大型转炉优化造渣工艺提高脱磷的效果

 针对转炉冶炼存在的转炉前期化渣速度慢,冶炼终点钢水、炉渣氧化性高,终点磷含量控制不稳定等问题,利用炉渣熔化性测定、热力学平衡计算、炉渣矿相分析的方法研究了260 t转炉造渣、供氧工艺。结果表明,转炉初期渣熔化温度为1 330 ℃,不利于转炉前期化渣;终渣熔化温度为1 200 ℃,不利于转炉后期的炉衬维护;终点钢水磷含量与渣钢间磷平衡值差距较大,说明转炉吹炼终点动力学条件不足;炉渣中游离氧化钙含量较高,有部分未熔化的石灰。通过优化转炉渣料加入顺序和数量,强化转炉终点氧枪枪位控制、底吹搅拌等技术措施,可获得较高的转炉终点脱磷率和渣-钢间磷分配比,使终点渣-钢间磷含量更接近平衡;终点炉渣发育良好,游离氧化钙含量适中。

Effect of improving dephosphorization of molten steel by optimizing slagging in large converters

In the face of the problems of slow slagging speed, higher oxygen content of molten steel and iron oxide content of end-point slag, and unstable phosphorus content of molten steel at the end-point of BOF, the slag formation and oxygen supply process of 260 t converter were studied by slag melting measurement, thermodynamic equilibrium calculation and slag mineral phase analysis. The results show that the melting temperature of the slag is 1 330 ℃ at the initial stage of the converter, which is unfavorable for melting the slag in the early stage of the converter; the melting temperature of the final slag is 1 200 ℃, which is not conducive to the maintenance of the converter lining in the late stage of converter blowing; The difference of the phosphorus content between BOF end-point and the phosphorus equilibrium is large, indicating that the kinetic conditions of the BOF end-point are insufficient. The slag contains a high content of free calcium oxide and partially unmelted lime. By improving the order and quantity of slagging addition, strengthening the technical measures of oxygen lance position control and bottom blowing gas stirring at the end-point of BOF, a higher dephosphorization rate at the BOF end-poin and a phosphorus distribution ratio between slag and molten steel can be obtained, and the phosphorus content between slag and molten steel is closer to the equilibrium value; the BOF end-point slag is well developed and the free calcium oxide content is moderate.