BACKGROUND

The invention relates to a mining system for mining minerals in a deep sea and a method for mining minerals in a deep sea.

Known deep sea mining systems use a vessel that deploys a self-propelled miner onto the seabed. Such a miner moves along the seabed and collects minerals therefrom. The minerals are stored in a container at the miner and when the container is full the container is or the miner and the container are returned to the vessel to be emptied.

SUMMARY OF THE INVENTION

A disadvantage of the known mining systems is that the miners are affected by the properties of the subsoil when moving along the seabed. The miners can topple over or get stuck.

It is an object of the present invention to provide a mining system that is affected less by the subsoil properties of the seabed.

According to a first aspect, the invention provides a mining system for mining minerals from a seabed of a deep sea, wherein the mining system comprises a vessel floating at the water surface and a submerged mining assembly that is suspended from the vessel, wherein the mining assembly comprises a station above and spaced apart from the seabed, at least one first cable that suspends the station from the vessel, a mining head that is arranged to mine minerals from the seabed, an intermediate frame that extends between the mining head and the station, wherein one end of the intermediate frame is hingeably connected to the station and the opposite end of the intermediate frame is hingeably connected to the mining head, at least one container that is arranged to shuttle between the station and the vessel, and a transport arrangement between the mining head and the station that is arranged to transport the mined minerals from the mining head into the at least one container.

The mining system according to the invention comprises a mining head that collects minerals in the form of polymetallic nodules from the seabed. The minerals are transported by the transport arrangement from the mining head into a container that is located at the station. The station with the container containing the minerals is suspended from the vessel and is free from the seabed. When the container is full with minerals the container is shuttled to the vessel where it will be unloaded. In the mining system the majority of the weight of the mining assembly and the varying weight of the collected minerals is concentrated in the suspended station. The weight of the mining head that is supported by the seabed is limited to its own weight which is relatively low. Due to this low weight the mining head is less prone to topple over or to get stuck as a result of a soft seabed or undulations in the seabed and the mining system therefore is less affected by the seabed properties. The configuration of the intermediate frame allows the mining head to move and tilt with respect to the station while the station hovers at a substantially constant depth. Therefore the mining head can move along the uneven seabed without being hindered by the station. The intermediate frame may also provide support for the transport arrangement. In an embodiment thereof the intermediate frame is hingeable with respect to the station around a first hinge axis and the mining head is hingeable with respect to the intermediate frame around a second hinge axis, wherein the intermediate frame has a longitudinal axis between the station and the mining head, and wherein the first hinge axis and the second hinge axis are orientated perpendicular to the longitudinal axis. This configuration allows the mining head to move and rotate with respect to the station in limited directions which makes the relative motions of the mining head with respect to the station better controllable .

In an embodiment thereof the first hinge axis and the second hinge axis are orientated parallel to each other and parallel to the seabed. This configuration allows the mining head to move upwards and downwards and to rotate forwards and backwards with respect to the station while it prevents the mining head to move and rotate sideways with respect to the station. Therefor the station provides additional stability to the mining head.

In a further embodiment the station and the mining head are rotatable with respect to each other around the longitudinal axis of the intermediate frame. This configuration allows the mining head to tilt with respect to the station whereby the mining head can move along encountered seabed undulations.

In another embodiment the station and the mining head are rotatable with respect to each other around the longitudinal axis of the intermediate frame over a limited rotation stroke or angle. This configuration allows the mining head to tilt over a predetermined angle with respect to the station. The mining head can move along encountered seabed undulations while the station provides stability to the mining head when the mining head tends to tilt more than the predetermined angle.

In an embodiment thereof the first hinge axis is orientated parallel to the seabed, and wherein the station and the mining head are rotatable with respect to each other around the longitudinal axis of the intermediate frame over a limited rotation stroke or angle of plus or minus 20 degrees.

In an embodiment the mining head comprises a propulsion arrangement that is arranged to move the mining head along the seabed in a mining direction. The mining head moves along the seabed and the station follows the mining head. By providing the mining head with a dedicated propulsion arrangement the mining speed and the mining track can be matched to the encountered minerals on the seabed .

