Thermodynamic data for cement clinkering

Abstract

The proportions of cement clinker phases produced by the pyro-processing of a rawmaterial mix are often predicted through the Bogue equations, established in the 1930s; however, the Bogue approach is limited in its applicability. This presents a challenge as the cement industry is seeking innovative and more environmentally friendly cement clinker formulations and production processes. These often go beyond the limitations of the Bogue equations and more flexible approaches are required. Modern thermodynamic calculations allow this flexibility but rely on databases not freely available and often specialised for other applications. The title paper reviews the thermodynamic data for stoichiometric clinker phases and presents a new dataset. The dataset is validated, and its application demonstrated by case studies. Electronic CSV files containing the data which can be parsed for use with existing Gibbs energy minimisation solvers/software is distributed with this article as supplementary material.

Estimation of standard molar entropy of cement hydrates and clinker minerals

“…@A,C are the standard molar entropy and molar volume, respectively, of the constituent oxide or hydroxide. 1 is a constant and its value depends on the constituent type and their coordination state. Holland [16] has further simplified Eq.…”

“…Thermodynamics has long been crucial to materials science, with the field of cement being no exception. The past two decades have seen more uses of thermodynamics in studying cements, but the key advancements include the equilibrium calculations of cement clinkering [1,2] and of the hydration of cements which occur at much lower temperatures [3,4]. Progress has been made at pace with respect to the latter where the interest lies in predicting the phase assemblage of hydrating cements at standard pressure but over a wide range of temperatures from 10 to 100 °C.…”

Alite calcium sulfoaluminate cement: chemistry and thermodynamics

“…The thermodynamic assessment uses a previously developed model and database ) updated as discussed by (Hanein, Galan et al 2017). Thermodynamic data for ye'elimite have also been recently updated (Hanein, Sant et al 2018). The calculations and phase diagrams are constructed from free energy minimisation under the constraint of an elemental balance and all gases are assumed ideal; thus, fugacity can be equated with partial pressure.…”

Carbon footprint of calcium sulfoaluminate clinker production

“…The reference heat of formation at STP of ye'elimite is taken to be −8406.493 kJ/mol (Costa et al, 1972). Data for goethite (FeO(OH)) and gypsum (CaSO 4 .2H 2 O) are taken from Wagman et al, 1982, and the data for the remaining phases are taken from a thermodynamic dataset recently compiled by Hanein et al, 2015. The total heat demand of the kiln process is thus the sum of the theoretical heat plus an assumed fixed heat loss taken from the PC manufacturing kiln processes which is 2GJ per tonne of clinker (calculated from WBCSD, 2009b).…”