The potential use of iron and steel slags as building material is directly bound to their environmental impact, which is primarily related to the behaviour of individual slag minerals in contact with aqueous solutions, such as rainwater or groundwater; and to the solubility and mobility of heavy metals bound within those minerals, which pose a potential threat to the surrounding environment. In the course of the MileSlag project, an investigation of the interaction of slag mineral phases is conducted via simulation by using the software LeachXSTM/Orchestra. The solubility data of certain slag mineral phases is missing in the databases of the software and needs yet to be acquired. For this master thesis, an experimental sinter synthesis was conducted (T = 900 °C, t = 13 h) in order to gain a fluorine containing spinel phase (MgCr1,97O3,9F0,1) that is missing in the database from pure chemical precursors (MgF2, MgO, Cr2O3). The product was examined with FTIR spectroscopy and reflected-light microscopy. Since the experiment was unsuccessful, the causes therefore are discussed. Furthermore, the syntheses of vanadium-bearing larnite (β-Ca2SiO4), afwillite and jennite were planned. A sample of blast furnace slag from Donawitz, classified as glaucochroite, was investigated by X-ray diffraction regarding phase purity and subjected to solubility tests under inert nitrogen atmosphere (T = 25 °C, t = 119 h). The tests were discontinued as the material turned out to contain multiple mineral phases.