EA042142B1 - DREDGING METHOD AND DREDGING DEVICE - Google Patents

Description

The present invention relates to a dredging method, a dredging apparatus and the use of a dredging apparatus.

Dredging is generally defined as the underwater removal of sediments and their transportation from one place to another. Dredging is a process that may include the steps of lifting sediment from the waterbed and optionally the steps of transporting the sediment out of the dredged area, followed by final removal of the sediment. Optionally, sedimentary deposits can be loosened first.

Dredging may be carried out for a variety of reasons, such as clearing a harbor or waterway of a buildup of sediment that could obstruct navigation. Since harbors are usually deeper than the surrounding water area, sediments can accumulate and not be washed away by natural water flow, such as tidal water or river flow.

Examples of prior art dredging methods include using a surface grab or excavator to physically lift sediment into a bucket and transfer it to a bin for disposal. Another prior art method uses a self-propelled dump dredger which consists of a vessel connected to a trailed drag hopper in which sediment is pumped from the waterbed through the drag hopper into a bunker on the vessel.

Other prior art dredging methods include the use of fluid injection devices that pump water into the sediment to loosen it and reduce the density of the sediment, causing the sediment to be suspended above the water bed in what is known as a dense cloud. . The suspended sediments are then washed out by gravity. This method is particularly useful for use in rivers and tidal zones, where the resulting dense cloud of sediment can flow under the influence of gravity into deeper areas.

Another method of dredging uses cutter dredgers which consist of a rotating cutting head mounted in front of the suction head, the cutting head rotating along the axis of the suction pipe. The cut sediment is then sucked up by a suction pump. Such milling dredgers are designed to be used in a stationary position, even if they are mounted on a vessel; during operation, the vessel will be moored with legs or anchors.

Another method known in the prior art that is used to solve the problem of sedimentation in a shipping channel or harbor is seafloor leveling, in which a plow is towed behind a floating craft to level raised areas of sediment without actually removing the sediment from the waterbed.

Various attempts have also been made to create dredgers that operate on the waterbed and agitate the sediment using cutters or high pressure fluid jets. These floats may be self-contained floats (eg disclosed in GB 2543764 A) or may be pulled along the waterbed by another float, such as disclosed in US 2014/0238924 A1. Floats operating on the waterbed create a seal between the bottom surface of the dredger and the waterbed and use negative pressure to suck up and remove sediment.

Alternative dredgers known in the prior art work above the waterbed. For example, US 4,127,950 describes a suction head which draws sediment mixed with liquid into a vertical housing, after which separate gas jets expel the sediment from the housing. Such dredgers are characterized by large dimensions and low speed, since the necessarily massive closed body creates a lot of resistance when moving. Such dredgers also require pressurized fluid for liquid and gas injection devices, which is pumped from a surface vessel.

There are various problems associated with prior art dredging methods. For example, water injection dredging requires water to flow under gravity to clear suspended sediment, so it is of little use in coastal harbors that do not have slopes. Seabed leveling does not remove sediment, but simply levels it, and sediment can continue to build up over time. Self-propelled self-dumping dredgers, while often effective in clearing sediment, require specially built and expensive equipment, including a special vessel with a large bunker. Such equipment is characterized not only by high cost, but also by high operating costs. Dredging using a grab arm and/or excavator is also costly as it requires the use of a specially adapted vessel with a hopper to take in the excavated sediments.

- 1 042142

The use of dredgers placed on the waterbed is problematic because the waterbed, for example in a harbor, is rarely flat and contains a lot of solid debris, which makes such dredgers impractical and easily damaged. Garbage, often found on the waterbed in harbors, contains container lashings, which are long metal poles that fall from containers during loading and unloading. Container lashings can cause significant damage to the dredger, and significant repair time must be spent before the dredger can be used again, which incurs significant costs.

The present invention solves the problems associated with the prior art by providing devices and methods that are not only effective in removing sediment from a number of different types of waterbed, but are also relatively inexpensive to operate.

