Patent Application
20230074267
The invention relates to a deep-sea mining vehicle for collecting mineral deposits on a seabed at great depths and transporting said deposits to a floating device or other storage above water. The invention likewise relates to a method for collecting mineral deposits at great depths with the deep-sea mining vehicle, and to a suction head for use in a deep-sea mining vehicle. The mineral deposits can comprise polymetallic nodules, such as manganese nodules.
In view of the growing world population and increasing scarcity of natural resources, there is an increasing need for groundbreaking technologies for deep-sea mining. Polymetallic nodules occur on the floors of a number of oceans and contain essential raw materials, such as nickel, cobalt and manganese. After extraction, the metals present in the polymetallic nodules can for instance be applied in stainless steel, batteries, wind turbines, photovoltaic systems and other useful applications.
In deep-sea mining the seabed can lie a distance of 4000-6000 m and more from the sea surface, and deep-sea mining devices must therefore be able to withstand the high pressures and other difficult conditions prevailing at such depths in the vicinity of the seabed.
A deep-sea mining vehicle is generally lowered toward the seabed from a deep-sea mining ship. Use can be made here of launching devices designed particularly for this purpose, which can if desired be adapted to the design of the deep-sea mining vehicle. A riser pipe or riser string arranged between the deep-sea mining vehicle and the deep-sea mining ship further ensures that mineral deposits collected by the deep-sea mining vehicle are carried from the seabed to a storage situated above the water surface. For this purpose the deep-sea mining ship is provided with suitable pumping equipment. If desired, pumps can also be incorporated in the riser string at determined water depths. A flexible connection between the riser string and the deep-sea mining vehicle ensures that the vehicle is able to move relatively freely over the seabed.
KR 101 348 112 B1, KR 101 391 634 B1 and KR 101 348 111 B1 show a deep-sea mining vehicle provided with a suction head with an open suction side which is directed toward the seabed and along which the mineral deposits are taken up. The taking up of the mineral deposits and the transport thereof to an outlet is supported by a feed opening for water which is connected to an inlet of the suction head. The water is led toward the outlet via the open suction side.
CN 109 026 008 A, US 4,503,629 A and US 4,042,279 A disclose other mining vehicles.
It will be apparent that collecting polymetallic nodules and then transporting the collected polymetallic nodules to a floating device above the water surface must take place as efficiently as possible, considering the difficult conditions on site.
The present invention has for its object, among others, to provide a deep-sea mining vehicle whereby mineral deposits can be collected at great depths with an increased efficiency relative to the prior art.
For this purpose the invention comprises a deep-sea mining vehicle as described herein. The deep-sea mining vehicle for taking up mineral deposits from a seabed at great depth, and optionally transporting said deposits to a floating device, comprises a support frame provided with means for moving the vehicle forward on the seabed, with an at least temporary storage for the mineral deposits taken up, and further with a suction head with an open suction side which is directed toward the seabed and along which the mineral deposits are taken up, wherein the taking up of the mineral deposits and the transport thereof to an outlet, which is connected to a suction conduit leading to the storage, is supported by a gap-like feed opening for water which is connected to an inlet of the suction head and by a pressure chamber for carrying the water at a high exit speed through the feed opening and toward the outlet along an internal wall part which mutually connects the feed opening and the outlet, which wall part is curved such that the distance to the open suction side of the deep-sea mining vehicle decreases from the inlet and then increases again toward the outlet.
The curvature of the wall part, among other things, in combination with the gap-like feed opening and the exit angle of the gap-like feed opening provide for a more efficient take-up of the mineral deposits, such as manganese nodules, from the seabed. The exit angle of the gap-like feed opening preferably lies between 0° and 45° relative to the horizontal plane, preferably between 20° and 40°.
An embodiment of the invention relates to a deep-sea mining vehicle wherein the gap-like feed opening extends in a direction running parallel to a width direction of the suction head. The gap-like feed opening provides for a more uniform and continuous flow profile at the position of the open suction side, and furthermore advances a better attachment of the flow to the internal wall part. Flow losses may be reduced hereby. The gap-like feed opening ensures that the desired flow profile is achieved more quickly.
In yet another embodiment of the invention a deep-sea mining vehicle is provided wherein a cross-section of the gap-like feed opening is variable. The variable gap-like feed opening enables higher exit speeds, which may result in a more efficient suctioning of the mineral deposits.
