Technical field of the invention

This invention relates to a head for a device for collection of gravel from a submerged bed and a device including such a head.

Background to the invention

The applicant is aware that divers are utilised to collect gravel from the seabed and riverbed for mining purposes by manually operating a suction hose underwater. Often such collection is hampered due to adverse weather, sea conditions and low visibility. Further disadvantages of utilising divers are safety and operational limitations. Divers are limited to certain depths and dive times and often suffer from decompression illness.

Existing remote dredging or submerged bed mining devices such as described in US 2,125,740 and DE 195 46 845 A1 often clog up with debris due to the strong suction forces. Clearing arrangements such as that described in NL-A- 7018191 and WO 03/044285 A1 are mechanically complex and prone to failure in harsh working and environmental conditions typically found in submerged mining operations. Such devices are normally suspended from a crane or like apparatus.

It is an object of this invention to provide a device for collection of gravel from a submerged bed, with an improved clearing arrangement.

Genera! description of the invention

Accordingly, a first aspect of the invention provides a head for a device for the collection of gravel from a submerged bed, which head includes: a tubular body defining a first gravel intake opening and a second bypass water intake opening; a connection means for connecting the first and second intake openings to an inflow of a suction pump; and a bypass valve for opening or closing the second bypass water intake opening.

The head may include a means to open and/ or close the bypass valve. The means may be an actuator. The actuator may be operable by an operator and/ or actuateable by a presettable pressure differential between the ambient pressure and the inside of the tubular body, or a presettable pressure drop inside the tubular

body.

It will be understood that the term tubular includes any cross sectional shape and length sectional shape of the tube.

The bypass valve may be configured to close the second bypass intake opening under normal operating conditions and to open the second intake opening when the pressure in the tubular body drops to a certain point below the normal

operating pressure.

The bypass valve may include an urging means for urging the bypass valve to close the second bypass intake valve under normal operating conditions.

It will be appreciated that when the first intake becomes clogged with material during operation, the pressure in the tubular body will drop. Once a certain pressure is reached, the bypass valve will open the second intake to bypass the first intake. This will ensure that a flow to the suction pump is maintained to avoid damage to equipment if the first opening is blocked.

The first intake opening may be configured to form less resistance for intake of water relative to the second bypass intake opening, allowing the bypass valve to close automatically the second intake opening once the first intake has been unclogged.

The bypass valve may include an actuator operable by an operator of the device for collection of gravel from a submerged bed to operably open or close the second bypass opening.

The actuator may include a hydraulic or pneumatic piston and cylinder arrangement to hydraulically or pneumatically open or close the second intake. The hydraulic or pneumatic piston and cylinder arrangement may be operable by an operator of the device for collection of gravel from a submerged bed. An operable actuator allows the operator to fully bypass the first intake opening when the operator wishes to suspend suction or when the first intake opening becomes clogged. When the first intake opening is closed the material clogging the first intake can dislodge more easily.

The head may include a grid positioned over the first intake opening such that objects larger than the mesh of the grid are prevented, in use, from entering into the opening.

The head may include a grid shaker arrangement.

The head may include a grid suspension mounting for mounting the grid over the opening and to allow a certain measure of movement of the grid. The grid shaker arrangement may then also include a hammer arrangement for shaking or hammering the grid.

The hammer arrangement may include pneumatic or hydraulic hammers which are arranged to hammer against the grid to shake the grid, in use.

The hammer arrangement may be pneumatically or hydraulically operable by an operator of the device for collection of gravel from a submerged bed.

It will be appreciated that, in use, once the second bypass intake opening is opened, the shaking forces on the grid will dislodge material lodged in the grid. Once the operator is satisfied that the grid is cleared, normal operation device may continue by ending the shaking of the grid and closing the second bypass intake opening.

The head may also include an airlift arrangement to complement the suction pump. It will be appreciated that the airlift can fulfil the function of clearing unwanted

material covering the material to be mined without having to use the suction pump in a cost effective manner.

The tubular member may be bell shaped. The head may include a cover for at least partially covering the tubular member.

The head may also include a plurality of jets spaced about the opening and directed towards the submerged bed, in use; and a plurality of laterally directed jets spaced about the head which are independently operable such that the head can be operably moveable by an operator in any lateral direction as desired with propulsion from the jets.

The invention also extends to a device for the collection of gravel from a submerged bed, which device includes a head as described above.

The device may include controls for operating the bypass valve and/ or the shaker mechanism.

The invention also extends to a head for a device for the collection of gravel from a submerged bed, which head includes: a tubular body defining a gravel intake opening; a connection means for connecting the intake opening to an inflow of a suction pump, and/ or an airlift arrangement; a grid a grid positioned over the intake opening such that objects larger than the mesh of the grid are prevented, in use, from entering into the opening; and a grid shaker arrangement, as described above, for shaking the grid.

Detailed description of the invention

The invention is now described, by way of non limiting examples, with reference to the accompanying drawings.

In the drawings,

Figure 1 shows schematically a partial upper perspective view of an embodiment of the device for the collection of gravel from a submerged bed, in accordance with the invention; and

Figure 2 shows schematically a partial upper perspective view of the device.

Referring now to the drawings, reference numeral 10 generally refers to the device for the collection of gravel from a submerged bed. The device 10 includes a head 12, which is connectable with the connection means 13 and 15, respectively, to an inflow of a suction pump (not shown) and an outflow of a high pressure water pump (not shown). The head 12 includes a bell shaped tubular body 17 defining a first gravel intake opening 14, which is in fluid communication with the inflow of the suction pump. The head 12 also defined a second bypass intake opening 16. The head 12 further includes a first plurality of jets 18.1 spaced about the opening 16 and directed towards the submerged bed, in use. The head 12 also includes a second plurality of laterally directed jets 18.2 spaced about the head 12. The laterally spaced jets 18.2 are independently operable by and operator such that the head may be moved in any desired lateral direction. The head further includes a bypass valve 20 for opening or closing the second bypass water intake opening 16.

The bypass valve 20 includes an urging means in the form of a pair hydraulically urged piston and cylinders 22 for urging the valve 20 to close the second bypass intake opening 16 under normal operating conditions and to open the second intake opening 16 when the pressure in the tubular body 17 drops to a certain point below the normal operating pressure.

The first intake opening 14 is configured to form less resistance for intake of water relative to the second bypass intake opening 16, allowing the bypass valve 20 to close automatically the second intake opening 16 once the first intake opening 14 has been unclogged.

The pair of hydraulically urged piston and cylinders 22 for urging the valve 20 is also a hydraulic actuator for opening or closing the valve 20 operably by an operator of the device for collection of gravel from a submerged bed.

The head 12 further includes a grid 24 positioned over the first opening such that objects larger than the mesh of the grid 24 are prevented, in use, from entering into the opening 14. The head 12 also includes a grid shaker arrangement 26. The grid shaker arrangement 26 includes a grid suspension mounting 28 on the head 12 for mounting the grid 24 over the opening 14 and to allow a certain measure of movement of the grid 24. The grid shaker arrangement 26 also includes a hydraulic hammer arrangement 30 for shaking or hammering the grid 24. The hammering arrangement 30 is hydraulically operable by an operator of the device 10.

The head 12 also includes a cover (not shown).

It shall be understood that the example is provided for illustrating the invention further and to assist a person skilled in the art with understanding the invention and are not meant to be construed as unduly limiting the reasonable scope of the invention.