In the present study, black dross (BD) residue, a hazardous by-product generated during secondary aluminum production, has been evaluated as a possible raw material for the production of a calcium aluminate-based ladle fluxing agent to be used in the steel industry. The thermally treated BD [pretreated black dross (PBD)] used as a starting material, consisted of approximately 49.5 ± 3.5 wt% alumina and 0.3 wt% chloride. The effects of different process parameters on the properties of the produced flux were experimentally investigated, i.e., the CaO/Al2O3 ratio, the sintering temperature and time, and the cooling medium. The prepared samples were all sintered in a rapid high-temperature inductive furnace, and later characterized by SEM–EDS, XRD, XRF, and DTA/TG analyses. Dissolution tests were also performed using a synthetic slag simulating the carryover. Based on the presently obtained results, it can be concluded that the utilization of PBD as the alumina source during the production of a calcium aluminate fluxing agent shows promising results, and the optimum process conditions were established to be 1523 K for 15 min as the sintering temperature and time, water as the cooling medium, and a CaO/Al2O3 ratio of 0.94. Utilizing PBD as a raw material in the production of a value-added product would significantly reduce the need for the disposal of BD as a waste, and thereby help to decrease the overall environmental impact. It would also provide economic benefit to both the steel and aluminum industry.