A further embodiment is obtained by a deep-sea mining vehicle wherein a height of the gap-like feed opening is variable. The suction action of the deep-sea mining vehicle can hereby be adjusted depending on the (expected) properties of the mineral deposits.
Another embodiment relates to a deep-sea mining vehicle wherein the inlet has a teardrop-shaped cross-section and the teardrop debouches in the gap-like feed opening. With these measures a hydrodynamically optimized flow is obtained in the direction of the feed opening, and thereby a further increased efficiency.
Yet another embodiment relates to a deep-sea mining vehicle wherein the gap-like feed opening has an upper wall which runs continuously into the wall part. The upper wall of the gap-like feed opening and the wall part can thus optionally be formed from the same plate. The extended upper wall of the present embodiment provides an improved attachment of the water flow to the upper wall of the wall part. This results in less turbulence and so a more uniform, continuous flow over the width of the suction head.
In a further improved embodiment a deep-sea mining vehicle is provided wherein the wall part has a convex curvature from the inlet, comprises a linear middle part, and a wall part which has a concave curvature and connects to the outlet. The convex-straight-concave form of the upper wall in this embodiment provides for an optimized flow profile which on the one hand imparts as efficiently as possible a kinetic momentum to the taken-up mineral deposits and on the other hand discharges the mineral deposits as efficiently as possible to the outlet connected to the suction conduit leading to the storage. The linear middle part can have a length of 0 m to 3 m, more preferably 0.1 m to 2.5 m. If desired, a wall part with a convex form can be situated between the linear middle part and the wall part which has a concave curvature and connects to the outlet.
Yet another embodiment provides a deep-sea mining vehicle wherein the height of the linear middle part relative to a plane of the open suction side lies between 0 and 200 mm, and more preferably between 20 and 110 mm. The plane of the open suction side can be defined by lower edges of vertically running strengthening plates. These lower edges can come into contact with the underwater bottom but will generally be held at a relatively small distance above the underwater bottom during operation.
The angle formed by a longitudinal axis of the suction conduit with a horizontal can in principle be chosen within limits. A further optimized deep-sea mining vehicle has the feature that the angle formed by a longitudinal axis of the suction conduit with a horizontal plane lies between 30° and 80°, and more preferably between 40° and 50°. The selection of the angle of the suction conduit is a consideration weighing up the counteraction of the gravitational force on the mineral deposits – wherein the smallest possible angle relative to the horizontal is preferably opted for – and general structural and hydrodynamic properties of the vehicle – wherein the more compact the form of the vehicle, the greater the angle that is opted for.
A deep-sea mining vehicle according to yet another embodiment has the feature that the suction head comprises a second gap-like feed opening situated at the position of the outlet, and a second pressure chamber for carrying the water at a high exit speed through the second feed opening and toward the suction conduit which can be connected to the outlet. This improves the transport of taken-up mineral deposits to the suction conduit. The second gap-like feed opening helps improve the transport to the suction conduit. Due to the effect of the gravitational force, the mineral deposits will have a tendency to stay mainly on a lower side of the suction conduit. In order to help prevent the mineral deposits from “rolling back” the second water flow is maintained.
In an embodiment of the deep-sea mining vehicle the second pressure chamber is adjacent to the open suction side, and an underside of the second pressure chamber is provided with fingers for guiding taken-up mineral deposits. The fingers are placed relative to the open suction side present in a bottom surface of the suction head such that an underside of the fingers is situated above the seabed in use. In other words, the fingers are positioned high enough to prevent them from scraping in the seabed. The underside of the fingers lies above the linear middle part, whereby the linear middle part would touch the seabed first before the underside of the fingers were to touch the seabed.
Another embodiment provides a deep-sea mining vehicle wherein the suction head has a width and at least one of the wall part, the feed opening, the pressure chamber, the second pressure chamber and the outlet extends over the width of the suction head. The active parts of the suction head extending as widely as possible in this embodiment provides for optimization of the seabed surface area covered per passage of the vehicle, and so an optimization and further increase in production.
It is advantageous here for the wall part, the feed opening, the pressure chamber, the second pressure chamber and the outlet to all extend over the width of the suction head in the deep-sea mining vehicle according to an embodiment.
According to yet another embodiment, the production of the deep-sea mining vehicle can be improved when the vehicle comprises a number of suction heads disposed parallel to each other. The suction heads can here form a connected unit which can be operated collectively. It is preferably also possible to enable individual operation of the suction heads. It thus becomes possible to adapt the action of each suction head to the variability of the seabed, which can for instance be manifest in local height differences and/or the presence of possible obstacles, possibly with different dimensions.
