Inclusion modification by calcium treatment in liquid steel processing

对低氧化物微粒(夹杂物)含量的清洁钢的需求不断增加。这种不断增长的需求突显了我们目前在控制和预测钢液中微粒子发展方面的知识的局限性，其中微粒子的形成是当前工业炼钢过程中由400-1000 ppm的氧气造成的不可避免的后果。喷吹或送丝CA处理是钢水精炼中一种常用的变质氧化物夹杂物、脱硫钢和控制硫化物夹杂物形态的技术。钙的加入过少或过多都会导致氧化铝夹杂物的不完全或过多的变质，或形成固体铝酸钙或CaS，这对钢的可浇性是不利的。**拟议的项目将专注于随着钙的添加和钢液成分的变化而改变氧化铝微粒的物相、尺寸和形态，并发展信息，从而在工业规模上改进工艺设计。这将涉及热力学计算和实验室实验，由合作组织安赛乐米塔尔·多法斯科进行工业试验。对钢材加工过程中微粒的形成和发展的了解，将决定作为钢中氧和硫含量的函数的最佳钙加入量，从而预测最低成本的生产策略。******

There is an ever increasing demand for cleaner steels with a low oxide micro-particle (inclusion) content. This increasing demand has highlighted the limitations of our current knowledge in controlling and predicting micro-particle development during liquid steel where the formation of micro-particles is an unavoidable consequence of the current industrial steelmaking process resulting from 400-1000 ppm of oxygen in solution. Ca treatment by powder injection or wire feeding is a common technique used in steel refining to modify oxide inclusions, desulphurize steel and control the shape of sulphide inclusions. Too little or too much addition of calcium leads to incomplete or excessive modification of alumina inclusions or the formation of solid calcium aluminates or CaS, which are detrimental to the castability of steels.**The proposed project will focus on the modification of alumina micro-particles' phase, size and morphology as a function of calcium additions and composition of liquid steel, and develop information leading to improved process design at the industrial scale. This will involve thermodynamic calculations and laboratory experiments, with industrial trials by the partner organisation ArcelorMittal Dofasco. This understanding of how the micro-particles form and develop during steel processing will determine the optimum rate of calcium addition as a function of steel oxygen and sulphur content so as to predict the lowest cost production strategies. ******