Relaunching a process that uses 100% H2 for the direct reduction of iron ore

Developed two decades ago, Metso Outotec’s (MO; Helsinki, Finland; www.mogroup.com) Circored process is now being reintroduced as a proven way to help decarbonize the ironmaking process. Developed in the 1990s by the former Lurgi Metallurgie (now part of MO) and continually refined, Circored is a hydrogen-based process for the direct reduction of iron-ore fines to produce zero-carbon hot-briquetted iron (HBI) or direct-reduced iron (DRI), which is used in electric-arc furnaces (EAFs) for steelmaking. Circored uses 100% H2 as the reducing agent, which enables low-temperature operation (below 650°C) and avoids sticking problems associated with alternative DRI processes, says Sebastian Lang, director for Modeling & New Business of the Ferrous & Heat Transfer business line at MO. The process also operates at higher pressure (4 bars), which allows a reduction in equipment and piping sizes, thereby lowering capital expenditures (capex), he says. Circored is a two-stage reduction system consisting of a circulating fluidized-bed (CFB) reactor, in which the reaction is controlled by interfacial mass transfer, and a bubbling fluidized-bed (FB) reactor, in which the reduction reaction is diffusion controlled (diagram, right; and flowsheet,…