Kinetics of glass batch reactions

Modelling of the various processes of glass batch melting is an important tool in the design and optimisation of commercial melting tanks, and reaction thermodynamics and kinetics are a key component of any comprehensive model. While thermodynamic parameters can be calculated using commercially available databases, kinetic data are more complex as they are influenced by factors such as grain size, texture, mixing and compaction, and are best obtained using experimental methods. This study therefore measured the kinetics of crystalline phase formation in borosilicate/E-glass batches (CaSiO3, Ca 2SiO4, CaAl2Si2O8), and SLS batches (Na2Ca(CO3)3, Na 2SiO3, Na2Ca2Si3O 9) between 500 and 1300°C using in situ x-ray diffraction. Solid state reactions followed Johnson-Mehl-Avrami equations for diffusion controlled growth, while reactions in the presence of a molten borate followed first order kinetics (with respect to conversion fraction). High accuracy rate constants and activation energies have been measured for incorporation into batch melting models.