The present invention provides a dredging method comprising: suspending a dredging device from a floating craft, the dredging device comprising a frame;

a sediment mixing device for placement above a sediment layer on a water bottom, the sediment mixing device comprising a fluid injection device and a pump configured to inject fluid through the fluid injection device, the sediment mixing device and the pump being mounted directly on the frame;

separately, a retrieval device configured to move the mixed sediment from the waterbed and above the dredging device, the retrieval device comprising a pipeline and a pump for pumping the mixed sediment through the pipeline, the retrieval device and the pump being mounted on a frame; and a connector for connecting the dredging device to the floating craft;

placing the dredging device above the waterbed, but not in contact with the waterbed to be dredged to remove sediment;

mixing sediment using a sediment mixer;

extraction of sedimentary deposits using the extraction device;

creating a suspension of the extracted sediments under water and above the sediment mixing device; and moving the dredging device through the water;

moreover, sedimentary deposits are carried and deposited away from the dredged area under the influence of the natural movement of water.

The method according to the invention involves raising the mixed sediments into a higher water column in which the natural movement of the water is able to wash away the suspended sediments. In a harbor, this may mean raising sediment to a level higher than the seabed outside the harbor for tidal water to remove the sediment.

By having the dredging device work above the waterbed, the dredger is able to overcome the negative effects associated with many prior art devices by avoiding a significant portion of the debris and providing the ability to overcome uneven water bottoms.

The sediment being dredged may be light and loose, in which case the operation of the retrieval device alone may be sufficient to suck the sediment into the dredging device for retrieval without the need to operate the sediment agitator. However, if the sediment is heavy, compacted, or otherwise not agitated, a sediment agitator may be used.

The dredging device may use a number of different sediment agitation means in addition to the fluid injection device. The fluid injection device further comprises a pump, wherein the pump injects fluid through the fluid injection device into the sediment to loosen it prior to retrieval. The fluid injection device and the pump are mounted on the frame. The fluid injection device may be located on the lower surface of the sediment mixing device. In particular, the injection device may include an outlet located so as to discharge the fluid in a downward direction during use in the sediment located on the waterbed. More than one fluid injection device may be provided, as well as a plurality of fluid injection devices. The fluid injection device may comprise one or more conduits with a plurality of outlets or nozzles. The outlets may be evenly distributed along the pipeline. A bunch of

- 2 042142 pipelines can be arranged parallel across the width of the frame. One or more conduits may extend across the entire width of the frame. A plurality of pumps may be provided with one pump per fluid injector, or with a plurality of fluid injectors. The fluid introduced may be water, air, or a combination of the former and the latter. If the fluid is water, then preferably the fluid injection device may further comprise an inlet and, in use, water will be drawn from the aquatic environment surrounding the dredging device. In another embodiment, fluid may be supplied from the surface or from a floating vehicle to the dredging device.

Prior art dredgers pumping sediment agitation fluid typically use high pressure jets. High pressure is defined in the prior art as 800-1000 kPa (8-10 bar). Conversely, the fluid pumped by the dredgers of the present invention is pumped at low pressure (150-200 kPa/1.5-2 bar) or medium pressure (400-500 kPa/4-5 bar). Low or medium pressure has been found to be an advantage over high pressure jets because it requires less resources in terms of pump pressure and power usage and effectively mixes enough sediment.

The dredging device comprises a frame supporting a sediment mixing device and an extraction device. The present dredger operates above the water bed but not in contact with the water bed, however the framework may be strong enough to withstand contact with the water bed. This can happen when the dredger is lowered into place, if the water bottom is uneven, or if the boat is a boat and the water the boat is on is undulating. The frame may include shock-absorbing means to protect the dredger from impacting the water bed and/or debris that occurs during use. For example, the carcass may be provided with buffers mounted on the bottom surface of the carcass or, in another embodiment, may include heavy duty skids to protect the bottom surface of the carcass.

