Deep-Sea Mining Vehicle

Abstract

Described is a deep-sea mining vehicle for taking up mineral deposits from a seabed at great depth, and optionally transporting said deposits to a floating device. The vehicle includes a support frame provided with means for moving the vehicle forward on the seabed, a storage for the mineral deposits taken up, and further a suction head with an open suction side which is directed toward the seabed and along which the mineral deposits are taken up. The deep-sea mining vehicle is further provided with a control device for keeping the height of the suction plane within predetermined limits relative to the seabed. The control device makes use of measuring means for obtaining seabed heights at positions which precede the open suction side relative to the direction of movement and which extend over a width of the deep-sea mining vehicle. An actuator which is incorporated in a control circuit adjusts the height of the suction head on the basis of the seabed heights measured at the positions.

Claims

1. A deep-sea mining vehicle for taking up mineral deposits from a seabed at great depth, wherein the vehicle comprises a support frame provided with means for moving the vehicle forward on the seabed in a direction of movement, with a storage for the mineral deposits taken up, and further with at least one suction head with an open suction side which is directed toward the seabed and is provided in a suction plane, and along which the mineral deposits are taken up, wherein a width direction of the at least one suction head coincides with a width direction of the deep-sea mining vehicle, wherein the deep-sea mining vehicle is further provided with a control device for keeping the height of the suction plane within predetermined limits relative to the seabed, wherein the control device; comprises measuring means for obtaining seabed heights at positions which precede the open suction side relative to the direction of movement and which extend over a width of the deep-sea mining vehicle, and further an actuator which is incorporated in a control circuit and which is configured on the basis of the seabed heights measured at the positions to adjust the height of the suction plane of the at least one suction head such that it remains between the predetermined limits relative to the seabed, and wherein the measuring means comprise an elongate carrier which precedes the open suction side relative to the direction of movement, wherein the carrier is provided with a series of sources configured to generate a geophysical signal under water in the direction of the seabed, and with a series of receivers configured to measure a response signal returning via the seabed, wherein the carrier extends in the width direction of the deep-sea mining vehicle over a width of the deep-sea mining vehicle, wherein the at least one suction head has a width, the seabed heights measured in the width direction of the deep sea mining vehicle are filtered of outlying values, a subset of seabed heights over the width of the at least one suction head is determined, and a maximum seabed height over the width of the at least one suction head is calculated from the subset, wherein the actuator is configured on the basis of the calculated maximum seabed height to adjust the height of the suction plane of the at least one suction head such that it remains between the predetermined limits relative to the seabed.

2. The deep-sea mining vehicle according to claim 1, wherein the geophysical signal comprises a sound wave.

3. The deep-sea mining vehicle according to claim 1, wherein the measuring means comprise a multibeam.

4. The deep-sea mining vehicle according to claim 1, wherein the number of positions of which the seabed height is measured lies in width direction between 1 and 400, more preferably between 100 and 350, still more preferably between 200 and 300.

5. The deep-sea mining vehicle according to claim 1, wherein the intermediate distance of two adjacent positions of which the seabed height is measured lies in width direction between 1 and 3 cm, more preferably between 1.2 and 2.5 cm, still more preferably between 1.4 and 2 cm.

6. The deep-sea mining vehicle according to claim 1, comprising at least two suction heads disposed parallel to each other in the width direction of the deep-sea mining vehicle.

7. The deep-sea mining vehicle according to claim 6, comprising 2 to 10 suction heads, more preferably 3 to 5 suction heads.

8. The deep-sea mining vehicle according to claim 6, wherein the suction heads are controlled individually in the height relative to the seabed.

9. The deep-sea mining vehicle according to claim 1, wherein the predetermined limits amount to 0 and 200 mm, and more preferably 20 and 100 mm.

10. The deep-sea mining vehicle according to claim 1, wherein the measuring means precede a front side of the open suction side of the at least one suction head relative to the direction of movement by a preceding distance lying between 5 and 100 cm.

11. The deep-sea mining vehicle according to claim 1, comprising further measuring means for obtaining seabed heights at positions which precede the open suction side relative to the direction of movement and which extend over a width of the deep-sea mining vehicle, wherein the further measuring means comprise a slat which is connected to the frame and can move over the seabed in the direction of movement, and further comprise computing means for determining a seabed height from the measured incline of the slat.

