A hydrovac unit with a mud tank and water tank arranged symmetrically, so that the center of gravity does not substantially shift forwards or backwards during operation. The mud tank may be located inside the water tank. The mud tank may be supported and reinforced by external ribs, which may be fixed to the mud tank. The water tank may be formed by a rear face attached to the mud tank and a cylinder portion, the mud tank and rear face sliding into the cylinder portion for assembly and secured in place. The contents of the hydrovac unit may be dumped by tilting using a hoist. The tank assembly may be heated and insulated.

There is disclosed an excavation apparatus (5), such as an underwater excavation apparatus, having means for producing, in use, at least one vortex, spiral or turbulent flow in a laminar flow of fluid, e.g. water. The excavation apparatus (5) comprises a rotor (10) having a rotor rotation axis (A), wherein, in use, flow of fluid past or across the rotor (10) is at a first angle (α) from the axis of rotation (A). The excavation apparatus (5) comprises the rotor (5) and means or an arrangement for dampening reactive torque on the apparatus (5) caused by rotation of the rotor (10), in use. The turbulent flow is provided within, such as within a (transverse) cross-section, of the laminar flow.

There is disclosed an excavation apparatus (5), such as an underwater excavation apparatus, having means for producing, in use, at least one vortex, spiral or turbulent flow in a laminar flow of fluid, e.g. water. The excavation apparatus (5) comprises a rotor (10) having a rotor rotation axis (A), wherein, in use, flow of fluid past or across the rotor (10) is at a first angle (α) from the axis of rotation (A). The excavation apparatus (5) comprises the rotor (5) and means or an arrangement for dampening reactive torque on the apparatus (5) caused by rotation of the rotor (10), in use. The turbulent flow is provided within, such as within a (transverse) cross-section, of the laminar flow.

Hydro excavation vacuum apparatus that process spoil material onboard the apparatus by separating water from the cut earthen material are disclosed.

An elbow fitting for an excavating apparatus can include a curved cylindrical pipe that can include a first metal material. In an example, the fitting can be configured for coupling to a hose. The pipe can include an interior surface and an exterior surface. Optionally, a perimeter of the pipe does not exceed a diameter of a first end of the pipe. The fitting can include a cladding layer (e.g., a second metal material) that can be coupled to the first metal material within the interior surface of the pipe. The cladding layer can include an abrasion-resistant material. The cladding layer can be coupled to the pipe such as with a welding operation. The cladding layer can include one or more ridges. The cladding layer can corregate the interior surface of the fitting and exterior surfaces of the fitting which can come into contact with abrasive material.

A cutter head arranged to rotate about an axis of rotation for removing material from a water bed comprises a base ring positioned respect to the axis of rotation; a hub positioned with respect to the axis of rotation; a plurality of arms extending between the base ring and the hub, the arms comprising a plurality of cutting tools; and a plurality of skirts, each skirt extending from one of the plurality of arms to the hub to form a closed surface between the arm and the hub from a distal end of the cutter head toward the base ring and ending with a side configured to be parallel to a backplate, leaving an open channel between the skirt and the backplate.

There is disclosed an excavation apparatus (5), such as an underwater excavation apparatus, having means for producing, in use, at least one vortex, spiral or turbulent flow in a laminar flow of fluid, e.g. water. The excavation apparatus (5) comprises a rotor (10) having a rotor rotation axis (A), wherein, in use, flow of fluid past or across the rotor (10) is at a first angle (a) from the axis of rotation (A). The excavation apparatus (5) comprises the rotor (5) and means or an arrangement for dampening reactive torque on the apparatus (5) caused by rotation of the rotor (10), in use. The turbulent flow is provided within, such as within a (transverse) cross-section, of the laminar flow.

There is disclosed an excavation apparatus (5), such as an underwater excavation apparatus, having means for producing, in use, at least one vortex, spiral or turbulent flow in a laminar flow of fluid, e.g. water. The excavation apparatus (5) comprises a rotor (10) having a rotor rotation axis (A), wherein, in use, flow of fluid past or across the rotor (10) is at a first angle (a) from the axis of rotation (A). The excavation apparatus (5) comprises the rotor (5) and means or an arrangement for dampening reactive torque on the apparatus (5) caused by rotation of the rotor (10), in use. The turbulent flow is provided within, such as within a (transverse) cross-section, of the laminar flow.

A dredge system includes a dredger, a conduit and a self-priming pump. The dredger has an internal area and an outlet, and is configured to feed material into the internal area of the dredger. The conduit is coupled to the dredger adjacent the outlet and configured to transport the material from the internal area of the dredger to a receptacle. The self-priming pump is coupled to the conduit and is configured to pump the material from the outlet to the receptacle.

An environmentally-friendly semi-closed loop deep-sea ore hydraulic lifting system, comprises a water injection pump, a water injection riser, a deep-sea multiple high-pressure silo feeding device, a lifting riser, a dewatering device and a pipeline. The water injection pump and the dewatering device are fixed on a mining ship. The water injection pump is connected to the deep-sea multiple high-pressure silo feeding device through the water injection riser. The deep-sea multiple high-pressure silo feeding device is connected to the dewatering device through the lifting riser. The water injection pump is connected to the dewatering device through the pipeline. Seawater is pumped into the water injection riser by the water injection pump, then ore is fed into a high-pressure hydraulic pipeline by the deep-sea multiple high-pressure silo feeding device to be mixed with the seawater, and an obtained ore and seawater mixture is lifted to the mining ship on the sea surface.