The frame may have a generally flat, solid base or, in another embodiment, may be in the form of an open frame, preferably with an open base. The frame may be formed from metal or plastic tubes or the like.

The frame may include side panels, a top surface on which elements such as an extraction device and a sediment mixing device are located. The front and back of the frame can be open to allow heavy materials and debris to pass through the dredger that could otherwise damage the dredger. In addition, the open frame reduces the frame's resistance when moving through the water, thereby allowing for faster dredging than would be possible with state of the art dredgers.

The frame comprises side panels located opposite each other and one or more main panels arranged in parallel between the side panels and connected by one or more transverse elements.

One or more cross members may comprise a sediment mixing device, the latter comprising one or more conduits containing one or more fluid injection outlets, the sediment mixing device being connected to one or more pumps; moreover, the pump is connected to the inlet so that the fluid is sucked from the environment through the inlet.

Additionally or in another embodiment, one or more cross members may comprise an extraction device, the latter comprising one or more pipelines containing inlets into which mixed sediments are sucked for removal; wherein the retrieval device is connected to one or more pumps that are connected to a pipeline raised above the dredging device to remove the mixed sediment above the dredging device in use.

One or more transverse members may also be a rigid support bar. The rigid support bar may have a tapered leading edge to cut through any sediment buildup during use.

The frame may include skids connected to the bottom surface of the main and/or side panels. The leading edge of the main and side panels can be rounded to deflect debris.

At the front end of the dredging device, a guiding device may be provided to deflect debris generated on the waterbed. The guiding device may be a one-piece scoop to deflect debris either above or below and/or away from the dredging device. The guiding device can be made in the form of a grate, located at an angle and consisting of rods for the passage of water, so that the grate does not create too much resistance, but prevents debris from entering. Lattices can have corresponding

- 3 042142 current dimension so that debris such as lashings for securing containers cannot enter the dredging device even in the longitudinal direction, but without creating too much resistance in the water. A guide may also be provided on the top surface of the dredging device to protect the top of the dredging device, even if it is not provided on the front of the dredging device. The guide device may include inclined solid plates. Angled solid plates can be located in front of the pressure pumps.

If the frame is open, the back of the frame may be provided with offset flaps, which may be a deformable matte finish of rubber, plastic, or the like, to keep mixed sediment within the frame or under the frame for removal, but which will deflect when hard object or pressure.

The dredging device may further comprise a heave compensator located on the floating craft, the heave compensator maintaining the dredging device at the same level above the waterbed.

The extraction device comprises a pipeline and a pump configured to pump the mixed sediment through the pipeline. The conduit may have a first opening located on the bottom surface of the dredging device and a second opening located at the highest point of the dredging device when it is brought into operation. This arrangement ensures that the first opening is directed towards the mixed sediments, and the second opening is raised to a certain level, whereby the ejected sediments can be washed away by the natural movement of water during use. Therefore, the size and shape of the pipeline will depend on its intended use. For example, a longer pipeline may be provided on a dredger intended for use in a relatively deep harbor that is significantly deeper than the surrounding seabed, the sediment having to be carried to a relatively higher level so that the suspended sediment can be washed out at high tide. If the device is to be used in shallow water, such as in a canal or a harbor on a river, the piping must be relatively shorter.

The relative height of the pipeline can also be adjustable. The piping can be replaced with piping of different lengths or the length of the piping can be adjustable. The piping may be retractable or have modular extensions which may be removable. The angle of the pipeline relative to the dredging device is also provided to be adjustable so as to adjust the relative height of the pipeline above the dredging device.

The shape of the conduit can also be changed such that, for example, a wider second opening can distribute the recovered sediment more widely than a narrower second opening. Therefore, the pipeline may be in the form of a truncated cone, in which the second opening is wider than the first, or the second opening may be corrugated. The second hole can be split into two holes.