12. The deep-sea mining vehicle according to claim 11, wherein the slat is removable from the seabed.

13. A method for taking up mineral deposits on a seabed at great depth, the method comprising of providing a deep-sea mining vehicle according to claim 1, connecting the deep-sea mining vehicle to a suspension cable provided between a floating device and the deep-sea mining vehicle, lowering the deep-sea mining vehicle toward a seabed, and moving the deep-sea mining vehicle forward over or on the seabed in order to take up the mineral deposits.

14. The method according to claim 13, further comprising the step of transporting said deposits to the floating device.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0027] The invention will now be further elucidated on the basis of the following figures and description of a preferred embodiment, without otherwise being limited thereto. In the figures:

[0028] FIG. 1 is a schematic side view of an assembly of a floating vessel and a riser pipe connected thereto, to an underside of which is connected a deep-sea mining vehicle according to embodiment of the invention;

[0029] FIG. 2 is a schematic side view of a deep-sea mining vehicle according to an embodiment of the invention;

[0030] FIG. 3 is a schematic perspective front view of a deep-sea mining vehicle according to an embodiment of the invention;

[0031] FIG. 4 is a schematic perspective front view of a suction head of the deep-sea mining vehicle according to an embodiment of the invention;

[0032] FIG. 5 is a schematic perspective rear view of the suction head of the deep-sea mining vehicle according to an embodiment of the invention shown in FIG. 4;

[0033] FIG. 6 is a specified schematic side view of the deep-sea mining vehicle according to an embodiment of the invention shown in FIG. 1.

[0034] FIG. 7 is a visualization of measurements of the deep sea floor height obtained by the measuring means arranged on the deep-sea mining vehicle.

DESCRIPTION OF THE INVENTION

[0035] Referring to FIG. 1, a part is shown of a typical setup which is used in deep-sea mining of mineral deposits, such as polymetallic nodules. The setup typically comprises a transport system in the form of a tubular riser string 2 (which can have a length of several thousands of metres and connects to a floating vessel 1) to which mining equipment such as a deep-sea mining vehicle 3 is attached. A flexible connecting hose assembly 4 can be arranged between the lower end 7 of riser pipe 2 and the deep-sea mining vehicle 3 which is adapted to move on a deep-sea floor 5 and to collect mineral deposits therefrom.

[0036] Connecting assembly 4 comprises a flexible undersea hose 40 which is adapted to transport mineral nodules collected by vehicle 3 to the rigid riser pipe 2. Hose 40 can be provided with floating blocks 41 which compensate for the components' own weight and generate an upward force in a part of the hose and create an S-shape. Flexible connecting assembly 4 enables mining vehicle 3 to have a determined degree of freedom to move around on seabed 5, and ensures that the vehicle is not affected by the movements of riser pipe 2. In order to support and lift vehicle 3 steel hoisting cables (not shown) can be provided between the vessel 1 and the deep-sea mining vehicle 3.

[0037] If desired, the transport system in the form of a tubular riser string 2 of extreme length can also comprise a number of pump modules 10 which are arranged in lengthwise direction. Pump modules 10 are adapted to pump up mineral deposits (nodules) from seabed 5 in an upward direction 6, which is oriented away from seabed 5 toward the sea surface.

[0038] FIG. 2 shows a deep-sea mining vehicle 3 according to a preferred embodiment of the invention.

[0039] Deep-sea mining vehicle 3 typically comprises a support frame 300 which is provided with means 301 for enabling deep-sea mining vehicle 3 to be moved, for instance over the seabed. Such means can take the form of caterpillar tracks 301, wheels or other moving means.

[0040] In order to be able to take up mineral deposits support frame 300 is typically provided with a nodule collecting head 8, a hopper 32 and an outlet 33. A mixture of, among other things, water and mineral deposit, which is taken up by nodule collecting head 8, is transported from the seabed into deep-sea mining vehicle 3. In deep-sea mining vehicle 3, particularly in separating space 31, the mixture is split into at least two parts, for instance by arranging a filter 311 at an entrance of outlet 33. The mineral nodules are thus separated from the greater part of the water and several finer particles of the mixture. The water and finer particles of the mixture are ejected via outlet 33, back into the surrounding area.

