Ladle Desulfurization of Converter Low-Sulfur Pipe Steel

Abstract

Three stages of metal desulfurization in a ladle during production of low-sulfur pipe steel grade DNV SAWL 485 FD in the PAO MMK oxygen converter workshop are analyzed: the first stage is the treatment of semiproduct during metal delivery from a converter with solid slag-forming mixture; the second stage is steel processing in a ladle-furnace unit under a “white” slag; the third stage is the injection of fluidized lime into steel in a ladle-furnace unit. The relative amount of sulfur removed at different stages of treatment is compared. The greatest amount of sulfur, i.e., approximately three quarters of the total amount, is removed in the ladle-furnace during the second and third stages in the ratio 1:1.33. Dependences are revealed for the degree of metal desulfurization on the ratio of the lump lime weight to fluorspar weight, the specific consumption of fluidized lime and the intensity of its injection in the argon stream, are revealed for the second and third stages. Rational values are recommended for parameters in order to improve metal ladle desulfurization efficiency.