Fragmentation Behavior of Pyrite and Calcite during High-Temperature Processing and Mathematical Simulation

The fragmentation behavior of pure pyrite and calcite during coal combustion was examined in a laminar drop-tube furnace at 1300 °C. A scanning electron microscope (SEM) and a laser-diffraction particle sizer (Malvern) were used to analyze particle size variation from raw minerals to ash residues. Poisson distribution was used to simulate the particle size variation resulting from the fragmentation of mineral grains. The results for pyrite suggested that a large pyrite grain most likely generated four pieces of fragments, whereas a calcite was most likely expected to produce three segments due to fragmentation. The SEM images of calcite high-temperature residue indicated that the fragmentation of calcite could be more extensive at higher boiler flame temperatures. These simulated results can be used in a comprehensive model of ash formation in pulverized coal combustion.