Mercury transformation during coal combustion and pyrolysis

The attention was focused on the mechanism of mercury transport under different coal and reaction conditions. Firstly, the study was beginning with analyzing the mercury content of the residual after coal combustion and pyrolysis under different heating temperatures and heating time. The results indicate that during coal combustion mercury in coal samples discharge faster than during coal pyrolysis. Almost all mercury in coal samples discharged quickly at high temperatures (above 700°C) during coal combustion or pyrolysis. Secondly, the experiments were carried out in a quartz tube furnace. The aim of the work was to study the mechanism of mercury speciation and transport during coal combustion and pyrolysis. The experimental data indicate that the content of divalent mercury (Hg2+) becomes higher, the content of elemental mercury (Hg0) becomes lower at elevated temperatures during coal combustion and pyrolysis. On the other hand, during combustion more elemental mercury (Hg0) is oxidized faster than during coal pyrolysis under the same heating temperature; for different coals, even under the same heating temperature and reaction conditions, the mercury speciation is different.