Electrochemical anodic dissolution of FeCuNiCoMn alloy in ammonium solutions containing clorine ions

Abstract

The effect of chlorine ion concentration, temperature and current density on metal distribution among the electrolyte, cathode deposit and mud in the process of electrochemical dissolution of FeCuNiCoMn alloy in an ammonium medium is examined. High iron content (65.90%) compared to that of non-ferrous metals (12.07% Cu, 12.81% Ni, 1.30% Co) and Mn 5.33% is a specific feature of the alloy. The alloy was produced by means of high-temperature reduction smelting of manganese nodules from the Clarion Cliperrton area in the Pacific Ocean. It was found that electrochemical dissolution of the alloy is accompanied by formation of a CuNiCo-cathodic deposit and two types of mud: one tightly clinging to the anode surface, and another, finely suspended in the electrolyte. The highest-purity cathode deposit in mass %: 40.28 Cu, 50.27 Ni, 1.21 Co, 7.63 Fe and 0.61 Mn was obtained at ion ratio in the solution NH4+: Cl− = 2.5: 0.5, temperature 323 K, anodic current density 350 A/m2, separation of the anode and cathode spaces by a shielding screen, continuous removal of the anodic mud and maintaining of a constant pH in the electrolyte (10 ± 0.2). In these conditions, >99% of Fe and Mn, 25% Cu, 54% Ni and 52% of Co is transferred into the mud.