Mad Max goes deep

Apr 18, 2017 Environment ,Technology

A team of deep-sea robots will soon begin scouring the sea-floor near Papua New Guinea to recover precious minerals. Designed to operate at depths of up to 6000m, the machines are technological marvels, but not everyone is impressed, writes Lawrence Schaffler. Photos courtesy of Nautilus Minerals.

The robots have been developed by Nautilus Minerals Inc, a Canadian company which plans to mine the seafloor’s massive sulphide systems, a potential source of high-grade copper, gold, zinc and silver. Using technologies adapted from the offshore oil, dredging and mining industries, the robots are similar to bulk continuous mining machines seen in coal mines.

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Nautilus’ first copper-gold project – Solwara 1 – is under development in the territorial waters of Papua New Guinea. The company’s been granted an Environment Permit and Mining Lease for the site.

Further ahead, Nautilus plans to grow its interests in the exclusive economic zones and territorial waters of Papua New Guinea, Fiji, Tonga, the Solomon Islands, Vanuatu and New Zealand – as well as other areas beyond the Western Pacific.

Leading the operation are three types of robots called Seafloor Production Tools (SPTs) – the Auxiliary Cutter (AC), the Bulk Cutter (BC) and the Collecting Machine (CM). All are designed and built by the UK’s Soil Machine Dynamic in Newcastle upon Tyne.

The AC and BC excavate seafloor material in a continuous cutting process. The AC is a preparatory
machine that deals with rough terrain and creates ‘benches’ for the other machines to work. It operates
on tracks with spud assistance and has a boommounted cutting head for flexibility.

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The BC has a higher cutting capacity but is limited to working benches created by the AC. Both machines leave cut material on the seafloor for collection by the CM. The CM collects the material as a seawater slurry, with internal pumps pushing it through a flexible pipe to the Riser and Lifting System. SPTs are deployed from a Production Support Vessel using a lifting frame and operated via a power and control umbilical.

The minerals on the seabed have built up over millions of years. The deep-sea miners are eyeing three main types:

Polymetallic Nodules – found at depths of up to 6,000m, they form when metals collect on debris on the seafloor sediment such as fossils and even shark teeth. The nodules can be the size of
golf balls and contain minerals such as nickel, cobalt, copper and lithium. These are used in rechargeable batteries.

Ferromanganese crusts – found at depths between 400m and 5,000m, they contain cobalt and rare elements such as tellerium, used in solar cells. The crusts are difficult to mine because they have to be separated from the rocks they’re growing on – which risks diluting the minerals and making them less valuable.

Seafloor massive sulfides – these form around hydrothermal vents which release super-hot liquid from the earth’s crust and deposits minerals in the surrounding water. They contain metals such as copper, gold, zinc and silver.

The Solwara 1 deposit, at a water depth of 1600m, contains a copper grade of approximately seven percent. That compares with land-based copper mines, where these days the copper grade averages 0.6 percent. In addition, gold grades of well over 20g/tonne have been recorded at Solwara 1. The average grade on land is around 6g/tonne.

Nautilus Minerals has also been granted an exploration licence in the highly prospective Clarion Clipperton Fracture Zone (CCZ) of the Central Pacific, through its wholly-owned subsidiary Tonga
Offshore Mining (TOML). Sponsored by the Tongan Government, TOML has been granted some 75,000 km2 of prospective exploration territory by the International Seabed Authority (ISA) for an initial 15-year term.

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And it seems the appeal of deep-sea mining concept is catching. The International Seabed Authority, which regulates deep-sea mining globally, has granted 25 countries contracts to search for minerals.
Deep-sea mining isn’t a new concept. Diamond conglomerate De Beers has been shallow water mining the continental shelf of Southern Africa for many years.

Still, marine experts are concerned that deep-sea excavation may have a negative impact on deep ocean marine life, while others have serious doubts about the commercial and environmental viability of the Solwara 1 seabed mining project.

Says Natalie Lowrey, a member of the Deep Sea Mining Campaign NGO: “Despite securing bridge financing with its two biggest shareholders for the Solwara 1 project, Nautilus faces significant technological and financial uncertainties. They are yet to demonstrate that seafloor resource development is commercially viable and environmentally sustainable.”

“The Solwara 1 site is right in the middle of our fishing grounds and ocean currents operating at the site would bring pollutants to our shores,” adds Jonathan Mesulum, from the Papua New Guinea Alliance of Solwara Warriors.

The Parties to the Nauru Agreement, who control the world’s largest sustainable tuna purse seine fishery, have warned that sea bed mining could go down the same track as the tuna fishery – foreign companies over-exploiting Pacific Island resources with no tangible benefits delivered to local populations.