Preliminary Experiment on Elimination of Cr from Molten Pig Iron by Bessemerizing

Abstract

In 1952, a test on the elimination of Cr from molten pig iron was done with a 3 ton testing blast furnace of Yawata Iron & Steel Works. By this test, it was found possible to remove Cr from molten iron in the hearth by bessemerizing it under the condition of low temperature.
In 1954, some fundamental experiments were performed to determine the factors affecting the behavior of Cr during bessemerizing, particularly, the most favorable temperature for Cr-elimination using an 150kW H.F. electric furnace. For this purpose, air or O₂-enriched air was blown into the molten iron bath with various proportions of water to maintain bath temperature nearly at several intended levels and the change of bath composition during the bessemerizing was observed.
The results of this experiments were as follows:
1) The lower temperature was favorable for Cr-elimination, the upper limit of which was determind by initial Si-content of the bath. (about 1350° for 0.5% of initial Si).
2) The lower initial content of Si was favorable. If initial Si-content was lower, however, it needed to maintain bath temperature lower to prevent decarbonization which always accompanied desiliconization more or less.
3) As bessemerizing gas, O₂-enriched air was more efficient than air.
4) It was desirable to limit initial content of Mn under 0.8%, as it made difficult to remove Cr.