 are disposed at the distal or downstream end of the production tool relative to the injector arrangement comprising the injector module 60, with the injector module 60 being located at the proximal or upstream end of the tool 30.

As shown more clearly in fig. 8, in another embodiment, modules 60 and 62 may be axially and fluidly connected by an elongated housing 63 disposed therebetween. Such an elongated housing (any length) allows for adjustment of the distance between the nozzle and the eductor assembly 69 (fig. 6, discussed below) by extending the length of the first plenum 66 (discussed below).

The forward facing end of fluidization module 62 may be closed by nose cone 64 or mounted to nose cone 64. Also, referring to fig. 8, a drag bit comb 64b may be provided on the leading tip surface 64a of the nose cone 64. The drag bit comb 64b includes a plurality of leading edges projecting from a sharp front face adapted to effectively divide and direct fluid toward the sides of the production tool. In embodiments where a drag bit comb 64b is provided, the fluid resistance is reduced when the production tool is inserted into the borehole.

All three modules include substantially tubular wear resistant housings 60a, 62a, 64a of substantially the same diameter such that they provide a smooth cylindrical profile when assembled coaxially. The modules may be connected using a tapered lock/clamp ring design, a threaded screw design, and/or a flange bolt design. Each connection is sealed between each module using an O-ring to make it waterproof.

As shown in fig. 8, 9 and 10, the fluidization module 62 has an internal plenum 66 defined by the inner cylindrical surface 62b of the housing 62 a. In use, high pressure fluid is provided from the mining pipe 35 to the plenum 66 through the injector module 60 (described below). Such high pressure fluidizing fluid, such as water, passes from the annular passage 34 in the mining pipe, through the first outermost passage 34' in the injector module 60 (see fig. 6), and through the annular array of tubular ports 34 "in the crossover block 60b (see fig. 7), and into the plenum 66.

Referring to fig. 8, 9 and 10, fluidizing jet nozzles 42, 43, 44 are mounted in and supplied by fluid in plenum 66. Preferably, each nozzle comprises a modular nozzle unit mounted to the body of the first plenum 66 so that they can be easily replaced or repaired.

The nozzles are preferably arranged in a longitudinally spaced diagonal array, although the nozzles may be arranged in any desired configuration or array. In one embodiment, the central nozzle 43 is oriented substantially vertically, while the other nozzles 42, 44 are positioned respectively in front of and behind the centrally located nozzle 43. The front and rear nozzles 42, 44 are adapted to face substantially the sides of the tool.

It should also be noted that in the illustrated embodiment, all of the nozzles are located substantially above or on the axis of the fluidization module 62 (see, e.g., fig. 10). Thus, the nozzle array may be disposed on a semicircular face of the production tool so as to collectively direct a high pressure fluid jet over the tool for a scan of about 180 °. The scanning range of these jets may be slightly greater than 180 deg. if desired, so that a small portion is directed outwardly and downwardly relative to the horizontal plane of the tool. Thus, the nozzles may be disposed on the surface of the production tool to direct the high pressure fluid jets at a plurality of angles relative to each other, each angle varying from 0 to 100 degrees. Alternatively, the nozzles may also be arranged to direct the high pressure fluid jet in a fan shape of less than 180 degrees such that the jet is inclined slightly upwards from the horizontal plane of the mining tool, i.e. the nozzles are at an angle of 0 to 100 degrees with respect to each other.

Fig. 9 shows the side nozzles 42 and 44 longitudinally spaced from the central and upwardly facing nozzle 43, with the side nozzles 42 and 44 being located on generally opposite sides of a generally tubular mining tool. As shown in FIG. 10, the opposing nozzles 42 and 44 are preferably both disposed on the mining tool about 70 degrees from the central nozzle 43 such that the nozzle arrays collectively direct the high pressure fluid jets 41 over a scanning range of about 140 degrees above the mining tool.

The nozzles 42, 43, 44 may also be generally adjustable to direct fluid jets either forward or aft of the axis of the tool. This may be accomplished by physically replacing the nozzle unit with a different fluid jet firing angle, or by installing a nozzle unit whose jet direction is remotely controllable. Depending on a variety of factors, such as entrained solids concentration, desired flow rates, material properties, and stope profile, the nozzle angle may be adjusted to direct the fluidization jet between 0 degrees and 40 degrees toward the front or rear of the mining tool relative to the longitudinal axis of the tool. As shown in fig. 9, the nozzles 42, 43 and 44 are preferably inclined toward the rear of the mining tool by about 20 degrees.

