Evolved gas analysis (EGA) coupled with mass spectrometry, high temperature observation of the homogenisation of glass melts coupled with image analysis, x-ray diffraction and x-ray fluorescence were used to follow and elucidate the role of sulphur compounds during melting of a soda-lime-silica batch doped with sodium sulphate and carbon. The results of EGA analysis have shown that both carbon and carbon monoxide during the process may serve as reducing agents and that the ratio between carbon and sodium sulphate, as well as kinetic conditions determine the extent of sulphate reducing reactions. High temperature observations and x-ray analyses show that the subsequent reactions between sodium sulphate and sulphide and thermal decomposition of remaining sulphate accelerate fining of the melt, sand dissolution and lead to bubble nucleation & foaming.
