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

Abstract

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.

Transformation behaviors of excluded pyrite during O2/CO2 combustion of pulverized coal

“…The reasons are that the content of calcite in the sample was much less than that of pyrite and the fragmentation extent of calcite was less than that of pyrite at the same condition (Ref. [24]). …”

Influence of mineral transformation on emission of particulate matters during coal combustion

“…Hence, most of Na and K vaporize and condense during combustion, and finally, they exist in PM 1 . The vaporization of Si and Al is minor, and accordingly, dominate in PM [1][2][3][4][5][6][7][8][9][10] . Ca and Fe have a bimodal distribution.…”

“…3.5 SEM micrographs of PM 1 and PM [1][2][3][4][5][6][7][8][9][10] To obtain an idea of the morphology of submicron and supermicron ash particle, some of the filters have been analyzed using SEM. Figure 4(a) and (b), which is magnified 80 000 and 100 000 times respectively, shows a SEM image of a typical PM 1 collected on the filter.…”

“…In brief, the majority of PM 10 are formed from four formation mechanisms: 1 Char fragmentation [1][2][3][4], 2 Included mineral coalescence [5][6][7], 3 Excluded mineral fragmentation [8], and 4 Vaporization and subsequent condensation of the volatile metallic elements [9][10][11][12]. The former three mechanisms mentioned above are believed to be mainly responsible for the bulk of the supermicron ash particles formed.…”

“…Although much work has been done to date, only few studies can be found in literature in China, where the consumption of coal is one of the most important sources for energy needs. This paper aims to study particle size distribution, emission concentration and elemental compositions of PM 1 and PM [1][2][3][4][5][6][7][8][9][10] . Reaction temperature and oxygen content are comprehensively considered.…”