BACKGROUND

[0001] The present disclosure relates generally to the field of subsea mining, and more particularly, to systems and methods of subsea mining utilizing a grab-based mining system.

[0002] Collection of mineral resources or other materials from underwater deposits on sea floors may be accomplished through various methods of subsea mining. The separation of the mineral deposits from the surrounding rock of the sea floor and the transportation of the collected mineral deposits from the sea floor to the surface represent two aspects of subsea mining that must be addressed to make the subsea mining technically feasible and economically viable. Some subsea mining systems may involve dredging or vacuuming mineral deposits from the sea floor or extracting the minerals with other relatively expensive, underwater equipment. However, the nature of the existing systems restricts their use in deeper water depths. To date, typical subsea mining systems have been mechanically limited to shallow water depths (less than 200 meters).

SUMMARY

[0003] One embodiment relates to a method of deep sea mining including excavating a volume of material from the sea floor using a mining grab; transferring the excavated material from the mining grab to a transport receptacle; moving the transport receptacle to adjacent a surface vessel; and transferring the excavated material from the transport receptacle to the surface vessel.

[0004] Another embodiment relates to a system for subsea mining, including a surface vessel; a mining grab configured to be operated remotely from the surface vessel and excavate material from the sea floor; and a vertical transport system. The vertical transport system includes at least one transport receptacle configured to receive excavated material from the mining grab and transport the excavated material to the surface vessel; and a winch system usable to raise and lower the at least one transport receptacle between the sea floor and the surface vessel. [0005] Another embodiment relates to a subsea mining system comprising a mining grab configured to excavate material from a sea floor, the mining grab being a round-nose mining grab; a remote operated vehicle configured to be controlled from a remote location and to control operation of the mining grab; and at least one transport receptacle configured to receive material excavated by the mining grab and transport the material to a surface vessel.

[0006] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only, and are not restrictive of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Features, aspects, and advantages of the present disclosure will become apparent from the following description, appended claims, and the accompanying exemplary embodiments shown in the drawings, which are briefly described below.

[0008] FIG. 1 is a schematic view of a subsea mining system according to an exemplary embodiment.

[0009] FIG. 2 is a perspective view of a portion of the surface vessel of the subsea mining system of FIG. 1 according to an exemplary embodiment.

[0010] FIG. 3 is a perspective view of the mining grab a transport receptacle of the subsea mining system of FIG. 1 according to an exemplary embodiment.

[0011] FIG. 4 is a perspective view of the mining grab unloading material into one of the transport receptacles of the subsea mining system of FIG. 1 according to an exemplary embodiment.

[0012] FIG. 5 is a perspective view of a transport receptacle unloading system for the subsea mining system of FIG. 1 according to an exemplary embodiment.

[0013] FIG. 6 is a flowchart of a method of deep sea mining utilizing the mining system of FIG. 1 according to an exemplary embodiment. DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0014] Prior to discussing the various exemplary embodiments disclosed herein, it should be understood that as utilized herein, the terms "approximately," "about," "substantially," and similar terms are intended to have a broad meaning in harmony with the common and accepted usage by those of ordinary skill in the art to which the subject matter of this disclosure pertains. It should be understood by those of skill in the art who review this disclosure that these terms are intended to allow a description of certain features described and claimed without restricting the scope of these features to the precise numerical ranges provided. Accordingly, these terms should be interpreted as indicating that insubstantial or inconsequential modifications or alterations of the subject matter described and claimed are considered to be within the scope of the invention as recited in the appended claims.

[0015] Referring in general to FIGS. 1-6, a deep water subsea system and method of using the system for excavating or extracting mineral resources or other excavated material from the ocean floor is shown. The system uses a grab mining device deployed from a surface vessel to extract the material from the sea floor and receptacles for transporting the material to the surface. As the material is hoisted up to the surface in the receptacle and the empty receptacle is lowered back down to the sea floor, the grab mining device may continue to excavate minerals for transport in additional receptacles. At the surface, the material may be sized, dewatered, and stored using the surface vessel. The material may then be transported to bulk carriers for transport to processing facilities. The surface vessel, the grab mining device, and the receptacles represent a minimal infrastructure that can be easily repositioned to excavate or extract mineral resources or other materials from a number of locations.

[0016] According to various exemplary embodiments, the system can be utilized for a wide variety of subsea resources, including seafloor massive sulfide (SMS) deposits, phosphate rock, manganese nodules, and diamonds. The sizing and dewatering system utilized on the surface vessel can be modified for the intended resource.

