复吹转炉冶炼低磷钢工艺

Process of smelting low phosphorus steel in combined blowing converter

探讨了复吹转炉采用常规冶炼工艺和脱磷预处理直炼工艺冶炼低磷钢的工艺条件。A、B两厂采用常规冶炼工艺，当炉渣w（T.Fe）=16 %～24 %，炉渣碱度为3.5时，要稳定冶炼w（P）＜0.01 %的低磷钢时，终点w（C）应控制在0.05 %以下。C、D厂采用脱磷预处理直炼工艺，当一倒w（C）〈0.10 %时，钢水w（P）能控制在0.01 %以下。预处理直炼工艺脱磷、脱碳期的关键是控制总渣量和半钢磷含量，为使冶炼w（P）〈0.01 %低磷钢的同时吨钢总渣量控制在90 kg以内，当脱磷期倒渣率达到40 %～50 %时，半钢w（P）最高应控制在0.026 %～0.037 %。

The present paper discusses the process conditions of smelting low phosphorus steel by conventional process and hot metal dephosphorizing pretreatment and direct steel-making process in combined blowing converter. Steel Plants A and B adopted the conventional process. For those two Plants when the（%T. Fe）is 16-24% and the slag basicity is 3.5 the low phosphorus steel with w（P） less than 0. 01% can be consistently produced only if the end-point w（P） in steel is controlled in less than 0.01%. Neverthe- less Plants C and D introduced the hot metal dephosphorizing pretreatment and direct steel-making process. For them the w（P） in steel can be controlled in less than 0. 01% as soon as the condition of w（C）〈0. 10 % is achieved. For the latter one of those two processes the key points in the dephosphorizing and decarburizing phases are controlling the total slag volume and [P] after dephosphorizing pretreatment. In order to control the total slag volume/ton steel within 90 kg in smelting the low phosphorus steel with [P] less than 0. 01% the highest level of [P] after dephosphorizing pretreatment should be controlled in 0. 026-0. 037 %0 when the deslagging rate in the period of dephosphorization arrives at 40 %-50%.