Deepwater Technology for Deep Sea Mining

The recent agreement reached on deep sea mining by the Canadian mining company Nautilus Minerals and the government of with Papua New Guinea highlights the importance of deepwater technology developed for the O&G industry. The project will extract ores of copper, gold and other valuable metals from a depth of 1,500m. Nautilus Minerals, has been interested in mining the seabed minerals off Papua New Guinea (PNG) since the 1990s but was locked in a lengthy dispute with the PNG government over the terms of the operation.

Under the agreement just reached, PNG will take a 15% stake in the mine by contributing $120m towards the costs of the operation. The mine will target an area of hydrothermal vents where superheated, highly acidic water emerges from the seabed, where it encounters far colder and more alkaline seawater, forcing it to deposit high concentrations of minerals, resulting in a seabed where ores contain much more gold and copper than ores found on land. Environmentalists argue that mining the ocean floor will prove devastating, causing lasting damage to marine life and that the precise effects remain unknown. However it cannot be overlooked that for an extremely poor country such as PNG, the potential wealth derived from deep sea mining may be a vital source of income. According to Nautilus, the mine will have a minimal environmental footprint, covering the equivalent of about 10 football fields and focusing on an area, which is likely to be rapidly re-colonized by marine life. As this will be the first attempt to extract ore from the ocean floor, the operation will be watched closely.

Nautilus Minerals had a temperature probe left in place for 18 months that was found to have "high grade copper all over it". For decades, the idea of mining these deposits and mineral-rich nodules on the seabed, was dismissed as unfeasible because of the engineering challenge and high cost. But the boom in offshore oil and gas operations in recent years has seen the development of a host of advanced deep sea technologies at a time when intense demand for valuable metals has pushed up global prices. The mine, known as Solwara-1, will be excavated by a fleet of robotic machines steered from a ship at the surface. The construction of the largest machine, a Bulk Cutter weighing 310 tons, has just been completed by an underwater specialist manufacturer, Soil Machine Dynamics (SMD), based in Newcastle, UK. The plan is to break up the top layer of the seabed so that the ore can be pumped up as a slurry. The agreement with PNG now clears the way for Nautilus to order a specialist vessel to manage the operation. Mining operations could start within five years.

Source: BBC and Nautilus Minerals