The pumps can be supplied with a power supply. Said power supply may be provided on the frame or on the surface craft. The power packs may be installed on the dredging device, or may be installed on an existing watercraft, or the watercraft may be adapted to install an auxiliary power unit to supply power to the pump or pumps. The power supply to the pumps can be cabled from the surface. Power can be supplied in the form of electricity or hydraulic pressure.

The device according to the invention is provided to be towed on the waterbed by a floating vehicle, such as a boat. However, in some situations the floating vehicle may be replaced by a land vehicle, for example if dredging is being carried out in a canal. Therefore, the dredging device is provided with a connector for connecting the dredging device to a vehicle. The dredging device may also include a winch that can be mounted on a vehicle to raise and lower the dredging device into the water. In some embodiments, the dredging device may be provided with its own self-propelling means.

The present invention also provides a dredging device for placement above the waterbed but not in contact with the waterbed to be dredged to remove sediment, the device comprising a frame;

a sediment mixing device for placement above a sediment layer on a water bottom, the sediment mixing device comprising a fluid injection device and a pump configured to inject fluid through the fluid injection device, the sediment mixing device and the pump installed

- 4 042142 on frame;

separately, a recovery device configured to move the mixed sediment from the water bottom and above the dredging device, the recovery device comprising a pipeline and a pump designed to pump the mixed sediment through the pipeline and create a suspension of the extracted sediments under water and in a higher water a column above the sediment mixing device, wherein the extraction device and the pump are mounted on the frame; and a connector for connecting the dredging device to the floating craft.

The dredging apparatus may be as disclosed in connection with the method of the present invention.

The invention also provides the use of a dredging device as disclosed herein, the use comprising suspending the dredging device above, but not in contact with, the waterbed to be dredged to remove sediment;

extracting the mixed sediment using the extraction device, and depositing the excavated sediment below water and above the dredging device.

For a better understanding, the present invention will now be described in detail, by way of example only, with reference to the following figures, in which FIG. 1 is a schematic representation of a dredging device in accordance with the present invention;

in fig. 2a is a schematic end sectional view of an alternative dredging device;

in fig. 2b is a schematic sectional view of the alternative dredging device shown in FIG. 2a;

in fig. 2c is a schematic plan view of the dredger shown in FIG. 2a and 2b;

in fig. 3 shows a schematic view of the harbor and one embodiment of the dredging device used;

in fig. 4 is a front and top perspective view of a dredging device in accordance with the present invention;

in fig. 5 is a rear and top perspective view of the dredging device shown in FIG. 4, in accordance with the present invention;

in fig. 6 is a perspective view of the bottom surface of the dredging device of FIG. 4 and 5;

in fig. 7 is a side view of the dredging device according to FIG. 4-6;

in fig. 8 is a front view of the dredging device according to FIG. 4-7;

in fig. 9 is a plan view of the dredging device according to FIG. 4-8.

in fig. 10 is a front view of another example of a dredging device in accordance with the present invention;

in fig. 11 is a sectional view of the dredging device shown in FIG. 10; and in FIG. 12 is a front and top perspective view of the dredging device of FIG. 10 and 11.

In FIG. 1 shows a schematic representation of a dredging device, generally designated 100, for use in the method of this invention. The dredging device 100 includes a frame, generally indicated at 110, a recovery device, consisting of a pipeline, generally indicated at 120, and a pump 130, a sediment mixing device, generally indicated at 140, a pump 150, and a connector 160 for connecting the device 100 for dredging to a floating craft. The dredging device is designed to be placed above the waterbed and not in contact with the waterbed containing the sediment to be removed. The sediment is then removed by a recovery device located above the dredging device 100, after which it enters a higher water column. Once removed by the recovery device, the mixed sediments are washed away by natural water movement, such as tidal movement or the flow of a river.

In FIG. 2a-2c show another embodiment of the dredging device, generally indicated at 200. The dredging device 200 includes a frame, generally indicated at 210. The frame 210 has a generally rectangular base shape, as shown in FIG. 2c. The frame 210 has a front long surface 211, a rear long surface 212, side surfaces 213, 214, a top surface 215, and a bottom surface 216. As most clearly shown in FIG. 2a, the corner junction of the front long surface 211 and the bottom surface 216 is chamfered to form an inclined surface 217 so that the front surface 211

- 5 042142 stepped in relation to the bottom surface 216.

