Calcination of phosphate ore is one of the methods of
ore processing,
i.e., increasing the phosphorus content (P2O5) in the ore. However, this process is very energy-intensive and
not economically justified in most cases. It can be improved by using
additives to lower the required calcination temperature. In this work,
several samples of phosphate ores were subjected to thermal analysis
using thermogravimetry coupled with mass spectrometry (TG-MS) to study
their behavior during the calcination process. Then, selected phosphate
ore from the Tunisian deposit was mixed with NaCl, KNO3, or Na2CO3 and calcined in various regimes
(temperature and time). Uncalcined samples, together with obtained
calcinates, were also subjected to thermal analysis by TG-MS. Temperature
ranges in which the mass loss occurred were defined and discussed.
Appropriate models of sample weight loss were derived and visualized
by using the response surface methodology. Explanations of possible
processes observed during the heating of phosphate ore samples with
inorganic salt addition were proposed.