Method of extracting material from a sub-surface formation, and probe assembly for such extraction

Abstract

There is described a method of extracting material from a sub-surface formation.  One or more probe assemblies are inserted into the sub-surface formation comprising soil.  The soil within a zone of influence of the one or more probe assemblies is liquefied by vibrating the one or more probe assemblies and ejecting a fluid from the one or more probe assemblies and into the sub-surface formation.  The liquefied soil is extracted from the sub-surface formation.

Description

 Field

[01] The present disclosure relates to material extraction, and in particular to methods of extracting a target material, such as minerals or soil, from a sub-surface formation. The disclosure further relates to a probe assembly that may be used for such extraction.Background

[02] Traditional land-based methods of mineral extraction include, for example, open pit mining. Such methods, however, are generally expensive, equipment-intensive, and highly disruptive to the surrounding environment. Moreover, environmental damage, including excessive greenhouse gas emissions, caused from open pit surface mining can be extensive.

[03] In contrast, conventional offshore mining methods employ mechanical excavators and a processing plant on a floating barge. As a result, the depth of mining is limited by the boom and stick length of the excavator, and tidal influences. Furthermore, excavated material typically includes non-mineral bearing gravels, cobbles, and boulders, and this material can generally only be removed from the top few feet of the sea floor. Material is also lost as the bucket is raised from the sea floor to the processing plant due to the angle of the bucket and washout from surrounding waters.

[04] Meanwhile, small offshore mineral extraction methods rely on divers who descend to the sea floor and manipulate a suction dredge to extract placer deposits from the surface of the sea floor. Such methods, however, yield very low production and recovery rates, are highly weather dependent, and can be dangerous to the personnel involved.

[05] Similarly, traditional methods of dredging waterways and ports involve the use of barge-mounted mechanical equipment of varying types. Such methods typically involve the digging of the seabed, and some may involve the suction of materials in combination with digging. These methods are expensive, equipment-intensive, and relatively inefficient.Summary

[06] According to a further aspect of the disclosure, there is provided a method of extracting material from a formation, comprising: inserting one or more probe assemblies into the sub-surface formation comprising soil; liquefying the soil within a zone of influence of the one or more probe assemblies, wherein the liquefying comprises vibrating the one or more probe assemblies and ejecting a fluid from the one or more probe assemblies and into the sub-surface formation; and extracting the liquefied soil from the sub-surface formation.

[07] The sub-surface formation may further comprise a target material. The extracting may further comprise extracting the target material with the liquefied soil from the sub-surface formation.

[08] The extracting may comprise sucking the liquefied soil through the one or more probe assemblies and out of the sub-surface formation.

[09] The fluid may comprise one or more of pressurized air and pressurized water.

[010] The liquefying may further comprise repeatedly raising and lowering the one or more probe assemblies within the sub-surface formation.

[011] Inserting the one or more probe assemblies into the sub-surface formation may comprise inserting the one or more probe assemblies into a first location in the sub-surface formation. The method may further comprise removing the one or more probe assemblies from the first location and inserting the one or more probe assemblies into a second location in the sub-surface formation.

[012] The first location may be spaced from the second location by 2-3 feet.

[013] The method may further comprise removing the one or more probe assemblies from the second location and inserting the one or more probe assemblies into further locations in the sub-surface location so as to form a grid of locations into which the one or more probe assemblies have been inserted in the sub-surface formation.

[014] Adjacent rows of the grid may be offset from one another by about 1.25 – 1.75 feet.

[015] The extracting may comprise filtering the liquefied soil such that only particles having a diameter less than 100 mm are extracted.

[016] The one or more probe assemblies may comprise a first probe assembly and a second probe assembly. The liquefying may comprise vibrating at least the first probe assembly and ejecting the fluid from at least the first probe assembly and into the sub-surface formation. The extracting may comprise sucking the liquefied soil through the second probe assembly and out of the sub-surface formation.

[017] The extracting may further comprise sucking the liquefied soil through only the second probe assembly and out of the sub-surface formation.

[018] The sub-surface formation may comprise a subterranean formation, part of a seabed, or part of a floor of a waterbody.

[019] The method may further comprise separating the extracted target material from the extracted soil.

[020] The target material may comprise one or more of placer minerals, rare earth minerals, and oil sands.

[021] The liquefying may comprise vibrating the first and the second probe assemblies.

[022] Inserting the one or more probe assemblies into the sub-surface formation may comprise inserting the one or more probe assemblies using one or more follower tubes connected to the one or more probe assemblies.

[023] Inserting the one or more probe assemblies into the sub-surface formation may comprise inserting the one or more probe assemblies using one or more flexible cables connected to the one or more probe assemblies.

[024] According to a further aspect of the disclosure, there is provided a probe assembly for use in extracting material from a sub-surface formation, comprising: an elongate housing having an upper end and a lower end for inserting into the sub-surface formation; a vibrator at the lower end of the housing for imparting vibrations to the material within a zone of influence of the vibrator; one or more fluid ejectors for enabling a fluid pumped from the upper end of the housing toward the lower end of the housing to be ejected out of the housing; and one or more suction conduits extending at least partway along a length of the housing and configured to allow liquefied soil sucked into the one or more suction conduits to be directed toward the upper end of the housing.

[025] The probe assembly may further comprise a nose cone at the lower end of the housing and comprising apertures formed therein for allowing liquefied soil to be sucked into the housing via the nose cone.

[026] The apertures in the nose cone may be connected to the one or more suction conduits for allowing liquefied soil to be sucked into the one or more suction conduits via the nose cone.

[027] The probe assembly may further comprise a mesh-like structure positioned between the upper and lower ends of the housing, wherein the mesh-like structure comprises apertures formed therein for allowing liquefied soil to be sucked into the housing via the mesh-like structure.

