Abstract
In cobalt-rich manganese crusts, valuable metals such as cobalt, nickel and copper are mainly contained as amorphous phases in the manganese oxides or iron oxyhydroxides without forming definite mineral phases. The mined ores, however, are expected to be likely accompanied with the substrate rock, e.g. basalt and limestone, because usually the cobalt-rich manganese crusts are found as pavement-like thin layers on seamounts. Thereby, mineral processing can be thought to be effective for separation of the metal-bearing crusts from the accompanied substrates.
On the basis of mineral processing experimental data acquired by the Deep Ocean Minerals Association (DOMA), the data qualification and re-evaluation by applying an economic evaluation model are presented in this paper. Using the data from gravity concentration, magnetic separation and froth flotation, their separation performances are estimated by Newton efficiency and technical efficiency methods. The relationships between the separation efficiencies and the internal rate of return calculated from the economic evaluation model are compared with the variation of some parameters.
As the results, it is shown that technical efficiency can be used effectively for the evaluation of mineral processing in some cases. Evaluating by Newton efficiency turns out to be an effective criterion in case of more than 66% substrate ratio in the mined ore, and the technical efficiency less than 52% substrate ratio. The applicability of the two efficiencies in 52 to 66% substrate ratio is case by case.
