Abstract
In order to develop the effective way of nitrogen removal from molten steel in the electric arc furnace steelmaking, an attempt was made to accelerate the reaction by the simultaneous decarburization. The iron ore powder was blasted on to the molten steel surface with Ar carrier gas under atmospheric pressure. The melt was 20 kg. The temperature was 1850 to 1950K. The gas flow rate was 3.33 and 4.17×10-4m3/s (STP). The ore blasting rate was 0.167, 0, 417 and 0.500 g/s. The results are summarized as follows;
(1) By the blasting of iron ore, the decaburization occurs resulting in the acceleration of nitrogen removal several times than the mere Ar blasting.
(2) Under the hard blasting condition, the nitrogen content decreased from 70 to 28 ppm for 1, 000 s, while the carbon content decreased from 0.55 to 0.12 wt%.
(3) When the carbon content is larger than 0.09 wt%, the decarburization was controlled by the oxygen transfer and CO bubbles are formed in the melt. When it is less than 0.09 wt%, however, the decarburization was controlled by the carbon transfer and the reaction occurs only on the melt surface.
(4) It is concluded that the effective nitrogen removal is possible even under atmospheric pressure, in the ranger where the decarburization reaction is controlled by the oxygen transfer.
(5) The effective interfacial area is 7 times at most as much as the cross sectional area of furnace.