[028] The apertures in the mesh may be connected to the one or more suction conduits for allowing liquefied soil to be sucked into the one or more suction conduits via the mesh-like structure.

[029] One or more apertures formed in the one or more suction conduits may be sized to only allow particles of a size of no more than 100 mm to flow therethrough. The apertures in the nose cone may be sized to only allow particles of a size of no more than 100 mm to flow therethrough. The apertures in the mesh-like structure may be sized to only allow particles of a size of no more than 100 mm to flow therethrough.

[030] The one or more suction conduits may extend along an exterior of the housing.

[031] According to a further aspect of the disclosure, there is provided a pair of probe assemblies for use in extracting material from a sub-surface formation, comprising: a first probe assembly comprising: an elongate housing having an upper end and a lower end for inserting into the sub-surface formation; one or more fluid ejectors for enabling a fluid pumped from the upper end of the housing toward the lower end of the housing to be ejected out of the housing; and a second probe assembly comprising: an elongate housing having an upper end and a lower end for inserting into the sub-surface formation; and one or more suction conduits extending at least partway along a length of the housing and configured to allow liquefied soil and the material sucked into the one or more suction conduits to be directed toward the upper end of the housing.

[032] The first probe assembly may further comprise a vibrator at the lower end of the housing for imparting vibrations to the material within a zone of influence of the vibrator.

[033] The second probe assembly may further comprise one or more fluid ejectors for enabling a fluid pumped from the upper end of the housing toward the lower end of the housing to be ejected out of the housing.

[034] According to a further aspect of the disclosure, there is provided a system comprising: a pumping device; a probe assembly comprising: an elongate housing having an upper end and a lower end for inserting into a sub-surface formation; a vibrator at the lower end of the housing for imparting vibrations to soil within a zone of influence of the vibrator; one or more fluid ejectors for enabling a fluid pumped by the pumping device from the upper end of the housing toward the lower end of the housing to be ejected out of the housing; and one or more suction conduits extending at least partway along a length of the housing and configured to allow liquefied soil sucked into the one or more suction conduits to be directed toward the upper end of the housing.

[035] The system may further comprise a processing plant for receiving from the probe assembly the liquefied soil extracted from the sub-surface formation by the probe assembly.

[036] The system may further comprise a storage container for receiving the liquefied soil.

[037] This summary does not necessarily describe the entire scope of all aspects. Other aspects, features and advantages will be apparent to those of ordinary skill in the art upon review of the following description of specific embodiments.Brief Description of the Drawings

[038] Embodiments of the disclosure will now be described in detail in conjunction with the accompanying drawings of which:

[039] FIG. 1 shows a probe assembly according to an embodiment of the disclosure;

[040] FIGS. 2A and 2B show front and side views of a probe assembly according to an embodiment of the disclosure;

[041] FIGS. 3A and 3B show front and side views of the probe assembly of FIGS. 2A and 2B ejecting fluid into a sub-surface formation, according to an embodiment of the disclosure;

[042] FIG. 4 shows a probe assembly ejecting fluid and extracting liquefied soil and minerals from a sub-surface formation, according to an embodiment of the disclosure;

[043] FIG. 5 is a flow diagram of a method of extracting a target material from a sub-surface formation, according to an embodiment of the disclosure;

[044] FIGS. 6A and 6B show a probe assembly being inserted into a sub-surface formation in which the target material is overlain by overburden material, according to an embodiment of the disclosure;

[045] FIG. 7 shows a probe assembly being inserted into multiple different locations of a sub-surface formation in which the target material is overlain by overburden material, according to an embodiment of the disclosure;

[046] FIG. 8 shows a grid of locations and associated spacings at which a probe assembly is inserted into a sub-surface formation, according to an embodiment of the disclosure;

[047] FIG. 9 shows dual probe assemblies being used to liquefy soil and extract the liquefied soil and minerals from a sub-surface formation, according to an embodiment of the disclosure;

[048] FIGS. 10A and 10B show dual probe assemblies being inserted into a sub-surface formation in which the target material is overlain by overburden material, according to an embodiment of the disclosure;

[049] FIGS. 11A and 11B show front and side views of a probe assembly without a follower tube, according to an embodiment of the disclosure;

[050] FIGS. 12A and 12B show front and side views of the probe assembly of FIGS. 11A and 11B ejecting fluid into a sub-surface formation, according to an embodiment of the disclosure;

[051] FIG. 13 shows a probe assembly being used for dredging or removing material from a waterbody floor, according to an embodiment of the disclosure;

[052] FIG. 14 shows a probe assembly being inserted into multiple different locations of a sub-surface formation to dredge or remove material from the waterbody floor, according to an embodiment of the disclosure; and

[053] FIG. 15 shows a grid of locations and associated spacings at which a probe assembly may be inserted into a sub-surface formation to dredge or remove material from the waterbody floor, according to an embodiment of the disclosure.Detailed Description

[054] The present disclosure seeks to provide improved methods of extracting material from a sub-surface formation, and an improved probe assembly for such extraction. While various embodiments of the disclosure are described below, the disclosure is not limited to these embodiments, and variations of these embodiments may well fall within the scope of the disclosure which is to be limited only by the appended claims.

[055] Generally, according to embodiments of the disclosure, there are described methods of extracting a target material, such as sand, placer minerals, rare earth minerals, or oil sands, from a sub-surface formation. A sub-surface formation may be any formation that is below the surface of the Earth, whether that surface is land or water. A sub-surface formation therefore comprises subterranean formations as well as formations within the seabed or within the floor of a waterbody, such as an ocean, lake, river, harbor, or other waterway.

