Mineralogical and chemical characterization of Joule heated soil contaminated by ceramics industry sludge with high Pb contents Francesco Dellisanti, Piermaria L. Rossi, Giovanni Valdrè ⁎ Dipartimento di Scienze della Terra e Geo-Ambientali, Università di Bologna, Piazza di Porta, S. Donato, 1 I-40126, Bologna, Italy Received 2 March 2007; received in revised form 21 May 2007; accepted 22 May 2007 Available online 31 May 2007 Abstract This research deals with the first attempt to vitrify by a Joule heating process soils contaminated by Pb (2.85 wt.%) from ceramic industry sludges. Physical, mineralogical, and chemical characterization of the glasses were obtained by using several imaging and analytical techniques, namely Scanning Electron Microscopy (SEM) with coupled Energy Dispersive Spectroscopy (EDS), X-Ray Diffraction (XRD), X-Ray Fluorescence (XRF) and by a specifically built-in sensor for “in-situ” temperature measurements of the melt. The chemical stability of the glass produced by the process was determined by leaching tests. The progressive heating and successive melting of the soil led to decomposition of organic compounds and removal of volatile metals. The cooling of the melt formed a monolithic glass with the aim of immobilizing the heavy metals and inorganic contaminants. All the glasses were found, on a macroscopic scale, mineralogically, chemically and morphologically homogeneous independent of the starting composition. However, on a microscopic scale an inhomogeneous glass matrix was observed. SEM- EDS and XRD revealed the presence of micro-sized Pb particles and Zr 2 SiO 4 (zircon) crystals. In agreement with the microscopical observations, leaching tests indicated high leaching behaviour for Pb. These results should be considered as a general study of the technological effectiveness of vitrification by Joule heating technology with a view to scaling up the process on a field scale and to the treatment of large amount of inorganic industrial wastes containing high amounts of Pb. © 2007 Elsevier B.V. All rights reserved. Keywords: Joule heating vitrification; Remediation treatment; Glassy materials; Thermal process; Lead 1. Introduction Abundant literature deals with treatments based on physical and thermal properties of soils by vitrification process to remediate inorganic contaminants (Jacob, 1991; Johnson and Cosmos, 1989; Jouan et al., 1986; Komatsu et al., 1990; Orfeuil, 1987). In particular, many efforts have been devoted to develop in-field remediation treatments, in order to prevent or at least reduce the risks related to the removal of contaminated materials. Significant research findings on in-situ vitrification technology (ISV) can be found for instance in reports of the United States-Environmental Protection Agency (Richardson et al., 1995), and of the Pacific Northwest Laboratory (Buelt and Bonner, 1989; Buelt et al., 1987; Farnsworth et al., 1990; Kuhn, 1992; Thompson et al., 1992; Timmerman and Peterson, 1990). Int. J. Miner. Process. 83 (2007) 89 – 98 www.elsevier.com/locate/ijminpro ⁎ Corresponding author. Tel.: +39 51 2094943. E-mail address: giovanni.valdre@unibo.it (G. Valdrè). 0301-7516/$ - see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.minpro.2007.05.008