Treasure on the ocean floor

　　TODAY, deep-ocean mining is done only by the oil and gas industry. Yet the dream of mining the mineral wealth of the deep has never gone away. Now two firms hope to succeed where others have failed.
　　Nautilus Minerals, based in Vancouver, is the more advanced of the pair. It has an exploratory licence from Papua New Guinea and has already begun drilling operations 1,600 metres below sea level off the east coast of the country. Another company, Neptune Minerals, based in London and Sydney, has completed test drilling in the deep waters near New Zealand.
　　Nautilus's deep-water exploration relies on a modified deep-sea remotely operated vehicle (ROV) of the kind normally used in the oil and telecoms industries. It has a manipulator hand containing drilling and cutting tools that allow the robot to retrieve samples of rock from the ocean bed. So far the drilling has only been exploratory, but the prospects look good.
The presence of these rich deposits has been known about for years, says Steven Scott, a geologist at the University of Toronto. He has been researching underwater geology since the 1980s, and in the 1990s he co-discovered the deposit that Nautilus is exploring. So why has it taken so long to move towards the commercial exploitation of deep sea massive sulphide deposits? Mr Heydon says it is because the ROV technology has only recently become capable enough. He eventually hopes to use rock-cutting ROVs that will drive across the sea floor, grinding ore as they go and sending it to the surface via a tube at a rate of 400 tonnes per hour. It might also be possible to lift large deposits using compressed air.
　　All of this can be done, Mr Heydon believes, for about half as much as opening a new landbased mine. Nautilus has spent about $12m in the past year on exploration, and Dr Scott says one test drilling found deposits 19 metres deep. Unlike manganese nodules, which are like golf balls scattered across the seabed, these deep-ocean deposits occur in small areas around extinct hydrothermal vents. Such concentrated deposits ought to make underwater mining highly efficient.
　　Even if the economics stack up, however, Nautilus and Neptune must overcome concerns over environmental damage. Dr Scott argues that underwater mining will be far less disruptive to the environment than terrestrial mining: there will be no piles of waste rock, since the deposits are directly on the sea floor. And whereas the oil industry lays pipelines underwater, mining would not leave any permanent structures behind. But governments will need to be convinced of the merit of these arguments before mining can begin.

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海底宝藏

　　今天，深海采矿只是在石油和天然气工业领域得以实现。然而开发深海金属矿藏的念头始终萦绕在人们脑海中。现在两家公司正希望去实现别人未能完成的愿望。
　　位于温哥华的鹦鹉螺矿业公司是这两家公司里比较超前的一家。它拥有巴布亚新几内亚的开发执照并且已经开始在该国东海岸海面下1600米处进行钻探。另一家公司是海王星矿业公司，分别设在伦敦和悉尼。该公司已经在新西兰附近完成了深水钻探。
　　鹦鹉螺公司的深水开发依赖于一种由普通用在石油和电信工业上的深水远程操作工具改进而来的机器。这种机器有一个操作臂，其中包括了钻头和开掘工具，使得机器人可以从深海海底回收岩石样品。到目前为止这种钻探仅仅是探索性的，但是其前景很看好。
　　知道这些富矿的存在已经有多年了，多伦多大学地质学家史蒂芬•斯科特说。史蒂芬•斯科特自20世纪80年代就开始研究水下地质学。在20世纪90年代，他与别人共同发现了鹦鹉螺公司正在开发的这个矿藏。那么为什么深海金属硫化物矿的商业化开发要等这么长时间？海登说，这是因为ROV技术只是在最近才得以真正用于实战。他最终希望能用可以横穿海底的岩石开掘机ROV将矿石碾碎，然后通过一条管道以每小时400吨的速度将其运至海面。利用压缩空气来向海面运送大块矿石或许也是可行的。
　　海登相信，只要花费相当于一个陆地矿井一半的费用，所有这些就都可以实现。斯科特博士说，鹦鹉螺公司过去的一年中在勘测上花费了1200万美元，有一次钻探发现了19米深的矿物层。与锰结核像高尔夫球洞一样分散在海底不同的是，这些深海矿物层则在熄灭了的海底烟囱附近小范围内存在。这样的集中式分布可以使水下开采效率大大提高。
即使经济上的问题堆积如山，鹦鹉螺公司与海王星公司仍必须克服人们对于环境破坏的忧虑。斯科特辩解说水下开采将比陆地开采带来的环境破坏少得多：由于是直接在海底作业，因此将不会有大量的岩石废料。由石油工业在海底铺设的管线而留下的永久建筑，在采矿业中将不会出现。但是在开采启动之前，政府仍需相信这些辩解中提到的优点。