One-dimensional steady-state thermal model for rotary kilns used in the manufacture of cement

Peer reviewedPostprin

Evidence of scawtite and tilleyite formation at ambient conditions in hydrated Portland cement blended with freshly-precipitated nano-size calcium carbonate to reduce greenhouse gas emissions

Acknowledgements We thank CCM for its financial support of a PhD student ship tenable by LJM. Electron Microscopy was performed in the ACEMAC Facility at the University of Aberdeen by Mr. J. Still. Several of our group have contributed to discussion and provided samples, so thanks go to Wanawan Pragot and M. Ara Carballo-MeilanPeer reviewedPostprin

A New, Carbon-Negative Precipitated Calcium Carbonate Admixture (PCC-A) for Low Carbon Portland Cements

Funding: The first named author L.M., a PhD scholar at the University of Aberdeen working under the supervision of M.S.I. and F.P.G., is sponsored through a fully funded studentship by CCM (UK) Ltd. Acknowledgments: The cements used in this work were kindly provided by Hanson Cement UK. Electron Microscopy was performed in the ACEMAC Facility at the University of AberdeenPeer reviewedPublisher PD

Production of belite calcium sulfoaluminate cement using sulfur as a fuel and as a source of clinker sulfur trioxide : pilot kiln trial

The authors gratefully acknowledge the financial support provided by the Gulf Organization for Research and Development (GORD), Qatar, through research grant number ENG016RGG11757. The authors would also like to acknowledge Thomas Matschei and Guanshu Li for the stimulating and fruitful discussions concerning the development of this work. The continuous support prior to, during and after the pilot kiln trial from Vadym Kuznietsov and the entire team at IBU-tec is also greatly appreciated.Peer reviewedPublisher PD

Advances in clinkering technology of calcium sulfoaluminate cement

Acknowledgement The authors gratefully acknowledge the financial support provided by the Gulf Organisation for Research and Development (GORD), Qatar, through University of Aberdeen research grant number ENG016RGG11757. Funding Information: Gulf Organisation for Research and Development (GORD) (ENG016RGG11757)Peer reviewedPostprin

Enthalpy of formation of ye’elimite and ternesite

Calcium sulfoaluminate clinkers containing ye’elimite (Ca4Al6O12(SO4)) and ternesite (Ca5(SiO4)2SO4) are being widely investigated as components of calcium sulfoaluminate cement clinkers. These may become low energy replacements for Portland cement. Conditional thermodynamic data for ye’elimite and ternesite (enthalpy of formation) have been determined experimentally using a combination of techniques: isothermal conduction calorimetry, X-ray powder diffraction and thermogravimetric analysis. The enthalpies of formation of ye’elimite and ternesite at 25 °C were determined to be − 8523 and − 5993 kJ mol−1, respectively

Alite calcium sulfoaluminate cement: chemistry and thermodynamics

Calcium sulfoaluminate (C$A) cement is a binder of increasing interest to the cement industry and is undergoing rapid development. Current formulations do not contain alite; however, alite calcium sulfoaluminate (a-C$A) cements can combine the favourable characteristics of Portland cement (PC) with those of C$A cement while also having a lower carbon dioxide footprint than the current generation of PC clinkers. This paper presents two results on the formation of a-C$A clinkers. The first is a thermodynamic study demonstrating that the production of a-C$A clinker is possible without the use of mineralisers, doping with foreign elements, or using multiple stages of heating. It is established that a-C$A clinker can be readily produced in a standard process by controlling the oxygen and sulfur dioxide fugacity in the atmosphere. This allows for the stabilisation of ye’elimite to the higher temperatures required for alite stability. The second result establishes that when using fluorine to mineralise a-C$A clinker production, the iron content in the clinker is also an important variable. Although the exact mechanism of alite stabilisation is not known, it is shown that alite formation increases with the combination of calcium fluoride and iron (III) oxide in the mix

Modification of the ferrite phase in cements by manganese substitution

The effect of manganese substitution into the crystal structure of the ferrite phase, Ca//2(Fe//2// minus //xAl//x)O//5, has been studied by X-ray diffraction, analytical electron microscopy and differential thermal analysis. The introduction of manganese into Ca//2Fe//2O//5 and Ca//4Fe//2Al//2O//1//0 produces a distortion of the crystal structure marked by an expansion of the b axis but without changes in crystallographic symmetry. The limits of solid solution of manganese in both phases were determined. The presence of manganese in the Ca//2Fe//2O//5 phase suppresses its ferromagnetic character.Peer reviewe

Calcium carbonate decomposition

Calcium carbonate decomposes under well-defined conditions giving CaO (solid) and CO2 (gas). The process kinetics are known to be strongly influenced by the CO2 partial pressure and temperature. In dynamic conditions, as in thermogravimetric analysis (TG) and differential thermal analysis (DTA), kinetics influence the observed heat effect and mass losses, as was shown in semi-static studies by Hyatt et al. (J Am Ceram Soc 41:70-74, 1). However, differing DTA and TG curve shapes are reported in the literature even under supposedly comparable conditions. The differences are attributed in part to the design of the equipment and in part to differing crystalline states of the precursor calcium carbonate. To resolve these uncertainties, the TG has been performed at different heating rates and at different but controlled partial pressures of CO2. The results are reported and critically evaluated in the light of the data obtained, and the kinetic parameters as reported by Hyatt et al. (J Am Ceram Soc 41:70-74, 1) are re-evaluated. © 2012 Akadémiai Kiadó, Budapest, Hungary