Two coals with different content of calcium were blended and combusted using a drop tube furnace in air at 1450℃. Emission properties of PM_<10> were studied. A random Coalescence-fragmentation Model was developed to simulate the size distributions and chemical compositions of PM generated during the combustion of both single and blended coals. The results show that samples with higher content of calcium and iron release lower amount of PM_<10>. For the case of coal blend of 40/60 with about 22wt% of calcium and iron, about half amount of PM_<10> is reduced. Meanwhile, the simulated results of particle size and chemical forms of PM show good agreement with their experimental data. These results indicate that the high amount of calcium and iron in raw samples improve the viscosity of particles and then promote the coalescence of fine Al-Si(<10 μm ) with Ca or Fe-bearings to form larger Ca-AI-Si or Ca-Fe-Al-Si, and therefore the emissions of PM_<10> is reduced.
