Effect of Temperature, Time, and Cooling Rate on the Mineralogy, Morphology, and Reducibility of Iron Ore Sinter Analogu
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https://doi.org/10.1007/s11837-020-04452-6 Ó 2020 The Author(s)
SINTERING OF OXIDES AND CONCENTRATES
Effect of Temperature, Time, and Cooling Rate on the Mineralogy, Morphology, and Reducibility of Iron Ore Sinter Analogues TOBIN HARVEY ,1 MARK I. POWNCEBY,2 JEFF CHEN,3 NATHAN A.S. WEBSTER,2 THI BANG TUYEN NGUYEN,1 LEANNE MATTHEWS,1 DAMIEN O’DEA,4 and TOM HONEYANDS1,5 1.—The Australian Research Council (ARC) Research Hub for Advanced Technologies for Australian Iron Ores, University of Newcastle, Callaghan, NSW 2308, Australia. 2.—CSIRO Mineral Resources, Clayton, VIC 3168, Australia. 3.—Centre for Advanced Microscopy, Australian National University, Canberra, Australia. 4.—Marketing Iron Ore, BHP, Brisbane, QLD 4000, Australia. 5.—e-mail: [email protected]
Analogue sinter tablets were produced at temperatures between 1250°C and 1320°C, with a range of hold times and cooling rates. Platy silico-ferrite of calcium and aluminum (SFCA) morphology was identified in samples produced at 1250°C using reflected light microscopy; however, quantitative x-ray diffraction (XRD) identified the presence of the SFCA phase, with no SFCA-I detected. This proves that the platy SFCA morphology common in analysis by reflected light microscopy cannot be attributed to the SFCA-I mineral without further analysis. Micro-XRD and electron probe micro-analysis (EPMA) were carried out on an area of platy SFCA confirming this result. The sinter analogue tablets were reduced in a 30% CO, 70% N2 gas mixture at 900°C in a tube furnace thermo-gravimetric analyzer. The degree of reduction of the tablets in this study was found to be controlled by the porosity of the samples, rather than by the morphology or mineralogy of the bonding phase.
INTRODUCTION The continued growth of iron and steelmaking, combined with environmental pressure to reduce greenhouse gas emissions, makes the optimization of the iron ore sintering process more important than ever. Sintering is a process by which a mixture of fine-grained iron ores (< 6.3 mm), fluxes, and coke are 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. Key quality parameters important for producing a good sinter include high strength, low impurities, high porosity and permeability, and high reducibility. All of these are influenced in some way by the mineralogy of the sinter, which in turn is dependent on variables such as temperature, composition, and fuel.
(Received August 17, 2020; accepted October 16, 2020)
In an attempt to understand and improve the properties of sinter, many authors have studied the mineralogy and morphology of iron ore sinter, with a focus on the bonding phase that is formed as a result of the high-temperature reactions. In order to generate a suitable sinter for ironmaking, the bonding phase must be physically strong, permeable to reducing gases in the blast furnace and easily reduced. Over the past 50 years, a significant body of work has d
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