Research Article Investigations into Recycling Zinc from Used Metal Oxide Varistors via pH Selective Leaching: Characterization, Leaching, and Residue Analysis Toni Gutknecht, 1 Anna Gustafsson, 1 Christer Forsgren, 2 Christian Ekberg, 1 and Britt-Marie Steenari 1 1 Industrial Materials Recycling, Department of Chemical Engineering, Chalmers University of Technology, Kemiv¨ agen 4, 412 96 Gothenburg, Sweden 2 Stena Metall AB, Fiskhamnsgatan 8D, Box 4088, 400 40 Gothenburg, Sweden Correspondence should be addressed to Toni Gutknecht; tonig@chalmers.se Received 12 May 2015; Accepted 5 August 2015 Academic Editor: Fernando Pelisser Copyright © 2015 Toni Gutknecht et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Metal oxide varistors (MOVs) are a type of resistor with signifcantly nonlinear current-voltage characteristics commonly used in power lines to protect against overvoltages. If a proper recycling plan is developed MOVs can be an excellent source of secondary zinc because they contain over 90 weight percent zinc oxide. Te oxides of antimony, bismuth, and to a lesser degree cobalt, manganese, and nickel are also present in varistors. Characterization of the MOV showed that cobalt, nickel, and manganese were not present in the varistor material at concentrations greater than one weight percent. Tis investigation determined whether a pH selective dissolution (leaching) process can be utilized as a starting point for hydrometallurgical recycling of the zinc in MOVs. Tis investigation showed it was possible to selectively leach zinc from the MOV without coleaching of bismuth and antimony by selecting a suitable pH, mainly higher than 3 for acids investigated. It was not possible to leach zinc without coleaching of manganese, cobalt, and nickel. It can be concluded from results obtained with the acids used, acetic, hydrochloric, nitric, and sulfuric, that sulfate leaching produced the most desirable results with respect to zinc leaching and it is also used extensively in industrial zinc production. 1. Introduction It is the vision for Europe to have market and policy incentives in place by 2020 that will stimulate new innovations in resource efcient production methods with all companies being able to measure their lifecycle resource efciency [1]. It is with this vision that the importance of this work comes to light. Electrical transmission and distribution equipment such as insulators and protective equipment will become a potentially large source of solid waste suitable for recycling as opposed to landflling. Recycling of the used varistor mate- rial and production waste promotes sustainable production and consumption. Moreover, improving waste management makes better use of resources while encouraging less depen- dence on imports of raw material [1]. In Sweden, there is an initiative to recycle MOV as opposed to landflling due to environmental concerns, rising costs of landflling, awareness of the potential value of the material in the MOV, and the quantity of material available for recycling. In Sweden from 2009 to 2013 over 500 tons of MOV was available for recycling [2]. However, a commercial method for recycling of the MOV is not yet available and the material is at the moment stored or landflled. If the ZnO was purifed and converted to zinc metal the value of the metallic zinc would be over $800,000 USD [3]. Te used varistors are primarily not mixed with other types of waste materials but kept in a separate fow which is a good starting point for a recycling process. Te authors have not found any literature on recycling of MOVs. Hindawi Publishing Corporation e Scientific World Journal Volume 2015, Article ID 653219, 11 pages http://dx.doi.org/10.1155/2015/653219