Metallurgical and gasification processes utilize carbon feedstock such as coal and petroleum coke in production of metal, power, and/or chemicals; but also generate large quantities of gas (high in CO2) and slag as by-products. During processing, slag forms as molten agglomerates from non-volatile components in feedstock, additives, and/or metal ores’ impurities. In this study, waste metallurgical and gasification slags were mixed at a specific ratio in the presence of industrial process waste CO2, resulting in a reaction generating energy – enough to convert CO2 to CO which can be used in other processes such as ore reduction, gas turbine power generation, and synthetic fuel production. A series of computational simulations suggest that the generation of H2 from H2O would also be possible using a similar mixed slag approach. Energy generated is expected to remain largely in excess after conversion. Slag would result in approximately 70% volume reduction, decreasing landfill burden.