Abstract
Ferric oxide which is a principal raw material for ferrite production contains anion as impurities. Because it has been generally produced from iron chloride or iron sulfate solutions obtained from acid-cleaning waste liquid. In this paper, we have investigated the effect of anions on the formation of Ni ferrite. It is shown that the spinel phase is formed at lower temperature in the case of using iron oxide containing a small amount of chloride ions compare with that case of sulfate ions. It was also found that the formation of nickel chloride during calcination resulted in the low temperature formation of Ni ferrite, and that iron oxide was not affected in its own activity. The reaction mechanism for the low temperature formation of Ni ferrite is considered to being via the formation of nickel chloride. Solid state reaction for the formation of Ni ferrite in the NiC12-Fe2O3 system is phase boundary controlled. The activation energy in the NiC12-Fe2O3 system was much lower than that of the value of Ni ferrite formation in the NiO-Fe2O3 system.
