The increasing consumer demand for higher quality steels has driven the evolution of additional secondary metallurgy systems. Examples of such systems are desulphurisation of hot metal or direct reduction processes.
In the desulphurization process, sulphur is removed from hot metal before being charged into the basic oxygen furnace for refining. Although the methods of addition may be different, reagents currently used are lime, calciumcarbide or metallic magnesium. The generated slag is rich in CaO or MgO with specific contents of sulphur and is cooled with water in special pits.
In the direct reduction process, DRI/HBI (direct reduced iron/ hot briquetted iron) is produced by reducing iron ore in solid state by gas or coal in a shaft oven (e.g. Midrex). The direct reduced iron is then used in an electric arc furnace, solely or with a mix of scrap.