Due to the increasing ecological awareness among our society, the requirement for more sustainable production in almost every sector is growing. Therefore, the metal producing industry faces intensified research activities in the area of the utilization of the residual wastes. One such sector is the lead and zinc producing industry. The slags produced by this sector contain besides toxic elements also high amounts of ferric oxide (FeO) but are landfilled instead of reprocessed. The retrieval of zinc, lead and iron from the slag can be achieved as the result of simultaneous reduction in a reducing metal bath process. Further, the reduction time under specified conditions is estimated by the created kinetic model. The model itself, which was previously created, takes the simultaneous reduction of zinc oxide (ZnO) and ferric oxide into consideration. The present thesis deals with the creation of a general kinetic model as well as with the comparison between the experimentally determined data and the calculated values of the model. Furthermore, the influence of the FeO-content and the temperature on the reaction rate are reviewed. For this purpose, experiments with a synthetic slag (basicity B2 = 1) and three different FeO-contents (0, 5 and 10 wt-%) have been conducted within a temperature range of 1400–1475 °C. In addition, a sufficiently precise validation is done to check if the created model can predict the concentration gradients for industrial slags with up to 30 wt-% of iron oxide. The results demonstrate that the reaction rate is not only increasing due to the growing temperature, but also with a higher initial concentration of FeO in the slag. Within the investigated temperature range, the reduced iron serves as a reduction agent for ZnO and supports the metallothermic reaction. This leads to an increased slagging of iron, which is reflected in the initial concentration growth of FeO.