Coating of iron oxide pellets for direct reduction

Depending upon their chemical composition and, to a lesser extent, on their physical properties, iron oxide pellets exhibit varying degrees of sticking tendency during direct reduction at elevated temperatures. For an efficient shaft furnace operation in direct reduction (DR), it is imperative to prevent pellets from sticking to each other and, hence, forming clusters. Coating of pellets with a suitable inorganic material has increasingly been gaining recognition amongst the pellet producers and DR plant operators as an effective method of preventing sticking. In this study, the effect of coating on the sticking of DR-grade pellets with low and high basicity (Midrex and HyL quality pellets, respectively) was investigated. The results show that bauxite and serpentine alone, and limestone and bentonite in combination are suitable materials for the prevention of sticking of both types of pellets.