Characterizing the decomposition of sulfatic phases as a function of the gas atmosphere
A method of evaluation is described with which the upper temperature limit of the stability can be determined with the aid of thermogravimetric data records for different heating rates. The dependence of the decomposition behaviour of calcium sulfate anhydrite on the oxygen partial pressure was investigated.
1 Introduction
The thermal decomposition of sulfatic phases takes place in accordance with (1), in which Me can represent the metals beryllium, magnesium or calcium. No hydrate phases occur with the sulfates of strontium, barium and radium so reaction 1a does not apply and only 1b takes place.
MeSO4 · nH2O → MeSO4 + nH2O↑ ⇥(1a)
MeSO4 → MeO + SO2↑ + ½O2↑ ⇥(1b)
The dewatering/dehydration takes place typically at temperatures above about 80 ºC and is complete at about 300 ºC. The water-free phase, anhydrite, remains but with further heating it also decomposes with the release of SO2. Knowledge of the...
