In this study, the changes of P2O5 content of phosphate rock during simultaneous calcination/sulfation in a fluidized-bed were investigated. P2O5 determination was carried out on samples with and without quenching of sulfated rock. The effects of the temperature and particle size on P2O5 content of either sample were determined. It was found that the decrease in process temperature favorably increased the P2O5 content of the sulfated samples. Since the calcination was the dominant reaction during the early stages of the process, there was an initial increase in P2O5 content of the sulfated samples. However, at later stages, there was a decrease in P2O5 extent of sulfated samples with an increase in the extent of CaSO4 formed during the reaction. The P2O5 extent, on the other hand, increased with decreasing particle size. The results showed that P2O5 content of 23.27% in raw ore may be increased up to 36% following the quenching of sulfated samples. (C) 2011 Elsevier B.V. All rights reserved.