In an embodiment thereof the propulsion arrangement comprises at least two parallel archimedes screws that are arranged to move the mining head along the seabed in the mining direction. Archimedes screw propulsion systems have proven to be robust. The archimedes screw propulsion system can move the mining head in a transverse direction which is advantageous to get around encountered objects on the seabed or to position it to an adjacent mining track.

In an embodiment the station is provided with a first thruster that is arranged to move the suspended station with respect to the seabed. The thruster may be used to steer the mining head by sideways movement of the station .

In an embodiment the mining assembly comprises multiple containers, wherein the multiple containers are arranged to shuttle alternatingly between the station and the vessel. At least one container is located at the station during the mining process whereby the mining process can be performed continuously.

In an embodiment the mining assembly comprises at least one second cable, wherein the mining head is connected to the at least one second cable. The second cable may be used to lower the mining head to the seabed. The second cable may additionally be used to assist the mining head to overcome steep sections in the sea bed or to lift the mining head over encountered objects.

In an embodiment the mining assembly comprises at least one third cable, wherein the at least one container is connected to the at least one third cable. The third cable is used to shuttle the container between the station and the vessel. The third cable is operable from the vessel and therefore easy to operate.

In an embodiment the at least one first cable is a shuttle guide for the at least one container. When the container is guided during shuttling between the station and the vessel the container is influenced less by sea currents, waves, and vessel motions. This results in more stable and thereby safer and faster transport of the container .

In an embodiment the at least one container is provided with a second thruster that is arranged to move the at least one container with respect to the station. The second thruster can actively compensate for the motions of the container that are induced by sea currents, waves and vessel motions, which results in more stable and thereby safer and faster transport of the container.

In an embodiment the transport arrangement comprises a suction pipe and a pump unit that are arranged to hydraulically transport the minerals from the mining head to the at least one container. By hydraulically transporting the minerals the generated flow contributes to dislodging the minerals in the form of nodules from the seabed at the mining head.

In an embodiment the mining assembly comprises a separation and filling assembly that is arranged to separate sediment that is associated with the mining of the minerals from the minerals, and that is arranged to fill the at least one container with the minerals and to discharge the sediment. By separating the sediment from the minerals the containers are filled with the minerals only. The mineral revenue per filled container is increased and the lifted weight of the containers is reduced.

In an embodiment thereof the mining assembly comprises a diffuser assembly that is arranged to transport the sediment from the at least one container back to the seabed. The diffuser assembly returns the sediment to or close to the seabed in a smooth manner, causing little turbidity and thereby causing little environmental impact.

In an embodiment the mining system comprises a distribution arrangement on the vessel and the vessel comprises at least one cargo hold, wherein the distribution arrangement is arranged to collect the minerals from the at least one container and to transport the minerals to the at least one cargo hold. The distribution arrangement distributes the minerals evenly over the vessel to ensure the stability of the vessel.

In an embodiment the mining system comprises a power supply that is located on the vessel where it is easy to access and maintain.

The invention further relates to the use of the mining system.

According to a second aspect, the invention provides a method for mining minerals from a seabed of a deep sea by means of a mining system, wherein the mining system comprises a vessel floating at the water surface and a mining assembly that is suspended from the vessel, wherein the mining assembly comprises a station above and spaced apart from the seabed, at least one first cable that suspends the station from the vessel, a mining head that is arranged to mine minerals from the seabed, an intermediate frame that extends between the mining head and the station, wherein one end of the intermediate frame is hingeably connected to the station and the opposite end of the intermediate frame is hingeably connected to the mining head, at least one container that is arranged to shuttle between the station and the vessel, and a transport arrangement between the mining head and the station that is arranged to transport the mined minerals from the mining head into the at least one container, wherein the method comprises the steps of positioning the vessel at a deep sea location that comprises minable minerals at the seabed, lowering the mining assembly into the sea, wherein the station remains spaced apart from the seabed while the mining head is placed on the seabed, mining minerals from the seabed via the mining head, transporting the mined minerals from the seabed into the at least one container by the transport arrangement, and shuttling the at least one container between the station and the vessel.

