Mesophase Microspheres from Distillation and Thermal Treatment of Coal Tar

We have investigated the formation of mesophase carbon microbeads in tar pitch generated by the coal coking in a steelmaking plant. Pitches were obtained at different distillation temperatures (643, 673 and 723 K). The distilled samples were then thermally treated in nitrogen atmosphere either at 723 K for 8 h (T1) for at 703 K for 4 h (T2). A new phase appears, seen in optical microscopy with a polarizing filter. Samples subjected to the T1 thermal treatment were found to form a discontinuous fluid phase distinct from the main phase. Formation of mesophase carbon microbeads is seen also in samples subjected to the T2 treatment, with the particle diameters from 30 to 60 mu m. The microbeads can be used as precursors for the synthesis of graphitic materials.