Spent NiMH batteries: Characterization and metal recovery through mechanical processing

The growing concern about the environment, associated with the continuous increase in the production of electronic equipment, such as computers, cell phones, mobile devices and consequently batteries, has induced research to develop new technologies to recycle the huge numbers of spent batteries generated in the last few years. The amount of spent NiMH batteries will tend to grow continually over the next few years. These batteries have in their chemical composition, valuable metals such as Ni, Co and rare earths. In the first stage of this work a characterization of NiMH batteries was done. Batteries from different brands and models were disembled and their components were characterized in relation to their chemical composition and main phases. In a second stage of this work, a sample of spent NiMH batteries was milled and the polymeric and metallic fractions were magnetically separated. The results obtained demonstrate that the recycling study, aimed at the recovery of Ni, Co and rare earths, is viable due to the great amount of these metals that are present batteries. It also demonstrates that magnetic separation is a very efficient process to recovery nickel alloys. However the effects of cadmium contamination (originating from fake batteries) will cause the recycling processes to be re-evaluated.