The Circored process is a two stage fluidized bed process. It operates at low reducing temperatures and uses natural gas to produce reducing gas by means of reforming. The process uses ore fines that have a particle size between 1mm and 0.03mm and produces HBI.

The iron ore fines are first dried and heated to about 800C in a fluid bed preheater system. The dried fines are then charged to a circulating fluidized bed (CFB). The heat required is generated by the combustion of natural gas and air that is introduced into the CFB. The fines are reduced to about 70% metallization in CFB. A portion of the partially metallized fines are withdrawn from CFB and enter the FB reactor. The FB reactor is compartmentalized into several sections, and has gas velocities in the range of 0.5 to 0.6 m/s. The fines reach a final metallization of 92 to 93% in the FB reactor. The off-gas leaving the top of the FB passes on to the CFB. The product leaves the FB reactor at about 630C, is then heated to about 680C, and briquetted.

The advantages of the process include:

• ability to process low-cost iron ore directly;
• good heat and mass transfer conditions in the circulating fluidized bed (CFB) furnace;
• low investment and operational costs (US DOE, 2003. p. 28)