End of life (EOL) electronics is known to be a valuable resource of base and precious metals, and its application as a secondary raw material in pyrometallurgical processes is steadily increasing. These types of materials inevitably introduce various impurities to the smelting furnaces, which may change the physical and chemical properties of the products and by-products of the operation. Alumina is one of the most common and significant oxide components associated with EOL electronics; therefore, its influences on different properties of the iron-silicate or fayalite-type slags are of particular interest to the non-ferrous metal producers. The current article summarizes the effects of an increased alumina concentration on slag thermo-physical properties (density, surface tension, viscosity, etc.). Operational difficulties, e.g. copper loss to the slag phase and foaming of the melt, resulting from such a change in slag composition are also discussed.