Nitrogen in SL/RN direct reduced iron : origin and effect on nitrogen control in EAF steelmaking
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Date
Authors
Erwee, Markus Wouter
Pistorius, Petrus Christiaan
Journal Title
Journal ISSN
Volume Title
Publisher
Maney Publishing
Abstract
In the steel plant considered here, direct reduced iron (DRI), produced by the coal based Stelco-Lurgi/Republic –National (SL/RN) process, makes up 50% or more of the total iron charge. The SL/RN DRI samples from a kiln cooler had high nitrogen contents (50-250 ppm, depending on particle size), contributing to elevated nitrogen levels in liquid steel produced in the electric arc furnaces. The proposed mechanism of nitriding of SL/RN DRI involves gaseous nitrogen (present within the rotary cooler) diffusing into the solid bed and is supported by a simple diffusion model. A strong correlation was found between the melt-in carbon content of the liquid steel and the final tap nitrogen content, with melt-in carbon of 0.3% C or higher resulting in nitrogen levels below 50 ppm at tap, even when charging DRI material that is high in nitrogen.
Description
Keywords
Rotary kiln, Direct reduced iron, Nitrogen control, Electric steelmaking, Stelco–Lurgi/Republic–National (SL/RN)
Sustainable Development Goals
Citation
Erwee, MW & Pistorius, PC 2012, 'Nitrogen in SL/RN direct reduced iron : origin and effect on nitrogen control in EAF steelmaking', Ironmaking and Steelmaking, vol. 39, no. 5, pp. 336-314.