The topic of this thesis was the characterisation and comparison of the melting and solidification behaviour of two granulated mould powders for the continuous casting of steel. The powders E–2011–009 und E–2011–018 were investigated with simultaneous thermal analysis and hot stage microscopy, the samples for mineralogical investigations, like X-ray diffraction, reflected light microscopy and scanning electron microscopy including electron probe microanalysis, were quenched after heat treatment at several temperatures or at 900°C. Both powders include the main components wollastonite, fluorite, fly ash and glass scraps. Secondary phases are carbon, quartz and calcite. In addition E-2011-009 includes periclase and E-2011-018 contains two different types of wollastonite and corundum. During the heat treatment water escapes, carbonates dissociate and intermediate phases like cuspidine, combeite, nepheline and NAS3 were formed. Also sodium-calcium-silicate and sodium-aluminium-silicate-sulfide in E-2011-009 and lazurite in E–2011–018 have been formed. The mould powder E–2011–018 has a lower bulk density, it sinters faster and melts earlier. The solidification behaviour of both mould fluxes is similar because of the dendritic growing with needle-like cuspidine crystals, although the cuspidine crystal size of the solidified mould flux E-2011-018 is larger.