How is direct-reduced iron made from iron ore?

Direct reduction (DR) is a metallurgical process used to extract iron from ore at temperatures below the melting point of the materials involved. Because the resulting product, known as direct-reduced iron (DRI), retains gangue, it requires subsequent processing to produce steel. This method is typically reserved for high-grade ores or pellets made from superconcentrates.1

The process is often conducted in shaft furnaces or rotating kilns using natural gas or coal as a reductant. In the widely used Midrex process:1

• A gas reformer converts methane into a mixture of carbon monoxide and hydrogen.1
• These gases are fed into a shaft furnace where they chemically reduce descending iron pellets at approximately 850° C (1,550° F).1
• The resulting metallized charge is cooled in the bottom of the shaft before being discharged.1

While some processes utilize rotating kilns heated by oil or gas burners, these generally yield more modest results compared to gas-based shaft furnace methods. Direct reduction serves as an alternative to the traditional blast furnace, which operates at much higher temperatures to produce molten iron.12