[0041] The mineral nodules are captured in hopper 32, which in this case serves as storage or as temporary storage. When deep-sea mining vehicle 3 forms part of a deep-sea mining setup as shown in FIG. 1, mineral nodules are pumped via this storage, optionally via a central discharge pipe of deep-sea mining vehicle 3, to the hose 40. In another embodiment it is possible for deep-sea mining vehicle 3 to be provided with a nodule bin for collecting the mineral nodules.

[0042] FIG. 3 shows a schematic perspective front view of deep-sea mining vehicle 3 according to an embodiment of the invention. From this perspective, it can once again be seen that deep-sea mining vehicle 3 comprises support frame 300 and caterpillar tracks 301. This perspective particularly shows that deep-sea mining vehicle 3 can, in addition to one, also comprise a plurality of nodule collecting heads 8 disposed parallel to each other.

[0043] In a situation of use such nodule collecting heads 8 spray water onto the seabed at a high speed so as to thus mix mineral deposit situated there with the supplied and surrounding water.

[0044] These nodule collecting heads 8 typically consist of pump 81, which provides water via one or more supply conduits to suction head 80 at a high pressure. Pump 81 can also be shared between two or more nodule collecting heads, wherein it provides water to both heads. From suction head 80 water is sprayed onto the seabed at high speed, such that mineral deposits which may be situated there are mixed with the supplied and surrounding water. This mixture of water and seabed is taken up via the nodule collecting heads into deep-sea mining vehicle 3, after which it is processed as described above with reference to FIG. 2. From head 80, the mixture is received by means of suction conduit 84 in nodule collecting head 8.

[0045] The one or more nodule collecting heads 8 can be controlled on the basis of measurements taken of the surrounding area via a measuring installation mounted on a measuring installation frame 83.

[0046] FIGS. 4 and 5 show respectively a schematic, perspective front and rear view of suction head 80 as part of nodule collecting head 8 of deep-sea mining vehicle 3, according to an embodiment of the invention. From this perspective it can once again be seen that nodule collecting head 8 consists, among other things, of suction head 80 and suction conduit 84. It can particularly be seen from this perspective that suction head 80 lies partially in suction conduit 84, wherein these elements are mutually connected by a height-adjusting actuator 851 and a guiding installation 852. Outlet 813, which has an outer periphery corresponding with an opening in suction conduit 84, is particularly arranged at least partially in suction conduit 84. Height-adjusting actuator 851 enables suction head 80 and suction conduit 84 to be adjustable relative to each other. This is achieved by moving outlet 813 into or out of suction conduit 84. Guiding installation 852 is arranged in order to further support this linear movement.

[0047] It can also be seen from this perspective that suction head 80 further consists of one or more water inlets 801, pressure chamber 802, open suction side 803, outlet 813, and an optional active suction space 804. Water which is provided from supply conduit 82 and is already under high pressure is collected in pressure chamber 802 via one or more water inlets 801. From pressure chamber 802, the provided water is sprayed at high speed into open suction side 803, particularly in the direction of the outlet.

[0048] When a nodule collecting head 8, of which suction head 80 forms part, is installed on deep see mining vehicle 3, open suction side 803 is directed in an environment of use toward the bottom on which deep-sea mining vehicle 3 rests, for instance the seabed. In a collecting head 8 installed in such a manner the longitudinal axis of suction conduit 84 preferably forms an angle with a horizontal plane of between 30 and 80 degrees, and more preferably between 40 and 50 degrees.

[0049] By aiming the water flow over the seabed a water flow is realized from pressure chamber 802 to suction conduit 84, and in this way the mixture of water and mineral deposit is sucked into suction conduit 84. The flow of this mixture into suction conduit 84 can be strengthened in active suction space 804 by spraying water into suction conduit 84 at high speed in suction direction of suction conduit 84. Water is supplied under high pressure to active suction space 804 via secondary water inlet 805. For this purpose the water can further be brought under pressure by a pump, for instance pump 81, and be provided to secondary water inlet 805 by a supply conduit, similar to supply conduit 82. With such an approach both mineral deposits situated on the seabed and mineral deposits buried partially under the seabed can be drawn up.

[0050] FIG. 6 shows a part of deep-sea mining vehicle 3. In this view it can once again be seen that deep sea vehicle 3 consists of support frame 300, which rests on caterpillar tracks 301.

[0051] It can further be seen in this view that suction conduit 84 is mounted on support frame 300, wherein outlet 813 of suction head 80 is arranged at least partially in suction conduit 84. Measuring means 83 further comprises a support 831 from which a navigation and positioning system 832 and measuring head 833 (multibeam) are suspended. The measuring system frame 83 is also provided with a mechanical fallback system 834.

