Thermal Characteristics of Selected Phosphate Ores and the Effect of Inorganic Salts on Their Calcination

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.

Automated summary

Calcination is an energy-intensive method of ore processing, but can be improved by using additives. In this study, phosphate ores were analyzed using TG-MS to understand their behavior during calcination. Experiments were conducted with phosphate ore mixed with NaCl, KNO3, or Na2CO3 at different temperatures and times. The response surface methodology was used to model the weight loss during calcination, and possible processes during heating were proposed.