introduction:

Pelletization is the most popular method of converting iron ore fines into agglomerates. Early work on pelletization took place in Sweden, but commercialization at large scale first occurred in the United States. In this case, processing technologies for low-grade taconite ores were needed due to exhaustion of the high-grade ores that had been mined in Michigan and Minnesota since the mid-1800s. Research on pelletization of Iron Range taconites began in the 1940s by a group at the University of Minnesota. One of the first pelletizers was a smokestack purchased from a junk dealer; turned on its side, the smokestack made a perfect drum pelletizer, roughly 76 cm in diameter, 1.5 m long. Pelletization has not changed greatly since those early years. Fine iron ore concentrate is mixed with a binder and water to produce pellets using a pelletizer, typically a drum or disc. These green pellets are dried at temperatures around 105 °C. Most pellets are then heated to a temperature of 1200–1300 °C to become hard enough to withstand storage and handling.

Based on composition and method of preparation, the pellets can be divided into three main categories: BF-grade pellets, DR-grade pellets, and rotary hearth furnace (RHF)-based pellets. Discussed below are the different binders and additives used in the industry and the stages of pelletizing (mixing, pelletizing, indurating). The textbook by Meyer is still the standard reference in the field.

BENEFITS OF PELLETIZED IRON ORE
 iron ore pellets also offer a number of benefits to steel producers, some of which include:

Improved productivity per cubic meter of blast furnace
Lower emissions and dust compared to sinter
Reduced requirement of coking coal
Improved handling and transportation
Reduced loss of product
Mitigation of particle crushing and subsequent blocking of the furnace (when pellets are properly produced)
Better in-furnace performance (pellets transfer heat better than powder)