High temperature behaviour of iron carbide

Iron carbide is a new alternative iron source currently that has been produced by Nucor via reaction of fine ore with CH4/H2 gas in a fluidized bed reactor. 1 It has the potentially significant advantage over other commercially available ironcarbon sources of being easily transportable, as a fine granular material. Fine granular sources of carbon injected into a steel bath should provide excellent removal of nitrogen because of the large surface area available for CO bubble formation, the CO bubbles acting as an absorbent for dissolved nitrogen in the steel. Trials by Nucor in a number of electric arc furnaces have reported significant removal of nitrogen, from 80 ppm to 30 ppm, without adversely affecting metal quality and with reduced overall energy usage. In order to gain a better understanding of the basic mechanisms associated with the addition of iron carbide into the melt bath, two commercial iron carbide powders, a sample from the Nucor (obtained in 1997) and another from the Wundowie pilot plant , were characterized using optical microscopy, SEM, XRD and particle size analysis. In addition, thermogravimetric analysis and differential thermal analysis (DTA) methods were employed to investigate the reactions occurring within the iron during heating.