Iron Ore Pellets and Pelletization Process Nov26

Iron Ore Pellets and Pelletization Process...

Iron Ore Pellets and Pelletization Process Pelletizing of iron ore was started in the 1950s to facilitate the utilization of finely ground iron ore concentrates in steel production. For the pelletizing of iron ore there are two main types of processes namely, the straight travelling grate (STG) process and the grate kiln (GK) process. In the STG process, a stationary bed of pellets is transported on an endless travelling grate through the drying, oxidation, sintering and cooling zones. In the GK process, drying and most of the oxidation is accomplished in a stationary pellet bed transported on a travelling grate. Thereafter, the pellets are loaded in a rotary kiln for sintering and then on a circular cooler for cooling. The pelletizing processes are discussed in the article under the link http://ispatguru.com/iron-ore-pellets-and-pelletizing-processes/. The pellets may be acid or fluxed pellets. Acid pellets – Basicity of acid pellets is usually less than 0.1. The fired pellet strength is, to a certain degree, due to hematite bridges of polycrystalline structure. These pellets normally have large volume of open pores. The reduction gas quickly penetrates through these pores into the pellet core and simultaneously attacks the structure in many places. This results into an early structural change which begins at low temperatures over the entire pellet volume. Fluxed pellets – These are also known as basic pellets. Basicity of fluxed pellets is greater than 0.1 and can vary. Basicity of normal basic pellets range from 0.1 to 0.6 and have low CaO percentage. During the firing of these pellets, a glassy slag phase consisting of SiO2, CaO, and Fe2O3 of varying percentage is formed. Due to increased flux addition, there is formation of some slag and due to it, there is to a certain extent slag bonding with...