The ejector module 60, which functions to extract or retrieve materials separated from the seam, is now discussed with reference to fig. 4, 5 and 6, as described below. The ejector module has a housing 60a, an intermediate tube 61 and a central tubular passage 32. Between the housing 60a and the tube 61, an annular passageway or channel 34' is formed. Similarly, between the intermediate tube 61 and the central tubular passage 32, an annular passageway or channel 33' is formed.

Again, it can be seen that once the eductor module 60 is separated from the fluidization module 62, the internal objects of the eductor module 60 (i.e., the tubes 61 and 32) and thus the eductor assembly 69 may be quite directly accessed for maintenance, modification, replacement, etc.

Within the ejector module 60 is an ejector assembly 69, the ejector assembly 69 comprising a diffuser assembly 72, a diffuser throat 73 and a motive nozzle (motive nozzle) 70 to form an axially symmetric ejector arrangement, wherein the diffuser throat inlet 73a is located downstream of the motive nozzle 70 (in this case downstream towards the proximal end of the tool) and the converging portion 73b of the diffuser and suction chamber 48 is disposed about a rear conical portion 67a of the second plenum 67, the rear conical portion 67a terminating at the nozzle 70.

The motive nozzle 70 is supplied with pressurized motive fluid (e.g., water) through the annular passage 33' and the port 33 ". Such fluid passes from the mining pipe 35 (not shown) along the channel 33' via the port 33 "into the plenum 67 and into the motive nozzle 70. As known to those skilled in the art, such an motive fluid for the diffuser assembly 72 creates a low pressure volume within the suction chamber 48. Inlet ports 71 are provided on either side of the eductor module 60 from which mined material may enter the eductor assembly 69 as a slurry that is a mixture of particulate matter entrained in groundwater and fluidizing fluid emitted from the fluidizing jets 42, 43 and 44. The slurry is then directed along the diffuser assembly 72 and thus into the channel 32 and along the channel 32 by the ejector motive jet emitted by the motive nozzle 70, the motive nozzle 70 being disposed just upstream of the minimum limit point at the diffuser throat inlet 73a of the diffuser assembly 72.

In conventional borehole production systems, it is generally desirable to have extraction/retrieval equipment at the distal or free end of the production tool and the fluid connection to the production or fluidization jet is very simple. The conduit will typically direct fluid to each nozzle for fluidization or mining. However, since the present invention proposes to place the nozzles 42, 43, 44 toward the distal end of the device and the extraction/eductor system toward the proximal end, it is not possible or desirable to have such a "one-to-one" fluid supply system.

It will be appreciated that the annular channels 34 'and 33' of the transverse block 60b in the eductor module 60, along with the cylindrical or tubular ports 33 "and 34", are shaped to pass between and around the internal module structure defining the inlet port 71 and the suction chamber 48. Preferably, the ports 33 "and 34" are arranged as clusters arranged in an arcuate manner around the horizontally and laterally arranged suction chambers 48.

As shown in fig. 7, the tubular ports 34 "are preferably arranged in two arcuate clusters around the suction chamber 48 of the ejector module 60 to supply fluid from the annular channel 34' to the plenum 66. The fluid is delivered from the plenum to a plurality of fluidization jet nozzles. As discussed below, preferably three fluidization jet nozzles 42, 43, 44 are disposed in the plenum 66 and directed outwardly to the housing 62a for breaking down minerals in the ore body.

In a similar manner, a plurality of tubular ports 33 "supply fluid from the annular channel 33' into the smaller second plenum 67. As shown in fig. 6, a baffle 68 may be provided at the front end of the ejector module 60, whereby a sealing boundary is defined between the rearward smaller second plenum 67 of the motive nozzle 70 and the larger forward plenums 66 of the fluidizing jet nozzles 42, 43, 44, described in the appropriate process. The second plenum 67 is adapted to receive fluid flow from the second or intermediate passage 33 of the mining pipe via the corresponding annular passage 33' of the injector module 60 and the tubular port 33 "of the lateral block 60 b.

As shown in fig. 7, the channel 33' preferably comprises two arced tube groups arranged between the suction chamber 48 and the tubular port 34 "so as to direct the fluid flow around the suction chamber 48. The fluid flow is different and separate from the fluid flow supplied to said first plenum 66 through the annular passage 34, such that the fluid pressure and flow rate can be adjusted accordingly to suit the requirements of the fluidising nozzles and/or the eductor.

