Measurement and Calculation of Nitrogen Removal Rate from Molten Iron to Gas Phase through CaO-Al₂O₃ Melts

Abstract

There is a limit for lowering nitrogen in steel because of pickup from atmosphere during and after degassing. Therefore, nitride capacity of various fluxes has been measured in order to examine the possibility of nitrogen removal by using slag. It is necessary to take into account the nitrogen reaction rate between gas and slag phases and know the nitrogen behavior through successive phases of metal, slag, and gas for the efficient removal of nitrogen in practical steelmaking process. In this study, nitrogen removed rate from molten iron-aluminum alloy to gas phase through CaO-Al₂O₃ melts has been examined and a mixed rate determining model has been applied through successive phases of metal, slag, and gas taking gas/slag reaction rate into consideration. For the effective removal of nitrogen from metal to gas phase through CaO-Al₂O₃ melts, it is important to keep oxygen pressure in the gas phase higher and oxygen potential at slag/metal interface lower.