Release behaviors of arsenic (As) during pyrolysis of two Chinese coal gangues were studied in this report. The pyrolysis experiments were carried out in a temperature programmed tube furnace under N2 atmosphere with different temperature (200-1200 ºC), residence time (0-50 min), heating rate (10-50 ºC min-1) and N2 gas flow rate (100-500 cm3 min-1). The experiment results, under different pyrolysis conditions, indicate that the release ratio of As increases with increasing temperature, as well as residence time during pyrolysis of coal gangues. Besides that, higher heating rate during pyrolysis of coal gangues can stimulate the As release from coal gangue to some extent. The release ratio of As increases to a maximum and then decreases when the N2 gas flow rate is increased. The results imply that different modes of ocurrence of As exist in two coal gangues. The As release has positive relation with the volatile matter release. As is more easily released than coal gangue matrix during coal gangue pyrolysis.

The dynamic release behavior of elemental Hg (Hg0) during thermal treatment of two bituminous coals was studied under N2, CO2 and air atmospheres. The results show that the profiles of Hg0 released present several peaks during thermal treatment of two bituminous coals. The Hg peak profiles for the same coal are different with the different atmosphere used. The amount of Hg0 released from the coals is about 92-94, 73-74 and 31-33% under N2, CO2 and air atmosphere, respectively. This indicates that the Hg0 is the dominant form during thermal treatment of the coals under N2 atmosphere whereas part of Hg0 is converted into the oxidized Hg during thermal treatment of the coals under CO2 and air atmosphere. The total Hg released is promoted by the volatile matter release to some extent while the Hg0 released is mainly affected by the atmospheres used.