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Lookup NU author(s): Nick Tzanetakis,
Emeritus Professor Keith Scott
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Nickel-metal hydride batteries contain valuable metallic components and although they are not considered a hazardous waste, recovery of these materials is necessary from an economic point of view. In this work a hydrometallurgical method for the dissolution and separation of the metals from cylindrical nickel-metal hydride rechargeable batteries was investigated. Hydrochloric acid was employed as the leaching agent to dissolve the metals from the batteries. Dissolution of metals was investigated as a function of acid concentration, leaching time and temperature. Suitable conditions for maximum metal dissolution were 3 h leaching with 4.0 mol dm-3 hydrochloric acid solutions at 95 °C. Extraction of 98% of nickel, 100% of cobalt and 99% of rare earth elements was achieved under these conditions. Separation of the rare earths from nickel and cobalt was preliminarily investigated by single batch solvent extraction with 25% bis(2-ethylhexyl)phosphoric acid. Efficient separation via complete extraction of the rare earths was obtained at a pH of approximately 2.5 while leaving nickel and cobalt in the raffinate. A shrinking particle model which can enable, under certain conditions, evaluation of the extent of metal dissolution present in nickel-metal hydride batteries was developed. A proposed electrochemical recovery of nickel and cobalt is also briefly discussed. © 2004 Society of Chemical Industry.
Author(s): Tzanetakis N, Scott K
Publication type: Article
Publication status: Published
Journal: Journal of Chemical Technology and Biotechnology
ISSN (print): 0268-2575
Publisher: John Wiley & Sons Ltd
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