The method and its embodiments relate to the practical implementation of the mining system according to any one of the aforementioned embodiments and thus have the same technical advantages. In particular, the configuration of the intermediate frame allows the mining head to move and tilt with respect to the station while the station hovers at a substantially constant depth. Therefore the mining head can during the mining step move along the uneven seabed without being hindered by the station. The intermediate frame may also provide support for the transport arrangement.

In an embodiment the intermediate frame is hingeable with respect to the station around a first hinge axis and the mining head is hingeable with respect to the intermediate frame around a second hinge axis, wherein the intermediate frame has a longitudinal axis between the station and the mining head, and wherein the first hinge axis and the second hinge axis are orientated perpendicular to the longitudinal axis.

In an embodiment the first hinge axis and the second hinge axis are orientated parallel to each other and parallel to the seabed.

In an embodiment the station and the mining head are rotatable with respect to each other around the longitudinal axis of the intermediate frame.

In an embodiment the station and the mining head are rotatable with respect to each other around the longitudinal axis of the intermediate frame over a limited rotation stroke.

In an embodiment the first hinge axis is orientated parallel to the seabed, and wherein the station and the mining head are rotatable with respect to each other around the longitudinal axis of the intermediate frame over a limited rotation stroke of plus or minus 20 degrees .

In an embodiment of the method for mining minerals, the mining head comprises a propulsion arrangement that is arranged to move the mining head along the seabed in a mining direction, wherein the method furthermore comprises the step of moving the mining head along the seabed in a mining direction by the propulsion arrangement, wherein the station follows the mining head while it is suspended from the vessel.

In an embodiment the station is provided with a first thruster that is arranged to move the station with respect to the seabed, wherein the method furthermore comprises the step of moving the station with respect to the seabed by the first thruster while the station is suspended from the vessel.

In an embodiment the mining assembly comprises multiple containers, wherein the multiple containers are arranged to shuttle alternat ingly between the station and the vessel, wherein the step of shuttling the at least one container between the station and the vessel comprises shuttling the multiple containers alternatingly between the station and the vessel, wherein during alternatingly shuttling of the multiple containers at least one of the multiple containers is located at the station.

In an embodiment the mining assembly comprises at least one second cable, wherein the mining head is connected to the at least one second cable, wherein the step of lowering the mining assembly comprises placing the mining head on the seabed by paying out the at least one second cable. In an embodiment the at least one first cable is a shuttle guide for the at least one container, wherein the step of shuttling the at least one container between the station and the vessel comprises guiding the at least one container by the at least one first cable.

In an embodiment the at least one container is provided with a second thruster that is arranged to move the at least one container with respect to the station, wherein the step of shuttling the at least one container between the station and the vessel comprises moving the at least one container with respect to the station by the second thruster.

In an embodiment the transport arrangement comprises a suction pipe and a pump unit that are arranged to hydraulically transport the minerals from the mining head to the at least one container, wherein the step of transporting minerals from the seabed into the at least one container comprises hydraulically transporting the minerals from the mining head to the at least one container.

In an embodiment the mining assembly comprises a separation and filling assembly that is arranged to separate sediment that is associated with the mining of the minerals from the minerals, and that is arranged to fill the at least one container with the minerals and to discharge the sediment , wherein the method furthermore comprises the step of separating the sediment from the minerals, filling the at least one container with the minerals and discharging the sediment.

In an embodiment the mining assembly comprises a diffuser assembly that is arranged to transport the sediment from the at least one container back to the seabed, wherein the method furthermore comprises the step of transporting the sediment from the at least one container back to the seabed.

In an embodiment the mining system comprises a distribution arrangement on the vessel, wherein the vessel comprises at least one cargo hold, wherein the distribution arrangement is arranged to collect the minerals from the at least one container and to transport the minerals to the at least one cargo hold, wherein the method furthermore comprises the steps of collecting the minerals from the at least one container and transporting the minerals to the at least one cargo hold.

The various aspects and features described and shown in the specification can be applied, individually, wherever possible. These individual aspects, in particular the aspects and features described in the attached dependent claims, can be made subject of divisional patent applications .

