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Indoor ocean floor

Project number 
Project leader 

Prof.dr. G.J. Reichart
Koninklijk Nederlands Instituut voor Onderzoek der Zee

Type project 
Technische wetenschappen
The bed of the deep sea is full of valuable minerals. How can you excavate them without damaging the surrounding environment? An enormous water basin is designed to clarify the impact of deep sea mining.
With an enormous water basin PhD student Frans van Grunsven carries out TTW research at the Delft University of Technology. The basin contains 25,000 litres of water and is a scale model that can be used to study how mining the ocean bed influences the water in the surrounding area.
Excavating areas of seabed
The influence can be large. The ocean bed contains enormous stocks of valuable minerals, which can provide the growing economy with a source of raw materials. To extract these minerals, mining companies want to excavate areas of seabed. The excavated sediment will be pumped to a ship where the valuable minerals will be separated from the worthless sediment. This sediment will then be returned to the seabed.
Pumping the ‘return sediment’ back, however, can considerably disrupt the seabed. It leads to turbid water, which can extend for many kilometres, and can have a major impact on marine life. Turbid water negatively affects the ability of organisms, including deep-water corals, to feed themselves by filtering plankton and other floating nutritional elements from the seawater.
Ground quartz
Together with master student Protogène Byishimo, Van Grunsven is studying whether you can limit the dispersal of turbid water by releasing the return sediment very close to the seabed. Van Grunsven uses an aluminium pipe that emits ground quartz in the water basin to simulate the outflow of return sediment. He can, for instance, vary the amount of sediment that exits the pipe and the height difference between the pipe and the seabed. This lets Van Grunsven investigate and simulate the ideal method of returning the sediment.
Public simulation model
Finally the study must lead to a publically available simulation model that companies can use to determine the impact of their mining activities – and how they can limit this impact as far as possible. There seems to be a high probability that industry will embrace the model. Various companies that are active in deep sea mining are investing in Van Grunsven’s research project.
Photography: Ivar Pel
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