Due to convenient synergies, the process gases blast furnance gas, coke oven gas and converter gas from integrated steel plants have a high potential to be used as carbon sources for the Power to Gas-process. In this work, first steps towards realization have been taken by evaluating the impact of the CO-CO2-ratio as well as of the presence of Nitrogen in the reactand stream on the conversion of the methanation. Analysis shows, that higher CO-ratios, while keeping the H2-excess constant, positively influence methanation. Further the assumption emerges, that Nitrogen as inert gas, inhibits methanation beyond its influence on partial pressure and retention time. To minimize the experimental effort for further investigations on methanation, the fixed bed methanation reactor was modeled in Aspen Plus using a kinetic approach of Kopyscinski. Compared to measurement data the simulated COx-conversion only slightly differs, for the valid temperature range of the model of 200°C to 400°C. The absolute deviation for the COx-conversion does not exceed 5% in 92% of the simulated cases, while showing a mean deviation of 1.6%. As the influence of inert gas in the reactand stream is not considered in the kinetic model, this is only valid in the absence of Nitrogen. As methanation is ideally operated at 200°C to 350°C, the most relevant temperature range is already successfully modeled. Still there is potential for extending the model to consider higher temperatures and evaluate the influence of inert gases. Based on the positively evaluated kinetic model, the whole process of the three stage methanation as part of a Power to Gas unit in an integrated steel plant was implemented in Aspen Plus.