[056] A probe assembly is inserted into the sub-surface formation which may comprise soil particles and void space comprising water and air mixed with the target material. Soil within a zone of influence of the probe assembly is then liquefied. In particular, the probe assembly is caused to vibrate and eject a fluid, such as a pressurized gas or liquid, from out of the probe assembly and into the sub-surface formation. The soil within the zone of influence may be considered to be soil that is sufficiently close to the probe assembly so as to break apart under the influence of the vibrations and the ejected fluid. The liquefied soil, as well as any target material mixed with the liquefied soil, is then extracted from the sub-surface formation. For example, by applying a pressure differential between a top and a bottom of the probe assembly, the liquefied soil and target material may be aspirated or sucked up through the probe assembly to the surface for further processing.

[057] Soil liquefaction may occur when a saturated or partially saturated soil substantially loses strength and stiffness in response to an applied stress (such as shaking during an earthquake) or in response to a sudden change in stress condition. As a result of liquefaction, a material that is ordinarily a solid may behave as a liquid.

[058] According to some embodiments, the “target” material that is being extracted may comprise sand / soil on the floor of a waterbody, in the absence of any associated minerals. Therefore, the methods and systems described herein may be used to dredge the waterbody floor, by extracting the material (i.e., the sand / soil) that is comprised in the waterbody floor. The extracted material may then be directed to storage, without the need for processing. In such cases, the goal of the method is not necessarily to extract minerals from the waterbody floor for downstream processing, but rather to lower the level of the waterbody floor, for example for the safe passage of marine craft.

[059] Generally, throughout this disclosure, soil may be homogeneous (comprising, for example, only sand, silt, clay, gravel, cobbles, or organics) or non-homogeneous (comprising any combination of soil types, including but not limited to sand, silt, clay, gravel, cobbles, and / or organics).

[060] These processes, as well as the probe assembly that may be used for the processes, will now be described in further detail in connection with the drawings.

[061] Turning to FIG. 1, there is shown an example of a probe assembly 100 that may be used for sand, placer mineral (or other target material) extraction, as described herein. For clarity, probe assembly 100 is shown without any suction tubes, but examples of suction tubes attached to probe assembly 100 are shown for instance in FIGS. 2A and 2B, described in further detail below. Probe assembly 100 may be referred to as a vibro-flotation device (or “vibroflot” for short). Probe assembly 100 includes a housing comprising a follower tube 12 connected at a lower end thereof to a vibrator 14. Housed within vibrator 14 is an electric or pneumatic motor 16 with an output coupled to an eccentric shaft 18. Rotation of eccentric shaft 18 under the power of electric or pneumatic motor 16 imparts high-frequency vibrations to vibrator 14, to be used in liquefying soil as described in further detail below. A vibration dampener 20 is positioned between follower tube 12 and vibrator 14, for dampening vibrations generated by vibrator 14 or otherwise preventing the vibrations from being transmitted to follower tube 12.

[062] A pair of stabilizing fins 22 are provided on opposite exterior sides of vibrator 14. Fins 22 may prevent probe assembly 100 from rotating too rapidly during operation. At a lower end of follower tube 12, adjacent vibration dampener 20, are provided a number of fluid openings 24 for enabling a fluid pumped through an interior of follower tube 12 to be jetted out into the medium (i.e., the sub-surface formation) through which probe assembly 100 is moving, as can be seen by fluid jets 26. There may be any suitable number of fluid openings 24. According to some embodiments, instead of fluid flowing through the interior of follower tube 12, suitable piping / tubing / conduits may be provided on the exterior of follower tube 12, and the fluid may be pumped through such conduits.

[063] Additional fluid openings 28 are provided along the length of vibrator 14. Fluid pumped through follower tube 12 may be directed into vibrator 14 via suitable conduits that may be coupled to fluid openings 28. Fluid openings 28 thereby providing additional locations at which the fluid pumped through follower tube 12 and vibrator 14 may to be jetted out of probe assembly 100.

[064] Probe assembly 100 further includes a nose cone 30 provided at the lower end of vibrator 14. Nose cone 30 is provided with an outer mesh covering to enable liquefied soil and other particulate matter (such as placer minerals) of a certain size to be sucked into suction tubes 34 (described in further detail below, and which may also be referred to as suction conduits), in response to a suction applied at nose cone 30 and suction tubes 34, causing a pressure differential between the surrounding soils within the zone of influence of probe assembly 100 and suction tubes 34 on the sides and bottom of probe assembly 100. Extraction of liquefied soil and minerals at the base of probe assembly 100 may be important for heavy minerals that tend to sink in the liquefied soil.

[065] FIGS. 2A and 2B show front and side views of probe assembly 100 described above, but showing suction tubes 34 provided on opposite exterior sides of probe assembly 100. The lower ends of suction tubes 34 are connected to nose cone 30 such that liquefied soil and minerals flowing into probe assembly 100 under suction are drawn into suction tubes 34 and may flow to the upper end of probe assembly 100 by flowing the entire lengths of suction tubes 34. Suction tubes 34 are provided with apertures 38 along a portion of their lengths (the portions adjacent the vibrator) such that liquefied soil and minerals may not only enter probe assembly 100 via nose cone 30 but may also be drawn into suction tubes 34 partway along the length of probe assembly 100. Apertures 38 may be sized to permit only particles of a predetermined size, such as 3” or less, to enter suction tubs 34.

[066] A flexible coupling 32 is provided between suction tubes 34 attached to vibrator 14 and suction tubes 34 attached to follower tube 12. Vibrator 14 may bend and flex at its joint with follower tube 12, and so flexible coupling 32 may decrease associated stresses on suction tubes 34.