An injector pump 220 is mounted on top surface 215. Injector pump 220 is in fluid communication with a plurality of fluid injectors, generally indicated at 218, configured to inject fluid under bottom surface 216. The fluid injectors are disposed along the length of frame 210 between side surfaces 213, 214 and are configured to inject fluid into the sediment for mixing. Fluid injectors 218 may be aligned adjacent ramp 217. Frame 210 is substantially hollow and includes conduit 219 from injector pump 220 to fluid injectors 218. The injection pump 220 further includes an inlet 221 for drawing in water from the environment during use before pumping it through the fluid injection devices 218 . In this case, the fluid is water, but in other embodiments, it can be air or a mixture of air and water. The fluid, especially if it includes air, can be injected from the surface.

Mounted on the frame 210 is a recovery device pump, generally designated 230. The recovery device pump 230 includes an inlet 231 for drawing water and mixed sediment from the environment during use, which is then pumped out through an outlet, consisting of a pipeline, generally indicated 240. Conduit 240 generally comprises a frustoconical tube, although in another embodiment it may be substantially cylindrical or have a corrugated or forked distal end for a wider distribution of sediment. The fluid drawn in through the inlet 231 of the injector pump 230 is discharged through conduit 240. Although not shown, the injector pump 220 and the extractor pump 230 are powered by a power source capable of being installed on the injector 200 or via a cable from the surface. .

Injection pump 220 and retrieval device pump 230 can be detachably attached to frame 210. In service, the pumps can be damaged by underwater debris, such as container lashings, so if equipped with detachable attachment, they can be replaced if damaged and cannot be repaired during operation. dredging time. Due to this, the negative consequences of downtime can be prevented.

The skids 250 are arranged parallel along the side edges of the bottom surface 216 of the frame 210. The skids 250 are attached to the bottom surface 216 of the frame 210 by stops 251 which contain shock absorbers (not shown). The skids 250 and shock absorbers protect the frame 210 if the frame 210 accidentally comes into contact with the water bed during use. In another embodiment, the stops may be solid and contain no shock absorbers.

A guide 260 is attached to the front long surface 211 to deflect debris that may come into contact with the dredging device while being towed through the water during use.

A connector 270 is provided on the leading edge of the frame 210 for connecting the dredging device 200 to the watercraft. In FIG. 3 shows a schematic side view of a harbor, generally indicated at 300, comprising a piece of land, generally indicated at 310, and a harbor wall, generally indicated at 320, in which sea water, generally indicated at 330, is located. above it is a layer of sedimentary deposits 350, which is to be dredged. On the other side of harbor wall 320 is the open sea, and as shown in FIG. 3, the seabed 390 is relatively higher than the harbor bottom 340. Tidal waters can enter and exit the harbor, however, due to the relative height difference between the harbor bottom 340 and the seabed 390, the sediments 350 on the harbor bottom 340 cannot be washed away even if mixed.

Dredging device 200, as disclosed in part of FIG. 2a-2c are placed above, but not in contact with, the sediment layer 350. The dredging device 200 is towed over the harbor floor 340 and over the sediment layer 350 by a boat 360 moving on the surface 330 of the water. The boat includes a winch and a cable 370 that is attached to the connector 270 of the dredging device 200 not only to raise and lower the dredging device 200 into the water, but also to tow the dredging device 200 along the sediment layer 350. In this embodiment, a power supply 380 is located on the surface of the boat 360 to provide power to the pumps 220 and 230 located on the device 200, although in other embodiments, the boat may be equipped with an auxiliary power unit that can directly power the pumps 220 and 230.