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be elucidated on the basis of an exemplary embodiment shown in the attached drawings, in which :

Figures 1A and IB are an isometric side view and a top view of a mining system comprising a mining assembly according to an embodiment of the invention shown in its inoperative raised position;

Figure 1C is a schematic side view of the mining system with the mining assembly shown in its operative lowered position;

Figures 2A and 2B respectively are an isometric side view of the operational mining assembly as shown in figure 1C, an isometric side view of the mining assembly from the opposite side as shown in figure 2A during emptying the mining assembly; and

Figures 2C and 2D respectively are an isometric close up of a mining head of the mining assembly as shown in figure 2B, and an isometric close up of a station of the mining assembly as shown in figure 2B; DETAILED DESCRIPTION OF THE INVENTION

Figures 1A, IB and 1C show a mining system 10 according to an embodiment of the invention. The mining system 10 comprises a mining vessel 11 that floats in a deep sea 1, having a depth D between the water surface 2 and the seabed 3. In this application by deep sea 1 a sea having a depth D that is greater than the depth D where conventional dredgers, such as trailing suction hopper dredgers, operate in. Conventional dredgers operate in depths D up to approximately 150 meter whereas the mining system typically operates in depths D of 1000 meter, 2000 meter, 3000 meter, 4000 meter, 5000 meter or more. Minerals in the form of polymetallic nodules 5 lie on the seabed 3 or are partially or completely buried in the seabed 3 by sediment. The nodules 5 comprise a high amount of specific metals, such as manganese, nickel, copper or cobalt. Such nodules 5 are typically located in the Central Pacific and are minable .

The mining vessel 11 comprises a hull 12 floating at the level of the water surface 2, a deck 13, a main cabin or accommodation 14 and multiple cargo holds 15. The mining vessel 11 supports on its deck 13 a main suspension 20 and an auxiliary suspension 30 that are embodied as A- frames or derricks. A mining assembly 100 is suspended from the main suspension 20 and auxiliary suspension 30. The mining assembly 100 comprises a station 110, first cables 101 that suspend the station 110 from the main suspension 20, a mining head 130, a second cable 131 that suspends the mining head 130 from the auxiliary suspension 30, an elongate intermediate frame 150 that extends between and is hingeably attached to the station 110 and the mining head 130, two skips or containers 111 that shuttle between the station 110 and the vessel 11, and third cables 102 that suspend the containers 111 from the main suspension 20. The containers 111 are guided by the first cables 101. The cables 101, 102, 131 may be steel cables or synthetic cables. Synthetic cables are applied when working in greater depths D as the aggregated weight of steel cables can become very high in these conditions .

Each first cable 101, second cable 131 and third cable 102 is guided through one or more pairs of sheaves 17 to winches 16 that are located at the vessel 11. The winches 16 are operable to lower and raise the mining assembly 100 with respect to the suspensions 20, 30 by paying out and hoisting up the long cables 101, 102, 131. Not shown motion compensation systems compensates for the influence of the ship motions on the cables 101, 102, 131 in order to keep the station 110 at a constant height with respect to the seabed 3. The motion compensation systems in combination with the winches 16 also compensate for the varying loaded weight of the nodules 5 in the containers 111 and the resulting fluctuation of the length of the long cables 101, 102, 103. The motion compensation system may be a heave compensation system or a constant tension system and may be a stand-alone system or a system that is incorporated into the winches 16. The winches 16, the mining system 100 and the motion compensation system are powered and controlled by a not shown power supply unit and control unit that are located at the vessel 11.

The entire mining assembly 100 is movable with respect to the vessel 11 between an inoperative raised position in which the mining assembly 100 is raised above the water surface 2, preferably with the bottom part of the containers 111 raised above the deck 13, and an operative lowered position in which the station 110 is positioned near and spaced apart from the seabed 3 over a distance E of 1-50 meters, and the mining head 130 stands on the seabed 3.

As best shown in figures 2A and 2B the intermediate frame 150 comprises a longitudinal space frame truss 151, a first frame 156 in the extension of the space frame truss 151 and a turning gland 170 that rotatably connects the space frame truss 151 and the first frame 156. The turning gland 170 allows the first frame 156 and the space frame truss 151 to rotate around their common longitudinal axis Q with respect to each other over a limited rotation stroke. The first frame 156 is hingeably connected to the mining head 130 to allow the first frame 156 to hinge with respect to the mining head 130 around a first hinge axis A that is orientated perpendicularly to the longitudinal axis Q of the first frame 156 and substantially parallel to the seabed 3. The space frame truss 151 is hingeably connected to the station 110 to allow the space frame truss 151 to hinge with respect to the station 110 around a second hinge axis B that is orientated perpendicularly with respect to the longitudinal axis Q of the space frame truss 151 and substantially parallel to the seabed 3.

