Each coal of five samples was separated into three groups by a sink-float method in order to clarify the distribution of As and Se in the coal matrix. The heavy fraction of density-separated coal showed higher contents of both elements rather than the light fraction. Results of HNO_3 extraction indicated that parts of As and Se in the heavy fraction associated with pyrite. During pyrolysis, the release extent of As gradually increased with the increase of temperature, while the release extent of Se drastically increased above 800℃.
