Investigation into how the magnesia, silica, and alumina contents of iron ore sinter influence its mineralogy and properties (original) (raw)
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ISIJ International, 2010
Sinters were produced in the pilot plant using four different ore mixtures with varying proportions of iron ores, fluxes and coke. All the resulting sinters were characterised by chemical and granulometric analysis, degradation testing during reduction in the blast furnace (RDI test), cold resistance testing (Tumbler test), reducibility testing, determination of softening and melting temperatures, and determination of the sinter structure by electron microscopy. The obtained result allow for the establishment of better operation conditions to manufacture sinters.
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The sintering process is a thermal agglomeration process, and it is accompanied by chemical reactions. In this process, a mixture of iron ore fines, flux, and coal particles is heated to about 1300 °C–1480 °C in a sinter bed. The strength and reducibility properties of iron ore sinter are obtained by liquid phase sintering. The silico-ferrite of calcium and aluminum (SFCA) is the main bonding phase found in modern iron ore sinters. Since the physicochemical and crystallographic properties of the SFCA are affected by the chemical composition and mineral phases of iron ores, a crystallographic understanding of iron ores and sintered ore is important to enhance the quality of iron ore sinter. Scrap and by-products from steel mills are expected to be used in the iron ore sintering process as recyclable resources, and in such a case, the crystallographic properties of iron ore sinter will be affected using these materials. The objective of this paper is to present a short review on resea...
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Iron ore sinters are considered as multi-phase materials, with a heterogeneous microstructure. The amounts of the different phases mainly hematite, magnetite and a dicalcium silicate are contributing factors to a number of important on the sinter quality. The behavior of phase formation during the sintering process has a significant of effect on the chemical composition of sinter and controlling microstructure and concentration of silicoferrites of calcium and aluminum (SFCA). The mineralogical distribution of different phases determines the microstructure of the sinter which imparts the quality of the sinter. In this study, the microstructure of the sinter has been examined by considering the chemical composition, the mineralogy, the morphology and the spatial arrangement of the various mineral phases formed during sintering. The chemical composition in the process of sintering (especially CaO, Al2O3, Fe2O3, SiO2 etc.) were made optimum control and all parameters that can effect on...
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The physical properties of iron ore sinter are largely influenced by raw material properties, in particular the bulk ore composition and its associated mineralogy. The levels of Fe, SiO 2 , Al 2 O 3 , MgO and other elements, together with the nature of the minerals in the fine ore and associated sintering conditions play a major role in determining the abundance and type of hightemperature bonding phases that form during sintering. This study using natural ores combines in situ X-ray diffraction experiments in model sinter systems with laboratory-based compact sinter tests to examine the links between iron ore composition and sintering conditions and their effects on sinter strength. Results help to establish the critical compositional and thermal parameters that control the bonding phase chemistry, which in turn influences the strength, a key sinter quality parameter of the sinter matrix.
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Life Science Journal
In this study provides an overview of chemical and physical properties of commercial iron ores as well as their influence on sintering performance. The sinter structure and its characteristics mainly depend on the raw material chemistry, phase body, crack distribution and the sintering process parameters. The aim of the studies is to present a new approach to the characterization of complex macrostructures and microstructures, especially those found in effect of sinter quality and productivity. A number of the commercial iron ores were tested in an industrial sinter plant to study the effect of iron ore composition on the sintering properties. Sintering process was performed for each individual using iron ore as constant basicity, coke dust and flux. The sintering properties of blending ores, including productivity, tumbler index (TI), suitable moisture and coke rate were approximately equal except reduction degradation index (RDI) values, to the weighted means of the individual ores. An important feature of this system is the simultaneous use of X-Ray Diffraction and Scanning Electron Microscope (SEM-EDS) which enables to determine both macro and microstructure of a sinter with high accuracy.
Comparison of the Mineralogy of Iron Ore Sinters Using a Range of Techniques
Minerals
Many different approaches have been used in the past to characterise iron ore sinter mineralogy to predict sinter quality and elucidate the impacts of iron ore characteristics and process variables on the mechanisms of sintering. This paper compares the mineralogy of three sinter samples with binary basicities (mass ratio of CaO/SiO2) between 1.7 and 2.0. The measurement techniques used were optical image analysis and point counting (PC), quantitative X-ray diffraction (QXRD) and two different scanning electron microscopy systems, namely, Quantitative Evaluation of Materials by Scanning Electron Microscopy (QEMSCAN) and TESCAN Integrated Mineral Analyser (TIMA). Each technique has its advantages and disadvantages depending on the objectives of the measurement, with the quantification of crystalline phases, textural relationships between minerals and chemical compositions of the phases covered by the combined results. Some key differences were found between QXRD and the microscopy te...