[067] Suction tubes 34 may have a diameter of, for example, 4”, 6”, 8”, 10”, or 12”. More or fewer than two suction tubes 34 may be affixed to the exterior of probe assembly 100. According to some embodiments, suction tubes 34 may be extend at least partially within the interior of probe assembly 100.

[068] As can also be seen in FIGS. 2A and 2B, probe assembly 100 may additionally include one or more meshed portions 36 for also enabling liquefied soil and minerals to enter suction tubes 34. In particular, meshed portions 36 are fluidly coupled to suction tubes 34 such that liquefied soil and minerals may flow into suction tubes 34 via meshed portions 36.

[069] FIGS. 3A and 3B illustrate probe assembly 100 of FIGS. 2A and 2B ejecting pressurized water / air from fluid openings 24 and 28.

[070] FIG. 4 illustrates probe assembly 100 inserted into a subterranean formation 40 comprising soil mixed with a target material such as placer minerals. The vibrations of vibrator 14, combined with fluid jets 26 emitted from probe assembly 100, define a zone of influence 42 of probe assembly 100 where the subterranean formation is liquefied. According to some embodiments, zone of influence 42 may extend up to a radius of 3 feet from probe assembly 100, depending on the surrounding soil type. Zone of influence 42 may be considered to include all soil that is susceptible to liquefy in response to the vibrations and fluid jets 26 emitted by probe assembly 100. Liquefaction of the soil may occur as a result of increasing the pore pressure and reducing the effective stress of the soil to zero, and may allow probe assembly 100 to descend to relatively significant depths below ground at a relatively rapid pace. Liquefied soil, combined with placer minerals mixed therein, is then drawn into suction tubes 34 of probe assembly 100, via apertures 38, meshed nose cone 30, and meshed portion 36. Soil that is not located within zone of influence 42 is located too far from probe assembly 100 and is therefore not sufficiently liquefied, or not liquefied at all, and therefore is not able to be drawn into probe assembly 100.

[071] There will now be described various methods of extracting a target material, such as placer minerals, from a sub-surface location. A general method is first described in the context of FIG. 5.

[072] As can be seen from FIG. 5, at block 52, one or more probe assemblies are inserted into a sub-surface formation comprising soil (e.g. sand, gravel, cobbles, silt, clay, organics, or a mixture thereof) and the target material. According to some embodiments, the target material may be placer minerals. Placer minerals may include, for example, gold, gold ore (or other mineral ore), diamonds, garnet, iron, platinum, ruby, sapphire, tin, titanium, uranium, zirconium, and other heavy mineral and ore deposits. The target material may additionally include rare earth elements and mineralization, and oil from oil sand formations.

[073] At block 54, soil within the zone of influence of the one or more probe assemblies is liquefied. In particular, one or more of pressurized air and pressurized water are ejected from various openings provided along a length of each probe assembly. In tandem, the vibrator of each probe assembly is caused to vibrate. The combination of the vibrations and the ejection of one or more fluids from each probe assembly causes the soil within the zone of influence of each probe assembly to be liquefied.

[074] At block 56, the liquefied soil and any target material mixed with the liquefied soil are extracted from the zone of influence. In particular, in response to a pressure differential between suction tubing 34 and the liquefied soil surrounding a probe assembly (for example using a pump at the surface), the liquefied soil and target material flow toward apertures 38, nose cone 30, and meshed portions 36 that limit the particle size, and are sucked into the probe assembly, for example via tubing provided along an exterior of the probe assembly (as described above).

[075] At block 58, the extracted target material is separated from the extracted soil using suitable processing equipment. For instance, gravity-assisted separation may be used to separate the extracted target material from the extracted soil.

[076] As will be described in further detail, a similar method may be used to dredge the floor of a waterbody. In such a case, the extracted material (i.e., soil / sand) is not necessarily processed but, instead, may be simply stored in storage for future use / disposal.

[077] FIGS. 6A and 6B show a probe assembly 60 being inserted into a subterranean formation 62 comprising a target mineral zone 64, for the extraction of placer minerals therefrom. As can be seen, probe assembly 60 is connected to an assembly comprising a crane 66 with a boom 68, pipe and hose extensions, a water and / or air supply 70, one or more suction pumps 72, and a processing plant 74.

[078] Crane 66 is configured to lower probe assembly 60 from the ground surface (in the case of extracting minerals from the ground) or from a floating barge or similar vessel (in the case of extracting minerals from the sub-surface seabed). As described above, probe assembly 60 liquefies the soil in the vicinity of probe assembly 60 as probe assembly 60 is lowered under its own weight, through vibration and injection of water and / or compressed air to the surrounding soil matrix (FIG. 6A). Depending on the soil matrix composition and groundwater conditions, varying quantities of water or air may be used to facilitate the liquefaction of the soil matrix. Target mineral zone 64 may comprise the column of soil that is penetrated by probe assembly 60 as probe assembly is lowered, or target mineral zone 64 may comprise one or more soil layers at specific depths below the ground or seabed surface.

[079] Once probe assembly 60 has reached target mineral zone 64, probe assembly 60 is raised slowly from the bottom of target mineral zone 64 to the top of target mineral zone 64 (FIG. 6B). The raising and lowering of probe assembly 60 is repeated within target mineral zone 64 to agitate, loosen, and extract the soil and placer minerals within target mineral zone 64. Repeatedly raising and lower probe assembly 60 with or without water injection also helps prevent the soils around the follower tube from consolidating as positive pore pressure dissipates over time. Preventing consolidation of the liquefied soil may be assisted by providing fluid jets along a portion of or along the full length of the follower tube. Such fluid jets may assist in forming a liquefied slurry zone centered around the follower tube.

