Low Solubility of Calcined Phosphate: Surface Area Reduction or Chemical Composition Change?

Abstract

Calcination process is one of several methods used for upgrading the calcareous phosphate ores. However, the ore characteristics change after exposure to high temperatures. Therefore, in this study, calcination experiments for beneficiation of this ores are conducted in a laboratory scale by using muffle furnace. In addition, the physical and chemical changes on calcareous phosphate from Al-Jalamid locality, Saudi Arabia, were investigated. The results indicated that there are physical and chemical changes in the calcined product. The first observation was the change in color of the calcined products. Also, the surface area change of the calcined products was reported. The surface area measurements, XRD, FTIR, and SEM of calcareous phosphate before and after calcination indicated that although, the emission of CO₂ gas, as a calcination product, creates some pores at the particle surface, the sintering of phosphate at high temperature leads to surface area reduction. Therefore, it was revealed that the surface area reduction and the formation of new phases such as tri-calcium phosphate and calcium silicate are the main reasons for low phosphate solubility.

Keywords:

• Beneficiation
• calcareous phosphate
• calcination
• phosphate ores

Acknowledgments

The authors acknowledge the support of Phosphate and Mineral Processing Chair, Chemical Engineering Deptartment, King Saud University for conducting this research work.

Notes

*-loss-on-ignition.