This work describes a recovery process of cadmium from spent nickel-cadmium batteries by a new hydrometallurgical route based on the selective extraction in hydrochloric acid medium with tributylphosphate (TBP), alone or dissolved in kerosene. The best results were obtained when TBP concentration was at least 75 vol%. Nickel extraction was negligible under these conditions. It was isolated after processing the rafinate through an anionic ion-exchange column. Final wastes generated are basically sodium chloride solutions, with no turbidity, color or heavy metals present in significant amounts.

A extração de metais com solventes orgânicos é uma poderosa ferramenta para ajudar a separação de complexas misturas de metais presentes em baterias usadas e dispositivos eletroeletrônicos, evitando assim o uso de produtos tóxicos ou de rotas experimentais geradoras de uma grande quantidade de resíduos finais. Este trabalho descreve um processo de recuperação de cobalto presente em baterias níquel metal-hidreto (Ni-MH) usadas por meio de uma nova rota hidrometalúrgica. O elemento foi extraído de uma solução em meio clorídrico com Cyanex 272 (ácido 2,4,4-trimetil-pentil fosfínico) dissolvido em querosene. Os melhores resultados foram obtidos quando o pH estava ligeiramente alcalino (7,2) e a concentração de Cyanex em querosene era 5% vol. A recuperação do cobalto atingiu 99% m/m. Foi também possível recuperar um precipitado contendo lantanídios (La, Ce, Pr) e ítrio, que foi purificado pela dissolução em ácido clorídrico seguido de adição de oxalato de amônio. O níquel também foi isolado como um precipitado impuro após a recuperação do cobalto e dos lantanídios. Os residuos finais gerados ao longo do processo são principalmente soluções de cloreto de sódio, sem coloração, turbidez ou metais pesados em quantidades significativas.

Metals extraction with organic solvents is a powerful tool to aid separation of complex mixtures of elements present in spent batteries and electronic devices, thus avoiding the use of toxic chemicals or experimental routes which generate high amounts of final wastes. This work describes a recovery process for cobalt present in spent Ni-MH batteries by a new hydrometallurgical route. The element was extracted in a chloride-bearing medium with Cyanex 272 (2,4,4-trimethyl-pentyl fosfinic acid) dissolved in kerosene. The best results were obtained when pH was slightly alkaline (7,2) and Cyanex concentration in kerosene was 5% vol. Cobalt recovery reached 99 wt%. It was also possible to recover a crude precipitate containing lanthanides (La, Ce, Pr) and yttrium, which was purified by dissolving it in HCl followed by addition of ammonium oxalate. Nickel was also isolated as an impure precipitate after cobalt and lanthanides recoveries. Final wastes generated along the separation processes are mainly sodium chloride solutions with no color, turbidity or heavy metals present in significant amounts.

This work presents a basic study on the processing of spent Zn/MnO2 and alkaline batteries in acid or basic media. Promising results were obtained after fusion with NaOH or KHSO4, which allowed a good separation between Mn from Zn and these metals from other metal components. Processing of spent batteries is a complex procedure, which includes disassembly of these materials, the use of corrosive and high-energy consuming media and the management of final residues.