DEVELOPMENT OF AN ENVIRONMENTALLYFRIENDLYAND HIGHLY EFFICIENT METHOD FOR THESEPARATIONOF Co(II) AND Ni(II) IONS FROMCd–Co–Ni CAKEINTERMEDIATES

Selective recovery of cobalt from Cd–Co–Ni cake intermediates is problematic due to the chemical similaritiesamong accompanying ions and the environmental impacts of traditional separation techniques. Most existingtechniques have low selectivity for Co(II) and are reagent-hungry, with secondary waste generation, especiallyinreal industrial by-products. Here, an environmentally friendly hybrid pyrometallurgical-hydrometallurgical methodis proposed for the selective separation and recovery of Co(II) from industrial Cd–Co–Ni cakes. The methodconsists of a sequence of steps, namely controlled oxidative-sulfation pretreatment, pH-regulated separationof interfering ions, and selective complexation of Co(II) with 2-nitroso-1-naphthol-3.6-disulphonic acid (NNDA). Theeffective conceptual separation of interference suppression and cobalt complexation is the method's novelty, enabling the selective recovery of Co(II) from complex multicomponent matrices. The formation and stability of theCo-NNDA complex were confirmed by UV–Vis spectrophotometry, X-ray diffraction, IR spectroscopy, andanalysis of particle size. In the pH 5.5–6.0 and 25–30 °C ranges, selective retention and recovery of cobalt wereachieved with high phase purity and reproducibility (RSD < 5%). The results indicate the potential of the developedmethod to recover cobalt from metallurgical waste streams, from economic and environmental perspectives.

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