Direct Reduction Process

A direct reduction process produces metallic iron, commonly called direct reduced iron or sponge iron, by chemically removing oxygen from solid iron ore using a reducing gas or carbon-based reductant at temperatures well below the ore's melting point, yielding a porous solid product rather than the liquid iron a blast furnace produces. Commercial direct reduction became practical in the second half of the twentieth century as reliable natural-gas-based processes, most notably the Midrex process introduced in 1969, offered ore-producing regions without abundant coking coal an alternative route into steelmaking that a blast furnace's coke requirement could not support. Direct reduced iron is typically fed into an electric arc furnace as a clean, consistent scrap substitute, and interest in direct reduction has grown further in the twenty-first century because a version of the process using hydrogen as the reducing gas instead of natural gas offers a path to making steel with substantially lower carbon dioxide emissions.