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Soon, nodules to be mined from seabed

SHUBASHREE DESIKAN
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Polymetallic nodules viewed through camera.— photo: sPECIAL ARRANGEMENT
Polymetallic nodules viewed through camera.— photo: sPECIAL ARRANGEMENT

Finally, deep seabed mining of polymetallic nodules is about to become a reality. According to a March 21 paper in Nature , a U.K. firm, Lockheed Martin, will soon be taking up mining operations in a 58,000 sq. km area in the Pacific Ocean.

Quoting the U.K. Prime Minister David Cameron, Mark Schrope, a freelancer, writes that this venture could add £40 billion to the U.K. economy over the next 30 years. Schrope makes the point that the International Seabed Authority (ISA) in Kingston, Jamaica, which grants the exploration rights, has also granted rights to several other countries and that work towards harvesting is slow.

In the case of India, it may be in a position to harvest the nodules from the seabed in about two years, when the technology is fully developed. India has been a pioneering investor in this research.

India has been allocated 150,000 sq. km in the Central Indian Ocean Basin (CIOB) by ISA for pursuing developmental activity for mining for polymetallic nodules. It has been estimated that the total area covered by nodules in the Indian Ocean is a whopping 10-18 million sq km. Of this, the mass of polymetallic nodules in the area allocated to India (Indian Pioneer area) is estimated to be 380 million metric tonnes (mmt).

Of the total amount, manganese may account for about 92.60 mmt. The other minerals like cobalt, nickel and copper account for 0.56 mmt, 4.70 mmt and 4.30 mmt respectively, according to Dr. M. Atmanand, Director of National Institute of Ocean Technology (NIOT), Chennai. NIOT is the agency that has been developing the technology for deep-sea mining.

The way these minerals will be used is well known — cobalt in medical treatment and nickel in batteries, for instance. Mining for these is of strategic importance as there is no terrestrial source of these metals in India.

The nodules on the Indian Ocean bed are found at a depth of about 6,000 metres and the closest point of the nodule fields is at a distance of about 2,500 km off the Kanyakumari coast. NIOT has so far tested their machines only up to a depth of 5,000 metres. These machines would harvest and crush the nodules before bringing them to the surface.

Yet, the challenges of developing the technology do appear formidable — the high pressure of 600 bar that exists at that depth (6,000 m) is one of them.

Like in the case of quicksand, soil on the seabed has low bearing strength. So a special tank-like underwater mining machine has been devised to move on the seabed and collect the polymetallic nodules.

An environmental impact assessment (EIA) has already been carried out by the Goa-based National Institute of Oceanography (NIO).


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