The configuration of the station 110, the intermediate frame 150 and the mining head 130, as described above, ensures that the intermediate frame 150 spaces apart the mining head 130 from the station 110. The hingeable connections allow the mining head 130 to move upwards and downwards and to rotate forwards and backwards with respect to the station 110. The turning gland 170 allows limited sideways rotation or heel of the mining head 130 with respect to the station 110. The angle over which the turning gland 170 allows the first frame 156 and the space frame truss 151 to rotate over the limited stroke is maximal plus or minus 30 degrees from the center position in which the first hinge axis A and the first hinge axis B are parallel which makes the limited total stroke 60 degrees, preferably maximal plus or minus 20 degrees from the center position which makes the total limited stroke 40 degrees .

As best shown in figure 2C the mining head 130 furthermore comprises a second frame 132 having a U-shaped main support beam 133 that is orientated substantially parallel to the seabed 3 and struts 134 that are attached to the main support beam 133 and that bridge the space between the legs of the U-shaped main support beam 133. The struts 134 form a framework that is partially raised with respect to the main support beam 133 and the seabed 3. The struts 134 provide rigidity to the second frame 132 and provide protection for the mining head 130. A three leg sling 135 connects the second cable 131 to the second frame 132.

A propulsion arrangement in this example in the form of a pair of parallel archimedes screws 140 is attached to the underside of the second frame 132. The archimedes screws 140 are positioned at opposite sides of the mining head 130. A suction head 145 is located between the archimedes screws 140 near one end of the second frame 132. In the lowered position of the mining assembly 100 the archimedes screws 140 and the suction head 145 rest on the seabed 3. The archimedes screws 140 provide traction to push the mining head 130 in a mining direction M.

The two archimedes screws 140 comprise cylinders 141, opposing helical flanges 142 that are provided around the outer surface of the cylinders 141, endcaps 143 at each longitudinal end of the cylinders 141, and drive units 144 for rotationally driving the cylinders 141 around the longitudinal axis thereof with respect to the endcaps 143. The archimedes screws 140 are attached to the second frame 132 by spacers 136 that are positioned between the endcaps 143 and the main support beam 133 of the second frame 132. The archimedes screws 140 are positioned below and are orientated parallel to the legs of the U-shaped main support beam 133.

The archimedes screws 140 counter-rotate to move the mining head 130 forwards in the mining direction M, moving the suction head 145 along the seabed 3. The mining head 130 may also be moved backwards or sideways by respectively counter-rotating the archimedes screws 140 in the opposite direction or by rotating both archimedes screws 140 in the same direction.

The suction head 145 is located below and orientated parallel to the web of the U-shaped main support beam 133. The width of the suction head 145 is substantially equal to the distance between the center lines of the archimedes screws 140. A damper 147 attaches the suction head 145 to the web of the U-shaped main support beam 133. The damper 147 allows for relative motions between the suction head 145 and the second frame 132.

As best shown in figure 2D the containers 111 are in this embodiment cylindrically shaped and are tapered towards the bottom. The container 111 defines a top opening 113 at its top and a smaller bottom opening 114 at its tapered bottom. The top opening 113 is covered and closed off by a lid 115 that has two pipe holes 116 and the bottom opening 114 is provided with a valve 117 to open and close the bottom opening 114. A container flange 118 extends perpendicularly from the circumference of the container 111 at the top thereof. The third cables 102 are attached to the top of the container flange 118 at opposite sides of the top opening 113. The container flange 118 is provided with two cable holes 119 at opposite sides of the top opening 113. The first cables 101 pass through the cable holes 119. The containers 111 are movable with respect to the station 110 by paying out and hoisting up the third cables 102 while the containers 111 are guided by and move along the first cables 101. The containers 111 may additionally or alternatively be guided by, for instance, a thruster that is provided on each container, wherein the thruster is arranged to move the at least one container with respect to the seabed or station while suspended by the third cables .

