<Original Papers>Hydrogen Reduction of Iron Sand Ores in a Fluidized Bed

The reduction in a fluidized bed has been recently developed as one of the most effective methods for the treatment of fine iron ores. For the purpose of utilizing iron sand ores, pyrite, lateryte ores and so on for iron industry, the authors studied the reduction of iron sand ores which are reserved in large quantities in our country. First, using a reactor tube 8.9 cm in diameter made of acrylic acid resin, a model experiment was carried out at room temperature in order to determine the optimum fluidized conditions suitable to this equipment. Then hydrogen reduction of iron sand ores in a fluidized bed, using the stainless reactor tube with the same dimension as used in the model experiment, was carried out at 700～1,050℃. The results obtained from the experiment were as follows : (1) The velocity of hydrogen gas for the moderate fluidized state was 16-32 cm/sec. at room temperature and the charge weight of samples was in the range of 500-1,000g. These conditions obtained by the model experiment were applicable to the actual fluidized bed reduction of iron sand ores. (2) The rate of reduction of iron sands at one atmospheric pressure of hydrogen was from 80 to 90% in 120 minutes at 800℃ at which the reaction was mainly controlled by chemical reaction. It was observed in the microscopic inspection that the reaction zone did not proceed topochemically. (3) Sintering phenomena of iron sand ores were observed over 100℃ which might be the upper limit of reducing temperature in fluidized bed. (4) It was clear from X-ray analysis and microscopic inspection that illumenite in iron sand ores was much less reduced under the temperature of 900℃