The metallurgical processes of steelmaking generate slags as by-products, which are often landfilled. To avoid this deposition and utilise the raw material potential, mixtures of different metallurgical residues combined with suitable correction substances were evaluated for use as a supplementary cementitious material. For this purpose, potential combinations, according to given critical values such as the basicity or the correlation of the slag masses, were calculated. These were melted to reduce the valuable metals and to separate them from the mineral fraction. The systematic cooling of the liquefied material was achieved through wet granulation. Practical implementation at laboratory scale consisted of melting the mixtures in a graphite crucible using a resistance furnace, wet granulation, and drying. The granulate was then crushed, sieved, and finally, the metallic fraction was removed by magnetic separation. The conclusions present the technological suitability of the different mixtures for cement binding, according to their chemical composition, and assess the accuracy of MS Excel Solver. Furthermore, the achievable reduction rates of iron, manganese, and chromium were determined and the separation of the valuable metals and impurities from the mineral fraction was analysed. Additionally, the composition of the accruing gas phase and possible process losses are shown by a material flow analysis.