USE OF FBC BOTTOM ASH AS A RAW MATERIAL FOR THE SYNTHESIS OF LOW-CO 2 CEMENTS ++ A. Telesca*, M. Marroccoli*, M. L. Pace*, G.L. Valenti*, F. Montagnaro** and T. R. Naik*** *Dipartimento di Ingegneria e Fisica dell’Ambiente, Università degli Studi della Basilicata, Viale dell’Ateneo Lucano 10, 85100 Potenza (Italy), gianlorenzo.valenti@unibas.it **Dipartimento di Scienze Chimiche, Università degli Studi di Napoli Federico II, Complesso Universitario del Monte di Sant’Angelo, 80126 Napoli (Italy) ***Department of Civil Engineering and Mechanics, University of Wisconsin, 53211 Milwaukee (USA) Abstract: The environmentally friendly features of calcium sulfoaluminate (CSA) cements can be enhanced by the use of industrial by-products as partial or total substitutes for the natural materials (limestone, bauxite, gypsum) involved in their manufacture. To this regard, FBC bottom ash (a source of CaO, CaSO 4 , SiO 2 and Al 2 O 3 ) is worthy of consideration due to further limestone saving and reduced CO 2 generation promoted by its high content of uncarbonated lime. Synthetic CSA clinkers were obtained in a laboratory electric oven by heating for two hours at temperatures ranging from 1150° to 1300°C four ternary and eight binary mixtures (with and without limestone, respectively) containing FBC bottom ash and anodization mud or alumina powder (Al 2 O 3 -rich industrial by-products, in place of bauxite). X-ray diffraction analysis, carried out on the burnt products, showed a very good conversion of reactants and a high selectivity towards the main CSA cement component, 4CaO·3Al 2 O 3 ·SO 3 . + The 21 st international conference on Fluidized Bed Combustion (21 st FBC), Universita` di Napoli “Federico II”, June 3 – 6, 2012, Napoli, ITALY. Keywords: fluidized bed combustion ash, by-products utilization, sustainable development, calcium sulfoaluminate cements. INTRODUCTION About 7% of the anthropogenic carbon dioxide is emitted by the cement industry world-wide, from about 2.500 million tonnes of cement production; it is generated by both limestone calcination and fossil fuel combustion (Naik, 2008). A valuable contribution to the reduction of CO 2 emission can be achieved by the manufacture of special cements such as calcium sulfoaluminate (CSA)–based cements, consisting of 4CaO·3Al 2 O 3 ·SO 3 (calcium sulfoaluminate, as the major component) and other secondary constituents such as 2CaO·SiO 2 (dicalcium silicate), CaSO 4 (anhydrite), calcium aluminates, sulfo-silicates and silico- aluminates (Deng et al., 1980; Mehta, 1980; Kurdowski et al., 1986; Mudbhatkal et al., 1986; Muzhen et al., 1992; Yanmou and Muzhen, 1993; Kouznetsova, 1997; Muzhen et al., 1997; Arjunan et al., 1999; Telesca et al., 2011). Compared to ordinary portland cements, CSA cements are high-performance (Mehta, 1973; Glasser and Zhang, 1999; Bernardo et al., 2006; Bernardo et al., 2007; Marroccoli et al., 2007, a; Buzzi et al., 2010; Gastaldi et al., 2011; Winnefeld et al., 2011) as well as energy-saving and low- CO 2 binders. These last features are due to the lower synthesis temperature in the kiln associated with the reduced limestone requirement and, therefore, reduced CO 2 generation (Gartner, 2004; Marroccoli et al., 2007, b; Damtoft et al., 2008; Marroccoli et al., 2010, a). Further enhancements in terms of environmentally friendly characteristics can be achieved if some industrial by-products are used instead of the natural materials (limestone, bauxite and gypsum) necessary for the CSA cement manufacture (Sahu and Majling, 1994; Belz et al., 1995; Ikeda et al., 1997; Bernardo et al., 2003; Marroccoli et al., 2008; Marroccoli et al., 2009). FBC by-product from coal combustion is essentially a source of CaO, CaSO 4 , SiO 2 and Al 2 O 3 , and can be a very useful raw material for the synthesis of CSA cements (Bernardo et al., 2003; Marroccoli et al., 2010,