The dissolution of FeCuNiCoMn alloy, with composition in mass %: 65.90 Fe, 12.07 Cu, 12.81 Ni, 1.33 Co, 5.33 Mn and 2.56 others in aqueous SO2-H2SO4-H2O medium has been investigated. The alloy was obtained during reduction smelting of manganese nodules from the Clairon Clipperton zone of the Pacific Ocean. It has been established that the presence of SO2 in the solution led to selective dissolution of the alloy: Fe, Ni, Co and Mn were extracted in leach solution and copper concentrated into insoluble residue. The chemical composition of the residue in mass % was: 54.9 Cu, 4.8 Fe, 3.3 Ni, 0.3 Co, 0.4 Mn and 30.9 S. It can be classified as sulphide copper concentrate because copper is present in the form of CuS and Cu7S4. On the basis of the experimental results a two-stage scheme for selective dissolution of the alloy has been proposed. The optimum conditions for the first stage were as follows: 18 g.L-1 SO2, sulfuric acid 7.2 % (v/v), temperature - 348 K, pulp density 5 %, time 2 h for initial particle size -125 μm. During the second stage oxidizer air with 0.025 Nm3/h flow for one hour was used. Metal extraction in the leach solution was as follows: 98.3 % Fe, 94.3 % Ni, 94.1 % Co, and 99.2 % Mn. Copper concentration in the solution was 0.05g.L-1.


That fact makes them an alternative raw material source for production of these metals. Up-to-date PMN processing schemes fall into two main groups: hydrometallurgical and combined pyro-hydrometallurgical. In the first group the methods for selective recovery of the metals from sulfuric acid solutions in the presence of SО2 are the most advantageous (Pahlman and Khalafalla, 1979, Kanungo et al., 1988, Acharya et al., 1999, Janda et al., 2001, Partenov et al., 2004).

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