STUDY ON DECOMPOSITION OF GOETHITE/SIDERITE IN THERMAL MODIFICATION THROUGH XRD, SEM AND TGA MEASUREMENTS

The decomposition of goethite and goethite/siderite concentrates into hematite with thermal modification was studied through the measurements of X-ray diffraction (XRD), scanning electronic microscope (SEM) and thermal gravimetric analysis (TGA). The experimental results showed that goethite decomposed into hematite directly at around 300 degrees C without any intermediate phase and the decomposition of siderite completed at 500 degrees C. Nanoscale granular structures were observed in the thermally treated products. It deserves highlighting that the decomposition processes proceeded from surfaces into bulks.