During deep sea mining of polymetallic nodules, a crawler collects nodules by suction head. In the process, sediment is being pumped in together with the nodules. The water-sediment mixture is released via an exhaust system, leading to a sediment-laden density current. The mixing of the density current plays an important role in the dispersion of sediment into the water column.
IMDC has set up a Computational Fluid Dynamics (CFD) model to study the dispersion of the sediments near the exhaust, as well as to optimise the design of the exhaust diffusor.
The study shows that if the diffusor is designed well, the sediment exhaust can be contained in a density current with limited dispersion.