ABSTRACT
Important quality parameters of sinter are its strength, reducibility, and its degradation during reduction, also the softening and meltdown characteristics. Broadly, these indices of sinter are guided by its mineralogical and morphological characteristics and their changes, which are influenced by the temperature profile across the sintering bed. These indices, along with their significance and ways to improve (these) on an individual basis—including various research and development and case studies being adopted in sinter plants across the world—are outlined. The contributing factors affecting the sinter qualities are outlined. These are raw material characteristics, sinter chemistry (basicity and contents of MgO, FeO, Al2O3), and operational parameters (granulation of sinter mix, maximum temperature and its holding time, sintering speed, coke addition, etc.). The sizing of coke and fluxes and their split addition in the mix, also the granulation in improving the positioning of these particles in the mix leading to better combustion and heat transfer regime are described. The rationale of conducive fusion and diffusion bonding to improve the sinter strength and means to achieve these are mentioned. The assimilation characteristics of ores and other mix materials are guiding factors in this respect. The minerals—their types and distribution in sinter, and its porosity, which affects the reducibility, are described. The causes and mechanism of the sinter reduction–degradation index (RDI) are mentioned in the Chapter. The secondary hematite in sinter, which is formed on oxidation during its cooling, undergoes stresses. The process- and operation-related methodologies to improve sinter RDI are outlined. The effect of alumina on strength and sinter RDI and its interinfluence with its CaO and FeO contents are discussed; also, the salient ways improve sinter RDI are outlined.
