Abstract:
Chemically beneficiated high silica/alumina iron ore rejects (27-76 percent Fe2O3) were used to synthesize iron oxides of purity 96-98 percent with SiO2/Al2O3 ratio reduced to 0(.)03. The major impurities on chemical beneficiations were Al, Si, and Mn in the range 2-3 percent. A 99(.)73 percent purity Fe2O3 was also prepared by solvent extraction method using methyl isohutyl ketone (MIBK) from the acid extracts of the ore rejects. The magnesium ferrite, MgFe2O4, prepared From these synthetic iron oxides showed high resistivity of similar to 10(8) ohm cm. All ferrites showed saturation magnetization, 4 piM(s), in the narrow range of 900-1200 Gauss and the Curie temperature, T-c, of all these Fell within a small limit of 670 +/- 30 K. All ferrites had low dielectric constants (epsilon'), 12-15, and low dielectric loss, tan delta, which decreased with the increase in frequency indicating a normal dielectric dispersion found in ferrites, The presence of insignificant amount of polarizable Fe2+ ions can be attributed to their high resistances and low dielectric constants. Impurities inherent in the samples had no marked influence on the electrical properties of the ferrites prepared from the iron ore rejects, suggesting the possibility of formation of ferrite of constant composition, MgFe2O4, of low magnetic and dielectric losses at lower temperatures of 1000 degrees C by ceramic technique.
