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Understanding Dredging


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A Holistic Approach to Predict, Measure and Reduce Environmental Pressures of Polymetallic Nodule Collection

€ 20,-


Presented during:

WODCON XXIII - Dredging is changing - The Practice. The Science. The Business.


R.L.J. Helmons


"There is an expected increase in demand of critical raw materials, e.g. nickel and cobalt, mainly driven by the shift towards renewable energy solutions and the increase in production of electric vehicles. That trend has raised the interests for the mining of polymetallic nodules. The most extensive nodule depostions are found on the abyssal plains of the deep seas. In spite of their economic interest, concerns have been raised regarding the environmental impact of deep sea mining. Of major concern are sediment plumes that will be generated by the mining activities. Such turbidity flows might impact the environment through sediment dispersion and bottom blanketing within the vicinity of the mining site could potentially bury benthic organisms, clog the respiratory surfaces of filter feeders and pollute the food supply for most benthic organisms. How far these plumes can reach and how severely they affect the deep-sea ecosystem is presently unknown (Washburn, et al., 2019). Given these uncertainties, from a technical point of view, it is of importance to 1) be able to accurately predict where these plumes will travel and what deposition layer will be generated and 2) identifying under what conditions dispersion of said plumes will be minimal. Most of the nodule collector systems designs are targeted for a high nodule pickup efficacy and capacity. However, this is only part of the collectors performance, the sediment release conditions should also be included. Optimization of the release conditions of these sediments is expected to allow for a significant reduction of the spread of the turbidity flows. It is in the so-called near-field (

Keywords: Deep-sea mining; flocculation; monitoring; hydraulic excavation, sediment dispersion



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