Direct Reduced Iron and its Production Processes Mar16

Direct Reduced Iron and its Production Processes...

Direct Reduced Iron and its Production Processes Direct reduced iron (DRI) is technically defined as iron ore which has been reduced to metal without melting it. Hot briquetted iron (HBI) is a densified form of DRI to facilitate its handling and transport. History The first patent was in 1792 in United Kingdom presumably utilizing a rotary kiln but the development of the modern direct reduction (DR) process began in the middle of 19th century. Since 1920 more than 100 DR have been invented and operated. Most of them have not survived. The modern era of DR production began on December 5, 1957 when the HYL process plant first started production at Hylsa. TheĀ  first plant using Midrex process came into operation in May 17, 1969 at Oregon Steel mills in Portland, Oregon. DRI Production process A DRI production process is one in which the solid metallic iron is obtained directly from solid iron ore without subjecting the ore or the metal to fusion. The process principle is shown in Fig. 1. Fig 1 DRI process principle Major DRI production processes are either gas based or coal based. Feed material in a DRI process is either iron ore sized to 10 to 30mm or iron ore pellets produced in an iron ore pellet plant. In the gas based plant the reactor, the reduction reaction takes place is a shaft furnace. The shaft furnace works on counter current principle where the iron ore feed material moves downward in the furnace by gravity and gets reduced by the up flowing reducing gases. The pressure and temperature in shaft furnace in HYL process is 5-6 bars and 800-850 deg C. The same in Midrex process is 1-1.5 bar and 800-850 deg. C. In a coal based plant the...