Next Article in Journal
Rheological Properties of Cemented Paste Backfill with Alkali-Activated Slag
Previous Article in Journal
The Origin and Evolution of Ore-Bearing Rocks in the Loypishnun Deposit (Monchetundra Massif, NE Fennoscandian Shield): Isotope Nd-Sr and REE Geochemical Data
Previous Article in Special Issue
Raman Study of Barite and Celestine at Various Temperatures
Open AccessArticle

In Situ Hyperspectral Raman Imaging of Ternesite Formation and Decomposition at High Temperatures

1
Institut für Geowissenschaften, Universität Bonn, 53115 Bonn, Germany
2
RWE Power AG, Research and Development, Kraftwerk Niederaußem, 50129 Bergheim, Germany
*
Author to whom correspondence should be addressed.
Minerals 2020, 10(3), 287; https://doi.org/10.3390/min10030287 (registering DOI)
Received: 8 February 2020 / Revised: 17 March 2020 / Accepted: 19 March 2020 / Published: 21 March 2020
(This article belongs to the Special Issue Modern Raman Spectroscopy of Minerals)
Knowledge of the high-temperature properties of ternesite (Ca5(SiO4)2SO4) is becoming increasingly interesting for industry in different ways. On the one hand, the high-temperature product has recently been observed to have cementitious properties. Therefore, its formation and hydration characteristics have become an important field of research in the cement industry. On the other hand, it forms as sinter deposits in industrial kilns, where it can create serious problems during kiln operation. Here, we present two highlights of in situ Raman spectroscopic experiments that were designed to study the high-temperature stability of ternesite. First, the spectra of a natural ternesite crystal were recorded from 25 to 1230 °C, which revealed a phase transformation of ternesite to the high-temperature polymorph of dicalcium silicate (α’L-Ca2SiO4), while the sulfur is degassed. With a heating rate of 10 °C/h, the transformation started at about 730 °C and was completed at 1120 °C. Using in situ hyperspectral Raman imaging with a micrometer-scale spatial resolution, we were able to monitor the solid-state reactions and, in particular, the formation properties of ternesite in the model system CaO-SiO2-CaSO4. In these multi-phase experiments, ternesite was found to be stable between 930 to 1020–1100 °C. Both ternesite and α’L-Ca2SiO4 were found to co-exist at high temperatures. Furthermore, the results of the experiments indicate that whether or not ternesite or dicalcium silicate crystallizes during quenching to room temperature depends on the reaction progress and possibly on the gas fugacity and composition in the furnace. View Full-Text
Keywords: ternesite; dicalcium silicate; calcium sulfate; high-temperature; in situ; Raman imaging ternesite; dicalcium silicate; calcium sulfate; high-temperature; in situ; Raman imaging
Show Figures

Figure 1

MDPI and ACS Style

Böhme, N.; Hauke, K.; Neuroth, M.; Geisler, T. In Situ Hyperspectral Raman Imaging of Ternesite Formation and Decomposition at High Temperatures. Minerals 2020, 10, 287.

Show more citation formats Show less citations formats
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Access Map by Country/Region

1
Back to TopTop