Electrolytic reactors for the recovery of cadmium from leaching solutions

Sousa, N. R. and Borges, P. M R and Magueijo, V. M. and Brito, P. S D and Sequeira, C. A C (2002) Electrolytic reactors for the recovery of cadmium from leaching solutions. Key Engineering Materials, 230-232. pp. 416-419. ISSN 1013-9826

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Abstract

A study has been made of the cathodic deposition of cadmium ions from artificial aqueous and dilute solutions produced by the leaching of spent nickel-cadmium batteries. These solutions contained about 20 g/L Cd, 50 g/L Ni and 1 g/L Co. Two types of electrochemical reactors have been used: a parallel-plate reactor and a packed bed reactor with and without solution recirculation. The deposition processes were carried out galvanostatically and the effect of several electrolysis parameters on the recovery of cadmium was analysed. The concentrations of CdSO4 during and after electrodeposition were determined by atomic absorption spectroscopy. The minimum electrode potentials required for electrodeposition to be achieved were established; in addition the composition of the electrodeposits was also estimated. Extraction efficiencies of 80% Cd were achieved. Electrodeposit compositions were about 70% Cd, 10 % Ni, < 0.5% Co, and ∼20% Na2SO4, Fe, oxides. It has been shown that the parallel-plate reactor is the most suitable for our purpose leading to figures of merit with high efficiency values.