Study on Formation Kinetics and Mechanism of Barium-Calcium Phosphoaluminate Mineral

Barium-calcium phosphoaluminate ((C,B) 8 A 6 P) mineral was synthesized by introducing Ba 2+ into the lattice of calcium phosphoaluminate (C 8 A 6 P) mineral and it owned the better hydration activity than C 8 A 6 P. In this study, the formation kinetics and mechanism of (C,B) 8 A 6 P mineral was firstly systematically explored. The experimental results indicated that calcination temperature had a significant effect on the formation of (C,B) 8 A 6 P mineral. The conversion rate of (C,B) 8 A 6 P mineral was less than 0.5 and reaction rate was less than 9.4 × 10 -7 with the holding time of 8 h at 1500-1530 °C. Nevertheless, the conversion rate and reaction rate reached 0.8 and 9.4 × 10 -7 , respectively, with the holding time of only 2 h when the calcination temperature ranged from 1540 °C to 1560 °C. In addition, the Jander equation was feasible for the formation of (C,B) 8 A 6 P with activation energy of 1310 kJ ∙ mol -1 at 1500-1530 °C, while the Ginstling equation was feasible for use with activation energy of 324 kJ ∙ mol -1 when the calcination temperature ranged from 1540 to 1560 °C.