1、Chapter 2 钢铁冶金 Ores and mining Iron making Steelmaking,钢铁冶金在国民经济中的地位材料、能源、信息是现代社会发展的三大支柱产业。而钢铁材料又是材料中的重中之重。 钢铁材料性能优良 力学性能和物理化学性能 加工性能目前尚不能为其它金属材料所代替。 铁的蕴藏量极为丰富 钢铁的生产成本比其它金属低得多。,2.1 Ores and mining,铁矿石,炼铁坯料,铁锭,钢锭及钢管,Iron Ore treatments 铁矿石生产,地壳中元素储量,Iron ores are found all over the world, but their d
2、istribution is unequal.,Underground mining,乌克兰的露天采矿场景,Open pit mining (露天开采） showing a 12.25 inch rotary drill in the foreground.,Giant Coal Bucket,There are several types of iron ores which are listed in Table 1.,The refined ore is enriched（富含） to being over 60 percent iron by these methods and is
3、often formed into pellets（小球） before shipment.,Iron pellets produced by direct reduction,2.2 高炉炼铁 Ironmaking in Blast furnace 2-2-1 高炉炼铁的生产工艺过程及特点1.高炉炼铁的本质2.生产工艺过程及特点,高炉冶炼过程：是一个连续的、大规模的、高温生产过程。特点：繁重的、连续的、大规模的高温生产。,高炉出铁场景,2-2-2 高炉炼铁原料和燃料1.炼铁原料：铁矿石 2.熔剂：石灰石 3.燃料：焦炭,.,炼铁原料 Raw materials for ironmaking,
4、三种原料所起的作用？ 2吨铁矿石 + 1吨焦炭 + 0.5吨石灰石 1吨 生铁,2-2-3 高炉冶炼理化过程 The operation of the blast furnace is called reduction. 1）燃料的燃烧：fuel (coke) combustion C + O2 CO2 generating high temperature: 16001750 CO2 + C CO,2）铁的还原： Iron oxides can be reduced with CO. This is a process in which oxygen is removed from a co
5、mpound, in this case, iron ore. The oxygen is combined with carbon to form carbon dioxide (CO2), and the metallic iron is released from its oxide state, leaving molten iron with about 4 percent carbon. Fe2O3, Fe3O4, FeO react with CO Fe 被还原成铁,3）铁的增碳 4）其它元素的还原：Mn、Si、P(phosphorus)These elements can be
6、 reduced with carbon. 5) 脱硫 desulfurization : FeS + CaO CaS + FeO CaS can be removed with slag. 6) 造渣 slag formation： 是矿石中的废料、燃料中的灰分与溶剂的熔合过程。 熔合后的产物就是渣。Important roles of slag : protection for metal,2-2-4 高炉产品 1）pig iron:炼钢生铁、铸造生铁、特种生铁 纯铁 Pure iron is a soft, easily bent metal having limited usefuln
7、ess. 2）gases：含有CO、CO2、CH4、H2、N2 as fuels to heat furnaces and for daily use 3）slag: for making cement, bricks and paving This slag is ground up and used as an aggregate for concrete products and asphaltic concrete roads.,2-3 Steelmaking Steel is iron combined or alloyed with other metals or nonmetal
8、s such as carbon.,2-3-1 炼钢用的原材料 炼钢实质金属料：非金属料2-3-2 炼钢方法 1.转炉炼钢法 2.平炉炼钢法 3.电炉炼钢法,1. 钢中锰、硫的作用 Plain carbon steel actually contains a small amount of the metal manganese as a scavenger to remove unwanted oxygen and to control sulfur. Sulfur is difficult to remove from steel, and iron sulfide (the form i
9、t naturally takes in iron) is deleterious to steel, but if manganese is present, it combines more readily than iron with the sulfur, forming manganese sulfide, which is not harmful to the steel. For this reason no steel is made without manganese.,2.钢中碳元素的作用 The element carbon causes steel to be such
10、 a useful material since it can be hardened by heat treatments. Only a small amount of carbon is needed to make steel: 低碳钢（0.200.30 ） 0.20 percent to 0.30 percent for low carbon steel, 中碳钢（0.400.60 ） 0.40 percent to 0.60 percent for medium carbon steel, 高碳钢（0.601.0） 0.60 percent to over 1 percent fo
11、r high carbon steel.,Steel can contain up to 2 percent carbon, but over that amount it is considered to be cast iron, in which excess carbon forms graphite. （C2 铸铁，其中的碳以石墨形式存在）3.钢中的合金元素 Steel can be given many different and useful properties by alloying the iron with other metals such as chromium, n
12、ickel, tungsten, molybdenum, vanadium, and titanium and with nonmetals such as boron and silicon.,2-3-3 炼钢的实质,Decarbonization（脱碳） Desulfuration（脱硫） Deoxidation （脱氧） Alloying （合金化）,1). Decarbonization（脱碳）: main reaction in steelmaking By means of direct oxidation: C + O2 2CO indirect oxidation: 2Fe +
