Ferro alloys represent an irreplaceable additive for stainless steel production and is of great importance for materials like nickel-based and other steel alloys. In the manufacturing of ferronickel alloys, oxide ores are used. The metallurgical production of these alloys is achieved by smelting and reducing lateritic ores in an electric arc furnace. Ferronickel slags exhibit high melting points and acidic character which causes strong corrosion of the refractory material. The focus of this work comprises the evaluation of the slag components MgO, SiO2, FeO, CaO and Al2O3, and their influence on the melting behaviour of ferronickel slags. Additional important investigations deal with slag-refractory reactions and the formation of further phases. The main focus was the characterisation of the behaviour, from softening to flow temperature. Moreover, the examinations include investigations via scanning electron microscopy for determination the slag-refractory interface as well as thermodynamic calculation. The data from these investigations serve as the base for a refractory corrosion model, which enables a corrosion forecast of different refractory materials. Moreover, the results should improve the process run and optimize the slag metallurgy in ferroalloy production. In addition, the development of a corrosion indicator took place, which displays the wear of the applied refractory material in metallurgical aggregates. Therefore special oxide depots were positioned in refractory bricks. At a defined corrosion stage these oxides are release to the slag and detected, therefore offering information about the wear rate of the refractory material. The combination of lab scale tests and thermodynamic calculations should ultimately provide a path for improving the refractory lifetime and performance.