Desulfurization in Steelmaking

Steelmaking basically involves two consequential processes: an oxidation process performed in the furnace, followed by a reduction (refinement) process performed in the ladle.

Ladle metallurgy objectives including homogenization, vacuum degassing, deoxidation, temperature adjustment, alloying and refining (including desulfurization) are mostly performed in ladles during the secondary steelmaking process where a desired slag formation and proper slag control are key to produce a clean commercial steel.

Sulfur is one of the most unwanted and detrimental impurities within the steel that undesirably affects the properties and the quality of the steel. Thus, desulfurization (sulfur removal from liquid steel) is needed as a key process that is mainly achieved in ladles during secondary steelmaking.

In Steel Desulfurization, several factors simultaneously effect the extent of sulfur removal from the molten steel:

• capacity/potential of the slag for sulfur removal
• steel-slag reaction
• oxidation state of the steel/slag
• slag basicity/amount/viscosity
• temperature

Desulfurization occurs in two ways: During rising of the liquid slag particles` interaction with the molten steel and during the interaction of the accumulated top slag and the molten steel.