The station 110 comprises a container frame 112 that determines circular container holes 120 that correspond to and that fit securely around the container 111. The top of the container frame 112 supports the container flange 118 and the container 111 sits inside the container holes 120. The bottom part of the container 111 with the bottom opening 114 and the valve 117 protrude below the container frame 112.

A thruster 103 is attached to the container frame 112 at the side opposite to the intermediate frame 150. The propulsion direction of the thruster 103 is parallel to the seabed 3 and perpendicular to the mining direction M. Therefore the heading of the mining assembly 100 can be adjusted by using the thruster 103 to rotate the station 110 in a rotation direction R around the mining head 130.

The station 110 comprises braces 107 that are attached to one side of the container frame 112. The braces 107 support a separation and filling arrangement 121 that comprises a Y-shaped first supply pipe section 122 wherein the base extends from the side of the container frame 112 where the intermediate frame 150 is attached to, and the arms branch of towards the respective container holes 120. Each arm of the first supply pipe section 122 is provided with a supply valve 123. Near each container hole 120 a second supply pipe section 124 and a third supply pipe section 125 are rotatably connected to the respective arms of the first supply pipe section 122. The separation and filling arrangement 121 furthermore comprises a Y-shaped first discharge pipe section 126 wherein the base extends from the side of the container frame 112 opposite to the first supply pipe section 122 and the arms branch of towards the respective container holes 120. Each arm of the first discharge pipe section 126 is provided with a discharge valve 127. Near each container hole 120 a second discharge pipe section 128 and a third discharge pipe section 129 are rotatably connected to the respective arms of the first discharge pipe section 126.

Sections of the first supply pipe section 122, the second supply pipe section 124, the first discharge pipe section 126 and the second discharge pipe section 128 are arranged with their center line along a common third hinge axis C that is orientated in the longitudinal direction of the container frame 112, that is raised with respect to the container holes 120 and that is located outside the profile of the containers 111 as seen in top view. The distal ends of the second supply pipe section 124 and the second discharge pipe section 128 extend perpendicularly with respect to and are hingeable around the third hinge axis C. A first actuator 105 is provided between the container frame 112 and the second supply pipe section 124 and second discharge pipe section 128. The first actuator 105 is operable to move the distal ends of the second supply pipe section 124 and the second discharge pipe section 128 between a filling position wherein these are positioned above the container 111 at the pipe holes 116 of the lid 115 to fill the container, and a shuttling position wherein these are positioned outside the profile of the container 111 as seen in top view.

Sections of the first supply pipe section 122, the third supply pipe section 125, the first discharge pipe section 126 and the third discharge pipe section 129 are arranged with their center line along a common fourth hinge axis D that is orientated in the longitudinal direction of the container frame 112, that is raised with respect to the container holes 120 and that is located outside the profile of the containers 111 as seen in top view. The distal ends of the third supply pipe section 125 and the third discharge pipe section 129 extend perpendicularly with respect to and are hingeable around the fourth hinge axis D. A second actuator 106 is provided between the container frame 112 and the third supply pipe section 125 and third discharge pipe section 129. The second actuator 106 is operable to move the distal ends of the third supply pipe section 125 and the third discharge pipe section 129 between a filling position wherein these are positioned above the container 111 at the pipe holes 116 of the lid 115 to fill the container, and a shuttling position wherein these are positioned outside the profile of the container 111 as seen in top view. The station 110 comprises at the side of the first discharge pipe section 126 a diffuser assembly 180 that has a diffuser 181 that is suspended from an outrigger 182 by a diffuser cable 183. A flexible exit pipe 184 connects the base of the Y-shaped first discharge pipe section 126 and the diffuser 181.