2013
Sintering is a process by which a mixture of iron ores, fl uxes and coke is agglomerated in a sinter plant to manufacture a sinter product of a suitable composition, quality and granulometry to be used as burden material in the blast furnace. This process is studied and researched in the steelmaking industry in general, and in sinter plants in particular, as well as in universities and metallurgical research centres throughout the world. As a result of this research, and the experience accumulated over many years, the sintering process is well understood. Nevertheless, despite this good knowledge of sintering, there are still a number of issues that need to be studied. The present work provides information on the iron ores that form part of the mineral mix which, once granulated, is loaded onto the sinter strand where it is partially melted at a temperature of between 1250-1350 °C and undergoes a series of reactions that give rise to the formation of sinter; a material of a suitable...
2015
Sintering is a process by which a mixture of iron ores, fl uxes and coke is agglomerated in a sinter plant to manufacture a sinter product of a suitable composition, quality and granulometry to be used as burden material in the blast furnace. This process is studied and researched in the steelmaking industry in general, and in sinter plants in particular, as well as in universities and metallurgical research centres throughout the world. As a result of this research, and the experience accumulated over many years, the sintering process is well understood. Nevertheless, despite this good knowledge of sintering, there are still a number of issues that need to be studied. The present work provides information on the iron ores that form part of the mineral mix which, once granulated, is loaded onto the sinter strand where it is partially melted at a temperature of between 1250-1350 °C and undergoes a series of reactions that give rise to the formation of sinter; a material of a suitable...
Influence of Iron Ore Fines Feed Size on Microstructure, Productivity and Quality of Iron Ore Sinter
ISIJ International, 2011
The sinter structure and its characteristics mainly depend on the raw material chemistry, size, size distribution and the sintering process parameters. In sintering process heat is supplied by coke breeze in the sinter mix to raise the bed temperature to achieve partial fusion and diffusion bonding. Airflow rate and flame front speed in sintering process has been found to guide the performance of the sinter plant and these parameters mainly depends on the sinter bed permeability. The flame front speed (bed permeability) has been considered as one of the important operating parameter and it depends on several factors; the feed size of the sinter being one of the most important parameter among them. Since iron ore proportion is at higher side in the sinter mix, its size fraction is very important. JSW Steel sinter plant receives iron ore fines of-10 mm size from Bellary-Hospet region which consist of 3 to 9% bigger than 10 mm and 30 to 35% smaller than 0.15 mm size fraction. It is well known that larger particles favour diffusion bonding and smaller particles favour slag bonding in sintering process. Accordingly, the study of the assimilation characteristics of different size range iron ore has an important role to control the reactions in the sinter bed and to obtain the target mineral structure. Too much variation in coarser and finer particle size range in sinter mix, the behavior of these +10 mm and-0.15 mm particles have been a subject of investigation and it is necessary to understand the role of iron ore particle size on sinter microstructure, sinter strength, sinter RDI, and productivity. In present work pot grate sintering experiments have been carried out in laboratory with different level iron ore size (mean particle size from 1.22 to 3.95 mm) to understand the influence of iron ore mean particle size on mineralogy, productivity, physical and metallurgical properties of the sinter. Sinter productivity increased with increase in iron ore mean particle size due to increased flame front speed (FFS) and improved bed permeability with lower sintering time. Sinter with iron ore mean particle size of 2.59 mm (Classifier fines) yielded better sinter strength with lower fines (-5 mm) and lower RDI. Higher sinter strength is due to effective distribution of acicular silico ferrites of calcium and alumina (SFCA) phases. The improvement in sinter RDI is due to the change in proportion of magnetite and hematite phase with flame front speed.
2009
Mineralogical characterization for two ultra basic production sinter-test sinter pairs was made using optical microscopy and scanning electron microscopy. Basicities (CaO/SiO2) of the sinter pairs were 2.1 and 2.3 respectively. Despite of the equal composition, the mineralogy and microstructure of the corresponding test and production sinters were significantly different. The production sinters were composed mainly of fine-grained equigranular matrix rich in newly formed magnetite. Sporadically, some coarse magnetite or olivine relicts created a porphyritic-like structure. The matrix magnetite was clearly the primarily crystallized phase with interstitial vitreous slag, SFCA phase, dicalcium silicate, siliceous dicalcium titanoferrite, tertiary hematite and/or hematite-dicalcium silicate intergrowths. The test sinters were characterized by a porphyritic-like structure with a great amount of relatively coarse magnetite and olivine relicts in a newly formed fine-grained matrix having ...