The operation of the mining tool will now be discussed.

The modules 60, 62 and 64 are coaxially connected to each other and then connected to the mining pipe. The apparatus is positioned within the borehole and pressurized fluid is provided to the fluidization/mining jet and eductor as disclosed above. Both the fluidization and mobilization fluid flow rates gradually rise to the operating flow rates and pressures. Once at the operational flow rate and pressure, the nozzles 42, 43 and 44 begin to emit fluidized jets which break down the mineral seam material in the semicircular or swept area as the mining tool is withdrawn through the seam toward the surface. Preferably, the disintegration is performed as a fluidization process rather than a cutting process, which is accomplished by a small number of large-volume larger nozzles rather than a larger number of smaller nozzles. To achieve stable fluidization of adjacent seam material, each nozzle is adapted to direct a jet of high pressure fluid sufficient to fluidize the target seam material, thereby forming a semi-circular "back taper" of fluidized material flowing adjacent the mining tool. While the fluid pressure required to decompose the target material will depend on several operating factors such as mineral type, seam strength and drilling pressure, the sand targeted in the present invention requires a jetting pressure of 100 to 140bar (10,000 to 14,000 kPa). Preferably, the nozzle is adapted to direct a jet of fluid of about 120 bar.

By adjusting the outlet diameter of each nozzle, the above injection fluid pressure can be further optimized for the mineral matter to be mined, the shape of the seam and/or the desired fluid flow. The discharge velocity of the jet fluid, and thus the impact energy, may be increased by decreasing the diameter, resulting in increased cutting of the mineral seam material adjacent the conditioned nozzle. Conversely, if mineral seam fluidization is desired, a relatively larger nozzle diameter is used to provide increased flow rates, particle fluidization, and subsurface flow. In this way, strategic placement of nozzles having different diameters can assist in the movement of the target material by providing a fluid flow of an appropriate mixture having cutting and/or fluidization characteristics so as to maximize the overall material flow and decomposition within the seam. Thus, the outlet diameter of the nozzles arranged on the mining tool may be in the range from 5mm to 40 mm. Preferably, a nozzle comprising an outlet diameter of 8mm to 20mm is provided along the mining tool to maximize fluidization and recovery. In a preferred configuration, the nozzles 42, 44 arranged on the sides of the mining tool are larger than the central vertically arranged nozzle 43. In a specific embodiment, the side nozzles have a diameter of about 14mm and the center nozzle has a diameter of about 8 mm.

The broken down material produced by the cutting and/or fluidizing fluid jet falls into a so-called capture zone 46 of relatively low pressure on either side of the eductor module 60, adjacent to one or more inlet ports 71 at the periphery of the housing 60 a. When falling into this low pressure capture zone, the decomposed material mixes with and becomes entrained in groundwater and/or high pressure sprayed fluid.

Additionally or alternatively, the fluidization fluid jets are directed at the seam to cause substantial fluidization of adjacent seam material. Fluidized material flows within the seam toward a capture zone from which the fluidized material is collected and recovered as a slurry via the one or more inlet ports 71.

Furthermore, loss of seam integrity caused by movement and removal of the seam material promotes further erosion or partial collapse of surrounding material, thereby causing further fluidization of the target seam. Any one or any combination of the above flow features may be used to facilitate mobilization and bulk recovery of target seam material using the apparatus and methods of the present invention.

The resulting slurry containing particulates of the material released from the seam is collected from the capture zone 46 through one or more inlet ports 71 in the eductor module 60, from where it enters the suction chamber 48, and the suction chamber 48 communicates with the central passage 32 of the mining pipe 35 and the adapter module 35a via a diffuser 72 containing a diffuser throat 73. One or more inlet ports 71 may be present on opposite sides of the tool or at different angular positions and/or one inlet port 71 may be present on the top surface of the housing 60 a. In some embodiments, the ports are positioned substantially flush with the axis of the apparatus or vertically lower about the mining tool than the nozzle array to effectively receive slurry produced by fluidizing the mineral seam material. In the preferred embodiment where the nozzle array is arranged for directing fluidizing fluid at 140 degrees of sweep over the tool, two side inlet ports 71 are arranged on opposite lateral sides of the housing 60 a.