[0017] While the term "sea floor" will be used to describe the location of the mineral deposits or other material collected, it should be understood that the system is not restricted to bodies of water commonly called seas. The system may be used to collect resources such as minerals from a wide variety of underwater locations and the floor from which the resources are collected may therefore be at the bottom of any suitable body of salt water or fresh water at an appropriate depth.

[0018] Referring now to FIG. 1, a subsea mining system 10 is shown according to one exemplary embodiment. The system 10 includes a surface vessel 12 at the surface 14 of a body of water. The surface vessel 12 is dynamically positioned and provides the support structure and services for the mining system 10, temporary storage of a mined material resource such as a mineral deposit, and trans-loading of the resource to another facility or vessel. The system 10 is configured to collect the material from an excavation area 18 at the floor 16 of the body of water. From the surface vessel 12 (e.g., through a moon pool), a vertical transport system 20 (e.g., hoist system, lift system, winch system, etc.) is used to deploy one or more transport receptacles 24 (e.g., containers, bins, buckets, etc.) to and from the floor 16. A mining device such as a grab 30 is also deployed toward the floor 16. The grab 30 is powered by an umbilical cord 32 and is raised and lowered from the surface vessel 12 via cables 34. In some embodiments, umbilical cord 32 and cables 34 may be integrated into a single integrated umbilical. Once at the excavation area 18, the grab 30 is maneuvered remotely from the vessel with a remotely operated vehicle (ROV) 36. The grab 30 is used to extract the material from the floor 16. The material is emptied from the grab 30 into the receptacle 24, which is then raised to the surface with a cable 25 and an active heave compensated hoist or winch 22 while the grab 30 remains at or near the floor 16. The filled receptacle 24 is drawn back to the surface vessel 12 and the material is transferred to the surface vessel 12, such as to a processing system 40 on-board the surface vessel 12. According to an exemplary embodiment, the material is emptied from the receptacle 24 into a bin 42, where it is sized and dewatered. The material is then transferred to a storage area 44 (e.g., storage hopper), where it may be held until the storage area 44 has reached capacity. The material may then be transferred from the storage area 44 to another storage or processing area, such as a shore-based loading facility or another vessel, such as a bulk carrier.

[0019] In an exemplary embodiment, the mining system 10 may be utilized at a depth of between approximately 500 meters (m) and 2500m. In a preferred embodiment, the mining system 10 may be utilized at a depth of between 1000m and 2500m. In a particularly preferred embodiment, the mining system 10 may be utilized at a depth of at least 1500m. The raising and lowering of the transport receptacles 24 may therefore take a substantial time. According to an exemplary embodiment, the vertical transport system 20 includes multiple transport receptacles 24. At least one receptacle 24 may therefore by present at the floor 16 to be filled by the grab 30 while one or more additional receptacles are being raised, lowered, or emptied into the processing system 40.

[0020] Referring now to FIG. 2, one end of the surface vessel 12 is shown according to an exemplary embodiment. The upper portion of the vertical transport system 20 includes an unloading system 50 coupled to the surface vessel 12. The unloading system 50 receives the transport receptacles 24 and automatically empties the material from the receptacles 24 into the processing system 40 via, for example, a mechanical tripping mechanism. The unloading system 50 includes a frame 52 with shuttles 54 that are configured to receive transport receptacles 24 brought up from the floor 16 with the winch 22. The shuttles 54 are moveable along rails 56 between a first position, shown in FIG. 2 and a second position, shown in FIG. 5. In the first position, the transport receptacles 24 may be loaded onto or unloaded from the shuttle 54. In the second position, as described in more detail below with reference to FIG. 5, the shuttle 54 moves the transport receptacles 24 to a position where they may be emptied into the processing bin 42.

[0021] Referring now to FIG. 3, a portion of excavation area 18 is shown according to an exemplary embodiment. The transport receptacles 24 are lowered to a position on the sea floor 16 proximate to the grab 30 at the excavation area 18 (e.g., around approximately 30 meters from the grab 30). The transport receptacles 24 include and are supported by one or more supports 26, which are configured to provides stable support for the transport receptacles 24 on the possibly irregular terrain of floor 16.

[0022] The transport receptacle 24 includes a body or container 60, a lid or cover 62 that is hingably coupled to the container 60, and a bracket 64 coupled to the container 60. As indicated above, one or more supports (e.g., legs, platforms, etc.) may be used to properly support transport receptacle 24 on the floor 16. The cover 62 is moveable from an open position, in which it is generally perpendicular to the open top of the container 60 and a closed position in which it covers the open top of the container 60. In one embodiment, the bracket 64 is pivotably coupled to the container 60 and is coupled to the cover 62 with a linkage 66. Other configuration of the container and cover may be used according to various other embodiments. The hoist cable 25 is coupled to the top of the bracket 64. When the transport receptacle 24 is lowered onto the floor 16 such that the floor 16 supports the container 60, the tension in the cable 25 may be reduced, allowing the weight of the bracket 64 to pull the cover into the open position via the linkage 66.

