Cover Story
What's the state of play?
At this stage of play, what form of deep seabed mining makes commercial sense? The mining of 20 million tonnes of mineral-enriched pods — say 20-million tonne pods, each the size of three football fields.
A mining rig would work from pod to pod. This is what is envisaged by Nautilus Minerals Corporation, formed by Australian geologists who hope to strike it rich within the 200-mile exclusive economic zones of Papua New Guinea. It says it will be the first miner of submarine copper and zinc ore bodies.
- ADVERTISEMENT -
 |
|
|
Its target is the mound of mineralised material built up around hydrothermal vents by the fallouts from them.
These have been detected in the economic exclusive zones (EEZs) of Papua New Guinea, Tonga, Fiji, and Vanuatu, and in some other parts of the Pacific.
In the latest of cruises by Japan in collaboration with SOPAC, a Japanese ship drilled into a maximum of 20 metres of what geologist Nobuyki Okamoto said was a 100 by 30-metre area, 3000 metres deep containing 70,000 tonnes of materials in the North Fiji Basin.
Thirty-three ore showings were detected at 22 drilling sites. Copper showings ranged from 4.04 percent to 6.93 percent; zinc from 3.17 to 0.61 percent; gold at 1.83 grams per tonne to 0.86 grams; and silver from 71.20 grams to 24.31 grams.
Drilling was “very difficult” and in some areas the mount was penetrated only by one metre, Okamoto told Islands Business.
“There is still much more research required before we are able to truly understand these mineral deposits,” he said.
“In my opinion we want to collect as much data as possible before we can decide about deep sea mining.”
SOPAC (South Pacific Applied Geoscience Commission) has asked Japan to begin a third phase of exploration in Niue, Fiji, the Marshalls and Cook Islands from March next year.
Japan is presently the most active Pacific seabed researcher. Officials from Japan’s government mineral exploration and research agency said on previous visits to Suva that Japan’s long-term interest in seabed minerals was derived from the almost complete absence of minerals in its own territory and its desire to locate strategic sources of minerals that might become unobtainable from land mines due to political or other difficulties.
David Heydon, Nautilus Mineral’s chief operating officer, says geologists behind the company were prepared to invest in pioneering seabed mining of copper and zinc.
“The majority of mineral wealth (in future) is likely to be in the oceans.”
The company has just developed a five-metre bucket system for grabbing samples from depths as great as 6000 metres.
It is working with a British company, Seacore, which is involved in equipment for drilling and sampling, and with a big Australian company, Worley Investments, one of the top five private engineering companies in the world specialising in offshore gas and oil recovery. It is working on the feasibility of a whole mining system for mining depths up to 2300 metres.
The valid way to assess seabed mining economics is to first determine capital and operating costs. “This tells you the minimum size you need to find to be economic and therefore what your exploration and drilling targets are.
“Our studies show you need to find 20 million tonnes in a minimum of one million-tonne pods, each of an area of about three football fields.”
Nautilus was designing a mining system able to mine at a rate of one million tonnes a year.
A Worley study to show the best method was due to be complete in November. “We will then gear up to explore over the next two years to locate 20 million tonnes of ore bodies. But what Nautilus needed first was research data from Fiji, Tonga and Papua New Guinea. This would help formulate the best exploration strategy for the best chance of success. The three islands states would then know what resources they had and would be positioned to make informed decisions on whether to allow mining or not.
“At the moment no one knows how big or small the resource is. We need the governments to work with us to get all the data from these research groups.”
Heydon says that a 70,000-tonne mound was too small to waste time drilling as the cost of setting up a ship with anchors and moorings was not justified. The Japanese drilling may have left the Fiji Mines Department thinking that the Japanese were testing the resource.
“Our view is that drilling such a small pod is only academic and not testing the resource. However, it does show that the system in the area is highly mineralised and that our exploration approach to look for a million-tonne deposit in the area is valid. Mining in say a 100- square kilometre area has negligible environmental implications,” Heydon says.
“You would only disturb say three football fields and then move to another area many kilometres away. Mining one million tonnes a year equates to only just over one cubic metre extracted a minute — about the same as a backhoe excavator.
At SOPAC, director Simpson advocates caution in issuing mining licences that would let a miner “pick the eye out" of tenements. From a resource management point of view, on land you wouldn’t let somebody take all the good stuff and be left with the dross. How are you going to get anybody interested in that?
“The Japanese study of the North Fiji Basin is one of the few projects which has started to give us an idea, just an idea, of what could be there. When you look at the area the Japanese drilled and put it on a map of the Pacific, it is like the size of a swimming pool on Viti Levu (Fiji’s largest island).”
Just dredging it is not really in the long-term interest of Pacific islands countries. “You want those who are mining to be also investing in trying to extend the life of the mine. These are models which one uses on land.”
