• Purpose of this thesis: Optimization of the utilization of crucible gas in the plant operation of voestalpine Stahl Donawitz. The current situation should be examined, a model of the generation and utilization provided, and a strategy for optimum utilization should be found. • Method: As status quo about how much crucible gas is usable is not known in detail, the amount per heat had to be calculated out of recorded data from the steel plant. A detailed Simulink model was built up, in which the utilization path of crucible gas was modeled from takeover at the steel plant to its utilization at the power plant. Thermodynamic changes of the crucible gas have been implemented in the model, to get accurate behaviour of the model in the aspect of gasometer volumes. The trade off of maximization of crucible gas utilization versus minimization of natural gas utilization was analyzed. Different control strategies have been evaluated in the Simulink model by application of real world data of an analyzed week. In conclusion some potentials for improvement of the plant equipment, which got apparent during analysis, have been analyzed and evaluated. • Result: Next to solid results concerning the usable amount of crucible gas per heat there have been some fundamental insights into how to improve utilization of crucible gas: – The pipe capacity of between the gasometer and the application point of the crucible gas is to low. Half of the flaring losses are are due to this bottleneck. – The manual control of crucible gas utilization is to defensive. The savings that could be made by a more offensive control outweigh the cost of natural gas utilization, which is inevitable with more offensive crucible gas utilization. – The bottleneck of the pipe capacity could be removed by replacement of a pipe section between gasometer and crucible gas blower. Amortization of this replacement should be less then two years at worst.