This process of fluidising the mineral seam material continues as the mining tool is withdrawn from the borehole, and is subsequently captured as a slurry and transported to the surface. The nozzles 42, 43, 44 break down and fluidize the material from the seam, which is entrained and mixed with both water and groundwater from the fluidising jet from where it is recovered/collected by the eductor module 60 and returned to the surface.

However, it will be noted that the one or more inlet ports 71 and the eductor assembly 60 are toward the proximal end of the apparatus. This is completely counterintuitive. It seems inefficient to have the recovery device essentially upstream of the fluidization and/or cutting jet. However, the inventors have obtained an elegant and efficient method and design that not only works at least as well as prior art systems, but, as noted above, provides a number of benefits over conventional systems.

Several factors are considered and balanced to determine the optimal spacing of the eductor arrangement in the proximal/upstream direction from the fluidization and/or cutting nozzles. These factors include, but are not limited to, the number and arrangement of inlet ports, nozzle fluid pressure, solids entrainment concentration, stope geometry, production tool size, and suction pressure created by motorized fluid flow rates and back pressure. Thus, one or more inlet ports for the suction chamber may be arranged from one or more nozzles in the proximal or upstream direction at a distance in the range of 0 to 5 meters. Preferably they are spaced from each other by 1 to 4 meters. More preferably, the one or more eductor inlets are spaced 1 to 2 meters, and most preferably about 1.5 meters, from the central vertical nozzle of the diagonally disposed nozzle array.

These one or more inlet ports 71 may also include a corresponding grill, screen or screen structure adapted to provide sufficient suction pressure to the eductor mechanism throughout the suction chamber 48 and diffuser 72 while also controlling the entrained particle size of the mined material entering the eductor module for recovery to the surface. Thus, these grid or screen structures are typically designated to allow slurry to enter the eductor module at a flow rate for any given solids concentration, desired recovery flow rate, and particle size. Thus, theseThe target slurry flow rate of the grid or screen structure may be in the range of 50 to 500m ³ In the range of/h, preferably between 100 and 300m ³ Between/h. Under specific operating conditions, the grid or screen structure 74 is sized to permit about 175m ³ The slurry flow rate/h is such as to generate a suction pressure of about 6bar in the suction chamber.

Further to the above, a grid or screen structure is also specified to control oversized of slurry-entrained mineral seam material entering the eductor arrangement. Controlling the grain size in the form of grain size is important in ensuring that the grain velocity is maintained between the mining tool and the surface throughout the mining pipe. By maintaining a sufficient particle velocity, sedimentation and clogging of the interior of the mining pipe can be avoided. Thus, the grid or screen structure is designated to allow slurry comprising particles having a diameter substantially between 20% and 99% of the narrowest point of the recovery channel to reach the surface, i.e., the diameter of the diffuser throat 73 including the throat inlet 73a of the eductor assembly 69.

To achieve the above operating parameters, the grid or screen structure is adapted accordingly. A series of grid arrangements may be used including, but not limited to, a strip grid, a perforated grid, a rectangular grid, and a wire-structured filter mesh. The material for the grid or screen structure is adapted to the grinding operating conditions of the mining tool. Thus, materials used include, but are not limited to, hard-wearing metal alloys (such as high carbon Abrasion (AR) steel), ceramics (such as metal borides, nitrides or carbides), and/or structural metals coated with the ceramics.

The number, size and shape of these perforations are carefully optimized in order to achieve the desired operating parameters. Thus, the number of holes may be in the range of 2 to 300, and the hole size diagonal is in the range of 100 to 10 mm. In a preferred embodiment shown in fig. 4 and 5, one or more of the inlet ports 71 comprises a tungsten carbide grid 74 having six circular through holes 75. Preferably, the diameter of these through holes is 43mm.

Particulate matter entrained in the groundwater and injected fluidizing fluid is directed as slurry along the diffuser assembly 72 and thus enters through the injector motive jet emitted by the motive nozzle 70 and is directed along the passageway 32 just upstream of the minimum limit point of the throat inlet 73a of the diffuser throat 73.

It will be appreciated that the longitudinal tubular passage 33 "and cylindrical tube 34" of the ejector module 60 may be shaped to pass between and around the internal module structure defining the inlet port 71 and the suction chamber 48. Preferably, the duct forms two such clusters arranged in an arcuate manner around the horizontally and laterally arranged suction chambers 48.