As best shown in figures 2A and 2B the longitudinal space frame truss 151 has two parallel top members 152, a bottom member 153 parallel to the top members 152 and multiple connecting members 154 that connect the top members 152 and bottom members 153. At the end of the space frame truss 151 near the mining head 130 a tube shaped first collar 155 is attached to the space frame truss 151 in the extension thereof. The turning gland 170 connects the space frame truss 151 to the first frame 156 that comprises a tube shaped second collar 157, two arms 158 that extend obliquely from the second collar 157 at opposite sides thereof near the turning gland 170 and that bend to an orientation parallel to the second collar 157, and tubular beams 159 that space apart the arms 158 from the second collar 157. The distal ends of the arms 158 correspond to the distal ends of the U-shaped main support beam 133 of the mining head 130 and are connected thereto by first hinges 137 that are positioned along the first hinge axis A. The space frame truss 151 comprises a wide section 164 at the end near the station 110. At the wide section 164 the top members 152 are spaced further apart from each other. The ends of the top members 152 at the wide section 164 correspond to two container frame members 108 that protrude horizontally from the container frame 112. The top members 152 are connected to the container frame members 108 by second hinges 109 that are positioned along the second hinge axis B.

The first supply pipe section 122 is connected to the suction head 145 by a transport arrangement embodied as a suction pipe 146 having a pump unit 163 integrated therein. The suction pipe 146 runs through the space frame truss 151, the turning gland 170 and the first frame 156. The pump unit 163 is located within the wide section 164 of the space frame truss 151. The suction pipe 146 is provided with a third hinge 149 that is positioned between the first hinges 137 along the first hinge axis A and a fourth hinge 138 that is positioned between the second hinges 109 along the second hinge axis B. Near the third hinge 149 and the fourth hinge 149 the suction pipe 146 is flexible.

An umbilical cable 104 is connected between the mining assembly 100 and the vessel 11 to provide power to the drive units 144 of the archimedes screws 140, the pump unit 163, the supply valves 123, the discharge valves 127, the first actuator 105, the second actuator 106 and the thruster 103.

As best shown in figures 1A and IB the vessel 11 is provided with a distribution arrangement 40 to distribute the mined nodules 5 to the cargo holds 15. In this example the distribution arrangement 40 comprises collectors 41 that collect the mined nodules 5 from the containers 111. The collectors 41 are supported by longitudinal collector support frames 42 that are orientated parallel to the deck 13 and substantially perpendicular to the longitudinal direction of the vessel 11. The collector support frames 42 are individually movable between an inboard position in which the collectors 41 are located on the deck 13 of the vessel 11 and an outboard position in which the collectors 41 are located below the containers 111 outboard the vessel 11 to receive the nodules 5. The collector support frames 42 hold first conveyors 43 that, in the outboard position, receive the nodules 5 from the collectors 41 and transport them to a second conveyor 44. The second conveyor 44 is positioned on deck 13 level substantially along the longitudinal center line of the vessel 11 and transports the nodules 5 from the first conveyors 43 to third conveyors 45 at the cargo holds 15. The third conveyors 45 transport the nodules 5 from the second conveyor 44 and deposit them in the cargo holds 15. The minerals in the form of polymetallic nodules 5 are mined after sailing the vessel 11 to a deep sea 1 location that comprises minable nodules 5 at the seabed 3. When the vessel 11 is at its position the mining assembly 100 is lowered from its raised position to its lowered position in which the station 110 is positioned to remain near and spaced apart from the seabed 3. Subsequently the mining head 130 is lowered with respect to the station 110 onto the seabed 3 by the second cable 131.

The archimedes screws 140 move the mining head 130 forwards in the mining direction M, moving the suction head 145 along the seabed 3. The station 110 trails or follows the mining head 130 and the thruster 103 directs the heading of the mining assembly 100. The station 110 hovers while the mining head 130 follows the undulations of the seabed 3. When the mining head 130 encounters an obstruction on the seabed 3 it is lifted over the obstruction by the second cable 131 while the station 110 remains at the same depth. The vessel 11 follows the mining assembly 100 in the mining direction M. The length of the cables 101, 102, 131 between the vessel 11 and the mining assembly 100 allows for leeway therebetween in the horizontal direction.

The pump unit 163 sucks sea water into the suction head 145. The encountered loose nodules 5 are sucked into the suction head 145 with the sea water and nested nodules 5 are either dislodged by the suction of the suction head 145 or by the mechanical force applied on the nodules 5 by the forward moving suction head 145. Sediment are sucked in with the nodules 5 and seawater as well. The process flow comprising the mined nodules 5, sea water and sediment is, in this example, hydraulically transported or elevated to the level of the station 110 through the suction pipe 146 using sea water as the transport medium.

