he fragmentation experiments of quartzite particles were carried out in a bench-scale hot state fluidized bed rig.The influence factors

such as initial size of particles (2.5—6 mm) and bed temperature (650—950℃) on the fragmentation were investigated.The results showed that the fragmentation index Sf increased with increasing bed temperature and particle initial size.The fragmentation was very limited when bed temperature was lower than 650℃.The particles size distribution analysis showed that it was compressive thermally-induced stresses within the outer region of particles that caused the particle to fracture with many small fragments.A gray forecasting model GM (1

3) was developed to predict the thermal fragmentation of the quartzite particles based on the gray theory.The average prediction residual error is lower than 8.79%.The critical fragment diameter was forecasted by using the model GM (1

3).