In use, the dredging device 200 is lowered from the boat onto the sediment layer 350 located above the harbor floor 340 using a winch 370. The pressure pump 220 is operated by a control device (not shown) and a power supply 380 and pumps water 330 through the inlet 221 from harbor 300 to conduit 219 in housing 210 and out through fluid injection devices 218 located on bottom surface 216 of housing 220 to move

- 6 042142 sewage sediments 350. Injecting water into the layer of sediments 350 leads to a decrease in the density of sediments, as well as loosening the settled sediments 350. Then, the pump 230 of the extraction device sucks the loosened sediments 340 through the inlet 231 and removes the sediments, as shown in cloud 400, at a level that is above the level of the seafloor 390. Since the mixed sediment 400 is in a higher water column than the seafloor 390, tidal water 330 entering and leaving the harbor 300 is able to extract the ejected layer 400 sediment deposits and set it aside from the harbor.

In FIG. 4-9 show another embodiment of a dredging device, generally designated 500. This dredging device 500 can be used in the method of the present invention and as described above with reference to FIG. 3. The dredging device 500 includes a frame containing a frame, generally indicated at 510. The frame 510 includes a plurality of structural components arranged parallel to each other and supported by transverse members. The advantage is that the frame is strong and can withstand contact with the water bottom and underwater debris. In addition, the open frame design reduces drag in the water.

The structural components of the frame 510 include opposing side panels 520 and main panels 530. The main panels 530 are equidistant between the opposing side panels 520 and have substantially the same shape as the opposing side panels 520. The side panels 520 and main panels 530 are connected by a cross member 540 located under the side panels 520 and main panels 530 and oriented along the front side, and another cross member 550 located under the side panels 520 and main panels 530 and oriented along the rear side. The bottom surface of the main panels 530 and opposite side panels 520 includes skids, generally designated 560. The skids 560 are provided to protect the frame 510 in case of occurrence and contact with the water bed during use.

The dredging device 500 is provided with a fluid injection device for injecting fluid into the sediments on the waterbed to mix and/or dilute them. The injection device includes a pair of injection pumps, generally indicated at 570, which are located in equal positions on both sides of the frame 510, while the injection pumps 570 contain inlet holes, generally indicated at 580, in the form of pipelines extending from the injection pumps 570 and raised above frame 510 to suck in water from the environment for injection into the sediment. The inlets 580 are raised above the frame 510 so as not to suck in the sediment that has been ejected by the dredging device 500. The pumping devices also include a pair of fluid outlets, generally indicated at 590. The fluid outlets 590 comprise a pair of parallel pipes 600, 610 extending between the upper front corners of the opposite side panels 520 and between the midpoints of the upper edges of the side panels 520, located opposite each other. The main panels 530 are also connected to parallel conduits 600 and 610. Each of the conduits 600, 610 includes a series of downwardly directed nozzles 620 through which fluid is injected into the sediment during use. Two pipes 620 are provided between each side panel 520 and/or main panel 530, although this number can be increased or decreased accordingly. Each of the parallel tubes 600 and 610 is in fluid communication with the pressure pump 570 through conduits, generally indicated at 630.

The dredging device 500 further comprises a retrieval device, generally indicated at 640, which includes a retrieval device pump 650 that, during use, sucks mixed sediment from the bottom surface of the frame 510 and deposits it in a water column above the level of the dredging device 500. The extractor 640 further comprises a tube 660 which is located between the side panels 520 at their upper rear corner, thereby providing additional support for the frame 510, and the extractor tube 660 is also connected to the equidistant main panels 530. The extractor tube 660 comprises a series of downward openings 670 into which mixed sediment deposits are sucked during use. From the extractor pump 650 exits the extractor conduit 680 which extends above the inlet ports 580 of the injector. Injector pump 650 and conduits 680 are securely attached to frame 510. During use, mixed sediments are pumped into openings 670 located on extractor tube 660, sucked into the extractor pump 650, and then discharged through the extractor conduit 680.

