The ironmaking blast furnace

For the purposes of discussion, it is useful to consider the blast furnace as operating in four consecutive zones. At the fourtlr, bottom, zone the oxidation of coke at the tuyeres canres the temperamre to levels in excess of 2100 K. The next zone, which operates in the temperature range 1600-1900 K is where the liquid metal and slag are formed. The second zone, sometimes referred to as the thermal reserve zone, is where the CO2-C reaction to produce CO, the so-called solution reaction mainly occurs, and die reduction of h on is completed. In the first zone, at the top of the furnace, tire primaty reduction of 

A heat balance for the blast furnace produced by Michard et al. (1967), shows tlrat nearly 80% of the heat generated in tire furnace is used to produce and melt the iron and slag. The gas which emerges from tire first zone is further used to pre-heat the ah injected in the tuyeres in large stoves. The process thus runs at a vety high efficiency, botlr from tire point of view of tire amount of metal and slag produced and from the heat generation and utilization. 

It is the presence of a large amount of FeO in the lead-zinc furnace slag which produces a liquid at 1550 K, compared with the higher melting, virtually iron-free, slag in the odrer furnace. 

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The most important industrial reaction of this kind occurs in the ironmaking blast furnace in which iron oxide ore is reduced by carbon in the form of coke. The mixture is heated by the combustion of part of the coke input in air to produce temperatures as high as 2000 K. The reduction reaction is carried out via the gas phase by the reaction... 

The reduction of iron ores is carried out on the large industrial scale in the ironmaking blast furnace, where CO is the reducing gas and the product is liquid... 

A model for studying the formation of burden layers in the ironmaking blast furnace has been developed on the basis of a single-point measurement of the stock level by radar. The model, which, furthermore, makes use of geometrical conditions of the problem at hand, has been kept conceptually simple so it can be applied to track the burden distribution in operating blast furnace. The model has been tuned to data from a... 

The lead blast furnace operates at a lower temperature than the iron blast furnace, die temperature at the tuyeres being around 1600K as opposed to 1900K in the ironmaking furnace (see p. 333) and this produces a gas in which die incoming air is not completely reduced to CO and N2, as much as one per cent oxygen being found in the hearth gas. 

Ironmaking in the United States did not expand rapidly until after the Revolutionary War. Then, as the colonists moved westward, the need for iron prompted the estabUshment of ironworks near the new settiements. A blast furnace built by Jacob Anschut2 in 1796 was the beginning of the iron and steel center in Pittsburgh, Pennsylvania. 

Ironmaking refers to those processes which reduce iron oxides to iron. By the nature of the processes, the iron produced usually contains carbon and/or other impurities which are removed in downstream processing. There are three principal categories of ironmaking processes, in order of commercial importance blast furnace, direct reduction, and direct smelting. 

Blast Furnace. The blast furnace is the predominant method for making iron. Estabhshed for centuries as the premier ironmaking process, blast furnace ironmaking both enabled and profited from the Industrial Revolution. Although the fundamental principles of operation are unchanged, the blast furnace has evolved into a highly efficient and productive process. 

The blast furnace (Fig. A, opposite) remains the basis of ironmaking though the scale, if not the principle, has changed considerably since the eighteenth century the largest modem blast furnaces have hearths 14 m in diameter and produce up to 10000 tonnes of iron daily. 

HyL [Hojalata y Lamina] A direct reduction ironmaking process in which pellets or lumps of ore are reduced in a batch reactor using a mixture of hydrogen and carbon monoxide. Used in countries which have natural gas and cannot afford to invest in blast furnaces. Developed in the 1950s in Mexico by the Hojalata y Lamina Steel Company (now Hylsa) and the MW Kellogg Company, and now operated in nine other countries too. See DR. 

ITmk3 [mark 3 indicates that this is a third generation ironmaking process, marks one and two being the blast furnace and direct reduction] A modification of the Fastmet process, for making molten iron. Pelleted iron ore fines are reduced with a solid reductant. The iron in the reduced pellets separates as molten metal, uncontaminated by gangue. Developed in 1996 by Midrex Corporation and Kobe Steel. Commercialization is expected in 2003. 

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