Discharge options for Direct Reduced Iron and its Hot Transport Dec14

Discharge options for Direct Reduced Iron and its Hot Transport...

Discharge options for Direct Reduced Iron and its Hot Transport The two main methods of producing direct reduced iron (DRI) are (i) gas based process in a vertical shaft furnace and (ii) coal based process in a rotary furnace.  In both the processes the reduction reactions take place in solid state and the maximum furnace temperatures are in the range of 850 deg C to 1050 deg C. In the coal based process, the produced DRI is mixed with char that is needed to be separated from DRI. Hence DRI-char mixture is cooled in a rotary cooler and then char is separated from DRI by the magnetic separation process. In the case of vertical shaft furnace processes, since char is not present along with DRI, there are three discharge options available. These are cold DRI (CDRI), hot briquetted iron (HBI), and hot DRI (HDRI). Most of the vertical shaft DRI furnaces have been built for the production of CDRI. In these furnaces the DRI produced after reduction is cooled in the lower part of the furnace to about 50 deg C. CDRI is temporarily stored in Silos for passivation before it is transported to a nearby steel melting shop for its use later. CDRI has got the property of auto ignition and need special precautions during transport and storages as required by the International Maritime Organization (IMO). CDRI is most suited material for the continuous charging in the EAF. HBI is now being produced since more than 30 years. It is the desirable method of preparing DRI for storage and transporting it by sea going vessels. For the production of HBI, hot DRI is discharged from the vertical shaft furnace at a temperature of around 700 deg C. The hot DRI is sent to...