[080] Suction pump(s) 72 create suction at the lower end of probe assembly 100. As a result, suction pump 72 causes liquefied and otherwise loosened sand, gravels, silts, clays, organics, or placer minerals, or a mixture thereof within target mineral zone 64 to be sucked into probe assembly 60. The suction pipes along the outside of probe assembly 60, upper housing and the nose cone, as described above, may include one or more filters (such as a screen or mesh) for ensuring that only soil and placer particle sizes that are less than a specified diameter (e.g. less than 100 mm, or in some cases less than 75 mm) may enter the suction tubing for pumping to processing plant 74. The silt, clay, sand, gravel, organics, or placer minerals, or a mixture thereof, form a slurry with the groundwater and / or injected water and are extracted from the target mineral zone 64. The remaining in-situ coarse gravel and cobbles that have been washed clean of all fine materials will remain in place at depth.

[081] The aspirated material is brought up to the surface. Once at the surface, the extracted soil and placer minerals may be processed in processing plant 74 which may be, for example, a conventional processing plant where placer minerals may be, for instance, gravity-separated from the liquefied soil and processed. Depending on the nature of the mineral deposit, if further processing is desired beyond gravity separation, then the slurry can be pumped through piping to more complex processing plants.

[082] As can be seen in FIG. 7, once the material within target mineral zone 64 is substantially removed, probe assembly 60 is raised above the ground or seabed level and repositioned adjacent to the previous insertion location and plunged again to target mineral zone 64 where the process is repeated. The process may be continued in a grid pattern with probe assembly 60 positioned within 2-3 feet of the previous insertion location, and with each successive row being offset from the previous row by up to 1.5 feet, until substantially all soils and placer mineral deposits have been removed from target mineral zone 64. An example of such a grid pattern is shown in FIG. 8. As can also be seen in FIG. 7, portions of subterranean formation 62 directly above the zones of liquefaction in target mineral zone 64 have reconstituted following removal of probe assembly 60.

[083] According to some embodiments, the method of mineral extraction may be performed using dual probe assemblies, as shown in FIG. 9. FIG. 9 shows a pair of probe assemblies 100a and 100b being used to liquefy soil and extract the liquefied soil and associated minerals to the surface. The depiction of probe assemblies 100a and 100b is similar to probe assembly 100 shown in FIGS. 1, 2A, and 2B, and like elements are referenced using like reference numbers.

[084] According to this embodiment, both probe assembly 100a and probe assembly 100b are used to liquefy the soil, whereas generally only probe assembly 100b is used to extract the liquefied soil and associated minerals. As a result, probe assembly 100a does not require any suction tubing or similar means to extract the liquefied soil and minerals. In addition, there is no need for probe assembly 100a to include any outer mesh coverings and / or a meshed nose cone for permitting the extraction of liquefied soil and minerals out of the sub-surface formation. For instance, as can be seen in FIG. 9, nose cone 30a of probe assembly 100a may be a solid nose cone without any apertures formed therein.

[085] Probe assembly 100b is tasked with extracting the liquefied soil and minerals. However, it is still advantageous for probe assembly 100b to be configured for fluid ejection to facilitate the penetration and liquefaction of the soil matrix, and so probe assembly 100b is also configured to enable a fluid to be ejected out of openings provided along the length of probe assembly 100b for the purposes of liquefying the surrounding soil (as described above).

[086] Generally, probe assemblies are allowed to rotate since they are typically suspended from a freely-rotating cable that is connected to the crane’s boom. In order for probe assembly 100b to efficiently extract the liquefied soil and minerals, rotation of probe assembly 100b should ideally be restricted at the transom 71, thereby preventing or at least minimizing rotation during operation of the suction means at surface. This may ensure that suction tube 34b on the side of probe assembly 100b that is closest to probe assembly 100a is kept as close as possible to the zone of liquefied soil located between probe assembly 100a and 100b. In addition, rotation of probe assembly 100a may be prevented or at least minimized so that the primary ejection and flow of fluid from probe assembly 100a may always be directed toward probe assembly 100b, by ensuring that the fluid openings on the side of probe assembly 100a that is closest to probe assembly 100b are always directed toward probe assembly 100b. Alternatively, an equal amount of fluid may be ejected from both sides of probe assembly 100a (only the water being ejected toward probe assembly 100b is shown in FIG. 9). The dual probe assembly arrangement shown in FIG. 9 may enable a positive pressure to be generated at probe assembly 100a, while a negative pressure may be generated at probe assembly 100b. This may assist in creating conditions for liquefied mineral-bearing soils or oil sand slurries to flow from probe assembly 100a to probe assembly 100b.

[087] There are many ways that rotation of a probe assembly can be limited, for example by using mechanical devices where the follower tube is connected to transom 71 (e.g. welded chains may be used to prevent the probe assemblies from rotating at transom 71).

[088] FIGS. 10A and 10B show dual probe assemblies 60 being inserted into a subterranean formation 62 comprising a target mineral zone 64, for the extraction of placer minerals therefrom. FIGS. 10A and 10B are similar to FIGS. 6A and 6B, and like features are labelled using like reference numbers.

[089] Methods of placer mineral extraction as described herein may significantly improve yield (milligrams of mineral per cubic meter of processed soil) by only removing placer-containing soils at defined target mineral zones. The method avoids bulk excavation and the unnecessary transportation and processing of large cobbles and boulders, and may reduce wear and tear on equipment.

[090] Conventional open pit mining may require the removal of significant quantities of overburden soil to reach mineralized target zones. This overburden soil must be stockpiled for later site restoration, resulting in the double handling of non-mineralized soils at a significant expense in time, equipment, and cost. In addition, open pit mining requires the excavation by diggers (excavators and bulldozers) and transportation by truck of mineralized soils from the target zone to a processing facility, requiring the stockpiling and double handling of mineralized soils through an equipment-intensive process. Embodiments of the disclosure may eliminate the need to transport and double-handle overburden soil and ore-containing material, may minimize environmental impact and the resultant need for restoration to the land, and may significantly reduce greenhouse gas emissions per quantity of extracted mineral. The methods of mineral extraction described herein may therefore offer significant advantages over conventional open pit mining.

