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针对钢液钙处理的钙加入量精准计算问题,对使用经典热力学对钙处理的热力学计算进行了归纳总结,并使用FactSage热力学软件进行了精准钙处理计算。钙处理的主要目的是把钢水中的不可变形的固体夹杂物(特别是Al2O3基的夹杂物)变性成可变形的液体夹杂物,特别是可变形的钙铝酸盐。影响喂钙量的主要因素是钢水成分(特别是钢中总氧含量、酸溶铝含量和钢中硫含量)和温度。钙加入钢水后可以生成多种夹杂物,包括CaO·6Al2O3、CaO·2Al2O3、12CaO·7Al2O3、3CaO·Al2O3、CaO、CaS。这些化合物中仅仅12CaO·7Al2O3和3CaO·Al2O3在钢水温度下是液态的,随着钙加入量的增多,往往会出现多种固体夹杂物和多种液体夹杂物共生的状态。钙加入量的原则应该是:保证生成的夹杂物都是液态的,且不生成固态的CaS夹杂物。因此,钙处理存在着一个最低加入量和最高加入量的“液态窗口”问题。钙的最低加入量是为了保证夹杂物是液态的,钙的最高加入量是保证不生成固体的CaS夹杂物。研究也针对某厂LF精炼过程中喂钙铝线(钙铝质量比为1∶1)的精准加入量进行了优化计算。在钢水温度为1 571℃的条件下,实现夹杂物“液态窗口”的钢中钙质量分数应该在(22.6~47.4)×10-6;如果钙铝线实际收得率为30%,那么喂线长度应该在197~334m。目前现场喂线长度偏高,为350m,检测发现喂线后夹杂物中CaO也稍稍偏高。研究结果表明,目前开发的钙处理洁净钢最佳喂钙量的计算可以用于指导实际生产实践。
In view of the precise calculation of the amount of calcium added into the molten steel, the thermodynamic calculation of the calcium treatment using classical thermodynamics is summarized and the accurate calcium calculation is performed using the FactSage thermodynamic software. The main purpose of calcium treatment is to deform non-deformable solid inclusions (especially Al2O3-based inclusions) in the molten steel into deformable liquid inclusions, in particular deformable calcium aluminates. The main factors affecting the amount of calcium feeding are the composition of molten steel (especially the total oxygen content in steel, acid-soluble aluminum content and sulfur content in steel) and temperature. After the addition of molten steel, calcium can form various inclusions, including CaO · 6Al2O3, CaO · 2Al2O3, 12CaO · 7Al2O3, 3CaO · Al2O3, CaO, CaS. Of these compounds, only 12CaO.7Al2O3 and 3CaO.Al2O3 are liquid at the temperature of the molten steel. With the increase of the amount of calcium added, a variety of solid inclusions and various liquid inclusions often occur. The principle of adding calcium should be: to ensure that the resulting inclusions are liquid, and does not generate solid CaS inclusions. Therefore, there is a “liquid window” problem with a minimum amount and a maximum amount of calcium added. The minimum amount of calcium is added to ensure that inclusions are liquid, the maximum amount of calcium added is to ensure that does not generate solid CaS inclusions. The research also optimized the precise amount of calcium-aluminum wire (calcium-aluminum mass ratio of 1: 1) fed into a refinery during LF refining. When the molten steel temperature is 1 571 ℃, the calcium content in the steel containing inclusions “liquid window” should be in the range of (22.6 ~ 47.4) × 10-6; if the actual yield of calcium aluminum wire is 30% Then feed line length should be in the 197 ~ 334m. Currently on-site feed line length is high, for the 350m, found that CaO feed line is slightly higher inclusions. The results show that the current Calcium Calcium processing clean steel calculation of the best calcium can be used to guide the actual production practice.