The frame 510 and the booster pumps 570 are protected from underwater debris by gratings 690 that are hinged to the upper rear of the frame 510 and are slanted to deflect debris generated in the water above the frame 510. Front edges of the opposing side panels 520 and main panels 530 are also rounded to deflect debris either above or below frame 510. Grilles 690 are hinged to provide

- 7 042142 oven the possibility of servicing pressure pumps and pipelines.

Along the rear of the frame 510, between each main panel 530 and the side panel 520, are resiliently deformable plates 700, which may be made of rubber, plastic, or the like. Plates 700 extend downward from the top of frame 510, where they are connected to the frame, to the bottom of frame 510, and thus close the open rear of frame 510. Plates 700 are designed to contain mixed sediment within frame 510 to allow it to be removed through the openings. 670 extraction devices. However, if the frame 510 contains too much sediment so that the pressure inside the frame increases to a certain limit, or if an object such as container nail or other heavy debris enters the frame 510, this will be enough to deform the plates 700 away from frame 510 to allow excess sediment or debris to be ejected from the rear of frame 510.

The dredging device 500 is attached to the floating craft with a set of cables. Four cables, generally designated 710, are connected to connectors on frame 510 near the retrieval pump and are combined into one cable (not shown) that is connected to a winch at the rear of the craft (also not shown).

This cable 710 is used to raise and lower the dredger during use and to determine its depth in the water. Additionally, cables 720 are provided at the front of the dredger 500 and are connected to the front of the opposing side panels 520. The cables 720 extend under the watercraft and are secured to the front of the watercraft. These cables are provided to keep the frame 510 stable during use and to keep it at the correct depth. If cables 720 are not provided at the front, then the dredger 500 may rise in the water upon contact with sediment.

The cables 710 may also be connected to a stabilizer which is located on the watercraft, the stabilizer keeping the dredger level above the waterbed during use.

In this embodiment, the retrieval pump and booster pump 650, 570 are powered by electricity from the craft, which is supplied through a composite hose, generally indicated at 730, consisting of a series of wires leading to a power source on the craft. The pressure pump and the pump of the retrieval device 570, 650 are usually powered by electricity. However, in some embodiments, they may be hydraulic, in which case the composite hose 730 will also contain a hydraulic pipe or pipes leading to the floating craft.

In FIG. 10 and 12 show another embodiment of a dredger, generally designated 800, in accordance with the present invention. The dredging device 800 is a variation of the dredging device 500 and, therefore, similar reference numerals are used where appropriate. If the dredger 500 is provided with a grate guide 690 to protect the pumps from debris, then the dredger 800 is instead provided with inclined plates 810 mounted on the body 820. The plates 810 may be formed from metal or other rigid material and located at an angle to deflect debris over the top of the 800 dredger. In particular, during use of the dredger 800, container lashings, which are rigid metal poles, may be exposed. The 810 plates will be able to deflect lashings even if they hit the front of the 810 plates.

The frame 820 of the dredger 800 is further provided with a top panel 830 which is provided with holes 840 to allow access under the top panel 830.

Another difference compared to the dredging device 500 is that the retrieval device conduit 850 has a forked distal end so that the dredged sediment is ejected over a wider area in the water. Extractor conduit 850 is supported by frame 860.

In FIG. 11 is a sectional view taken along line X-X of the device shown in FIG. 10. This sectional view shows the extractor tube 660 having an opening 670 and parallel tubes 600, 610 at the fluid outlet 590 that are connected to the nozzles 620. FIG. 11 also shows transverse members 540, 550 which are angled from the horizontal and have tapered leading edges to enable shearing and deflecting any sediment that may develop during use.

