JPS6455315A - Method for pretreating molten iron by converter slag - Google Patents

Abstract

PURPOSE:To effectively utilize converter slag by mixing powdery solid particle of the slag generating from the converter blowing with sub-raw material at the time of pretreating by blowing the sub-raw material into the molten iron before oxygen blowing in the converter. CONSTITUTION:At first separated heat of molten iron to the heat for pretreating is ordinarily blown by the ordinary converter blowing process. That is, the molten iron tapped from the blast furnace is directly carried to the converter and the molten iron containing high impurity quantity is blown under existence of a large quantity of slag. Then, when C content in the molten iron is lowered to the prescribed value, O2 top blowing is stopped to complete the refining. Next, the molten steel only is tapped at the steel tapping stage and after the molten slag remained in the converter is poured into a tundish, at blast slag granulation stage, the molten slag is blasted by strong blasting through a blower while discharging from a tundish nozzle and solidified to obtain the granular slag. This slag is separated from the product, and mixed into powdery lime and while blowing it into the molten iron in a molten iron ladle, O2 gas is blown to pretreat the molten iron at the molten iron pretreating stage.