A sea change for mining

A Nautilus bulk cutter for deep sea mining. (Image: Nautilus Resources)

The International Seabed Authority (ISA) has granted over 25 contracts to various countries for deep sea and seafloor mineral exploration. Countries on this list include Russia, China, India, Japan, Brazil and several countries in Europe, among others.

Deep-sea mining has a storied history; people have been attempting to tap the mineral potential of the Earth’s oceans for decades, with mixed results. As far back as the 1960s, interested parties have explored the concept with research vessels; the discovery of hydrothermal vents, which spew mineral-rich deposits from fissures in the earth’s surface.

Despite the recognition for potential, the early days of deep-sea mineral exploration produced little in the way of tangible commercial results. Early attempts to mine manganese from the sea floor resulted in over $US500 million in wasted funds. There has been some success mining at shallow depths of less than 200 metres, however, particularly among diamond miners in African countries such as Namibia and South Africa — De Beers is a notable advocate — but other minerals have eluded the mining industry at large.

Testing the waters

Recently though, things are starting to change, and technology is finally catching up to the vision. Deep-sea mining is seeing something of a comeback; in September, a Japanese team successfully mined gold and zinc off the coast of Okinawa using a track-driven, autonomous mining vehicle.

The month-long dig, led by the Japan Oil, Gas and Metals National Corporation (JOGMEC), is part of the nation’s efforts to further test the viability of mining robots for deep-sea extraction. The machine mined at a depth of roughly 1600 metres at an ore deposit off the Okinawan coast estimated by the Japanese Economy, Trade and Industry Ministry to contain zinc levels equivalent to the country’s annual consumption. Commercialised mining is due to begin at this, and six other ore deposits, by 2020, with the aim of becoming a viable resource producer. In a similar vein, Japan became the world’s first country to successfully extract methane hydrate, when engineers — also from JOGMEC — found a way to depressurise methane hydrate from offshore deposits into methane gas.

Over in the UK meanwhile, in the depths of the once-bustling Whitehill Yeo clay pit in Devon, something likewise stirs. An EU- funded venture called the Viable Alternative Mine Operating System (aka VAMOS, stylised as ¡VAMOS!) is being used to extract minerals from flooded sites. Project partners include the Cornwall Mining Alliance (CMA), Marine Minerals and FUGRO. The aim of the project is not just to sweep flooded and abandoned mines, but as extensions of open-cut mines. The underwater nature of the excavation also allegedly reduces noise and environmental impact.

“With future mineral prices increasing as a result of the growing demand and depletion of higher grade onshore deposits, marine mining will progressively become more economic,” explained Mike Proudfoot, chief executive officer of Marine Minerals, “particularly for the recovery of phosphorates for fertiliser production and minerals from manganese crusts; these [will be used] to feed the increasing population and for the move to electric transport.”

Proudfoot comes from a tin mining background, and his company is currently working on a subsea tin recovery project that collects seabed tin fragments that have been washed into the sea as part of previous ground-based mining operations. While this project is more complementary to traditional mining methods than other subsea mining programs, Proudfoot still believes recovery of marine-based minerals has the potential to become dominant.

“Whilst globally there are a number of significant accumulations of minerals that have been washed into the seas post mining that may become economic to extract, these are insignificant compared with the natural accumulations of minerals in the oceans that will be mined in the future,” he explained.

“Global dominance of marine-recovered minerals is still quite a long way off, but it will eventually happen. Recovery of alluvial-concentrated minerals such as tin, gold, zircon and titanium will increase as methods improve, reducing recovery costs.”

Mineral water

There are several different types of minerals available for extraction from the seabed. Polymetallic nodules, located up to 6000 metres under the sea surface, form from metal collected on debris and detritus on the seabed, and can contain rich deposits of copper, cobalt, nickel and lithium, all of which are in-demand components for clean energy technology and electric vehicle production; ferromanganese crusts that form on the seabed surface are abundant in rare earth elements such as tellurium, useful for the production of solar cells.

The aforementioned hydrothermal vents are the third major undersea mineral source suitable for mining, with mineral-rich sulphides spewing in a constant stream from the sea floor. Hydrothermal vents are extremely rare, covering an estimated 34 square miles globally, and its environs are teeming with life.

Indeed, the environmental impact on marine life is a large concern for opponents of deep-sea mining, as dragging and digging of the ground could displace entire ecosystems, particularly in the deep ocean, which contains thousands, or potentially even millions of unknown species. In April 2016, Floridian company Odyssey Marine Exploration was denied a deep ocean exploration licence by Mexican environmental authorities on the basis of a single issue; the effects of dredging on sea turtles.

“Each venture [will need] to conduct detailed environmental impact assessments of their planned processes and adopt changes to mitigate the effects,” explained Proudfoot. “These will vary depending on local conditions.”

The Voyage of the Nautilus

This is a concern that has dogged the operations of companies like Nautilus, currently hosting what is perhaps the world’s most ambitious deep-sea mining project. The Canadian operator hopes to begin deep-sea mining operations using thermal vents by 2020 with the aid of three (initial) machines.

Three vehicles, including a bulk cutter (weighing 310 tonnes), an auxiliary cutter, and a collector, and collectively known as the seafloor production tools (SPTs) are to be used by the company for its maiden project Solwara 1 in Papua New Guinea, the first proposed Pacific deep-sea mine. The vehicles will pump extracted minerals as slurry via a subsea slurry lift pump (SSLP) connected to a riser and lifting system (RALS) to the surface for collection aboard a 227 metre-long vessel.

The operation, vast in scope, cost and ambition, has been a long time coming, with Nautilus granted an approval from the Papua New Guinea Department of Environment and Conservation (DNC) at the end of 2009. The mine’s life is expected to last 30 months, with the possibility of extension up to five years dependent on further scoping.

The first phase of the operation will concentrate on extracting ore from the seafloor to be collected and transported for external processing, while the second phase will concentrate on the construction of a treatment facility.

Nautilus indicated resources of 7.2 per cent copper, five grams of gold per tonne, 23 grams of silver per tonne and 0.4 per cent zinc over one million tonnes of initial findings, with inferred resources of 8.1 per cent copper, 6.4 grams of gold per tonne, 23 grams of silver per tonne, and 0.9 per cent of zinc over another 1.5 million tonnes.

Following a slow funding round that saw the project start date slip from 2018 to 2020, having received its licence in 2011, Nautilus has seen its share of criticism too, not only from environmentalists, but the former attorney general of Papua New Guinea as well, who has previously referred to the project as ‘high-risk’ and ‘not professional’, but Nautilus has described the project as experimental, and has not committed to a feasibility study.

The group has recently revealed it will require $US350 million to finish financing on the project, which is to be collected by the company’s investment group Deep Sea Mining Finance (DSMF), who are registered in the British Virgin Islands.

Whether or not the company suffers the same setbacks as Odyssey remains to be seen, but whatever the result, deep-sea mining is far from washed up.