Seabed mining involves a suction pump that pulls sand up from the seabed to a dredger ship above. The sand will often then be sorted while still at sea, with the valuable minerals or metals extracted and exported offshore, while whatever’s left is dumped back into the water causing a ‘sediment plume.

Why is it important?

• Disturbance of the seafloor. The scraping of the ocean floor by machines can alter or destroy deep-sea habitats, leading to the loss of species and fragmentation or loss of ecosystem structure and function.
• Sediment plumes.
• Pollution.

Two technologies being considered for commercial mining of the ocean floor are continuous line bucket system (CLB) and hydraulic suction systems. CLB is the preferred method and transfers the mud up to the ship in a conveyor belt type system.

The deposits are mined using either hydraulic pumps or bucket systems that take ore to the surface to be processed. Marine minerals include sea-dredged and seabed minerals.

Techniques for mining minerals in the marine environment may involve seafloor suction dredging, seafloor slurry pipes, use of tracked vessels on the seafloor and seafloor cutting/fragmentation. Following extraction and processing, tailings (unwanted material) are deposited back onto the seafloor.

Seafloor mining has the potential to help meet demand for many minerals used worldwide and could help bolster the economies of developing nations in one of two ways. However, seafloor mining also has the potential to take a toll on the life in the sea.

TechnipFMC, Wilhelmsen and NorSea are investing in Norwegian deep-sea mining company Loke Marine Minerals (Loke) to enable the energy transition. TechnipFMC is a co-investor in Loke Marine Minerals with an ownership of 18% while Wilhelmsen and NorSea together acquired an 18% stake in the company.

Seabed Mining (SBM) is a growing industrial field that involves extracting submerged minerals and deposits from the sea floor. To date, mining for sand, tin and diamonds has been generally limited to shallow coastal waters. Other areas of current most likely occur off the coast of Papua New Guinea.

The three major deep sea mineral deposits that have excited commercial interests include Seafloor Massive Sulphides (SMS), Manganese Nodules and Cobalt-rich Crusts. When this happens the minerals that are formed and fall to the sea floor include high concentrations of metals such as Copper, Gold, Silver, Zinc and Lead.

Mining can pollute the aquatic environment by producing sediment, changes in pH, toxic heavy metals, and alterations in stream channel and s t r eam f 1 ow. Sediment accrues in streams naturally and at moderate levels can be a beneficial component of anadromous fish habitat.

Past attendees:

• ABS USA.
• Nautilus Minerals Inc.
• IHC Mining B.V.
• Geomarine Ltd.
• UK Seabed Resources.
• Subsea Minerals Ltd.
• De Beers Marine.
• Neptune Minerals Inc.

At the same time, some seabed mining operations are already taking place within continental shelf areas of nation states, generally at relatively shallow depths, and with others at advanced stages of planning.

Rising demand for minerals and metals, including for use in the technology sector, has led to a resurgence of interest in exploration of mineral resources located on the seabed.

Through their spectral signatures, this technology allows us to identify and classify different types of minerals. NTNU’s contribution to the Horizon2020 Blue Mining project involves the development of an automated image analysis system for seafloor manganese nodules and massive sulfides.

The underwater hyperspectral imager (UHI), for example, is a valuable new resource for data gathering, but also has different operating constraints than a side-scan sonar – as it needs to be closer to the seabed. This work is part of the Marmine project.