gh LIQUID ORE FROM THE OCEAN FLOOR

We all know that huge mineral resources are hidden at the ocean floor – the so-called ferromanganese concretions, which grasping mankind has not reached yet. However, people have no other way out – they will have to descend to the ocean floor to mine metals, which are so much needed and the reserves of which on land are close to exhausting. This is applicable to such metals as cobalt, nickel, zinc, copper and others, the content of which in ferromanganese deposit in the ocean is comparable to their concentrations in continental deposit ores. Not to mention that manganese deposits are practically exhausted in the territory of the Russian Federation.

Nowadays, China, Korea and some other countries are actively getting ready to develop these resources. At the same time, Japan, India, the US and European companies that have invested hundreds of millions dollars in prospecting and oceanic ore development technologies are shutting down their activity – it is too expensive.

Russia is preparing for experimental mining of ferromanganese concretions, which is planned for 2011 through 2020. Since 2022, it is scheduled to start industrial development of the deposit assigned to the USSR back in the 80s of the past century in a rich ore deposit province of Clarion-Clipperton in the Pacific Ocean. The main problem in this sphere is to guarantee the ocean ecology preservation. Without such a guarantee, no mining can be allowed by the UN International Seabed Authority (ISA).

Manganese is the main metal that gives ores on the ocean floor. It exists in the form of a free hydroxide in the bottom sediment, the hydroxide possessing fantastic sorptive activity – the highest among natural sorbents. This property enables it to efficiently bind multiple metals from sea-water – up to three quarters of Mendeleyev Table. This is how the most precious and rich ore concentrates are being formed on the ocean floor. How can they be mined to the surface without disturbing ocean inhabitants?

Manganese hydroxides are extremely sensitive to environment conditions and they can exist in solid phase only in highly oxidizing conditions of the ocean floor. Should the conditions slightly change, manganese hydroxides begin to dissolve also releasing other metals. Researchers from the Geological Institute (Russian Academy of Sciences) have applied this knowledge and developed the technology for ore mining from the floor (so far, in a laboratory variant), which is safe for the ocean. The essence of the technology is that ferromanganese sediment base – manganese hydroxide – dissolves on the spot (on the ocean floor) under the influence of a special composition, thus releasing metal in the ionic form. All of this solution (without excess mixture, which sometimes makes 40%) can be lifted through hoses to the catching vessel. The solution oxidizes on the deck, and metals turn to solid state. Admixtures and substratum remain on the ocean floor, and the catching vessel gets the enriched solution and nothing redundant.

The researchers suggest to use a very lean acid solution (where minor hydrogen peroxide quantities are added) as a composition that will dissolve the required metals. In the acid medium, hydrogen peroxide manifests properties of a reducing agent, and the required ore dissolves easily. In fact, these particular redox processes take place on the ocean floor upon some conditions change, therefore, the composition is quite organic for the ocean and would not traumatize it.

The method tried at the laboratory is very good. It is still necessary to produce the industrial iron reactor nd to carry out field trials. And then, Russia and the UN will probably get the necessary guarantees to start deposit development on the Pacific Ocean floor.

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