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.
|Title of host publication||Proceedings of the World Dredging Conference, WODCON XXIII|
|Subtitle of host publication||Dredging is Changing|
|Number of pages||8|
|Publication status||Published - 2022|
|Event||WODCON XXIII - Tivoli Hotel, Copenhagen, Denmark|
Duration: 16 May 2022 → 20 May 2022
|Period||16/05/22 → 20/05/22|
Bibliographical noteGreen 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.
- deep sea mining
- sediment erosion
- polymetallic nodules
- hydraulic collector
- Coandă effect