13、 O2 2FeO C + FeO Fe + CO Carbon makes steel strong but too much of C is harmful.,carbon steel,cast iron over 2% of C,2). Desulfuration（脱硫）: FeS + CaO CaS + FeO CaS can be removed with slag. but C can help reduce FeO to form Fe in order to prevent opposite reaction: FeS + CaO + C Fe + CaS + CO * 锰亦能脱
14、硫，形成硫化锰 钢中必不可少的元素,3). Deoxidation （脱氧） 目的：用氧化剂除去钢液中残留的氧化亚铁中的氧，还原出铁，脱氧剂则被氧化，脱氧产物聚集上浮到钢液表面。 Me + FeO MeO + Fe 4). Alloying （合金化）Some elements are added to improve the properties of steel.,5. Steelmaking Methods 炼钢方法,steelmaking methods,These furnaces are not used interchangeably. Each system requires
15、different energy sources and different sources of raw materials. The kind of facility is therefore chosen for economic reasons and the availability of raw materials and energy sources.,The basic oxygen furnace (BOF) is designed to produce a high quality steel in a relatively short time, about one 20
16、0- to 300-ton heat (a single batch) per hour as compared to the 100 to 375 tons per heat in 5 to 8 hours of the open hearth process. The principal raw material used in the basic oxygen furnace is molten pig iron from the blast furnace.,The basic oxygen furnace (BOF) 转炉炼钢法,Molten iron from the blast
17、furnace is charged into one of two basic oxygen furnaces at Bethlehem Steel Corporations Bethlehem, Pa. plant. After the charge has been completed, the vessel will return to its upright position for the oxygen “blow“ during which the blast furnace iron, mixed with scrap and selected additives, will
18、be refined into steel.,One of two basic oxygen furnaces is charged with scrap. The charging machine empties scrap into the vessel before the hot metal is added. In addition to positioning and charging the loaded boxes of scrap, the charging machine also positions the heat shield that is utilized for
19、 testing during furnace turndowns.,Heat shield protects members of the basic oxygen furnace crew who are taking steel samples and a temperature measurement from the bath of molten metal. The steel sample is sent by pneumatic tube to the basic oxygen furnace (BOF) shop spectrometer laboratory for ana
20、lysis (Bethlehem Steel Corporation).,Open-hearth furnace 平炉炼钢法Open-hearth furnaces get their name from a shallowsteelmaking area called a hearth that is exposed or open to a blast of flames that alternately sweeps across the hearth from one end for a period of time and then from the other end of the
21、 furnace .,The furnace is charged (loaded) from a door in the side facing the charging floor Theoretically, an open hearth furnace can operate with blast furnace iron alone or steel scrap alone, but most operations use both in about equal proportions, varying with the price of scrap and the availabi
22、lity of molten iron.,Electric furnace 电炉炼钢法Electric furnaces lined with refractory (heat-resistant ceramic) materials produce a high-quality steel from selected scrap, lime, and mill scale. Most alloy and tool steels are made in electric furnaces, but for these high-quality steels selected scrap mus
23、t be used.,Electric furnaces are most competitive where low-cost electricity is available and where very little coal or iron ore is found. The charge is melted by the arcing between carbon electrodes and metal scrap. In some cases, the electrodes are 2 feet in diameter and 24 feet long.,Advanced Mel
24、ting and Refining 先进的熔炼及精练方法 Standard steelmaking furnaces are not capable of removing all impurities and unwanted gases. When higher grade specialty steels are needed, further processing is necessary. There are two types of these refining vessels, those that receive molten metal from conventional steel furnaces and those that remelt to refine it .,Vacuum Ladle Degassing Argon-Oxygen Decarburization Electron Beam Melting,
