Due to the increasing amount of residues in the iron and steel industry, it is important to ensure the availability of techniques and processes for their recycling. Environmental aspects are becoming more and more significant, furthermore the reuse of secondary resources shows enormous economic benefits. As about one quarter of the world’s steel production is carried out via the electric arc furnace route, a considerable amount of steel dust is produced during the process. Due to high heavy metal contents, the EAF dust would have to be landfilled - therefore in developed countries the dust has been recycled for several years with the majority of it being processed in the waelz kiln. However, recycling of one ton of steel dust produces 800 kg of slag. Although one of the main reasons for the steel dust recycling is the high concentration of zinc, which is recovered from the waelz kiln offgas, there are still significant amounts detectable in the remaining waelz slag. The slag’s current landfilling, due to high heavy metal contents, leads to a significant loss. Furthermore, considerable quantities of iron are lost to landfilling which has negative environmental and economic consequences. Therefore, techniques for the recycling of waelz slag have been investigated in the recent past. As the latest research works at the Chair of Nonferrous Metallurgy at the University of Leoben payed attention to the process development of a zero waste recycling process, this master thesis aimes towards the characterization of waelz slag and the evaluation of the range in which the certain elements and compounds can occur. For this, the chemical composition of eight different slags from Europe and Turkey was investigated. Furthermore, the slags were analyzed regarding their particle size distribution, their bulk density as well as their loss on ignition. Afterwards, the waelz slags were treated in a carbothermic reduction process under adjustment of a certain basicity for the simultaneously recovery of zinc and iron. Finally, the remaining slag and the iron phase were analysed and their possible uses in further industries like the cement and building industry as well as the iron and steel industry were considered, taking the relevant legislations into account. It was found that it is hardly possible to achieve a final slag composition with low enough amounts of chromium and other heavy metals for further uses in other industries. The amount of iron in the waelz slag was too low to collect the interfering metals during the process time of the experiments. However, to achieve the required values it could be helpful in future projects to mix different types of waelz slags to compensate high quantities of heavy metals with a higher mass of iron.