Key points
- The dewatering plant has a design capacity of 400 tonnes per hour and will screen seafloor massive sulphides before dewatering via centrifuges and filter presses down to eight microns.
- Dewatered product will be stored in the vessel’s hold for transshipment via Handimax vessels to Nautilus’s processing partner in China.
- Filtered water is returned through the enclosed riser system to drive the subsea lift pump and is discharged within 50 metres of the sea floor.
- The detailed design phase is due to finish in the fourth quarter of 2015, with fabrication starting in early 2016 and first production from Solwara 1 scheduled for 2018.
The contract for the detailed design of the Solwara 1 dewatering plant to be used on
Nautilus Minerals Inc.’s production support vessel has been awarded to the Brisbane office of the DRA Group.
Mike Johnston, Nautilus’s chief executive officer, commented: “The project team has been working closely with DRA for several years on studies and early engineering. DRA has extensive experience with similar floating dewatering/mineral processing facilities in related offshore industries. We are pleased to have them utilize this experience when they carry out the detailed design for our on-board processing facilities.”
DRA’s regional director, Donald Holley, commented: “It is pleasing for us to be able to apply DRA’s previous experience in designing vessel-mounted process plants to the Solwara 1 project. This special experience has been gained from our offshore diamond recovery projects off the coast of southwest Africa. It includes overcoming the challenges in designing and operating process plants mounted on ships resulting particularly from the impact of the dynamic environment from wave movement and the need for modular construction.”
About the detailed design work for the dewatering plant
The scope of work awarded to DRA involves the detailed design of the vessel-mounted material processing facilities. With a design capacity of 400 tonnes per hour, the plant will include screening the sea floor massive sulphides into a number of size fractions, followed by dewatering using centrifuges and filter presses, eventually filtering to eight microns. The combined dewatered product will then be temporarily stored in the vessel’s hold prior to transshipment through Handimax vessels to the company’s processing partner in China. The remaining filtered water is then returned through the enclosed riser system to drive the subsea lift pump and discharged within 50 metres of the sea floor, from where it originally came.
The detailed design phase is expected to be completed in fourth-quarter 2015, following which the vessel-mounted modules will be fabricated and precommissioned onshore prior to integration onto the completed vessel. Fabrication of the process plant is expected to commence in early 2016, with first production from the Solwara 1 project being scheduled for 2018.
