Experimental investigation of sediment erosion generated by a coandă-effect-based polymetallic-nodule collector

Experimental investigation of sediment erosion generated by a coandă-effect-based polymetallic-nodule collector

Alhaddad, S.M.S. (TU Delft Offshore and Dredging Engineering)
Helmons, R.L.J. (TU Delft Offshore and Dredging Engineering; Norwegian University of Science and Technology (NTNU))

2022

Owing to the absence of direct contact between hydraulic polymetallic-nodule collectors and seabed, hydraulic collection is deemed, from an environmental point of view, the most preferred technique in nodule mining. To design a hydraulic collector that results in minimum sediment disturbance, it is crucial to develop a solid understanding of the interaction between the collector and the sea bed. To this end, we performed a series of small-scale experiments where several operational conditions were tested, yielding the first quantitative data for sediment erosion resulting from the movement of a hydraulic collector over a sand bed. This paper presents and discusses the experimental results and observations. It is found that the collector’s forward velocity is inversely proportional to the bed-sediment erosion depth, since the bed is exposed to the flow for a longer time when the collector drives slower and vice versa. Contrarily, an increased jet velocity leads to a larger erosion depth. Furthermore, when the collector underside is nearer to the bed, a larger sediment layer is exposed to the water flow, resulting in a larger erosion depth. Finally, the experimental results show that a larger amount of water entrained into the collection duct results in a smaller erosion depth, implying that the flow velocities under the collector are lower in this case.

deep sea mining
sediment erosion
polymetallic nodules
hydraulic collector
Coandă effect

http://resolver.tudelft.nl/uuid:b4fc9804-e0cb-4791-ac76-a952596f0f95

WODA

2023-07-01

Proceedings of the World Dredging Conference, WODCON XXIII: Dredging is Changing

WODCON XXIII, 2022-05-16 → 2022-05-20, Tivoli Hotel, Copenhagen, Denmark

Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.

Institutional Repository

conference paper

© 2022 S.M.S. Alhaddad, R.L.J. Helmons