It is advantageous here for the deep-sea mining vehicle to be characterized according to an embodiment in that the suction conduits of the suction heads disposed parallel to each other debouch into one or more storages, preferably the at least temporary storage. For reasons of structural engineering it is indeed possible for a plurality of storages to be provided.
Yet another embodiment provides a deep-sea mining vehicle wherein the suction head or plurality of suction heads are height-adjustable relative to the seabed, in the case of a plurality of suction heads preferably independently of each other. This makes it possible to allow the suction head to operate in its optimal operating range (height above the seabed), this independently of the local bottom properties, which can for instance cause sinking down of the vehicle. In other words, the height becomes adjustable relative to the support frame. The suction head preferably does not touch the seabed during deep-sea mining operations and preferably remains at an optimal height above the seabed. In an embodiment the height adjustment takes place by means of linear guides which are arranged on the suction conduit and extend in the direction of the longitudinal axis of the suction conduit. The actuation can take place using hydraulic cylinders.
Another aspect of the invention relates to a suction head for a deep-sea mining vehicle according to the invention. The suction head is provided with an open suction side which is directed toward the seabed and along which the mineral deposits are taken up, wherein the taking up of the mineral deposits and the transport thereof to an outlet, which is connected to a suction conduit leading to the storage, is supported by a gap-like feed opening for water which is connected to an inlet of the suction head and by a pressure chamber for carrying the water at a high exit speed through the feed opening and toward the outlet along an internal wall part which mutually connects the feed opening and the outlet, which wall part is curved such that the distance to the open suction side of the deep-sea mining vehicle decreases from the inlet and then increases again toward the outlet.
According to yet another aspect of the invention, a method is provided for taking up mineral deposits on a seabed at great depth and optionally transporting said deposits to a floating device. The method comprises of providing a deep-sea mining vehicle according to the invention, connecting the deep-sea mining vehicle to a suspension cable provided between the 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.
In a further embodiment the deep-sea mining vehicle is hauled in toward the floating device after collecting of the mineral deposits.
The embodiments of the invention described in this patent application can be combined in any possible combination of these embodiments. Each embodiment can individually form the subject-matter of a divisional patent application.
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:
Referring to
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 componentsʹ 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. Power cables or umbilicals (not shown) are also provided between vessel 1 and deep-sea mining vehicle 3.
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. It is also possible to provide one pumping station (not shown) at the position of a lower side of riser string 2.
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 to and into the 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 at the position of a rear side of deep-sea mining vehicle 3, back into the surrounding area. The cross-section of outlet 33 increases toward the outer end so as to reduce the exit speed of the mixture at the rear side of the deep-sea mining vessel.
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
In a situation of use such nodule collecting heads 8 spray water over the seabed at a high speed so as to thus mix mineral deposit situated there with the supplied and surrounding water.
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 exit speed. 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
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.
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 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.
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 60 degrees, and more preferably between 40 and 50 degrees.
By aiming the water flow toward the seabed or parallel to 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 toward and into suction conduit 84 can be strengthened in the active suction space 804, for instance by spraying water into suction conduit 84 at high speed, in the suction direction of suction conduit 84. Water is supplied under high pressure to active suction space 804 via secondary water inlet 805. The secondary water inlet 805 ensures that there are fewer relatively low-speed zones in the suction conduit and there is less gravitational drop of the sucked-up mixture in outlet 813 and suction conduit 84. 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 in the seabed can be drawn up.
It can particularly be seen in this perspective that spraying of water into open suction side 803 at high speed is realized in that the connection between pressure chamber 802 and open suction side 803 consists of a gap-like feed opening 806. In order to further improve the throughflow the cross-section of pressure chamber 802 is preferably teardrop-shaped, wherein the teardrop debouches in gap-like feed opening 806. Because the section of feed opening 806 is significantly smaller than the section of water inlet 801, water is sprayed through feed opening 806 into open suction side 803 and toward suction conduit 84 at increased speed. Because the gap-like feed opening 806 is arranged parallel to and over the whole or almost the whole width of suction head 80, a water flow is further provided over the whole or almost the whole width of open suction side 803.
In a preferred embodiment the section of the gap-like feed opening 806 is variable. The height of gap-like feed opening 806 is preferably variable.
