The large perfect crystals of typical calcium ferrites were successfully synthesized by “solid-liquid reaction method” from mixtures correspond to CaO·Fe203, 2CaO·Fe203, Ca0·2Fe203, 4CaO·Fe0·4Fe2O3, 3CaO·Fe0·7Fe203 and 4CaO·Fe0·8Fe203, respectively. The mineralogical properties of synthesized calcium ferrites, i. e., optical characteristics, reflectivity, etching effect, microhardness and Xray diffraction pattern, were examined.
Besides Ca0·2Fe203 compound, a ternary calcium ferrite compound proved to exist, whose chemical composition is approximately similar to Ca0·2Fe203 and is estimated to be one of the followings 3CaO·Fe0·7Fe203, 4CaO·Fe0·9Fe203, or 4Ca0·2Fe0·9Fe203. X-ray diffraction patterns of CaO·Fe203, 2CaO·Fe203 and 4CaO·Fe0·4Fe203 were in agreement with the data of previous workers.
For determining metallurgical properties of binary calcium ferrites, about 2kg samples are synthesized by solid state reaction. The conventional testing methods for iron ores were applied, i. e., the JIS methods for testing reducibility, the rotation strength after reducibility test, the degradation strength after reduction at lower temperatures, and the temperature of shrinkage, softening and melting. The degradation strength after low temperature reduction of binary calcium ferrites is much higher than that of actual self-fluxed sinter.