In the continuous casting of steel, casting powder is added to the top of the liquid steel. It protects the steel from oxidation and thermally insulates the surface, but also serves as a lubricant for the solidifying strand. The melting processes of the mold powder are influenced to a significant extent by the contained carbon. In spite of the positive effects of this carbon, it also has negative influences on the quality of the steel, as carburization can occur, resulting in surface damage to the steel. Free carbon in the casting powder is particularly problematic in the production of low carbon (LC) and ultra-low carbon (ULC) steels. Apart from this problem, the carbon content in the casting powder also plays a role in the CO2 balance of steel production and should also be kept as low as possible from this point of view. Therefore, attempts are being made to replace the free carbon in the mold powder. A suitable substitute would be SiC, since the addition of a sufficient quantity of this raw material does not lead to a deterioration in the melting behavior of the casting powder. Subsequently, the product quality of the steel should not be affected negatively. In this work, based on the results of an analysis already carried out on a mold powder mixture with SiC conctrolling theformation of new solid and liquid phases, the minimum possible SiC content, at which the melting behavior of the carbon-free casting powder just corresponds to that of a conventional casting powder, is to be found. For this purpose, in the first step, defined amounts of the SiO2 content (20 wt.%, 15 wt.%, 10 wt.% and 5 wt.%) in the carbon-free casting powder are replaced by SiC. In addition, a sample without melt-regulating additives is prepared. Subsequently, the casting powder samples are temperature treated at 900°C, 1000°C, 1100°C and 1200°C for 10 minutes in a preheated furnace in order to investigate the melting behavior for different SiC contents. This investigation is then carried out in a second step using a scanning electron microscope (ZEISS, EVO MA 15) including energy dispersive analysis to determine phase paragenesis based on polished sections. Based on the results obtained, conclusions can be drawn about the reactions taking place in dependence on temperature. The results are compared with those of a conventionally used mold powder. On the basis of the investigations, it was found that the formation of new phases by reaction of the raw material components is shifted to higher temperatures with increasing SiC contents. The minimum SiC content is between 1.41-2.84 wt.%, since the melting behavior of mold powders with lower SiC content deteriorates considerably. It is no longer comparable with that of a conventional casting powder, but corresponds to that of the powder without melting controlling additives. When comparing the CO2 balance of the conventional casting powder and that with an SiC content of 2.84 wt.%, the CO2 savings are 52% and 33.87g/kg mold powder.