Effects of pellets size
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Process MetallurgyEffect of Iron Ore Pellet Size on its Properties and Microstructure
T. Umadevi, Prasanna Kumar, Naveen F Lobo, P.C. Mahapatra, M. Prabhu and Madhu Ranjan
JSW Steel Limited, Toranagallu – 583119, Bellary, Karnataka, India, uma.devi@jsw.in
The properties of the pellets and their microstructure mainly depend on the raw material mix proportion, raw material chemical composition and the physicochemical conditions like the temperature and oxygen partial pressure within the induration machine. The pelletising plant products are in the size range of 8 to 16 mm. With increasing pellet size, the sintering intensity, thermo-chemical conditions and formation of different phases vary across its cross section. The time required for varies reactions within the pellet is directly proportional to the pellet size. Because of differences in pellet size, the reduction and oxidation process takes place under different conditions resulting in different phases and microstructures. In this work, detailed studies were carried out on pellets of different size (8 to 16 mm) produced from a
4.2 Mtpa pellet plant for their physical, metallurgical and microstructural properties. It was observed that the pellets in the size range of +8 to -12 mm showed good strength and lower RDI. It was observed that the amount of hematite, magnetite, porosity, pore density, pore size and slag phase play a significant role on pellet strength and RDI.
Keywords: iron ore pelletizsation, pellet size, microstructure, physical properties, metallurgical properties
DOI: 10.2374/SRI08SP169; submitted on 4 November 2008, accepted on 26 March 2009
Introduction
Pelletization Process at JSW Steel Limited
During processing of pellets in a blast furnace, their physical, metallurgical and microstructural properties have a major influence on their reduction behaviour. The firing time, temperature, oxidation time and oxygen partial pressure are decisive for the structural changes