Estimation of Sintering Kinetics of Magnetite Pellet Using Optical Dilatometer

• Published in: Metallurgical and materials transactions. B, Process metallurgy and materials processing science Vol. 47; no. 1; pp. 309 - 319
• Main Authors: Sandeep Kumar, T. K., Viswanathan, Neelakantan Nurni, Ahmed, Hesham M., Andersson, Charlotte, Björkman, B.
• Format: Journal Article
• Language: English
• Published: New York Springer US 01-02-2016; Springer Nature B.V
• Subjects: Activation energy; Characterization and Evaluation of Materials; Chemistry and Materials Science; Hematite; Kinetics; Magnetite; Materials Science; Mathematical models; Metallic Materials; Minerals; Moles; Nanotechnology; Oxidation; Parameter estimation; Pellets; Process Metallurgy; Processmetallurgi; Sintering; Structural Materials; Surfaces and Interfaces; Thin Films; Hematite; Sinter Mechanism; Magnetite; Sinter Behavior; Green Pellet
• ISSN: 1073-5615; 1543-1916; 1543-1916
• DOI: 10.1007/s11663-015-0505-9

During induration of magnetite pellets, oxidation of magnetite followed by sintering of the oxidized magnetite (hematite) is desirable. Sintering of magnetite which hampers the oxidation of magnetite is aimed to be kept as low as possible. In succession to our earlier study on sintering behavior of oxidized magnetite (hematite), this paper focusses on the sintering behavior of magnetite phase in isolation with an objective to estimate their kinetic parameters. The pellets prepared from the concentrate of LKAB’s mine, which majorly contains (>95 pct) magnetite, are used for the sintering studies. Optical Dilatometer is used to capture the sintering behavior of the magnetite pellet and determine their isothermal kinetics by deducing the three parameters, namely—activation energy (
Q
), pre-exponential factor (
K
′), and time exponent (
n
) with the help of power law and Arrhenius equation. It is interesting to find that the time exponent (
n
) is decreasing with the increase in sintering temperature. It is also interesting to note that the activation energy for sintering of magnetite pellet shows no single value. From the present investigation, two activation energies—477 kJ/mole [1173 K to 1373 K (900 °C to 1100 °C)] and 148 kJ/mole [1373 K to 1623 K (1100 °C to 1350 °C)]—were deduced for sintering of magnetite, suggesting two different mechanisms operating at lower and other at higher temperatures. The estimated kinetic parameters were used to predict the non-isothermal sintering behavior of magnetite using the sintering kinetic model. Predicted results were validated using experimental data.