The steelmaking industry generates several by-products and wastes during the whole steel production process. Producing one ton of steel in a steel plant generates half a ton of by-products such as slags, dusts, and sludges. To meet the goal of achieving net-zero greenhouse gas emissions by 2050, handling such massive quantities of by-products is a major concern. As part of the CESAREF European network dedicated to developing sustainable applications of refractory materials, this project aims to transfer vanadium-bearing slags into high-alumina refractory castables. By implementing advanced mineral processing techniques for alternative calcium aluminate cement and grog aggregates, the project seeks to reduce reliance on natural virgin raw materials, thus promoting a circular economy. Reducing the usage of natural virgin raw materials minimizes costs related to their extraction and processing. The present work investigates the impact of vanadium-bearing residues introduced in self-flow castables formulation both as a typical bonding phase and as typical aggregates. Vanadium-bearing slag exhibits promising properties to be used as a secondary raw material in castable applications. Beyond its structure and chemical composition, its microstructure offers significant advantages for castables, particularly in terms of maintaining mechanical strength under high temperatures. This study evaluates the mechanical properties and microstructural analysis of both conventional castables and those incorporating slag, providing insights into their comparative performance.