The effect of foreign ions on the reactivity of the CaO-SiO2-Al2O3-Fe2O3 system -: Part I.: Anions

The subject of this paper is the effect of foreign anions an the reactivity of the CaO-SiO2-Al2O3-Fe2O3 system. One reference mixture and seven modified mixtures, prepared by mixing the reference sample with 1% w/w of chemical grade CaF2, CaHPO4, Ca-3(PO4)(2), CaS, CaCl2, CaSiF6, or CaSO4 were studied. The effect on the reactivity is evaluated on the basis of the free lime content (fCaO) in samples sintered at 1200 degreesC and 1450 degreesC. All the added compounds - except for the PO43- are found to improve the reactivity of the quaternary system, even at 1200 degreesC. According to their volatility at 1450 degreesC, the added compounds can be subdivided in three groups of low (SO42-, HPO42-), moderate (PO43-), and high volatility (S2-, Cl-). All samples have a final mineralogical composition, which corresponds to the structure of a typical clinker. (C) 2001 Elsevier Science Ltd. All rights reserved.