How two companies plan to dig metals off the ocean floor

Trans Tasman Resources, a private New Zealand firm, and Canada's Nautilus Minerals are the companies

Trans Tasman Resources, a private New Zealand firm, and Canada's Nautilus Minerals Ltd could be mining for metals from the seabed by 2017. Here's how they plan to dig the bottom of the ocean.

The project off the west coast of New Zealand's north island covers an area of about 66 square kilometres, at water depths of 20-42 metres.

A crawler machine, likened to a giant vacuum, will cut 11 metres into the seabed. Material will be pumped up to a processing plant on a ship, where iron ore will be separated using magnets.

TTR has applied to dig up to 50 million tonnes of rock a year. About 5 millon tonnes of that will be processed into iron ore concentrate, with the remaining material released back into the ocean by pipe to about 4 metres above the seabed.

Iron ore will be transferred onto a floating storage vessel and from there onto ships for export to steel mills.

NAUTILUS MINERALS SOLWARA 1 PROJECT

The Solwara 1 seafloor massive sulphide deposit lies in the Bismarck Sea in Papua New Guinea's territorial waters.

Nautilus will have to move 200,000 tonnes of volcanic ash from the site before it starts mining.

Nautilus plans to mine a total area of about 0.1 sq km on the seafloor about 1,600 metres under water, using three massive remote-controlled tools, one of which has already been built at a British factory.

The tools will cut into the seafloor, break the rocks and collect them in a slurry that will be piped 1.6 km to a production support vessel, where the ore will be removed.

The remaining water and rock will be sent back down another pipe nearly all the way back to the ocean floor.

WHO ELSE IS EXPLORING

The International Seabed Authority, a United Nations Agency based in Jamaica, is in charge of leasing in international waters. It has signed 17 exploration contracts with organisations backed by several countries, led by China, France, Japan, South Korea, Russia, and the United Kingdom.