The diffuser assembly 72, diffuser throat 73 and motive nozzle 70 are axially symmetric ejector assemblies 69 with the diffuser throat inlet 73a downstream of the motive nozzle 70 and the converging portion 73b of the diffuser and suction chamber 48 disposed about the aft conical portion 67a of the second plenum 67 terminating at the nozzle 70.

In a preferred embodiment, the fluidizing fluid in the form of high pressure water is delivered to the first plenum 66 along the annular channel 34 and adapter module of the mining pipe 35, and then along the annular channel 34' and tubular channel 34 "of the injector module 60. The high pressure water from the first plenum 66 is used to drive the nozzles 42, 43, 44, while the different and separate mobilized fluid streams fed from the intermediate channel 33 of the mining pipe 35 via the annular channel 33' and the tubular channel 33 "of the injector module are used to drive the injector assembly 69 within the injector module 60.

Various aspects of the injector arrangement, including the mobilization fluid flow rates through channels 33' and 33″ and the mobilization nozzle and diffuser specifications, are optimized to effectively and economically recover mined material over significant distances and subsurface depths. For fluidization water delivery pressures in the range of 80 to 140bar (8,000 to 14,000 kPa), the eductor configuration may be optimized for rotary joints returning slurry of mined rutile, ilmenite, and/or zircon material all the way to the surface, up to 500-1000m, a vertical height gain of 70m, and a flow rate of 200 to 400m ³ And/or hours. Such a configuration is highly effective in achieving economical recovery of heavy sand from an underground seam.

The domed head section 79 of the nose cone 64 closes the first plenum 66 on the distal side of the nozzle assembly and forms a barrier to seal the fluidization jet module 62 and connect the rear end of the nose cone 64. Nose cone 64 may include instrumentation for detecting the lateral orientation of the mining tool, and a plurality of sonar sensors 80 that provide a means to obtain or "see" the shape and volume of the cavity or stope and the shape of the face to allow the mining operator to see downhole and thus adjust the mining tool and the overall assembly as near real time as possible for optimal impact. These instruments preferably communicate with the surface operator via associated transmitter equipment and wireless technology, a modular system bolted to the mining pipe.

Referring to fig. 11, as the mining jet 41 ejected by the nozzle breaks down the material of the seam surrounding the mining tool and the particles are conveyed as a slurry along the central conduit passageway 32, the mining pipe 35 and attached mining tool 30 are slowly and steadily pulled back toward the ground location 18 to expose new seam material 10a to the jet and gradually expand the cavity or stope 45 within the seam.

The production tool is pumped to the surface at a rate that balances the volumetric flow rate of the fluidizing fluid and the solids concentration in the recovery slurry. Thus, the extraction rate may be in the range of 0.1 to 10 meters per hour and may be adjusted based on information including, but not limited to, stope profile telemetry from the sensor module and solids concentration in the recovered slurry. The mining tool is preferably withdrawn at a speed in the range from 1m/h to 3m/h, or even more preferably at 1.5 m/h.

Once the stope is established, the extraction rate is optimised to ensure that the ports defining the fluid entry into the eductor arrangement are not covered or blocked by the mineral seam material, thus avoiding any obstructions that prevent collection and recovery of entrained slurry. As shown in fig. 11, the suction chamber 48, which is longitudinally aligned with the ejector motive nozzle 70, is located downstream of the mining edge of the stope 45. Thus, the low pressure capture zone 46 remains free of mineral seam material that remains loose, allowing the eductor to be fed uninterrupted with mined slurry. During continuous production operations, the withdrawal speed, nozzle angle, and fluid pressure are adjusted to maintain this advanced position of the injector port relative to the stope edge.

In a typical full-scale mining operation, the illustrated mining configuration will be one of a plurality of such configurations arranged in parallel, thereby extracting material from a series of obliquely extending stopes spaced apart in the longitudinal direction of the seam. Each stope may be 6 to 20m wide, for example 10-15m wide, and 3-5m high. It is believed to be preferable to locate the corresponding boreholes such that the spacing is greater than the cavitation capacity of the mining tool so as to leave narrow longitudinally extending columns (e.g. 1m width) between the stopes. This allows for better management and control of the material extracted from each time.

When the stope is excavated, the corresponding mining tool and its associated mining pipe are withdrawn from the borehole and brought to the newly drilled borehole (beyond the nearest of those installed). The open bore just emptied can be used (with suitable equipment) to backfill the empty cavity, for example with non-valuable or waste tailings or the like separated from the previously mined valuable material.

