1 UNIVERSITÀ DEGLI STUDI DI MILANO Dottorato di Ricerca in Scienze della Terra Ciclo XXIX Advances in ordinary Portland cement clinker: reducing the environmental impact of the production process Ph.D. Thesis Matteo Galimberti ID nr. R10541 Tutor Prof.ssa Monica Dapiaggi Academic Year Coordinator 2015-2016 Prof.ssa Elisabetta Erba Co-Tutor Dott.ssa Nicoletta Marinoni 3 To my family and Sabrina 1 Contents Research aim……………………………………………………………………………………………5 Abbreviations ....................................................................................................................................... 8 The ordinary Portland cement clinker ............................................................................................... 11 1.1 Binding materials ................................................................................................................... 11 1.2 Historical milestones .............................................................................................................. 12 1.3 World cement production and cements classification............................................................ 13 1.4 OPC clinker production process ............................................................................................ 14 1.4.1 Raw materials selection, extraction and grinding .............................................................. 15 1.4.2 Raw meal preparation and pyro-processing ....................................................................... 15 1.4.3 Clinker cooling and gypsum addition ................................................................................ 16 1.4.4 Quality control parameters ................................................................................................. 16 1.5 Chemistry of OPC clinker pyro-processing ........................................................................... 18 1.5.1 Solid-state reactions taking place below 1300 °C .............................................................. 18 1.5.2 Clinkering reactions at temperature between 1300 and 1450 °C ....................................... 19 1.5.3 System cooling ................................................................................................................... 19 1.6 High temperature thermochemistry of clinker ....................................................................... 20 1.7 Clinker mineralogy ................................................................................................................ 22 1.7.1 Tricalcium silicate .............................................................................................................. 22 1.7.2 Dicalcium silicate ............................................................................................................... 25 1.7.3 Tricalcium aluminate ......................................................................................................... 26 1.7.4 Tetracalcium aluminium ferrite ......................................................................................... 28 1.7.5 Secondary clinker phases ................................................................................................... 28 1.8 Environmental impact ............................................................................................................ 29 Analytical techniques ........................................................................................................................... 33 2.1 X-ray powder diffraction ....................................................................................................... 33 2.1.1 The Rietveld method .......................................................................................................... 33 2.1.2 Refinement strategy ........................................................................................................... 34 2.2 X-ray fluorescence ................................................................................................................. 35 2.3 Scanning electron microscopy ............................................................................................... 36 2.4 Electron microprobe ............................................................................................................... 36 2.5 Optical microscopy ................................................................................................................ 36 Effects of limestones petrography on OPC clinker raw meals burnability .................................... 39 3.1 Introduction ............................................................................................................................ 39 3.2 Materials................................................................................................................................. 41 3.2.1 Geological overview .......................................................................................................... 41 3.2.2 Experimental methods........................................................................................................ 43 3.2.3 Results ................................................................................................................................ 47 2 Contents 3.3 Burnability test ........................................................................................................................ 53 3.3.1 Raw meals formulation and firing cycle ............................................................................. 53 3.3.2 Experimental methods ........................................................................................................ 54 3.3.3 Results................................................................................................................................. 55 3.4 Discussions ............................................................................................................................. 60 3.5 Conclusions............................................................................................................................. 63 The effects of minor elements on the clinkerization process ............................................................ 65 4.1 Introduction ............................................................................................................................. 65 4.2 Ex situ experiments ................................................................................................................. 67 4.2.1 Experimental procedure ...................................................................................................... 67 4.2.2 Results and discussion ........................................................................................................ 69 4.3 In situ temperature-resolved synchrotron XRPD experiments ............................................... 89 4.3.1 The synchrotron radiation ................................................................................................... 89 4.3.2 Experimental procedure ...................................................................................................... 89 4.3.3 Results and discussion ........................................................................................................ 93 4.4 Conclusions........................................................................................................................... 100 Heterogeneous raw meal systems ...................................................................................................... 103 5.1 Introduction ........................................................................................................................... 103 5.2 Materials: characterization and preparation .......................................................................... 105 5.3 Methods ................................................................................................................................ 107 5.3.1 Raw meals formulation ..................................................................................................... 107 5.3.2 Thermal treatment ............................................................................................................. 109 5.4 Results and discussion .......................................................................................................... 110 5.4.1 Fluorine-free raw meals .................................................................................................... 111 5.4.2 Fluorine-doped raw meals ................................................................................................ 116 5.5 Conclusions........................................................................................................................... 119 General conclusions ............................................................................................................................ 123 References ............................................................................................................................................ 127 Appendix .............................................................................................................................................. 137 Appendix A1 ..................................................................................................................................... 137 Appendix B1 ....................................................................................................................................