are used to separate the coarse particles from the slurry stream these coarse particles are considered to be free draining and will not require any mechanical dewatering to achieve the required moisture limit a vibrating basket centrifuge is used to provide mechanical dewatering of the medium particle size fraction to ensure the required moisture limit is reached hydro cyclones are then used to separate the valuable fine particles gt 0 006 mm from the slurry feed which have not been removed by the screen decks disk filters are used to dewater the valuable fines between 0 5 mm and 0 006 mm prior to loading on to the transport barge 108 this ore size fraction requires greater mechanical input vacuum to remove moisture the ore slurry waste water is then returned to the seafloor via a pump set and piping system a dewatering plant 104 is installed on the topsides surface facilities in this case the psv 106 to reduce the moisture content of the ore to below the transportable moisture limit tml of the ore reducing the moisture content below the tml allows safe carriage of the ore by ship it also reduces the cost of transport due to the reduced volume of material being shipped alternative embodiments may utilise any suitable other configuration of dewatering plant in the case of dewatering plant 104 failure the gathering machine 114 will disengage the seafloor 110 and continue pumping seawater the volume of.