[091] The probe assembly may reach mineral deposits at depths of up to two hundred feet within several minutes, without the removal of overburden soil and avoiding the costly and time-consuming activities of removing overburden to reach mineralized soils. The probe assembly can extract mineralized soils in precise target zones or sub-surface layers over large areas where conventional open pit mining is uneconomical. Extracted soil and mineral slurries can be pumped long distances to a processing plant and injected directly into the processing plant, preventing expensive transportation and handling costs. Surface restoration at mining completion may be significantly less disruptive and less expensive since the level of disturbance is minimal. By only extracting mineral-bearing soils, the mineral yield per cubic meter of soil disturbed may be orders of magnitude higher than conventional open pit mining, and the amount of greenhouse gases produced to extract one gram or one ounce of mineral may be orders of magnitude lower than conventional open pit mining.

[092] In offshore environments, current methods of placer mineral recovery are limited to seabed or near-seabed surface deposits typically within 6 inches to 3 feet of the seabed. Suction dredges typically are limited to mineral accumulations within the top foot of the seabed. whereas barge-mounted shovel operations (excavators) are limited by the water depth and boom and stick length of the equipment. Current methods are highly inefficient, limited in range and only economical in very rich deposits. The methods of mineral extraction described herein may therefore offer significant advantages over conventional offshore mining. For example, the probe assembly may not be limited by water depth, and can therefore target deposits in deeper water that conventional equipment cannot reach. The probe assembly described herein may not be limited to surface seabed mining and can extract mineralized deposits at significant depths beneath the seabed surface without the necessary removal of overburden, and may result in minimal and short-term disturbance to the seafloor. The methods of mineral extraction described herein may therefore address a number of shortcomings in offshore mining while significantly increasing the range, yield, and efficiency of the mining over conventional offshore mining methods.

[093] Furthermore, according to some embodiments, a probe assembly may be fitted with up to four suction slurry pumps similar to the EDDY Pump Corporation HD 12000 Heavy Duty Slurry Pump capable of transporting slurry mixtures with particles up to 12” (300 mm) in size. Such pumps, when operating at 45.6% efficiency, will move 1,590 cubic meters of material per hour and with a hydraulic head of 110 feet (33.5 m). Taking into account pump efficiency and a slurry composition of 2 parts water to 1 part particulate material, and allowing time for probe repositioning, a single probe assembly may process 330 cubic meters of material per hour, using one 12” pump or two 6” pumps. No overburden would be removed and, assuming 70% of the soil particles in the target zone were smaller than the specified filter size (75 mm to 100 mm) on the probe assembly’s suction tubing / nose cone, then the equivalent process rate of an excavator removing all such material is 470 cubic meters of material per hour. A dual probe assembly operating at 80% efficiency relative to a single probe assembly could be expected to process the equivalent of 753 cubic meters of material per hour. Methods according to the embodiments described herein may therefore extract the majority of mineral-bearing soils at two to four times the production rate of a conventional excavator with a two cubic meter bucket (production rate of 240 cubic meters of material per hour), and may generate 30% less of waste than conventional methods without the need to extract and process uneconomical sub-surface soils or to remove overburden.

[094] In addition to placer mineral deposits, methods of mineral extraction as described herein may therefore provide a valuable alternative to open pit mining for oil sands at shallower depths, and may also provide a valuable alternative to oil sands extraction for deeper deposits that are currently accessed using Steam Assisted Gravity Drainage (SAGD). Generally, methods of oil sands mineral extraction as described herein may be more energy efficient and environmentally friendly when compared to currently employed methods in the oil sands industry.

[095] As described above, in addition to being used to extract placer and other mineral deposits, the methods of liquefying and extracting soil material (e.g., sand) may be used to dredge the floors of waterbodies, such as rivers, lakes, and harbors. The methods described herein may therefore provide valuable alternatives to conventional dredging methods that are less efficient and cost-effective.

[096] When dredging the floors of waterbodies, there may be no need to use a probe assembly with a follower tube, since the objective is to remove material from the waterbody floor down to a specified depth, and the rigidity of the assembly is less important at shallow depths. Therefore, turning to FIGS. 11A and 11B, there are shown front and side views of a probe assembly 500 without a follower tube that may be used for such dredging. Instead of a follower tube, a heavy-duty steel or similar cable 120 may be used to lower probe assembly 500 to the waterbody floor, for example from a crane on a barge. The depiction of probe assembly 500 is similar to probe assembly 100 shown in FIGS. 1, 2A, and 2B, and like elements are referenced using like reference numbers.

[097] In addition, probe assembly 500 includes supply and extraction tubes 250 and 340 provided along the sides of probe assembly 500. As can be seen in FIG. 11A, supply tubes 250 extend down two opposite sides of probe assembly 500 and are configured to supply water (or some other fluid) for injection into the surrounding soil medium. As can be seen in FIG. 11B, extraction tubes 340 extend down the other two opposite sides of probe assembly 500 and are used to extract, through suction, liquefied soil and water to the surface for processing or storage. Extraction tubes 340 may be identical / similar to suction tubes 34 described above. For example, the lower ends of extraction tubes 340 may be connected to nose cone 300 such that liquefied soil flowing into probe assembly 500 under suction are drawn into extraction tubes 340 and may flow to the upper end of probe assembly 500 by flowing the entire lengths of extraction tubes 340. Extraction tubes 340 are provided with apertures along a portion of their lengths (the portions adjacent the vibrator) such that liquefied soil may not only enter probe assembly 500 via nose cone 300 but may also be drawn into extraction tubes 340 partway along the length of probe assembly 500.

