Mineralogical Characteristics and Isothermal Oxidation Kinetics of Ironsand Pellets

Abstract

An in-depth understanding of mineralogical characteristics and the oxidation behaviors of ironsand is of great significance to make the best of ironsand and develop Ti-containing pellets. This paper quantitatively characterized the mineralogical characteristics of the ironsand from East Java in Indonesia through X-ray diffraction (XRD-Rietveld) and scanning electron microscope (SEM-EDS). The results indicated that the mineral composition of the ironsand was magnetite (22.7%), titanomagnetite (40.9%), enstatite (17.1%), hematite⁻ilmenite solid solution (14.5%), and magnesium iron aluminum silicon oxide (5.8%). The microstructure characterization of pellets after oxidation showed that the porosity of the pellets decreased from 20.7% to 11.7% with temperatures ranging from 1073 to 1473 K. Moreover, the activation energies of ironsand pellets were calculated by using model-function method. The calculated data of different mechanism functions indicated that the chemical reaction mechanism for the early stage of the oxidation fit A2 (random nucleation and nuclei growth) well, the chemical reaction mechanism for the post-oxidation at 1073⁻1273 K fit F1 (chemical reaction) well, and the chemical reaction mechanism for the post-oxidation at 1373 and 1473 K fit D4 (diffusion) well. The reaction mechanism and the limited link was finally discussed based on the kinetic analysis and the mineralogical characteristics.

Keywords

• isothermal oxidation
• kinetics
• ironsand pellets
• mineralogy
• Ti-containing pellets