Reduction of Platelet Fe2O3 Single Crystal Reacted with Na2O, K2O, CaO and Silicate Slag at the Surface of Fe2O3 c Plane*
1983 年 23 巻 8 号 p. 639-645
詳細
1983 年 23 巻 8 号 p. 639-645
The effect of K2O, Na2O and CaO on the reduction behavior of Fe2O3 was investigated. Platelets of Fe2O3 single crystals were prepared by the flux method. The size of the crystals was approx. 3mm in width and 0.3mm in thickness. For the reaction of Fe2O3 with K2O, Na2O, and CaO, small amounts of each carbonate powder were placed on the flat plane (0001) of Fe2O3 and heated at 1100-1300°C in the air. It was confirmed by EPMA that the reaction products with those substances were formed on some parts of the Fe2O3 crystal. The crystals were reduced at 750°C in CO and H2 streams, and the surface structures were observed by SEM.
The results obtained were as follows. When alkaline metals (as Na2O, K2O) were present in Fe2O3, the abnormal swelling took place during the reduction. It was considered that the swelling was caused by (1) the cracking of the crystal at the early stage of the reduction, (2) the fibrous iron formation and (3) the carbon deposition on the reduced iron. The fibrous iron formation was also observed in the grain boundary of calcium ferrite. The reduction with a glassy slag (SiO2-Al2O2-CaO) was also investigated and no swelling phenomenon was shown.
