Structural changes in olivine (Mg, Fe) 2 SiO 4 mechanically activated in high-energy mills Peter Baláž a, ⁎, Erika Turianicová a , Martin Fabián a , Rolf Arne Kleiv b , Jaroslav Briančin a , Abdullah Obut c a Institute of Geotechnics, Slovak Academy of Sciences, Watsonova 45, 043 53 Košice, Slovakia b Norwegian University of Science and Technology, Sem Sælandsvei 1, N-7491 Trondheim, Norway c Hacettepe University, Mining Engineering Department, 06800 Beytepe, Ankara, Turkey ABSTRACT ARTICLE INFO Article history: Received 14 June 2007 Received in revised form 25 February 2008 Accepted 7 April 2008 Available online 12 April 2008 Keywords: Olivine Mechanical activation Milling Carbon dioxide Sequestration Structure This study evaluates the structural changes in olivine (Mg, Fe) 2 SiO 4 (deposit Åheim, Norway) generated by its mechanical activation. The high-energy milling in laboratory planetary and attrition mills as well as in an industrially nutating mill was applied during activation. To identify mechanically-induced changes in the mineral, scanning electron microscopy (SEM), X-ray diffraction (XRD), specific surface area measurement and infrared spectroscopy (IR) techniques have been used. The observed physico-chemical changes illustrate the possibility to modify the surface and/or volume properties of olivine depending on the applied activation mode. Infrared spectroscopy seemed to be suitable method for characterization of CO 2 absorption modified on olivine. © 2008 Elsevier B.V. All rights reserved. 1. Introduction The increasing atmospheric CO 2 concentration, mainly caused by fossil fuel combustion, has led to concerns about global warming (Huijgen et al., 2005). During the last 60 years, CO 2 concentrations increased over 30% compared to pre-industrial levels. Consequently, the focus has been placed on managing CO 2 emissions. Carbon management can be achieved through three different, but compli- mentary approaches: increasing the efficiency of energy conversion, using low-carbon or carbon-free energy sources and sequestering CO 2 emissions. There is strong tendency to develop technologies with a possibility to achieve zero emissions (Maroto-Valer et al., 2005). The idea of CO 2 sequestration was originally proposed by Seifritz (Seifritz, 1990) and first studied in more details by Lackner (Lackner et al., 1995). The basic concept behind CO 2 mineral sequestration is to mimic natural weathering processes in which Ca- or Mg-containing minerals are converted into Ca- or Mg-carbonates (Huijgen et al., 2005) as exemplified by the following equation ðCa; MgÞSiO 3 þ CO 2 →ðCa; MgÞCO 3 þ SiO 2 : The formed mineral carbonates are known to be stable over geo- logical time periods (of thousands to millions of years). There are several calcium and/or magnesium silicates suitable as mineral feedstock, e.g. wollastonite CaSiO 3 , enstatite MgSiO 3 , forsterite Mg 2 SiO 4 , fayalite Fe 2 SiO 4 , olivine (Mg, Fe) 2 SiO 4 , diopside CaMgSi 2 O 6 , talc Mg 3 SiO 10 (OH) 2 and serpentine Mg 3 Si 2 O 5 (OH) 4 . However, under ambient conditions the process of silicate minerals conversion according to Eq. (1) is slow and a significantly higher extent of sequestration reactions and faster conversion rates are needed for its technical feasibility (Huijgen et al., 2006). Enhancement of the chemical process by mechanical activation can results in major improvement of the reaction rate (Baláž, 2000). The potential of mechanical activation lies in its possibility to control and regulate the course of heterogeneous processes by the complex influence on solids via formation of different defects like a new surface area, dislocations, point defects, etc. There are several studies aimed at improving the pretreatment of various silicates by mechanical activation performed by high energy milling in order to improve their CO 2 seques- tration (O'Connor et al., 1999, 2000, 2002, 2004; Kalinkina et al., 2001; Kalinkin et al., 2003, 2004; Hredzák et al., 2004, 2005; Park and Fan, 2004; Kleiv and Thornhill, 2006; Kleiv et al., 2006; Zhang et al., 1997). The aim of the present paper is to investigate the physico-chemical properties of olivine mechanically activated in laboratory and indus- trial mills. The various experimental techniques will be applied to identify mechanically-induced changes in olivine structure. Int. J. Miner. Process. 88 (2008) 1–6 ⁎ Corresponding author. Tel.: +421 55 7922603; fax: +421 55 7922604. E-mail address: balaz@saske.sk (P. Baláž). (1) 0301-7516/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.minpro.2008.04.001 Contents lists available at ScienceDirect Int. J. Miner. Process. journal homepage: www.elsevier.com/locate/ijminpro