A desulphurization study of hot metal at SSAB Europe Luleå with added bottom stirring of nitrogen gas

• Main Author: Edvartsen, Mattias
• Format: Bachelor Thesis
• Language: English
• Published: KTH, Materialvetenskap 2015
• Subjects: desulphurization; desulfurizing; removal of sulfur; steel; bottom stirring; Metallurgy and Metallic Materials; Metallurgi och metalliska material; Luleå
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-169876

This bachelor degree project is about determining the impact that additional bottom stirring may have on the desulphurization process at SSAB Luleå. During one week of field work steel samples were collected from 39 different heats. 31 of the heats were samples with the bottom stirring function enabled and the remaining 8 heats without the bottom blowing function, which is the standard method today at SSAB Luleå and they can be referred as references. Data from 15 old reference heats were also used for analysis.Two different behaviors of bottom stirring appeared and they were therefore separated to type 1 and type 2 bottom stirring. Type 1 bottom stirring turned out to have highest possibility of all methods to reach dissolved sulfur content of maximum 0.001%. If the ingoing dissolved sulfur content is around 0.03% has type 1 bottom stirring 33% chance to reach 0.001% dissolved sulfur content already after 13.3 minutes of injection and that can save sulfur reagents. The method with highest reagent efficiency showed type 1 bottom stirring to have, on second place came type 2 bottom stirring and the references showed to have lowest reagent efficiency.