[098] FIGS. 12A and 12B illustrate probe assembly 500 of FIGS. 11A and 11B ejecting pressurized water / air from supply tubes 250, as seen by fluid jets 260.

[099] Turning to FIG. 13, there is shown an example of probe assembly 500 being used to dredge the floor 805 of a waterbody 800. Beneath floor 805 may be located a more solid subterranean formation 810, such as harder sedimentary layers or bedrock. Alternatively, when dredging sand to clear a waterway, formation 810 may simply comprise more sand that does not need to be removed because the desired depth of dredging has already been reached. As can be seen, probe assembly 500 is connected to an assembly comprising a crane 660 with a boom 680, pipe and hose extensions, a water and / or air supply 700, one or more suction pumps 720, and a processing plant or dredge sand storage 735.

[0100] Soil is liquefied around probe assembly 500 and extracted by slurry pump 720. Soil that has been extracted is directed to processing plant or dredge sand storage 735. In particular, the soil may be processed by a processing plant if it contains some other target material, such as minerals, that are desired to be separated from the soil. Alternatively, if the soil does not need to be processed, it can simply be stored in storage for future use / disposal.

[0101] As can be seen in FIG. 14, during the dredging, the soil reorganizes to the natural angle of repose of the native soil (typically 30 – 45 degrees) and forms a pyramidal or triangular structure 815. Each triangular “pile” of soil may then be further extracted by inserting probe assembly 500 into the pile, as can be seen in FIG. 14 with probe assembly 500 extracting soil from pile 812. The material being extracted may comprise sand or fine material deposited by tides and currents in waterbodies in which it is desirable to maintain a given water depth for the safe passage of marine craft. Alternatively, the underwater sand deposits may be extracted for other uses.

[0102] FIG. 15 shows an example extraction pattern that may be used when dredging the floor of a waterbody. According to one non-limiting example, for soil with a natural angle of repose of 30 degrees in a saturated condition, the spacing between insertion locations (i.e., locations at which the probe assembly is inserted) may be, for example, about 34.6 meters if the desired depth of soil material is 10 meters. Therefore, to mine an area with a square side length of 103.8 meters and to a depth of 10 meters would take 13 extractions: 9 primary extractions as indicated by reference 905, and 4 secondary extractions as indicated by reference 910. Each cone (10 meters deep and 34.6 meters in diameter) would take approximately 3 hours to mine. Of course, the precise spacing depends on the soil type and density. The above example is for loose sand with, as noted, a natural angle of repose of 30 degrees. The above example further assumes use of an EDDY Pump Corporation HD 12000 Heavy Duty Slurry Pump removing 26.5 cubic meters of slurry per minute.

[0103] The word “a” or “an” when used in conjunction with the term “comprising” or “including” in the claims and / or the specification may mean “one”, but it is also consistent with the meaning of “one or more”, “at least one”, and “one or more than one” unless the content clearly dictates otherwise. Similarly, the word “another” may mean at least a second or more unless the content clearly dictates otherwise.

[0104] The terms “coupled”, “coupling” or “connected” as used herein can have several different meanings depending on the context in which these terms are used. For example, as used herein, the terms coupled, coupling, or connected can indicate that two elements or devices are directly connected to one another or connected to one another through one or more intermediate elements or devices via a mechanical element depending on the particular context. The term “and / or” herein when used in association with a list of items means any one or more of the items comprising that list.

[0105] As used herein, a reference to “about” or “approximately” a number or to being “substantially” equal to a number means being within + / - 10% of that number.

[0106] Use of language such as “at least one of X, Y, and Z,” “at least one of X, Y, or Z,” “at least one or more of X, Y, and Z,” “at least one or more of X, Y, and / or Z,” or “at least one of X, Y, and / or Z,” is intended to be inclusive of both a single item (e.g., just X, or just Y, or just Z) and multiple items (e.g., {X and Y}, {X and Z}, {Y and Z}, or {X, Y, and Z}). The phrase “at least one of” and similar phrases are not intended to convey a requirement that each possible item must be present, although each possible item may be present.

[0107] While the disclosure has been described in connection with specific embodiments, it is to be understood that the disclosure is not limited to these embodiments, and that alterations, modifications, and variations of these embodiments may be carried out by the skilled person without departing from the scope of the disclosure.

[0108] It is furthermore contemplated that any part of any aspect or embodiment discussed in this specification can be implemented or combined with any part of any other aspect or embodiment discussed in this specification. 

Claims

1. A method of extracting material from a formation, comprising:inserting one or more probe assemblies into the sub-surface formation comprising soil;liquefying the soil within a zone of influence of the one or more probe assemblies, wherein the liquefying comprises vibrating the one or more probe assemblies and ejecting a fluid from the one or more probe assemblies and into the sub-surface formation; andextracting the liquefied soil from the sub-surface formation.

2. The method of claim 1, wherein:the sub-surface formation further comprises a target material; andthe extracting further comprises extracting the target material with the liquefied soil from the sub-surface formation.

3. The method of claim 1 or 2, wherein the extracting comprises sucking the liquefied soil through the one or more probe assemblies and out of the sub-surface formation.

4. The method of any one of claims 1-3, wherein the fluid comprises one or more of pressurized air and pressurized water.

5. The method of any one of claims 1-4, wherein:the liquefying further comprises repeatedly raising and lowering the one or more probe assemblies within the sub-surface formation.