The water which is carried from gap-like feed opening 806 through open suction side 803 flows along an internal wall part 811 which mutually connects feed opening 806 and suction conduit 84. This wall part is curved such that the distance to the open suction side 803 decreases from the inlet and then increases again in the direction of the outlet. Feed opening 806 preferably has an upper wall which continuous into wall part 811.
In this perspective it can also be seen more clearly how secondary water inlet 805 can supply water to active suction space 804, this being because secondary water inlet 805 debouches into a secondary pressure chamber 810. Pressure chamber 810 is connected to feed opening 814. The outflow direction P6 of feed opening 814 preferably lies in the same longitudinal axis as suction conduit 84. An outlet 813 of suction head 80 is also shown here, without this being partially received in suction conduit 84. Outlet 813 of suction head 80 is disposed relative to the other elements of suction head 80 such that it lies in line with the effective active suction space 804, and thereby elongates it.
In order to strengthen suction head 80 it is provided with a connecting beam 809 which connects pressure chamber 802 to a part of suction head 80 lying further toward suction conduit 84.
A number of water inlet guide fins 807 is provided in order to ensure a more uniform and guided flow of surrounding water to the open suction side 803. A number of (dis)mountable fingers 808 is disposed such that they do not dig into the sediment. Fingers 808 have in the first place the object of avoiding sucked-up mineral deposits, such as manganese nodules, from shooting through and not ending up in outlet 813 and suction conduit 84. The nodules which are situated under the suction head and have already been set into motion by the water jets (and into which some pumping energy has thus already been put) should preferably be transported to and into outlet 813 and suction conduit 84.
The strengthening elements are disposed in the longitudinal direction of suction head 80 such that they are suitable for preventing deformation when deep-sea mining vehicle 3 comes with the nodule collecting heads 8, which are generally installed on the front, into collision with its surroundings.
Relative to the width of suction head 80 at least one of wall part 811, feed opening 806, pressure chamber 802, second pressure chamber 810 and outlet 813 preferably extends over the width of suction head 80, more preferably of the whole width.
This cross-section particularly shows that the elements of suction head 80 together define a flow path (P1-7) with a determined flow direction. The water inlet debouches into the pressure chamber (P1). The gap-like feed opening forms the connection between the pressure chamber and the open suction side (P2). The open suction side is further connected via the optional active suction space (P3) to the outlet (P4). P5 further defines a water inflow from the surrounding area along the guide fins 807, P6 a secondary water inflow from the secondary gap-like opening 814, and P7 a water (in)flow from the rear side toward the effective active suction space 804 around the outer wall of pressure chamber 810 through fingers 808.
The various flow paths can combine as follows: P1 = P2, P2 + P5 + P7 = P3, and P3 + P6 = P4. In order to pose little hydrodynamic resistance to flow path P7 pressure chamber 810 is preferably positioned high enough relative to the seabed. It can further particularly be seen that internal wall part 811 comprises several identifiable segments, these together defining the form of the flow path, from the gap-like feed opening (P2) to the outlet (P4). A first wall part segment 811A is curved such that the distance to open suction side 803 decreases in the flow direction. First wall part segment 811A hereby preferably has a convex curvature relative to the flow path. Internal wall part 811 optionally comprises a linear middle part 811C wherein the distance to open suction side 803 remains constant. The height of linear middle part 811C relative to the plane of open suction side 803 will preferably lie between 20 and 200 mm, more preferably between 50 and 110 mm, and still more preferably between 75 and 95 mm. Internal wall part 811 also comprises a second wall part segment 811B, curved such that the distance to open suction side 803 increases in the flow direction. A third wall part segment 811D defines a part of wall part 811 which has a concave curvature relative to the flow path and connects to outlet 813.
These cross-sections particularly show that spraying water into optional active suction space 804 at high speed is realized in that the connection between secondary pressure chamber 810 and active suction space 804 consists of a second gap-like feed opening 814. Because water is sprayed with the flow direction (P3 & P4), mixture which has been sucked in and is situated in outlet 813 is discharged toward the rest of the deep-sea mining vehicle in accelerated manner. The advancing speed of the deep-sea mining vehicle can enhance the suction speed, particularly because the water inflow P5 from the surrounding area along the guide fins 807 is supported.
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.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2020/5114 | Feb 2020 | BE | national |
This application is the United States national phase of International Application No. PCT/IB2021/051445 filed Feb. 19, 2021, and claims priority to Belgian Patent Application No. 2020/5114 filed Feb. 20, 2020, the disclosures of which are hereby incorporated by reference in their entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IB2021/051445 | 2/19/2021 | WO |
