The volatilization characteristics and mode of occurrence of arsenic for three coals were studied by a customized isothermal thermogravimetric experimental system. Limited by online monitoring of gaseous arsenic

the volatilization characteristics of arsenic were determined by measuring the arsenic concentration of ash at the specified residence time in this paper. The volatilization ratio of arsenic at the various residence time was obtained and the volatilization characteristics of arsenic were fitted through B-spline curve. Mode of occurrence of arsenic in the coals and corresponding ashes at the specified residence time was measured by sequential chemical extraction method. The results showed that the volatilization ratio of arsenic increased gradually with temperature

while most arsenic volatilized in 700-1000℃ period. The volatilization rate of arsenic was correlated to the combustion rate of coal. The volatilization rate of arsenic was relative high due to the release of volatile matter

and it began to slow down with the increase of burning time. After coal combustion

the final volatilization ratios of arsenic for coals (WL

HY

and MH) were 49.5%

80.7% and 65.0%

respectively. The residue and sulfide arsenic would be partly migrated to be exchangeable state.