6. The method of any one of claims 1-5, wherein:inserting the one or more probe assemblies into the sub-surface formation comprises inserting the one or more probe assemblies into a first location in the sub-surface formation; andthe method further comprises removing the one or more probe assemblies from the first location and inserting the one or more probe assemblies into a second location in the sub-surface formation.

7. The method of claim 6, wherein the first location is spaced from the second location by 2-3 feet.

8. The method of claim 6 or 7, wherein the method further comprises:removing the one or more probe assemblies from the second location and inserting the one or more probe assemblies into further locations in the sub-surface location so as to form a grid of locations into which the one or more probe assemblies have been inserted in the sub-surface formation.

9. The method of claim 8, wherein adjacent rows of the grid are offset from one another by about 1.25 – 1.75 feet.

10. The method of any one of claims 1-9, wherein the extracting comprises filtering the liquefied soil such that only particles having a diameter less than 100 mm are extracted.

11. The method of any one of claims 1-10, wherein:the one or more probe assemblies comprise a first probe assembly and a second probe assembly; the liquefying comprises vibrating at least the first probe assembly and ejecting the fluid from at least the first probe assembly and into the sub-surface formation; andthe extracting comprises sucking the liquefied soil through the second probe assembly and out of the sub-surface formation.

12. The method of claim 11, wherein the extracting further comprises sucking the liquefied soil through only the second probe assembly and out of the sub-surface formation.

13. The method of any one of claims 1-12, wherein the sub-surface formation comprises a subterranean formation, part of a seabed, or part of a floor of a waterbody.

14. The method of claim 2, further comprising separating the extracted target material from the extracted soil.

15. The method of claim 2, wherein the target material comprises one or more of placer minerals, rare earth minerals, and oil sands.

16. The method of claim 11, wherein the liquefying comprises vibrating the first and the second probe assemblies.

17. The method of any one of claims 1-16, wherein inserting the one or more probe assemblies into the sub-surface formation comprises inserting the one or more probe assemblies using one or more follower tubes connected to the one or more probe assemblies.

18. The method of any one of claims 1-16, wherein inserting the one or more probe assemblies into the sub-surface formation comprises inserting the one or more probe assemblies using one or more flexible cables connected to the one or more probe assemblies.

19. A probe assembly for use in extracting material from a sub-surface formation, comprising:an elongate housing having an upper end and a lower end for inserting into the sub-surface formation;a vibrator at the lower end of the housing for imparting vibrations to the material within a zone of influence of the vibrator;one or more fluid ejectors for enabling a fluid pumped from the upper end of the housing toward the lower end of the housing to be ejected out of the housing; andone or more suction conduits extending at least partway along a length of the housing and configured to allow liquefied soil sucked into the one or more suction conduits to be directed toward the upper end of the housing.

20. The probe assembly of claim 19, further comprising a nose cone at the lower end of the housing and comprising apertures formed therein for allowing liquefied soil to be sucked into the housing via the nose cone.

21. The probe assembly of claim 20, wherein the apertures in the nose cone are connected to the one or more suction conduits for allowing liquefied soil to be sucked into the one or more suction conduits via the nose cone.

22. The probe assembly of any one of claims 19-21, further comprising:a mesh-like structure positioned between the upper and lower ends of the housing, wherein the mesh-like structure comprises apertures formed therein for allowing liquefied soil to be sucked into the housing via the mesh-like structure.

23. The probe assembly of claim 22, wherein the apertures in the mesh are connected to the one or more suction conduits for allowing liquefied soil to be sucked into the one or more suction conduits via the mesh-like structure.

24. The probe assembly of any one of claims 19-23, wherein one or more of:one or more apertures formed in the one or more suction conduits are sized to only allow particles of a size of no more than 100 mm to flow therethrough;the apertures in the nose cone are sized to only allow particles of a size of no more than 100 mm to flow therethrough; andthe apertures in the mesh-like structure are sized to only allow particles of a size of no more than 100 mm to flow therethrough.

25. The probe assembly of any one of claims 19-24, wherein the one or more suction conduits extend along an exterior of the housing.

26. A pair of probe assemblies for use in extracting material from a sub-surface formation, comprising:a first probe assembly comprising:an elongate housing having an upper end and a lower end for inserting into the sub-surface formation;one or more fluid ejectors for enabling a fluid pumped from the upper end of the housing toward the lower end of the housing to be ejected out of the housing; anda second probe assembly comprising:an elongate housing having an upper end and a lower end for inserting into the sub-surface formation; andone or more suction conduits extending at least partway along a length of the housing and configured to allow liquefied soil and the material sucked into the one or more suction conduits to be directed toward the upper end of the housing.

27. The pair of probe assemblies of claim 26, wherein:the first probe assembly further comprises a vibrator at the lower end of the housing for imparting vibrations to the material within a zone of influence of the vibrator.

28. The pair of probe assemblies of claim 26 or 27, wherein:the second probe assembly further comprises one or more fluid ejectors for enabling a fluid pumped from the upper end of the housing toward the lower end of the housing to be ejected out of the housing.

29. A system comprising:a pumping device;a probe assembly comprising:an elongate housing having an upper end and a lower end for inserting into a sub-surface formation;a vibrator at the lower end of the housing for imparting vibrations to soil within a zone of influence of the vibrator;one or more fluid ejectors for enabling a fluid pumped by the pumping device from the upper end of the housing toward the lower end of the housing to be ejected out of the housing; andone or more suction conduits extending at least partway along a length of the housing and configured to allow liquefied soil sucked into the one or more suction conduits to be directed toward the upper end of the housing.

30. The system of claim 29, further comprising a processing plant for receiving from the probe assembly the liquefied soil extracted from the sub-surface formation by the probe assembly.

31. The system of claim 29, further comprising a storage container for receiving the liquefied soil.

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