Below Image shows the hot briquetting process of HBI production. The DRI (Direct Reduced Iron) is released hot from the reduction process. The hot feed thrust into the nip in the middle of the two counterrotating rollers. The briquettes form in the rotating rollers. The above process happens at 650 -700 °C temperature and the pressing force of 120 kN/cm. A heavy sliding channel conducts the briquettes string to leave the rollers. If briquettes are made of fine, the production happens through fluidized bed.
A roller press which is designed particularly is the most important element in hot briquetting.
Generally, for hot briquetting of sponge iron, the factory consists of:
- Briquetting press having the screw feeder as well as material supply.
- Briquette string separator.
- Hot screen in order to remove fines happens when briquetting and separation.
- Bucket lift for re-turning of fines to briquetting press.
- Sliding channel.
On a whole, to simply explain, production of HBI consists of the following steps:
- Iron pellet get fed into the reactor
- Natural gas converted into reduction gas and after that, injected.
- Reduction gas will circulate in a closed system and get recycled
- The direct reduction process:
- Hot natural gas moves into the iron ore, from the bottom to the top, according to the counterflow principle
- The Oxygen content gets reduced; Direct Reduced Iron (sponge iron) is produced.
- DRI (Sponge Iron) is pressed into the briquettes (Hot Briquetted Iron).