Claims (16)

CLAIM 1. A method of carrying out dredging, including hanging a device for dredging to a floating vehicle, and the device for dredging contains a frame; a sediment mixing device for placement above a sediment layer on a water bottom, the sediment mixing device comprising a fluid injection device and a pump configured to inject fluid through the fluid injection device, the sediment mixing device and the pump being mounted directly on the a frame, wherein the fluid injection device comprises one or more pipelines, in which a plurality of nozzles are located; separately, a retrieval device configured to move the mixed sediment from the waterbed and above the dredging device, the retrieval device comprising a pipeline and a pump configured to pump the mixed sediment through the pipeline, the extraction device and the pump mounted directly on the frame; and a connector for connecting the dredging device to the floating craft; placing the dredging device above the waterbed, but not in contact with the waterbed to be dredged to remove sediment; mixing sediment using a sediment mixer; extraction of sedimentary deposits using an extraction device; creating a suspension of the extracted sediments under water and in a higher water column above the sediment mixing device; and moving the dredging device through the water; wherein the sedimentary deposits are carried and deposited away from the dredged area by the natural movement of the water. 2. The method according to claim 1, characterized in that the fluid injection device is located on the underside of the sediment mixing device. 3. A method according to claim 1 or 2, wherein the sediment mixer conduit has a first opening located on the bottom surface of the dredging device and a second opening located at the highest point of the dredging device. 4. The method according to claim 3, characterized in that the pipeline has the shape of a truncated cone, in which the second hole is wider than the first. 5. The method according to any of the previous paragraphs, characterized in that the pumps are powered by a power unit installed on the floating craft. 6. A method according to any one of claims 1 to 4, characterized in that the pumps are configured to be powered by a power supply installed on the dredging device. 7. A method according to any one of the preceding claims, characterized in that the dredging device and/or the floating device further comprises a guide device for deflecting debris generated on the water bottom. 8. A method according to any one of the preceding claims, characterized in that the floating vehicle further comprises a heave compensator, and the heave compensator maintains the dredging device at the same level above the waterbed. 9. A method according to any one of the preceding claims, characterized in that the frame contains cushioning means. 10. The method according to claim 9, characterized in that the shock-absorbing means comprise skids mounted on the lower surface of the frame. 11. A method according to any one of the preceding claims, characterized in that the frame is an open frame. 12. The method according to any one of the preceding claims, characterized in that the frame comprises side panels located opposite each other and one or more main panels arranged in parallel between the side panels, and the main panel and the side panels are connected by one or more transverse elements. 13. The method according to claim 12, characterized in that one or more transverse elements contain a sediment mixing device, and the sediment mixing device comprises one or more pipelines containing one or more fluid injection outlets, and the sediment mixing device deposits are connected to one or more - 9 042142 pumps, wherein the pump is connected to the inlet so that the fluid is sucked from the environment. 14. The method according to claim 12 or 13, characterized in that one or more transverse elements contain an extraction device, and the extraction device contains one or more pipelines containing inlets for suction of mixed sediment deposits for removal, and the extraction device is connected to one or a plurality of pumps that are connected to a pipeline raised above the dredging device to remove the mixed sediment above the dredging device in use. 15. Device for dredging for carrying out the method according to claims 1 to 14 for placement above the waterbed, but not in contact with the waterbed to be dredged with sediment removal, containing the frame; a sediment mixing device for placement above a layer of sediments on a water bottom, wherein the sediment mixing device comprises a fluid injection device and a pump configured to inject fluid through the fluid injection device, wherein the sediment mixing device and the pump are mounted directly on the frame , and the fluid injection device contains one or more pipelines, in which a plurality of nozzles are located; separately, a recovery device configured to move the mixed sediment from the water bottom and above the dredging device, the recovery device comprising a pipeline and a pump designed to pump the mixed sediment through the pipeline and create a suspension of the extracted sediments under water and in a higher water a column above the sediment mixing device, with the extraction device and the pump mounted directly on the frame; and a connector for connecting the dredging device to the floating craft. 16. The method of operating the device for dredging according to item 15, while the method of operation includes connecting the device for dredging with a floating vehicle using a connector; suspending the dredging device above the waterbed, but not in contact with the waterbed to be dredged to remove sediment; extracting the mixed sediments using the extraction device and making the extracted sediments slurry under water and above the extraction device.