Research article Recovery of valuable materials from spent NIMH batteries using spouted bed elutriation Eduardo H. Tanabe a, * , Diego F. Schlemmer a ,M ^ onica L. Aguiar b , Guilherme L. Dotto a , Daniel A. Bertuol a a Environmental Processes Laboratory (LAPAM), Chemical Engineering Department, Federal University of Santa Maria e UFSM, Santa Maria, RS, Brazil b Chemical Engineering Department, Federal University of S~ ao Carlos - UFSCAR, S~ ao Carlos, SP, Brazil article info Article history: Received 9 September 2015 Received in revised form 17 January 2016 Accepted 7 February 2016 Available online xxx Keywords: NiMH batteries Spouted bed Elutriation Recycling Mechanical processing abstract In recent years, a great increase in the generation of spent batteries occurred. Then, efficient recycling ways and correct disposal of hazardous wastes are necessary. An alternative to recover the valuable materials from spent NiMH batteries is the spouted bed elutriation. The aim of this study was to apply the mechanical processing (grinding and sieving) followed by spouted bed elutriation to separate the valuable materials present in spent NiMH batteries. The results of the manual characterization showed that about 62 wt.% of the batteries are composed by positive and negative electrodes. After the me- chanical separation processes (grinding, sieving and spouted bed elutriation), three different fractions were obtained: 24.21 wt.% of metals, 28.20 wt.% of polymers and 42.00 wt.% of powder (the positive and negative electrodes). It was demonstrated that the different materials present in the spent NiMH bat- teries can be efficiently separated using a simple and inexpensive mechanical processing. © 2016 Elsevier Ltd. All rights reserved. 1. Introduction The increase in the production of portable electronic devices and the continuous technological innovations resulted in a gener- ation of large amounts of spent batteries (Bertuol et al., 2009; Guevara-García and Montiel-Corona, 2012; Fernandes et al., 2013; Yadav and Yadav, 2014; Schneider et al., 2014; Cubas et al., 2015). Nickel metal hydride (NiMH) batteries are commonly used as po- wer source in electronic devices, like, mobile phones, digital cam- era, computers and hybrid electric vehicles (Rodrigues and Mansur, 2010; Innocenzi and Vegli o, 2012; Fernandes et al., 2013; Gasser and Aly, 2013). These batteries have advantages, such as, high po- wer capability, fast chargeedischarge rates and long cycle life (Gabis et al., 2014). However, NiMH batteries have high self- edischarge rate (Zhu et al., 2014). The main parts of NiMH batteries are: a cathode composed of nickel hydroxide material (in a dis- charged state); an anode made of a hydrogen storage alloy, con- sisting of nickel, manganese, cobalt, aluminum and mischmetal (mainly cerium, lanthanum, praseodymium and neodymium) in an AB 5 type structure (B]Ni, Co, Mn, Al; A ¼ lanthanides) with Y 2 O 3 or Yb 2 O 3 added for corrosion resistance; a separator between the two electrodes made of fine fibers (usually polyamide, polypropylene fleece or gauze); an electrolyte (typically KOH); a metal case; and a sealing plate provided with a selfereleasing safety vent (Pietrelli et al., 2005; Bertuol et al., 2006; Müller and Friedrich, 2006; Larsson et al., 2013). Efficient recycling processes should be developed to recovery these valuable metals from spent NiMH batteries and minimize the wastes generation. The recovery of these elements from spent NiMH batteries were previously exam- ined by leaching, solvent extraction, precipitation, magnetic sepa- ration, adsorption and electrochemical deposition (Bernardes et al., 2004; Tzanetakis and Scott, 2004; Yong-Feng et al., 2008; Bertuol et al., 2009; Li et al., 2009). The recycling of spent NiMH batteries is an important challenge regarding the treatment of hazardous wastes and recovery of valuable metals such as, nickel, cobalt and rare earths (Bertuol et al., 2009). In spent batteries, initially, a preetreatment process for metals liberation from iron case is necessary. This stage improves the recovery efficiency of target metals. The preetreatment consists of manual dismantling or mechanical processing including grinding, classification, and separation (by differences of density, weight, size, magnetic properties, etc.) (Ferreira et al., 2009; * Corresponding author. Environmental Processes Laboratory (LAPAM), Chemical Engineering Department, Federal University of Santa Maria e UFSM, Roraima Avenue 1000, 97105e900 Santa Maria, RS, Brazil. E-mail address: edutanabe@yahoo.com.br (E.H. Tanabe). Contents lists available at ScienceDirect Journal of Environmental Management journal homepage: www.elsevier.com/locate/jenvman http://dx.doi.org/10.1016/j.jenvman.2016.02.011 0301-4797/© 2016 Elsevier Ltd. All rights reserved. Journal of Environmental Management xxx (2016) 1e7 Please cite this article in press as: Tanabe, E.H., et al., Recovery of valuable materials from spent NIMH batteries using spouted bed elutriation, Journal of Environmental Management (2016), http://dx.doi.org/10.1016/j.jenvman.2016.02.011