Deep-Sea Mining: The Answer to Resource Scarcity?

With over 70 percent of the earth’s surface area underwater, scientists have been working on deep-sea mining techniques for decades. But in the face of fierce opposition from environmental protection groups and unsatisfactory technology, the concept has been more of a pipe dream than a viable method for replacing onshore resources. That could be changing.

Thanks to a dramatic improvement in underwater extraction techniques and continually shrinking surface reserves, the world’s first deep-sea mine is set to begin production off the coast of Papua New Guinea in 2019 at the latest. According to Henk van Muijen, Managing Director of wet mining technology specialist IHC Mining, the industry is about to take off.

“I am convinced that deep-sea mining will become a vital alternative to traditional mining methods and a solution to resource scarcity in the future,” he says. “Deep sea deposits have, on average, much larger grades than those commonly found onshore and with commodity prices recovering, it is becoming more attractive by the day.”

READYING THE TECHNOLOGY

On the technology side, IHC Mining has played an important role in the emergence of deep-sea mining as a viable solution. Drawing on its experience in the offshore oil and gas and dredging industries, the company launched its first subsea crawler in 2000 and has remote-harvesting technology that can operate at depths of up to 1,500m ready for testing. The crawlers, equipped with massive rock-crushing teeth, are designed to scoop up polymetallic nodules lying on the seabed and pump the recovered material via a magnet motor powered vertical transport system to the surface mining vessel. A processing plant is installed on the vessel to begin the first dewatering and storage process, before the ore is transferred to an onshore facility.

There is still a way to go. The mining vessels have limited ore and slurry storage capacity, placing strains on the economic viability of the activity, while many offshore deposits are found at depths deeper than 1,500m. But the basic technique has been defined. “There is a concerted effort to improve the maximum operating depth of the subsea crawlers to at least 2km,” says Van Muijen. “The vertical transport system needs to be sufficiently powerful and efficient to drag the ore to the surface.”

Another factor is the damage deep-sea mining would do to surrounding ecosystems, which is still somewhat unknown. Among a number of promising offshore discoveries was Exploraciones Oceánicas’ Don Diego phosphate project off the coast of Baja California Sur. But in the summer of 2016, Don Diego was blocked by a combination of local communities and Mexico’s state environmental protection agency SEMARNAT, on the basis that the risk deep-sea mining poses to marine life is too great. In response, IHC Mining is working on an EU- funded project, Blue Nodules, a collaborative effort from 14 different industry and research organizations focused on refining the techniques for mining manganese nodules on the seafloor. Recognizing the need to provide answers to environmental protection groups, the Blue Nodules project contains a large sustainability program.

“If we are going to dig into the seabed, we are inevitably going to influence the ecosystem to a certain degree so we are working alongside various knowledge and research centers to minimize this impact,” says Van Muijen. “We are conducting a number of offshore tests to measure the environmental impact of this new technology, including the noise and plumes created by the crawlers, the CO2 footprint and seabed alteration.”

MOVING INTO PRODUCTION

But the world’s underwater mineral resources are administered and regulated by the International Seabed Authority (ISA), which has so far only awarded exploration licenses to contractors; exploitation and production permits are still not widely available.

A select few governments, including Papua New Guinea, New Zealand and Namibia, are exempt from this legislation and there are already crawlers operating on diamond mining projects at depths of 150-200m off the coast of Namibia. But a much more advanced project in Papua New Guinea, Nautilus Minerals’ Solwara 1 operation, carries the hopes of the deep-sea mining industry. “It is a seafloor massive sulphide deposit (SMS) that contains high- grade copper, gold, aluminum and silver,” says Van Muijen. “We have been involved from the start as a possible technology provider and we follow it with great interest because it will be the first project that could move into commercial production.”3 types of deposits found on the seabed: polymetallic nodules, rocks and seafloor massive sulfides

In April 2017, the seafloor production tools arrived in Papua New Guinea ahead of submerged trials, and Nautilus is on track to start production in 2019. If successful, Van Muijen believes Solwara 1 will give the concept of deep-sea mining the green light, generating more interest in the technology from the international investor community and encouraging governments to provide backing to future projects from both a regulatory and financial perspective. But if not, he warns, “it would represent a setback that would take some time from which to recover.”

While the industry waits to see the results of Solwara 1, IHC Mining will continue to fine-tune its deep-sea mining technology. The Blue Nodules project should be completed by 2019, providing key answers to environmental questions, before going ahead with deepwater testing for the subsea crawlers. “The next step will be to install a pilot unit on the seabed that will be ready for commercial test operations in compliance with ISA regulations,” says Van Muijen. “We hope to achieve this by 2022 at the latest.”