Iron, manganese and other metals should be extracted from the ocean floor not in the form of ore but in the form of ore solution. According to the opinion of Elena Bazilevskaya, Ph.D. (Geologic-Mineralogical Sciences), who spent years on chemical and mineralogical investigations of ore concretions in the Pacific and Atlantic Oceans, such extraction technique is economically sound and environmentally safe.
Since the 80s of the last century, a deposit has been assigned to Russian in the rich ore province Clarion-Clipperton in the Pacific Ocean. However, ore extraction should not affect seabed ecology otherwise it will not be permitted by the UN International Seabed Authority. Ore is to be lifted from the ocean bottom on board the mining ship and to be delivered to the port for further processing. The existing lifting technologies provide for washing of lifted rock. At that, all of the dirt goes back to the ocean to the depth of several hundred meters. It is practically impossible to avoid water contamination and stirring-up of the bottom layer. Fine dredge arising upon ore extraction will accumulate on the gills of sea inhabitants and destroy them.
Nevertheless, economic considerations do not allow to refuse ore extraction: overland reserves of such strategically important metals as cobalt, nickel, zinc and copper are exhausting. They are contained in ferrimanganese sediments. Manganese in oceanic ores is found in the form of free hydroxide, which binds a large number of various metals from seawater (up to 3/4 of the Mendeleyev Periodic Table). Thanks to that property, manganous deposits form valuable ore concentrates. Manganese hydroxide are extremely sensitive to environmental conditions and can exist in solid phase only in highly oxidizing conditions of a contemporary ocean floor. In case of any temperature increase and oxygen content decrease in the seawater, manganese hydroxide dissolves and releases all metals bound with it. This easy solubility property of manganese hydroxides, and consequently that of the entire ore phase of ferrimanganese sediments can be used for mining of metals in the solute state.
According to the laboratory investigations data, complete extraction of ore phase and its separation from gob, i.e., ore-dressing, requires adding a bit of dilute acid (better sulphuric acid) and several drops of perhydrol to the sample. Perhydrol in the acid medium acts as a strong reducing agent and promotes dilution of manganese oxide and the metals bound to it. The acid amount is so small that it cannot act aggressively on the equipment. Ore dilution will take place in a closed chamber of a submarine reactor. The dissolved metals can be oxidized on board the ship, and they will pass to a solid phase.
The acid-perhydrol reducing method enables to extract practically 100% of all metals from the ore. Besides, the method can be applied to low-grade deposit development. The same principle is also applicable to cobalt bearing scums development. Apparently, raising of the ore solution from the ocean floor is more economical than lifting of the ore, which often contains up to 40% admixtures, as this will significantly reduce the price of ore concentrate transportation on-land. The ore field assigned to Russia is located more than 10,000 kilometers from Russian seashores.
Certainly, the idea is to be tested in the natural conditions to find engineering solution. However, the authors of the method do not doubt that this is quire a feasible task.