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1、EAF steelmaking,李岩,1,目录,炼钢历史炼钢科学的发展冶金流程图Overview of steelmaking processesFrenhanOxygen Steelmaking Processes电炉炼钢发展概况电炉炼钢内容框架Introduction of EAF,2,古代炼钢法,商代中期即公元前十四世纪开始使用陨铁，春秋晚期即公元六世纪左右出现人工冶炼的铁器。最初炼出的铁是用木炭加热和还原铁矿石得到的块铁，强化鼓风和加高炉身后又炼出了生铁。生铁在铸锻成器具过程中脱碳成钢是我国古代冶金技术的特点。,3,西汉后期，生铁冶炼已达到较高水平，能够为炼钢提供充足的生铁原料，发展了
2、炒钢技术。文献指出，我国的炒钢技术始于西汉中期（公元前二世纪）。炒钢是世界上最早用熔化生铁氧化熔炼的炼钢方法。炒钢就是把生铁加入炉膛中，燃烧木炭以提高炉温来使生铁升温借助空气中的氧和加入铁矿石的氧并通过人工搅拌，使生铁中的碳氧化，得到碳含量较低、可锻的钢或熟铁。,4,古代炼钢法,5,古代炼钢法,类似于什么已知工艺？,6,炼钢科学理论的发展炼钢理论,热力学,炼钢学科的起步和发展晚于炼钢生产；19世纪中期近代钢铁冶金方法发明成功后相当长一段时间里，钢铁冶金是一项技艺而不是科学；钢铁冶金从技艺发展成为科学，是从20世纪30年代，H. Schenck、J. Chipman等把化学热力学导入冶金领域，用
3、热力学方法研究冶金反应开始的；,7,热力学,20世纪40年代末至50年代，Schenck、Chipman等发表了大量有关炼钢反应的平衡常数、标准自由能变化等基础数据；20世纪60年代80年代，E.T. Turkdogan、J.F. Elliott、松下幸雄、不破佑、佐野信雄、水渡英昭等继续对炼钢化学反应的平衡常数、标准自由能变化、活度、炉渣磷酸盐容量和硫酸盐容量等进行了大量的研究和测定工作。20世纪80年代后，与炼钢反应有关的标准自由能变化、钢液中组元活度相互作用系数、炉渣主要组元的活度、炉渣硫酸盐和硫酸盐容量等大都有了较可靠的热力学数据；,8,微观动力学,炼钢反应动力学的研究开始得较晚，在2
4、0世纪5060年代，动力学方面的研究主要集中在微观动力学方面，如化学反应级数、反应速度常数、反应活化能、多相反应限制性环节等方面的研究；,9,宏观动力学,20世纪70年代后，炼钢反应宏观动力学研究开始活跃：G.H.Geiger、Szekely等将化工学科的“三传”(热量、质量、动量传递)用于分析研究冶金过程速率问题； 鞭岩、濑川清等提出了冶金反应工程学名称，引入化学反应工程学有关反应器设计、单元操作、最优化等方法分析研究冶金反应问题。20世纪90年代后，冶金反应宏观动力学和反应工程学取得了重要进展，有关炼钢冶炼和连铸过程流体流动、传热、反应等均基本可以用数学模型加以描述并计算求解，反应动力学研
5、究在实际生产过程自动控制中也得到了广泛的采用。,10,交叉学科,炼钢学科进展还表现在冶金知识与材料、计算机、电磁、环境等学科知识的交叉、融合和应用，如：在氧气喷头和喷粉冶金中应用空气动力学中可压缩流体和气相输送等知识； 在炼钢过程控制中广泛采用了声学、图像识别、专家系统、神经元网络等方面知识； 在连铸过程采用电磁、金属压力加工等知识； 热力学、凝固等商务计算软件等。,11,学科发展,在今后相当一段时间内，炼钢热力学不会再有显著的发展，在宏观动力学和反应工程学方面还会有一定的发展，而炼钢学科最重要的发展将会在液态钢的凝固加工、减少排放和排放物和废弃物再回收利用以及与信息、材料、环境等学科知识的交
6、叉、融合和应用方面。,12,现代炼钢流程,15,Overview of steelmaking processes and their developmentR.J. Fruehan,For the purpose of steelmaking can be roughly defined as the refining or removal of unwanted elements or other impurities from hot metal produced in a blast furnace(BF) or similar process or the melting and r
7、efining of scrap and other forms of iron in a melting furnace, usually an electric arc furnace(EAF).,16,Currently most all of the hot metal produced in the world is refined in an oxygen steelmaking process(OSM).A small amount of hot metal is refined in open hearths, cast into pig for use in an EAF o
8、r refined in other processes.,17,The major element removed in OSM is carbon which is removed by oxidation to carbon monoxide(CO). Other element such as silicon, phosphorous, sulfur and manganese are transferred to a slag phase.In the EAF steelmaking process the chemical reactions are similar but gen
9、erally less extensive.,18,Oxygen Steelmaking Processes,The oxygen steelmaking process rapidly refines a charge of molten pig iron and ambient scrap into steel of a desired carbon and temperature using high purity oxygen. Steel is made in discrete batches called heats. The furnace or converter is a b
10、arrel shaped, open topped, refractory lined vessel that can rotate on a horizontal trunnion axis.,19,Oxygen Steelmaking Processes,The basic operational steps of the process(BOF) are shown shematically in Fig9.1.,20,Oxygen Steelmaking Processes,The overall purpose of this process is to reduce the car
11、bon from about 4% to less than 1% (usually less than 0.1%), to reduce or control the sulfur and phosphorus, and finally, to raise the temperature of the liquid steel made from scrap and liquid hot metal to approximately 1635(2975F).,21,Oxygen Steelmaking Processes,A typical configuration is to produ
12、ce a 250 ton (220 metric ton) heat about every 45 minutes, the range is approximately 30 to 65 minutes. The major event times for the process are summarized below in Table 9.1.,22,Oxygen Steelmaking Processes,23,Oxygen Steelmaking Processes,These event times, temperatures, and chemistries vary consi
13、derably by both chance and intent. The required quantities of hot metal, scrap, oxygen, and fluxes vary according to their chemical compositions and temperatures, and to the desired chemistry and temperature of the steel to be tapped. Fluxes are minerals added early in the oxygen blow, to control su
14、lfur and phosphorus and to control erosion of the furnace refractory lining.,24,Oxygen Steelmaking Processes,Input process variations such as analytical(hot metal, scrap, flux and alloy) and measurement (weighing and temperature) errors contribute to the chemical, thermal and time variations of the
15、process.The energy required to raise the fluxes, scrap and hot metal to steelmaking temperature is provided by oxidation of various elements in the charge materials.,25,Oxygen Steelmaking Processes,The principal elements are iron, silicon, carbon, manganese and phosphorus, with lesser amounts of the
16、 liquid pig iron and the intense stirring provided when the oxygen jet is introduced, contribute to the fast oxidation (burning or combustion) of these elements and a resultant rapid, large energy release.,26,Oxygen Steelmaking Processes,Silicon, manganese, iron and phosphorus form oxides which in combination with the fluxes, create a liquid slag. The vigorous stirring fosters a speedy reaction and enables the transfer of energy to the slag and steel bath.Carbon, when oxidized, leaves the process in gaseous form, principally as carbon monoxide.,