Those skilled in the art will recognize that the invention described herein is susceptible to variations and modifications other than those specifically described. It is to be understood that the invention includes all such variations and modifications which fall within the spirit and scope of the invention.

Claims

1. A mining tool for mining a subterranean formation material by connection to a conduit structure extending from the surface to the subterranean formation along a borehole, the conduit structure having at least a first passageway, a second passageway and a third passageway, the first passageway and the second passageway for delivering high pressure fluid to the mining tool, respectively, and the third passageway for recovering a slurry containing the mined material, wherein the mining tool comprises:

a plenum connected to the first channel of the piping structure and adapted to receive a high pressure fluid from the first channel,

one or more fluidising jet nozzles in fluid communication with the plenum, operable to use the high pressure fluid to displace mineral seam material in the vicinity of the tool, and

an eductor arrangement adapted to recover and entrain the mined material in the high pressure fluid stream conveyed in the second channel to return the material as a slurry along the third channel, wherein the one or more fluidizing jet nozzles are disposed distally relative to the conduit structure and the eductor arrangement is disposed proximally relative to the conduit structure,

Such that in use the one or more fluidising jet nozzles render the material movable and the eductor is arranged at a proximal position relative to the conduit structure to recover the slurry while the production tool is continuously withdrawn along the borehole in the direction of the surface.

2. The mining tool of claim 1, wherein the one or more fluidization jet nozzles are disposed at least between 0 to 3 meters from the injector arrangement.

3. The mining tool of claim 2, wherein the one or more fluidization jet nozzles are disposed between 1 and 2 meters from the injector arrangement.

4. A mining tool as claimed in any one of the preceding claims, wherein the mining tool is disposed along a horizontal or substantially horizontal borehole.

5. A mining tool as claimed in any preceding claim, wherein the one or more openings providing fluid connection between the injector arrangement and the borehole comprise a grid or screen arrangement for controlling the slurry pressure therethrough and/or controlling the size of fragments of the material in the slurry.

6. The mining tool of claim 5, wherein the mining tool includes two openings disposed on opposite sides of the mining tool.

7. The mining tool of claim 6, wherein the two openings disposed opposite each other are vertically horizontal in use.

8. The mining tool of any of claims 5 to 7, wherein the grid or screen structure is adapted to maintain a slurry suction pressure of 400 to 800 kPa.

9. The mining tool of claim 8, wherein the grid or screen structure is adapted to maintain a slurry suction pressure of 600 kPa.

10. A method of mining subterranean mineral seam material comprising connecting a mining tool with a conduit structure extending along a borehole from the surface to the seam, the conduit structure having at least a first passageway, a second passageway and a third passageway, the first and second passageways for delivering high pressure fluid to the mining tool, respectively, and the third passageway for recovering a slurry containing the mined material, wherein the mining tool comprises:

a plenum connected to the first passage of the piping structure and receiving high pressure fluid from the first passage;

one or more fluidization jet nozzles fluidly connected to the plenum that direct the high pressure fluid to move material of the mineral seam adjacent the mining tool; and

An eductor arrangement for recovering and entraining the mined material in the high pressure fluid stream delivered by the second channel, returning the material as a slurry along the third channel,

the one or more fluidizing jet nozzles are disposed distally with respect to the conduit structure, and the ejector arrangement is disposed proximally with respect to the conduit structure,

wherein the production tool supplies fluid to the one or more fluidising jet nozzles and the injector while continuously withdrawing along the borehole in the surface direction so that the material loosens from the seam and is recovered as a slurry by the injector arrangement at the proximal end.

11. The method of claim 10, wherein material adjacent to the tool is loosened by high pressure fluid directed by the one or more fluidization jet nozzles, the fluidization jet nozzles being disposed at least between 0 and 3 meters from the injector arrangement.

12. The method of claim 11, wherein the one or more fluidization jet nozzles are disposed between 1 and 2 meters from the ejector arrangement.

13. A method according to any one of claims 10 to 12, wherein the subsurface mineral seam material is mined by a mining tool disposed along a horizontal or substantially horizontal borehole.

14. A method according to any one of claims 10 to 13, wherein the slurry pressure and/or chip size of the material recovered by the eductor is controlled by a grid or screen structure comprising one or more openings providing a fluid connection between the eductor arrangement and the bore.

