Deep Sea mining, like asteroid mining, is a relatively unconventional method of extracting Rare Earth elements (REEs). Unlike asteroid mining, however, deep sea mining has already been undertaken through projects such as deep sea diamond mining. Actual mining for REEs has not been attempted because of environmental issues and cost. These issues are much more complicated and not as easily fixed as other concerns. Deep Sea mining would be an effective way to obtain a large amount of rare earths; in one specific section of the ocean floor, "...one square kilometer could meet a fifth of the world's annual consumption of rare metals and yttrium..." (Phys.org, 2011). However, the economic viability of deep sea mining is still questionable. If the environmental and financial factors were cleared, then deep sea mining would definitely be a feasible option for the long term.
In order for deep sea mining to be implemented, suitable sites must be found. Deep sea remotely operated vehicles (ROVs) are able to obtain samples using drills and other cutting tools in order to analyze them for rare earth minerals. With the location of a suitable mining site, the ocean floor is ready to be harvested. Two technologies being considered for commercial mining of the ocean floor are continuous line bucket system (CLB) and hydraulic suction systems.
CLB is the preferred method and transfers the mud up to the ship in a conveyor belt type system. Hydraulic suction has a pipe running the mud up from the ocean floor and another pipe that transfers the tailings back to the ocean floor (Economist 2006).
Hydrothermal vents are the primary source for deep sea mines. These magma below these vents heats the surrounding seawater, which causes metals within the sediment to leach into the water. The subsequent shock of the cold water causes the metals to precipitate and form as solids in the sediment surrounding the vents. Because of these high concentrations, most deep sea mining would occur in the chimneys above the vents. Vents themselves would be preserved undamaged, but the chimneys would be destroyed. These chimneys, however, can be built back over time, and is the equivalent of "cutting grass" on the ocean floor (Begley, 2010).
Environmental cost is currently the biggest issue with deep sea mining. There are numerous controversies about whether or not testing deep sea mining is worth the damage it could cause to biodiversity in the ocean. The first step towards making deep sea mining into a feasible option would be to ensure the protection of "sensitive ecosystems and minimize the potential environmental impact of this industry" (Terradaily). These environmental costs come primarily from the intrusive nature of mining. Deposits are located near deep sea thermal vents, which sustain very unique ecosystems. There are thousands of previously undiscovered species first seen around these vents, and many more presumably to be discovered. Many are filter feeders, and many fear that the sediment stirred up by mining activities may not allow them to obtain enough nutrients.
However, this problem is not be nearly as troublesome as it may at first appear. Sea floor deposits are much more concentrated than those on land, meaning a significantly smaller volume of earth must be moved to extract the same amount of usable minerals. Less materials consequently have to be processed, which is what causes most of the environmental problems in the first place. Also, current technologies are able to minimize the actual sediment being thrown about, mitigating enough of the initial concern to justify further usage of these techniques (Begley, 2010). The extremely rich deposits near these vents mean that mining in these areas is very economically viable, and the environmental costs are minimal enough to warrant a further application of deep sea mining.
Very recently, a Canadian company called Nautilus Minerals was granted a 20-year lease by the Papua New Guinean government to mine offshore and operate up to a mile underwater. The intentions of Nautilus Minerals were to harvest the high grade copper, gold, zinc, and silver deposits on the ocean floor. The project was ambitious, as Nautilus Minerals was applying for exploration rights to thousands of square kilometers that cover many of the area's oceanic islands. The coast of Papua New Guinea seemed very promising to the company, but only a few weeks ago news was released of the termination of their pioneering project due to undisclosed disputes with the local government and an unwillingness to pay for the full costs of the endeavor (Milman, 2012). While disappointing, the CEO of Nautilus Minerals insists that the company is committed to "developing the world's first commercial seafloor copper-gold project and launching the deep water sea floor resource production industry, whilst maintaining an environmentally and socially responsible approach" (Nautilus Minerals Inc.).
Interestingly enough, India has decided to follow suit under competitive pressure by other leading REE resource developers such as China. The Indian government seems dedicated to harvesting the resources found in the Central Indian Basin, an area rich in nickel, copper, cobalt and potentially rare-earth minerals found in nodules. As of now, India is building a rare earth mineral processing plant in the coastal state of Orissa and is investing to buy a new exploration ship and the recommissioning of another for deep water exploration.
2012-2020: Exploratory mines are developed, as well as continual pursuit of new extraction technologies
2020-2025: Strict restrictions are put in place by some countries (mostly coastal nations) to protect their environment and minimize ecological impact
2025-2035: New technologies are developed as research of the ocean floor's ecology sheds more light on the matter of stabilizing the ecosystem
2035-2040: Implementation of those technologies occurs at a more rapid pace as the need for higher grade rare earth mines increases
2040+: Further expansion of deep sea mines across the oceans (focused on good sample areas).
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Begley, S. (2010, September 20). Mining's final frontier. Retrieved from http://www.thedailybeast.com/newsweek/2010/09/20/is-deep-sea-mining-bad-for-the-environment.html
Birney, Kristi, Amber Griffin, Jonathan Gwiazda, Johnny Kefauver, Takehiko Nagai, and Douglas Varchol. Potential Deep-Sea Mining of Seafloor Massive Sulfides: Case Study in Papua New Guinea. Retrieved from http://www.bren.ucsb.edu/research/documents/ventsthesis.pdf
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