DRIprosesser

DRIprosesser is a term used in the iron and steel industry to describe the family of processes that produce direct-reduced iron (DRI), also known as sponge iron. DRI is a solid iron product created by removing oxygen from iron ore without melting the ore, and it is primarily used as a feedstock for steelmaking, especially in electric arc furnaces and other facilities that can handle solid iron inputs.

Overview and development

Direct reduction technologies began to mature in the mid-20th century to take advantage of natural gas or coal-derived reducing gases. Commercial DRI processes were developed and refined by companies such as Midrex, HYL, and Energiron. These technologies are deployed in regions with abundant natural gas or coal resources and are adapted to various ore types and project scales.

Process principles

In a direct reduction plant, ore in the form of pellets or lumps is brought into contact with a reducing gas, typically rich in hydrogen and carbon monoxide. Reduction occurs at temperatures roughly between 800 and 1,100 degrees Celsius, producing solid sponge iron with low residual oxygen and variable carbon content. The process may include gas purification, cooling, and handling steps. The DRI product is often used directly in electric arc furnaces or blended with scrap for steelmaking.

Technologies and variations

Gas-based direct reduction uses natural gas or synthesized gas and is common where gas supplies are available. Coal-based or mixed-reducing-gas routes are used where coal resources are favored. Equipment configurations include shaft furnaces and rotary kilns, chosen according to ore quality, energy source, and plant economics. Hydrogen-based DRI is an area of ongoing development for lower-carbon steel production.

Applications and considerations

DRI provides a versatile iron feedstock with advantages in energy efficiency and process flexibility. Its environmental performance depends on the energy mix and feedstock; while natural gas-based DRI can reduce emissions relative to coke-based methods, lifecycle impacts vary by project.

See also: direct reduced iron, sponge iron, Midrex, HYL, Energiron.