At the station 110 the process flow enters the separation and filling arrangement 121 that directs the process flow to one of the containers 111. When the second supply pipe section 124 and the second discharge pipe section 128 are in the filling position and the supply valve 123 that is associated with the second supply pipe section 124 and the corresponding discharge valve 127 that is associated with the second discharge pipe section 128 are opened, the process flow is directed to one container 111. When the third supply pipe section 125 and the third discharge pipe section 129 are in the filling position and the supply valve 123 that is associated with the third supply pipe section 125 and the corresponding discharge valve 127 that is associated with the third discharge pipe section 129 are opened, the process flow is directed to the other container 111.

The process flow enters the container 111 and the heavy nodules 5 sink to the bottom thereof, thereby filling the container. The bulk of the sediment remains suspended in the sea water. As the container 111 is closed off by the lid 115 the process flow entering the container 111 causes an overpressure therein. As a result the sea water with the sediment discharges from the container 111 through the discharge pipes 126, 128, 129 and flows, in this example, via the exit pipe 184 and the diffuser 181 to the seabed 3. The diffuser 181 returns the sea water with the sediment to or close to the seabed 3 in a smooth manner, causing little turbidity and thereby causing little environmental impact.

In an alternative, not shown, embodiment at least a part of the sea water with the sediment is discharged from the container 111 and then returned to the mining head 130 via a return pipe. At the mining head the sea water with the sediment is discharged to the seabed 3 close to, preferably in front of the suction head 145 in the mining direction M, so that the discharged sea water is sucked into the suction head 145 again. This alternative embodiment provides a recirculation loop for the sea water between the suction head 145 and the containers 111 at the station 110. In the recirculation process sediment may be returned to the sea bed at the mining head 130 and the discharged sea water may aid in the dislodging of nested nodules 5. Optionally the return pipe is connected to the suction head 145 and the suction head 145 is arranged to recirculate the sea water towards the containers 111 at the station 110.

When one container 111 is full with nodules 5 the supply valves 123 and discharge valves 123 are switched in order to direct the process flow to the other container 111 and fill this container 111 with nodules. The respective supply pipe section 124, 125 and discharge pipe section

128, 129 associated with the full container 111 are moved to the shuttling position. The full container 111 is then shuttled by the third cables 102 from the station 110 to the main suspension 20 while being guided by the first cables 101. The full container 111 is then emptied as will be explained below. The empty container 111 is shuttled back to the station 110 and the respective supply pipe section 124, 125 and discharge pipe section 128, 129 associated with the empty container 111 are moved to the filling position. When the other container 111 is full the shuttling process as described above is repeated for this container 111.

During mining of the nodules 5 at least one container 111 is located at the station 110 to assure a continuous process flow and therewith a continuous mining of the nodules 5. The filling time of one container 111 is higher than the shuttle time of the other container 111. Factors that influence the filling and shuttling time of the containers 111 are amongst others the depth of the deep sea 1 and the density of the nodules 5 found on the seabed 3. The filling time is adjustable by tuning among others the size of the containers 111, the moving speed of the mining head 130 and the volume of the process flow. The shuttle time is adjustable by tuning amongst others the size of the containers 111 and the shuttle speed of the containers 111.

When the full container 111 is raised above the water surface 2 it is emptied by moving the collector support frames 42 to the outboard position wherein the collector 41 is located below the bottom opening 114, then opening the valve 117 of the container 111 and thereby releasing the nodules 5 into the collector 41, and then transporting the nodules 5 via the first conveyors 43, second conveyors 44 and third conveyors 45 to the cargo holds 15.

When all the cargo holds 15 are full the mining of the nodules 5 is stopped. The mining assembly 100 is raised from its lowered position to its raised position in which the mining assembly 100 is raised above the water surface 2. The vessel 11 sails to an unloading location and unloads the nodules 5. When the vessel 11 is empty the mining sequence as described above is repeated.

It is to be understood that the above description is included to illustrate the operation of the preferred embodiments and is not meant to limit the scope of the invention. From the above discussion, many variations will be apparent to one skilled in the art that would yet be encompassed by the scope of the present invention.