15. The method of claim 14, wherein the slurry is recovered through two of the openings disposed on opposite sides of the production tool.

16. The method of claim 15, wherein the mining tool is oriented such that the two oppositely disposed openings are horizontal in a vertical direction.

17. A method according to any one of claims 14 to 16 wherein the grid or mesh structure maintains the slurry suction pressure between 400 and 800 kPa.

18. The method of claim 17, wherein the grid or screen structure maintains the slurry suction pressure at 600kPa.

19. A mining tool for mining subterranean mineral seam material, comprising a plurality of fluidising jet nozzles arranged in one or more of the following configurations:

wherein a central fluidizing jet nozzle (a) and one or more side fluidizing jet nozzles (B) are disposed about the mining tool such that they each direct a flow of mobilizing fluid at an angle of no more than 100 degrees relative to each other;

Wherein one or more side fluidizing jet nozzles (B) are located at a longitudinally distal or proximal position along the mining tool relative to the central fluidizing jet nozzle (a);

wherein the central fluidizing jet nozzle (a) and one or more side fluidizing jet nozzles (B) comprise different nozzle outlet diameters such that, in use, the plurality of fluidizing jet nozzles loosen and break down subterranean mineral seam material adjacent the mining tool.

20. The mining tool according to claim 19, wherein two side fluidization jet nozzles (B) are arranged around the mining tool such that they each direct the mobilization fluid flow at an angle of 70 degrees relative to the directing fluid flow directed by the central fluidization nozzle (a).

21. The mining tool according to claims 19 and 20, wherein two side fluidizing jet nozzles (B) are arranged around the central fluidizing jet nozzle (a) such that they together form a longitudinally spaced diagonal nozzle array adapted to direct the flow of mobilizing fluid within 180 degrees around the mining tool.

22. The mining tool of any of claims 19 to 21, wherein the central fluidizing jet nozzle (a) comprises a smaller nozzle outlet diameter relative to the one or more side fluidizing jet nozzles (B).

23. A mining tool for mining a subterranean formation material by connection to a pipe structure extending from the surface to the subterranean formation along a borehole, wherein the mining tool comprises:

the outer shell of the shell is provided with a plurality of grooves,

a plenum within the housing connected to the first passage of the piping structure and adapted to receive mining fluid from the first passage,

24. The mining tool of claim 23, wherein at least the first and second passages are provided by an annular passage extending along at least a portion of the length of the housing.

25. The mining tool of claim 24, wherein the annular channels are formed in a nested array, the first and second annular channels being substantially coaxial and having different radii, nested within each other, and a third substantially tubular channel being provided coaxially and radially inwardly of the first and second channels.

26. The mining tool of claims 24 and 25, wherein the injector arrangement is also disposed in a position substantially coaxial with the third passageway.

27. The mining tool of any of claims 24 to 26, wherein the first and second annular channels are continuous or formed as an annular array of tubular ports.

28. The mining tool of any of claims 23 to 27, wherein the housing is provided in two parts, a nozzle part and an ejector part, the nozzle part defining the plenum and housing the one or more nozzles, the ejector part housing the ejector arrangement and defining an ejector inlet to retrieve the slurry and supply the slurry to the ejector arrangement, the first, second and third channels being formed in the ejector part and at least the first channel being formed in the nozzle part, the ejector part and the nozzle part being connectable such that the respective first channels are aligned in the ejector arrangement and nozzle housing part.

29. An apparatus for mining subterranean mineral seam material, the apparatus being adapted for connection to a conduit structure extending from the surface to the seam along a borehole, wherein the apparatus comprises:

two interconnectable modules comprising:

an ejector module releasably connected at a proximal end thereof to the conduit structure and containing an ejector arrangement adapted to receive motive fluid from the conduit structure;

a fluidization module releasably connected to the distal end of the eductor module and defining a plenum housing a plurality of fluidization nozzles adapted to receive fluidization fluid from the conduit structure through the eductor module; and

One or more inlets on the eductor module for receiving and delivering a slurry of material and fluid to the surface along the conduit structure,

wherein the ejector arrangement and the fluidising nozzle are releasably mounted within respective modules,

and wherein each of said modules has substantially the same outer diameter and is adapted to be coaxially connected in use.

30. The apparatus of claim 29, wherein at least two of the inlets are disposed on opposite sides of the eductor module.