Morphological analysis of ferrospheres isolated from fly ash collected from fields of an ESP

Abstract

The Ferrosperes (FS)/ magnetic concentrates isolated from fly ash (FA) collected from selected fields of electrostatic precipitator (ESP) were thoroughly analysed using scanning electron microscopy (SEM). Such morphological analysis revealed that the particles were essentially spherical in nature. A perusal of the microphotographs revealed that they were mostly ultrafine particles ( 2 - 10um). The size of the particles varied for samples isolated from the ash of different fields. Although no rigorous correlation can be made about the particles size dependence on the fields of ESP, however, it was observed that the particles were larger for samples belonging to fields 1 and 2 whereas smaller for samples belonging to fields 6 and 7. SEM images gave interesting information about the Fe bearing crystallites deposited on the surface of the aluminosilicate particles. A variety of geometrical patterns were observed for all samples. X-rays diffractions of various samples indicated that the predominant Fe bearing phases were hematite, magnetite and magnesioferrite. Chemical analysis revealed that FS have a very high content of Fe (46-65%). The hysteresis loops were very narrow, - supporting the previous contention made. Coercivity, magnetic saturation, remnant magnetization data were supportive evidences. From such analysis it appeared that these FS have potential multiple uses like catalyst for oxidation of hydrocarbon, EMI shielding (after polyaniline deposition) and use as soft magnetic concentrates.