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Chlorellestadite (Synth): Formation, Structure, and Carbonate Substitution during Synthesis of Belite Clinker from Wastes in the Presence of CaCl$_2$ and CO$_2$

Garbev, Krassimir ORCID iD icon 1; Ullrich, Angela 1; Beuchle, Günter ORCID iD icon 1; Bergfeldt, Britta 1; Stemmermann, Peter ORCID iD icon 1
1 Institut für Technische Chemie (ITC), Karlsruher Institut für Technologie (KIT)

Abstract (englisch):

The synthesis of low-temperature belite (C$_2$S) clinker from wastes of autoclaved aerated concrete and limestone was studied in the presence of CaCl$_2$ as a mineralizing agent. Synthetic chlorellestadite (SCE; Ca$_{10}$(SiO$_4$)$_3$(SO$_4$)$_3$Cl$_2$) forms in experiments at temperatures between 700 and 1200 °C. Samples were investigated by X-ray diffraction and Raman spectroscopy. In general, the amount of SCE depends mainly on the sulfate content and to a lesser extent on the synthesis temperature. At lower temperatures of formation, a non-stoichiometric SCE seems to crystallize in a monoclinic symmetry similar to hydroxylellestadite. Rietveld refinements revealed the presence of chlorine and calcium vacancies. Raman spectroscopy proved the partial substitution of sulfate by CO$_3$$^{2−}$ groups in ellestadites formed at 800 °C and 900 °C in air. Incorporation of CO$_3$ results in a shorter unit cell parameters and smaller cell volume similar to CO$_{3−}$apatite. At low temperatures, SCE coexists with spurrite intermixed on a very fine nm scale. At temperatures above 900 °C in air, ellestadite is carbonate-free and above 1000 °C chlorine loss starts in all samples.


Verlagsausgabe §
DOI: 10.5445/IR/1000150872
Veröffentlicht am 22.09.2022
Originalveröffentlichung
DOI: 10.3390/min12091179
Scopus
Zitationen: 1
Dimensions
Zitationen: 3
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Technische Chemie (ITC)
Publikationstyp Zeitschriftenaufsatz
Publikationsjahr 2022
Sprache Englisch
Identifikator ISSN: 2075-163X
KITopen-ID: 1000150872
HGF-Programm 38.05.02 (POF IV, LK 01) Metals and Minerals Cycle
Erschienen in Minerals
Verlag MDPI
Band 12
Heft 9
Seiten Artikel-Nr.: 1179
Projektinformation REPOST (BMBF, BMBF FONA, 033R249B)
Bemerkung zur Veröffentlichung This article belongs to the Special Issue Cement Related Minerals.
Gefördert durch den KIT-Publikationsfonds
Vorab online veröffentlicht am 19.09.2022
Schlagwörter chlorellestadite (synth), ellestadite, dicalcium silicate, X-ray diffraction, Raman spectroscopy, low-temperature recycling
Nachgewiesen in Web of Science
Dimensions
Scopus
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