[0052] The relative displacement between suction conduit 84 and suction head 80 is controlled by height-adjusting actuator 851. In order to further support this linear movement guiding installation 852 is arranged. Guiding installation 852 serves to reduce the torsional forces on the height-adjusting actuator. Water supply to suction head 80 is possible for multiple heights of suction head 80 in that the primary supply conduit 82A and secondary supply conduit 82B are made of a flexible material. Owing to the angle at which suction conduit 84 is mounted on support frame 300, displacement of suction head 80 will also always take place at an angle, particularly the same angle. When suction head 80 is displaced upward it is thus also always displaced at least partially rearward.

[0053] This setup is particularly configured to control the distance of suction head 80 to the underlying seabed. When the deep-sea mining vehicle comprises a plurality of suction heads, these can be controlled individually in the height relative to the seabed.

[0054] The plane of suction head 80 which is directed towards the seabed, referred to hereinafter as the suction plane, is adjusted in the height by the control device in order to keep this distance within determined limits.

[0055] This is realized by measuring head 833 for obtaining seabed heights at positions which precede the open suction side relative to the direction of movement and which extend over almost the whole width of deep-sea mining vehicle 3, and by height-adjusting actuator 851 which is incorporated in the control circuit and which is configured on the basis of the seabed heights measured at the positions to adjust the height of the suction plane of suction head 80 such that it remains between the predetermined limits relative to the seabed.

[0056] Measuring head 833 comprises sources which are configured to generate a geophysical signal, for instance a sound signal, under water in the direction of the seabed, and a series of receivers configured to measure a response signal returning via the seabed, wherein the carrier extends in the width direction of deep-sea mining vehicle 3 over a width of deep-sea mining vehicle 3. In order to ensure sufficient precision over the whole width the measuring means can comprise a multibeam. Instead of measuring at 1 location, such a multibeam measures at multiple locations, for instance 256, over the whole width of the vehicle. These positions are distributed over the whole width of deep-sea mining vehicle 3, whereby the intermediate distance of two adjacent positions of which the seabed height is measured lies in the width direction between 1 and 3 cm, more preferably between 1.2 and 2.5 cm, still more preferably between 1.4 and 2 cm. In other exemplary embodiments the intermediate distance of two adjacent positions can be chosen differently.

[0057] Actuator 851 can adjust on the basis of the calculated maximum seabed height the height of the suction plane of the at least one suction head 80 such that it remains between the predetermined limits relative to the seabed.

[0058] If, despite the above stated precautionary measures, suction head 80 is disposed closer to the seabed than the above stated limits, or if measuring head 832 were to fail for other reasons, mechanical fallback system 834 in the form of one or more slats connected to carrier 831 provide a solution. These can move over the seabed in the direction of movement, and the fallback system further comprises computing means for determining a seabed height from the measured incline of the slat. Such slats can be removed from the system.

[0059] FIG. 7 shows a schematic representation of such measurements. This figure shows a plurality of measuring points 92, measured by measuring heads 833, 832 and always arranged within an extreme measuring range 90. Measuring range 90 is divided into different zones, wherein a single zone 91 corresponds with a suction head 80 arranged at this width of deep-sea mining vehicle 3. All the zones together therefore roughly correspond with the whole width of deep-sea mining vehicle 3.

[0060] For a single suction head 80 the height to be set is determined on the basis of measurement 92 performed in the relevant zone. In order to prevent suction head 80 from being wrongfully lifted and thus lowering the suction capacity the measured seabed heights can be filtered of outliers. When there are enough measurements per width of suction head 80, it is safe to assume that the farthest outliers are caused by measurement errors. From the remaining measurements a maximum seabed height can further be calculated over the width of this suction head 80.

[0061] In order to prevent suction head 80 from constantly being moved upward and downward a number of successive measurements is taken over a predefined period of time, and an average value thereof is determined as desired height 93 of suction head 80. It is hereby possible that desired height 93 is not adjusted in time in the case of an unexpected, steep change, whereby it must be taken into account when setting up the above stated measuring system that a minimal amount of scraping over the bottom will have to be accepted.

[0062] The invention is not limited to the above described embodiment and also comprises modifications thereto to the extent these fall within the scope of the claims appended below.