热解气氛对晋城煤中汞析出的影响

Release behaviors of Hg during pyrolysis of Jincheng (JC) coal, a Chinese anthracite, were studied under N2, CO2 and H2 atmospheres in a temperature-programmed unit coupled with an on-line atomic fluorescence spectroscopy. In all the atmospheres, Hg release starts at about 200℃ and increases with the increase of temperature. The release ratio (RR) of Hg is more than 95% at 1200℃, which is higher than the corresponding volatile yield. Carbon in coal may be a reducing agent during the Hg emission. Under N2 atmosphere, 97% of Hg is released as elemental form. Under CO2 and H2 atmosphere, however, only 73% of Hg is released as elemental form due to the restriction of the chemical equilibrium. H2 can promote the release of volatiles and increase the release rate of Hg, which decreases the contact probability of mercury compound with C and results in the reduction of elemental form Hg.