Reduction tests were carried out on 14 specimens at 460°-1, 050°C with hydrogen gas for 0.5-4 hours. Graphic structure of ilmenite in magnetite has an influence to promote the reducibility at the lower temperature, but generally the reduction percentages are retarded in proportion to their titanium contents.
The reduction of ilmenite begins at above 460°C.
No characteristic relations between titanium content and reducibility were found at the higher temperature.
Oxidation tests were carried out on 18 specimens from yarious localities with a "Thermo-balance" and a combustion furnace in oxygen gas or free air current at 0-1, 200°C. The roasted products were then reduced with hydrogen gas at 500° and 800°C.
Oxidizing reaction of magnetite was observed to begin at about 200° in this experiment and that of ilmenite at 450°C. The reaction velocity is comparatively rapid in the latter case.
The reducibilities of iron sands were notably promoted especially in those of lesser titanium contents by the previousroasting; higher in their oxidized percentages higher reductions resulted.
The effective temperature of oxidizing roasting is suggested to be 850°-1, 000°C.