As concerning the problem that the service life of the bottom lance couldn＇t syn-chronize with that of the converter and the high product of carbon content and oxygen content in molten steel at the end point, such measures as optimizing the parameters for the oxygen lance nozzles, optimizing the process by bottom lance, optimizing the bottom blowing process and slag splashing process were taken. After that the combined blowing in full campaign was achieved and the product of carbon content and oxygen content at the end point in molten steel made by con-verter was reduced to 0.002 3.

The slagging mechanism and cooling influence of such magnesia fluxes as dolomite, magnesite, light-caicined dolomite and light-caicined magnesium granules for steelmaking by converter were analyzed and the effect of those magnesia fluxes on dephosphorization in converter , slag amount in converter and slag splashing in converter were also analyzed. And thus the application rules of these magnesia fluxes were summarized so that the stable operation in steelmaking by converter could be achieved.

In order to solve the problem of long steelmaking cycle for interfering with the ca-pacity of the 260 t converter, the old parameters for oxygen lance nozzles, control scheme for lances and dimensions for tapping hole were optimized in No. 4 Branch of General Steelmaking Plant of Angang Steel Co.,Ltd..The production practice results showed that the smelting cycle was shortened by 4.22 minutes, the indexes of oxygen consumption and content of FeO in slag at the end point were improved and therefore efficient steelmaking by converter was achieved.

为了稳定控制260 t转炉采用轻烧镁球冶炼时的终点磷含量,分析了转炉出钢温度、 终点氧值、 炉渣碱度和返干时机等对脱磷效果的影响.结果表明,当转炉终点氧值大于0.04％、炉渣碱度为2.5～3.3、转炉出钢温度小于1680℃、返干时间小于2 min时,转炉脱磷率较高且控制稳定.

分析了鞍钢微合金钢板坯中间裂纹的产生原因,采取了降低中间包钢水中的S含量、优化扇形段驱动辊压力和转矩、优化二冷水水量等措施.采取措施后,铸坯中间裂纹指数降低,连铸坯内部质量得到改善.

针对鞍钢260 t转炉钢包顶渣氧化性强的问题,优化了渣系、转炉出钢挡渣工艺、小粒白灰与改质剂的加入量及钢包底吹氩搅拌工艺.采取措施后,钢包顶渣FeO含量由12.52％降至9.54％,中间包T.[O]含量由0.002875％降至0.002237％,提高了钢水的洁净度.

以鞍钢260 t转炉生产的超低碳IF钢为对象,研究了超低碳IF钢的转炉冶炼工艺.结果表明,采取优化铁水罐折铁量提高转炉装入铁水比,增加复吹转炉底枪支数和供气流量进行强化冶炼,部分炉次采取零位搅拌工艺等措施后,能够降低吹炼终点碳氧积和终点氧含量,为RH精炼提供较好的初始条件.

Carrying out the comparative study on test method for determining the content of sulphur and different desulfurization processes,concrete measures for further adding more limes to increase the basicity in the slag are proposed in consideration of the existing desulfurization process.Based on the results for testing the compositions in the slag,it is concluded that the desulphurization efficiency by VD is restricted,and the desulphurization is operated mainly by LF acctully and therefore the deep desulphurization by LD-LF-CC can be achieved only if the desulphurization slag is ready.