[0023] According to an exemplary embodiment, the grab 30 is a round-nose grab bucket guided by the ROV 36. In other embodiments, grab 30 may be a clamshell grab. The ROV 36 includes a multitude of maneuvering thrusters 70 (e.g., propellers, etc.) that are operated from the surface vessel 12 to move the grab 30 about the excavation area 18. Sensors and positioning systems (e.g., 2D cameras, 3D cameras, other imaging systems, gyroscopes, sonar systems, GPS systems, etc.) may be provided on the ROV 36 and/or the surface vessel 12 to allow the operator to accurately position the grab 30 (e.g., heading, pitch, altitude, etc.) with the ROV 36 relative to a mineral deposit or other material resource in the excavation area 18, and relative to the transport receptacle 24. The umbilical 32 supplies electrical power from the vessel to the grab 30. The umbilical 32 may be deployed through a moon-pool on the vessel 12 by an active heave compensated winch system and extend through an opening 72 in the center of the ROV 36 to a hydraulic power source 74 mounted below the ROV 36. The hydraulic power source 74 opens and closes a pair of hinged jaws 78 via hydraulic actuators 76. The hydraulic system for the grab is configured to operate at the increased pressures experienced at the depths at which the mining system 10 operates.

[0024] Once positioned above a material to be collected, the grab 30 is lowered with the jaws 78 in an open position. The grab 30 may be utilized to remove overburden above a desired material. The weight and hydraulic closing power of the grab 30 allows the jaws 78 to penetrate, fracture, and extract "soft" rock (e.g., material with a hardness up to a 100 mPa UCS (unconfirmed compressive strength)). According to an exemplary embodiment, the grab 30 is capable of digging up to between 7-10 meters into the surface of the floor 16. Once the jaws 78 have closed and the grab 30 has collected and extracted a load of material, the ROV 36 guides the loaded grab 30 to the empty transport receptacle 24.

[0025] Referring now to FIG. 4, the grab 30 is positioned over the transport receptacle 24, and the jaws 78 are opened, allowing the mined material to be deposited into the container 60 of the transport receptacle 24. The container 60 may be sized such that multiple passes from the grab 30 are needed before the transport receptacle 24 is filled. For example, in one exemplary embodiment, the grab 30 may be configured to capture approximately 12 cubic meters of material and the transport receptacle 24 may be configured to have a capacity of approximately 40 cubic meters.

[0026] Once filled, the grab 30 is moved by the ROV 36 away from the transport receptacle 24 and the transport receptacle 24 is raised to the surface 14 by the winch 22. As the cable 25 is withdrawn, the bracket 64 is pulled upward, closing the cover 62. A lip extends about the periphery of the cover 62. When the cover 62 is in the closed position, the lip overlaps the rim of the container 60, creating a tortuous path for water and silt to travel between the interior of the container 60 and the surrounding water. The interaction between the cover 62 and the container 60 helps to retain the silt and other material within the transport receptacle 24, minimizing the amount of silt that escapes into the surrounding water due to water currents. This minimizes water column pluming and the environmental impact of the mining system 10 to the water around the excavation area 18. Further, reducing the amount of silt escaping into the surrounding water reduces the cloudiness of the water and increases visibility. The loose fit of cover 62 allows some water to travel between the interior and the exterior of the transport receptacle 24 so that the interior pressure of the transport receptacle 24 and the surrounding water pressure may be equalized as the transport receptacle 24 is raised and lowered between the surface 14 and the floor 16.

