Editorial Mining at new depths

It may not be next year, it may not be in the next decade, but eventually we’ll be mining on the ocean floor.

With massive sulphide deposits measuring 150 m in diameter or more and at least five metres thick grading 9% zinc, 8% copper with appreciable amounts of silver, gold and other minerals, it’s inevitable that we’ll get at them sooner or later.

There are, of course, significant problems. University of Toronto professor Steven Scott pointed out some of them while speaking at the Toronto branch of the Canadian Institute of Mining and Metallurgy recently as the Hamilton lecturer. Access is probably the most obvious. At depths below the ocean surface of 1,800 m or deeper, it’s even tougher to get at these mineral deposits than it was to prospect Nanisivik on Baffin Island in Canada’s Arctic or Ok Tedi in the jungles of Papua New Guinea.

Scott puts forth a very credible case for the eventual exploitation of these ocean bottom deposits, however. The “crusts” are quite friable and therefore require very little grinding. If some robotically controlled continuous mining machine could be put to work on the ocean floor, a slurry of massive sulphides could be pumped to a ship on surface where magnetic separation would produce a concentrate. The concentrate would be shipped to shore for smelting.

Such a mining method is likely to be environmentally benign, although there would be some disruption of marine plant and animal life. Magnetic separation, for example, would avoid chemical contamination of the ocean waters.

In short, the problems of access can be overcome by technology. More difficult to resolve will be political jurisdiction. With 200-mile offshore territorial rights being claimed, determining ownership in the South Pacific could be a nightmare.

Nevertheless, these deposits will someday be exploited, even though that someday could be a long way off. In the meantime, the knowledge Scott and other scientists are gaining into the formation of volcanogenic massive sulphide deposits is valuable right now. Scott and his colleagues have witn essed the very formation of these deposits, watched as the mineral bearing fluids spew forth from vents in the ocean floor, watched as the minerals precipitate out of the hot mineral-bearing solution comes in contact with the cold ocean water forming dense clouds, then settle to the bottom of the sea forming the potentially economic crusts.

By seeing more clearly how these deposits form, explorationists and mine developers on land gain knowledge of the same type of deposits formed eons ago by the same means. That can make their jobs a lot easier in determining where to look for economic deposits and where to mine.

The notion of mining the sea floor is not as far fetched as it was a mere decade ago. The technology is certainly in existence if not actually available in an “off-the-shelf” form. And some actual mining initiatives have been taken.

There’s exciting potential in this new frontier that can’t help but stir the adventurer’s spirit. Listening to Scott’s presentation, and watching a film of his “prospecting” on the ocean floor, it’s not hard to imagine this as the next quantum leap in mining for the twenty-first century.