Abstract
The processing of pipe metal in the ladle-furnace unit for the conditions of BOF shop, PJSC MMK is presented in the paper. It was established that in the first period of processing before the injection of fluidized lime, it is necessary to reduce the sulfur content in the metal till 0.005%. As a result of the injection of fluidized lime, approximately 37% of sulfur is removed and the remaining 16% is removed during further treatment of metal with a “white” slag. The average degree of metal desulfurization is 80%. A decreasing linear dependence of the sulfur content in the cast metal on the specific consumption of fluidized lime was revealed. For obtaining a sulfur content of DNV SAWL 485 FD steel of not more than 0.0015%, the specific consumption of fluidized lime should be basically not less than 2.2 kg per tone. As a result of the fluidized lime injection and the reduction of slag, the average value of the sulfur distribution coefficient increases from 43 to 123 (taking into account the time before casting the metal - up to 198 (about five times)). The dependences of the final sulfur distribution coefficient on the content of aluminum oxide in the slag of the first period (before the injection of lime) and on the specific consumption of fluidized lime are established. The final coefficient of sulfur distribution between the slag and the metal was varied in a very wide range: from 100 to 400. To increase the efficiency of ladle desulfurization of pipe steel, it is necessary to increase the content of aluminum oxide in the slag before blowing fluidized lime/ It favorably affects the reduction of oxidation and viscosity of the slag of the first processing period, as well as injection of fluidized lime in an amount of 2.2–2.8 kg per tone.
Keywords
Pipe steel, ladle-furnace unit, slag, fluidized lime, desulfurization.