Rendering wastes obtained from gold analysis by the lead-fusion fire-assay method non-hazardous Fernanda Batalha Magalhães a , Cornélio de Freitas Carvalho b, * , Eduardo Lyse Corrêa Netto Carvalho b , Maria Irene Yoshida c , Cláudio Gouvêa dos-Santos b a SGS GEOSOL Laboratories Ltd., 33200-000 Vespasiano, MG, Brazil b Chemistry Department, Federal University of Ouro Preto (UFOP), Campus Universitário, 35.400-000 Ouro Preto, MG, Brazil c Chemistry Department, Federal University of Minas Gerais (UFMG), Cidade Universitária, 30.123-970 Belo Horizonte, MG, Brazil article info Article history: Received 5 March 2012 Received in revised form 4 June 2012 Accepted 19 June 2012 Available online 7 July 2012 Keywords: Lead Crucible waste Leaching Chemical precipitation abstract The classical method of melting lead by fire-assay (Pb-FA) is the most frequently used analytical tech- nique in gold prospection. The crucible solid waste which is generated in this process is usually char- acterized by chemical and mineralogical composition, granulometric size distribution, and classified according to Brazilian Environmental Regulations. This study demonstrates how acid leaching can be used to remove lead from waste originally classified as hazardous by treatment with hydrochloric and nitric acids followed by chemical precipitation in sodium metasilicate solution. It is shown that for every 1000 kg of hazardous waste, 995.6 kg of non- harzardous waste can be recovered. Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction The contamination caused by industrial wastes from metallur- gical and chemical industries, and the mining of heavy metals typify a serious environmental problem that modern society has been facing for some time. Among wastes containing heavy metals, those containing lead usually attract much concern because of its natural occurrence, its ubiquity in the environment and as a consequence of several industrial activities that favor its wide distribution (Bagchi and Preuss, 2005; Carey and Nagelski, 1996; Göktepe, 2005; Wadanambi et al., 2008). In humans, eventually lead accumulates in bones, but early adverse effects are observed in the central nervous system, plasma, bone marrow and kidneys (Jarosi  nska et al., 2006; Navas-Acien et al., 2007; Weidenhamer et al., 2010). In geological materials, lead fusion fire-assay (Pb-FA) (Bugbee, 1981) is the most important chemical analytical method used for the determination of gold. This classical technique involves the preconcentration of the gold and separation into a metallic phase and silicates. It offers high levels of precision and accuracy, with detection limits as low as ng/g (Anderson et al., 2005). These advantages encourage the use of the Pb-FA method to the determination of the platinum group elements (PGEs): platinum, palladium, rhodium, iridium, ruthenium and osmium (Barefoot and Van Loon, 1999; Rao and Reddi, 2000). Industrial, research or teaching chemical laboratories using Pb- FA generate crucible waste contaminated with lead from the reduction of lead oxides. In general, this waste is produced after four cycles of fusion, after which the crucible is replaced (Fig. 1), to prevent sample contamination. Several reports in literature discuss gold analysis by the fire- essay method emphasizing the need to eliminate or reduce the amount of lead-containing waste which is unavoidably produced by this technique (Resano et al., 2006; Balaram, 2008; Berdnikov et al., 2010; Caporali et al., 2010; Roy et al., 2010; Compernolle et al., 2011). According to the Internal Round Robin for Gold Analysis (2007), there are 82 laboratories worldwide using the Pb-FA technique for gold evaluation, all of which will be sources of this waste. In Brazil alone, 1.5 million Pb-FA tests are performed every year, generating about 330 tons of waste containing Pb. This paper presents a study directed to the environmental characterization and classification of crucible solid waste produced from gold analysis by lead fusion fire-assay. The main objective of this study was to extract lead from waste by a leaching process followed by its chemical precipitation, in order to render such waste less hazardous. * Corresponding author. Tel.: þ55 313559 1711; fax: þ55 31 3559 1707. E-mail address: cornelio@iceb.ufop.br (C. de Freitas Carvalho). Contents lists available at SciVerse ScienceDirect Journal of Environmental Management journal homepage: www.elsevier.com/locate/jenvman 0301-4797/$ e see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.jenvman.2012.06.028 Journal of Environmental Management 110 (2012) 110e115