Removal of mercury from coal by mild pyrolysis and leaching behavior of mercury

Various types of coals were subjected to the pyrolysis at 300 and 400 °C (mild pyrolysis), and the removal of Hg from coal was determined. The removal efficiency of Hg greatly varied with coal type from 20 to 80%. The removal efficiency was dependent neither on the specific surface area of coal nor on the particle size of coal. The leaching of Hg from coal was tested using sulfur-containing chelating agents such as 3-mercaptopropionic acid (MPA). The Hg leaching efficiency also varied greatly with coal type. There was a good correlation between the degree of %Hg leaching in the MPA leaching and that of %Hg removal in the mild pyrolysis.