For achieving a realistic assessment of release behavior of arsenic in thermal treatment of a coal at high temperature,systematic investigation on quantifying the modes of occurrence of arsenic in a high arsenic coal and understanding of its release behavior in thermal treatment at high temperatures have been conducted.The quantitative assessments on the modes of occurrences of arsenic in the coal were achieved by means of a novel method combining the low temperature ashing followed by float-sink technique.Afterwards,a series of experiments on release behavior of arsenic in thermal treatment,e.g.pyrolysis,combustion and gasification,of the coal were conducted in a lab-scale drop tube furnace.Mineralogical characteristics of the coal were characterized by X-Ray Diffraction and Field Emission Scanning Electron Microscope with Energy Dispersive X-Ray Spectrometer.Distributions of arsenic in the coal were determined by using the Inductively Coupled Plasma Mass Spectrometry.The results showed that the separation of light minerals(Density<2.89g/cm3)fraction and heavy minerals(Density> 2.89g/cm3)fraction from the coal were successfully achieved by using the novel method.Pyrite is enriched in the heavy minerals fraction,and the proportion is over 60%(wt.%).Arsenic in the coal is as high as 265μg/g.Distributions of arsenic in low temperature ash and the two density fractions are 391μg/g,360μg/g,and 647μg/g.Arsenic in the coal studied majorly exhibit as organic associated and pyrite associated modes,and that are releasable in thermal treatment at the high temperature.The bleeding ratios are approaching to 85%when temperature ranging from 1200℃ to 1400℃.Arsenic,exhibiting as pyrite associated and organic associated modes in coal,would easily vaporize in thermal treatment at high temperature.However,if pyrite was intimately mixing with alumina-silicate,the arsenic associated with the pyrite is not releasable.Other modes of occurrence of arsenic in coal,e.g.arsenate minerals and/or clay minerals associated,would be more likely to fuse together with the alumina-silicate at high temperature thus remaining in the ash residuals rather than vaporize and release into the atmosphere.The vaporization procedure of arsenic,which present as pyrite associated mode in coal,probably occurs in company with the sulfur vaporization during pyrite decomposition at high temperature.