Iron Ore Agglomeration Processes and their Historical Development Dec28

Iron Ore Agglomeration Processes and their Historical Development...

Iron Ore Agglomeration Processes and their Historical Development There are four types of agglomerating processes which have been developed (Fig 1). They are (i) briquetting, (ii) nodulizing, (iii) sintering, and (iv) pelletizing. Fig 1 Agglomeration processes Briquetting is the simplest and earliest applied process. Fine grained iron ores are pressed in to pillow shaped briquettes with the addition of some water or some other binder under high mechanical compressive pressure. In the nodulizing process, fines or concentrate along with carbonaceous material are passed through inclined rotary kiln heated by gas or oil. The temperature inside the kiln is sufficient to soften but not high enough to fuse the ore. The nodules vary considerably in composition and are too dense, slaggy, lack required porosity and hence this process could not find great favour. Briquetting and nodulizing are cold binding processes and mostly used for the recycling of recovered iron ore wastes in the steel plant. Sintering and pelletizing are the processes of major importance for the iron production. During 2014, as per World Steel Association, the production of blast furnace iron and direct reduced iron were 1183 million tons and 73 million tons respectively. Most of this production has come from iron ore in the form of sinter and pellet. While the preferred feedstock for blast furnace iron is sinter and/or pellets, that of direct reduced iron is pellets only. Though accurate production data for sinter and pellets are not compiled, but world production of sinter and pellets together can be safely estimated to be well over 1300 million tons per year to support the iron production of 1256 million tons. Historically, the feedstock for the world?s blast furnaces was naturally occurring lump ores. During the mining of iron ores, large amounts were getting generated....

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...