Seabed mining poised for takeoff
Mining asteroids and the South Pole of the moon may sound too much like science fiction, but seabed mining is a different story.
Steven Scott, Emeritus professor of Geology at the University of Toronto and discoverer of the Solwara 1 seabed massive sulfide deposit off the coast of Papua New Guinea, predicts we will see an increasing reliance on mineral resources from the ocean floor over the next few years.
“Oceans and seas account for 71 per cent of the Earth’s surface,” he told delegates at the MassMin 2012 conference in Sudbury June 10th. “Of the remaining 29 per cent, 10 per cent is covered in ice, so we’re getting all of our mineral resources from just one-quarter of our planet.
Until now, the oceans, which exceed “the area of the moon and Mars times two, have more or less been ignored,” he said.
At the same time, demand for resources is increasing.
Seabed mining “is being driven by the demand for base and precious metals, especially copper, as countries such as China and India…strive to bring their standard of living and economies up to those of the developed world.”
Rapid urbanization and development in both countries “will put huge demands on resources for housing and appliances,” he said.
The green economy is also driving demand, said Scott. “Hybrid cars contain 50 kilograms of copper, all-electric cars have double that, and wind turbines contain one metric tonne of copper.”
At the same time, grades at our big open pit mines are down to a half of one per cent.
Ocean mining isn’t entirely new, said Scott. Diamonds are currently being mined at depths of 140 metres off the coast of Namibia and 60,000 tonnes a year of tin are being mined at depths of 50 metres off the coast of Indonesia.
One of the most promising ocean mining projects on the horizon is the seabed massive sulphide deposit that Scott discovered in the Manus Basin off Papua New Guinea.
He was doing research on the origin and behaviour of volcanic massive sulphide deposits when he made the discovery. “We weren’t prospecting,” he said. “We were doing pure science funded by the governments of Australia and Canada.
The most important of the 19 deposits found in the area is Solwara 1, 50 kilometres from the port of Rabaul and at a depth of 1,600 metres.
“Now, you’ll say ‘How are you going to recover something that’s sitting at 1,600 metres under the ocean.’ Well, which is easier to do? Go down through 1,600 metres of water or 1,600 metres of rock?” asked Scott.
Vancouver-based Nautilus Minerals obtained a mining license for Solwara 1 in January 2011 and, based on 247 drill holes, has a NI43-101 high-grade resource of 2.5 million tonnes, including 1 million tonnes in the indicated category grading 7.2 per cent copper and 5 grams per tonne of gold and an inferred resource grading 8.1 per cent copper and 6.4 grams per tonne of gold.
Mining the ocean floor at depths of 1,600 metres isn’t rocket science. “The oil industry has wells in the Gulf of Mexico at depths of 3,000 metres and, if they can work effectively in the deep ocean, so can the mining industry,” he said.
Nautilus Minerals was originally planning to begin mining Solwara 1 in 2010, but was delayed by the financial crisis of 2008. The company is now targeting 2013-2014 to start production, but that date may also have to be delayed due to a dispute with the government of Papua New Guinea and problems financing the construction of the ship that will be used by for mining.
Scott also predicts a move to mine manganese nodules from the ocean floor in the next few years. The potato sized lumps of iron and manganese oxides contain nickel, copper and cobalt at grades similar to those in the Sudbury Basin. The most interesting deposits are found in the Clipperton Fracture Zone between Hawaii and Central America at depths of 4,500 to 6,000 metres, “but that’s not a problem,” said Scott. “James Cameron went down to the bottom of the Mariana Trench in a one-man submersible and I myself have been down to 3,000 metres in submersibles. The technology exists, so it’s a challenge, but not an obstacle.”
Manganese nodules made headlines in the ’60s and ’70s during which time hundreds of millions of dollars were spent on exploration and R&D. Interest fizzled for a variety of reasons, but appears to be reviving with the establishment of the International Seabed Authority in 1996 and the formalization of a procedure for granting exploration licenses in international waters. The island nation of Tonga, for example, has teamed up with Nautilus Minerals to explore for manganese nodules in the Clarion Clipperton Zone, “so I expect to see things happening in the nodule business pretty soon,” said Scott.
Another company, Chatham Rock Phosphates, has an exploration license covering 4,276 square kilometres off the coast of New Zealand in an area believed to have significant deposits of phosphate and other potentially valuable minerals.
New Zealand is currently importing phosphate fertilizer from Morocco, but it’s a long way and expensive, said Scott. The deposit, located 450 kilometres east of Christchurch, is estimated to contain 1200 million tonnes of rock phosphate at a depth of 400 metres.
Chatham Rock Phosphates has teamed up with the Dutch dredging company Royal Boskalis Westminster N.V. to develop a process to mine the deposit and an environmental impact study is currently underway. Production is currently targeted for the fourth quarter of 2013.
On the other side of the world, another Vancouver-based company, Diamond Fields International, has partnered with Saudi Arabia’s Manafa International Trading Company to mine a seabed sedimentary sulphide deposit called Atlantis 11 Deep in the Red Sea. The low-grade metalliferous mud deposit sits at a depth of approximately 2,000 metres and contains 94 million tonnes of mineralization, including zinc, copper, silver and gold.
Seabed mining has several advantages over land-based mining, said Scott.
“Three of the most severe environmental consequences of land mining are acid mine waters produced by exposing iron sulphides to the atmosphere, large surface excavations of open pit mines and unsightly piles of waste rock from surface and underground excavations.
“Strong acids cannot be maintained in the ocean because they would be neutralized by alkaline seawater…there would be no subseafloor excavations and no waste rock to be removed…Also, there would be no permanent installations left on the seafloor…the seafloor mining machines would simply be hoisted aboard the surface platform and moved to the next site.”
There are also advantages at the human level, said Scott.
“No one lives on the seafloor, so mining there will not cause social disturbance as mining commonly does on land. We won’t have people telling us we can’t mine there because it’s a burial ground or something.”
Also, miners working in seabed mining won’t be wearing hard hats. They’ll be sitting in air-conditioned control booths on surface, a much safer working environment than an underground mine.
“Ocean mining won’t replace mining on land, but it will be an additional source of supply whose full potential is not yet known,” said Scott. “Today, 30 per cent of oil comes from offshore and, in some cases far offshore, so if the oil industry can do it, so can (the mining industry).”
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