[0027] Referring now to FIG. 5, a filled transport receptacle 24 is shown loaded in the unloading system 50 according to one embodiment. The transport receptacle 24 is raised out of the water by the winch 22 and is set on the shuttle 54, supported by a pair of arms 65. The transport receptacle 24 and the shuttle 54 are then advanced on the rails 56 from the first position to the second position. As the shuttle 54 moves toward the second position, it brings the transport receptacle 24 into contact with a stop 80 extending downward from the frame 52. The stop 80 contacts the top of the bracket 64, causing the bracket to rotate backward relative to the container 60 and move the cover 62 to the open position via the linkage 66. The bracket 64 moves to an over center position and the weight of the bracket 64 retains the cover 62 in the open position. Further movement of the shuttle 54 toward the second position brings the container 60 into contact with tip arms 82 coupled to the rails 56. The tip arms 82 causes the transport receptacle 24 to rotate about the pair of arms 65 and empty the contents (e.g., the excavated material and water) of the transport receptacle 24 out of the open top of the container 60 and into the bin 42 of the processing system 40. [0028] The processing system 40 is configured to drain the water from (e.g., decant, dewater, etc.) the excavated material. According to an exemplary embodiment, the bottom of the bin 42 is a grated or other open structure, allowing water to pass through the bottom and be collected for later use. The processing system 40 pumps the water to a holding tank 84, shown in FIG. 5 as being coupled to the frame 52 of the unloading system 50. The shuttle 54 is then moved along the rails 56 back toward the first position. As the shuttle 54 passes back over the tip arms 82, the transport receptacle 24 is rotated back to an upward position. From the tank 84, the water is released into the empty transport receptacle 24 through fill pipes 88. Filling the transport receptacle 24 with water lowers the buoyancy of the transport receptacle 24 and facilitates the lowering of the transport receptacle 24 to the floor 16. As the shuttle 54 passes under the stop 80, the stop 80 contacts the open cover 62 to close the transport receptacle 24. The winch 22 is then utilized to raise the transport receptacle 24 back off the shuttle 54 and lower the transport receptacle 24 back to the floor 16 to be refilled with excavated material with the grab 30.

[0029] The processing system is further configured to size the excavated material. The excavated material may be mechanically broken into particles of a certain desired size (e.g., less than 100 mm) to facilitate transport via conveyor belts to the storage area 44 for temporary storage. It should be noted that while the FIGURES generally illustrate raising and lowering transport receptacles relative to one end of the surface vessel and subsequently performing additional processing (e.g., dewatering, sizing, etc.) on the material, according to various other embodiments, excavated material may be raised and lowered relative to other portions of a surface vessel (e.g., via the moon pool) and directed to subsequent processing using other suitable means.

[0030] Referring now to FIG. 6, a method of deep sea mining 90 is shown according to an exemplary embodiment. The method 90 includes excavating a volume of material from the sea floor using a mining grab (e.g., mining grab 30) (step 92). As discussed above, the grab may be controlled by an ROV. The excavated material is then transported from the mining grab 30 to a transport receptacle (e.g., transport receptacle 24) (step 94). The transport receptacle is then moved from the sea floor to adjacent a surface vessel (e.g., surface vessel 12) (step 96). The excavated material is then transferred from the transport receptacle to the surface vessel (step 98). [0031] Once transferred to the surface vessel, the water transported with the excavated material from the sea floor may then be drained (step 100). The water emptied from the transport receptacle and drained from the excavated material is then collected and pumped to a storage tank (e.g. tank 84) (step 102). The water is then utilized to fill the empty transport receptacle (step 104). The transport receptacle filled with water is them moved from the surface vessel back to the sea floor adjacent the mining grab (step 106). The process of excavating material, and filling, transporting, and emptying the excavated material from the transport receptacle may then be repeated.

[0032] According to one exemplary embodiment, a transport receptacle cycle (e.g., the positioning, filling, raising, emptying, refilling, and lowering of the receptacle as described in steps 92-106) takes a length of time that is greater than the excavation and filling cycle for the grab (e.g., the excavation of the material and filling of the receptacle as described in steps 92-94). For example, in one exemplary embodiment, a grab may be capable of filling a receptacle in approximately 70 minutes and the receptacle cycle may have a length of approximately 150 minutes. The method 90 may therefore utilize multiple transport receptacles with a single grab such that one receptacle is filled while one or more additional receptacles are being transported to or from the surface vessel or being emptied on the surface vessel.

[0033] On-board the surface vessel, the excavated material may be mechanically broken to a desired particle size (step 108). The sized material may then be transferred to a storage area on the surface vessel (e.g. storage area 44) (step 110). Once the storage area is filled, the excavated material may be transferred from the storage area on the surface vessel to a bulk carrier or another storage area (step 112). After the storage area has been emptied, the method 90 may be repeated.

[0034] It should be understood that the construction and arrangement of the elements of the subsea mining system and method as shown in the exemplary embodiments are illustrative only. Although only a few embodiments of the present disclosure have been described in detail, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter recited. For example, elements shown as integrally formed may be constructed of multiple parts or elements. Some like components have been described in the present disclosure using the same reference numerals in different figures. This should not be construed as an implication that these components are identical in all embodiments; various modifications may be made in various different embodiments. It should be noted that the components and/or assemblies of the subsea mining system may be constructed from any of a wide variety of materials that provide sufficient strength or durability, in any of a wide variety of colors, textures, and combinations.