Fundamental aspects of bubble–particle attachment mechanism in flotation separation q B. Albijanic a,b,c,⇑ , O. Ozdemir c,d , M.A. Hampton c,e , P.T. Nguyen c , A.V. Nguyen c , D. Bradshaw b a Department of Metallurgical and Minerals Engineering, Western Australian School of Mines, Curtin University, Kalgoorlie, WA 6430, Australia b Julius Kruttschnitt Mineral Research Centre, The University of Queensland, Brisbane, QLD 4068, Australia c School of Chemical Engineering, The University of Queensland, Brisbane, QLD 4072, Australia d Department of Mining Engineering, Istanbul University, Istanbul 34320, Turkey e School of Veterinary and Life Sciences, Murdoch University, WA 6150, Australia article info Article history: Received 2 November 2013 Accepted 23 June 2014 Available online 15 July 2014 Keywords: Flotation Attachment time AFM Contact angle Adsorption abstract Analysis of bubble–particle mechanism is important for improving our understanding of flotation pro- cess. The research presented integrates microflotation experiments, bubble–particle attachment time measurements, and colloid and surface characterization and analysis. The bubble–particle attachment time was inversely related to the flotation recovery and the minimum attachment time matched the maximum flotation recovery, which occurred around mutual isoelectric point for the glass particles and air bubbles. Bubble–particle force measurements, performed with an Atomic Force Microscope (AFM), showed a similar trend. Additionally, the adsorption isotherm of the glass–dodecyl amine hydro- chloride (DAH) system indicated that there are the three adsorption regions, and the flotation recovery reached its maximum value in the second region of DAH adsorption on the glass surface. All results obtained in this study showed the important role of colloidal forces affected by surfactant adsorption in bubble–particle attachment. Crown Copyright Ó 2014 Published by Elsevier Ltd. All rights reserved. 1. Introduction Flotation is a widely used separation method in many indus- tries from metallurgical to chemical industries for separation of desired minerals or other solids in aqueous solutions (Leja, 1982). In this method, particles and bubbles collide, and if the particle is sufficiently hydrophobic, the bubble and the particle approach each other closely and attachment can occur (Fan et al., 2004; Leja, 1982; Nguyen and Schulze, 2004; Yoon, 2000). The bubble–particle aggregates are transported to the froth zone and collected in the concentrate launder. For that reason, bubble– particle attachment is a critical mechanism for successful flotation. The bubble–particle attachment interaction is not well-under- stood since it is determined by the colloid and surface chemistry aspects of both particles and air bubbles (Fan et al., 2004; Leja, 1982; Nguyen and Schulze, 2004; Yoon, 2000). Surface chemistry of particles is typically controlled by adsorbing of reagents (collectors) onto particle surfaces which changes wettability of particles from a hydrophilic to a more hydrophobic surface state. Although over the years extensive investigations a variety of experimental techniques have been used to study bubble–particle attachment such as bubble–particle attachment time (Ye et al., 1989; Yoon and Yordan, 1991; Albijanic et al., 2011; Albijanic et al., 2012), particle dropping technique (Verrelli et al., 2011), AFM bubble–particle measurements (Butt, 1994; Nguyen et al., 2003; Taran et al., 2009), bubble and particle zeta potential mea- surements (Ozdemir et al. 2009a), and flotation recovery experi- ments (Ye et al., 1989; Yoon and Yordan, 1991; Peng, 1996; Ozdemir et al., 2009b; Subasinghe and Albijanic, 2014), none of these studies have focused on an integrated approach to studying the attachment interaction between bubbles and particles in the same system. In this study, the main aim is to better understanding of bubble–particle attachment mechanism by determining the flo- tation recovery and colloid and surface characterization for the glass beads–dodecyl amine hydrochloride (DAH) system. http://dx.doi.org/10.1016/j.mineng.2014.06.008 0892-6875/Crown Copyright Ó 2014 Published by Elsevier Ltd. All rights reserved. q Parts of this paper were presented for XXV International Mineral Processing Congress, Brisbane. ⇑ Corresponding author at: Department of Metallurgical and Minerals Engineer- ing, Western Australian School of Mines, Curtin University, Kalgoorlie, WA 6430, Australia. Tel.: +61 8 9088 6117. E-mail address: boris.albijanic@curtin.edu.au (B. Albijanic). Minerals Engineering 65 (2014) 187–195 Contents lists available at ScienceDirect Minerals Engineering journal homepage: www.elsevier.com/locate/mineng