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Chemical reactions are an essential part of all metallurgical processes. Hence, computational thermodynamics (CTD), that makes it possible to study the spontaneities of chemical reactions, is one of the most important tools in metallurgical research and development. Within this thesis and its supplements, the role of computational thermodynamics in the research and development of AOD (Argon Oxygen Decarburization) and CRC (Ferrochrome Converter) processes used in the production of stainless steels has been analysed. In addition to the results of computational thermodynamics and their application in metallurgical practice, one purpose of this thesis has been to consider what is the role of computational thermodynamics and other tools of research and development as a link between metallurgical theory and practice. Furthermore, the consequences of this kind of analysis on research, development and education have been considered. The cases presented in this thesis and its supplements focus on the oxidation of silicon, carbon and chromium in CRC process, on nitrogen solubility in stainless steel melts in AOD process, on metal-slag-equilibria in CRC process as well as on melting and solidification of AOD and CRC slags. These cases have been chosen to represent different kind of reactions (i.e liquid-gas, liquid-liquid as well as liquid-solid reactions) taking place in the stainless steel refining processes. Briefly summarized, the role of CTD could be defined as essential but not adequate. The role of CTD is essential because chemical reactions are an essential part of all metallurgical unit operations and therefore it is not possible (or at least not meaningful) to model, control and optimize these processes without taking the reactions into account. The biggest shortcoming of the CTD in comparison with other methods used to study the chemical reactions is a need for precise validation of the results, since the accuracy of modelling is always limited by the accuracy of used models and initial values and assumptions. On the other hand, the role of CTD is not adequate since no information concerning the reaction rates can be achieved with CTD and, more importantly, chemical reactions are not the only relevant phenomena occurring in metallurgical unit operations. Despite of this, thermodynamic modelling is usually needed as a starting point for any metallurgical R&D involving chemical reactions.