November 2009

Deep-sea voice

CIM Distinguished Lecturer discusses seafloor massive sulphide deposits

By R. Pillo

In 1984, CIM Distinguished Lecturer Steven Scott, a pioneer and expert in seafloor massive sulphide (SMS) deposits, boldly predicted that in the future we would be mining sulphide ores on the ocean floor. More than two decades later, in a move that could revolutionize the mining industry, Toronto-headquartered Nautilus Minerals is the first company to commercially explore the seabed for gold and copper ore deposits. Positioning itself to become an ore producer by 2012, Nautilus’ main focus is on Solwara 1, a deposit site Scott co-discovered with Australian Ray Binns in 1996 offshore of Papua New Guinea.

Rich seafloor sulphide deposits are produced worldwide in underwater volcanic regions by hydrothermal vents, chimney-like edifices and mounds of precipitated mineral sulphides. Dubbed as “black smokers,” Scott was the first ore geologist and the first Canadian to explore these high-temperature vents. His lecture, “Seafloor massive sulphides – the dawning of a new industry,” takes an in-depth look at the ore deposits this deep sea prospector plans on mining.

CIM: How did you come to study SMS?

Scott: An article published in National Geographic in 1979 on the discovery of seafloor hydrothermal vents led me to it. I was initially drawn to them as a way of understanding the processes that produced volcanic-hosted massive sulphide deposits that we mine on land. I met Ray Binns during a lecture at Australia’s Commonwealth Scientific and Industrial Research Organisation [CSIRO] in Sydney in 1984. He commented that although they had some ideas on subsea exploration, they didn’t know how to go about it. That same evening, my wife stumbled on an announcement in the Sydney Morning Herald about CSIRO just acquiring a new oceanographic ship. I was on the phone with Binns that same night and we went to sea the next year.

CIM: Your first discovery was in 1983 followed by Solwara 1 in 1996. Did you even fathom such fruitful endeavours?

Scott: There certainly were some “Eureka!” moments. Prior to the first discovery, our hope was to understand how ores that formed on the deep seabed would help in the search for mineable deposits on land. We towed cameras above the seafloor and dredged rock samples from promising locales. With Solwara 1, we were just trying to find a place to do our research and ended up doing much better than we thought we would — we found a large, rich and potential mineable deposit. All our hard work was paying off. When Nautilus Minerals begins to mine the Solwara 1 deposit, expected in 2012, Binns and I can say that “we found a mine.” Not many research scientists can claim that.

CIM: What are the advantages and pitfalls of deep sea mining?

Scott: Because of its totally reusable infrastructure, mining SMS deposits has an advantage over mining on land, where the costs of extensive excavations, roads, power lines, accommodations, etc. have to be amortized over the life of a mine. Land deposits have to be large enough to cover the costs of both discovery and development, whereas, much of the discovery of subsea deposits such as Solwara 1 has already been done by scientific researchers like me. Seafloor mining leaves no shaft or other infrastructures behind and little waste rock because the deposits are sitting on the ocean bed and are not covered with rock. There are financial and technological challenges for recovering SMS deposits but these are surmountable. After all, the oil industry has been working in the deep offshore for decades.

CIM: There are growing concerns from many environmentalists and marine biologists over the destruction of the ecosystems around the sites. How can they be addressed?

Scott: There is interest in mining only dead vents where deposits have been left behind and there are few animals. The water temperature in active vents can reach as high as 400°C, which would severely damage the mining equipment. We do know that the biological communities around these sites are very resilient and they adapt quickly to changing environments. One way to prevent over-exploitation of hydrothermal vents is to designate some sites or some parts of a minesite as marine protected areas. Nautilus Minerals has completed a very detailed environmental impact statement for their Solwara 1 site that addresses the environmental concerns to the satisfaction of the PNG government and their independent advisors.

CIM: Why have you become part of 2009-2010 Distinguished Lecturer season?

Scott: I was born and raised in northwestern Ontario. After working at sea for 27 years, the program gives me a chance to return to the mining communities where I long ago did my research. A new industry of seafloor sulphide mining, in which I played a significant role as a research scientist, is about to take off thanks to forward-thinking people in industry. It is an exciting time and I want to bring that excitement to our CIM colleagues and to students.

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