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Use of DRI/HBI and SR/MBF Hot Metal in Iron- and Steelmaking
Published in Amit Chatterjee, Beyond the Blast Furnace, 2017
Because of its chemical and physical properties, sponge iron is becoming an important base material in foundries and is being used increasingly to replace pig iron and scrap in cupolas and induction furnaces. In order to reduce the production cost, many foundries replace pig iron with poor quality and less expensive steel scrap in increasing amounts. Because of the contaminants in scrap, however, this creates problems in meeting the quality requirements of the product, especially in the case of ductile iron grades. One of the major disadvantages of using pig iron in some cases is that it contains titanium (from 0.10 to 0.20%) whenever there is an appreciable amount of titania in the ore and coke is used for the production of hot metal. On the other hand, sponge iron does not contain any titanium, even from titania-bearing iron ores, since the reduction potential in all direct reduction processes is such that titania is not reduced to titanium. Although the effect of titanium can be neutralized by the addition of cerium or misch metal, this leads to extra cost. It has been estimated that the additional requirement of inoculant for every 0.1% titanium would be approximately 0.5 to 1.0 kg/t. In addition to the absence of tramp elements, sponge iron normally contains extremely low levels of sulfur, which allows the saving of magnesium alloys in the production of S.G. iron.
Iron-Making Processes
Published in Ram Pravesh Bhagat, Agglomeration of Iron Ores, 2019
The objective of the process is to produce sponge iron, which is used as a feedstock in steel making. Temperature maintained in the process is usually greater than 1,000°C However, the production cycle is long. The process suffers as more reducing agent is needed, and heat consumption is more than the indirect reduction (BF) route. The process is dependent on the reductant (a) coal and (b) gas and accordingly categorized.
Generation and Composition of Various Metal-Containing Industrial Wastes
Published in Hong Hocheng, Mital Chakankar, Umesh Jadhav, Biohydrometallurgical Recycling of Metals from Industrial Wastes, 2017
Hong Hocheng, Mital Chakankar, Umesh Jadhav
Sponge iron (direct reduced iron) is produced by the reduction of iron ore using noncoking coal with a small quantity of dolomite in a rotary kiln. An electrostatic precipitator (ESP), which is connected to a rotary kiln, produces a metal-containing dust, which accounts for nearly 40% of solid waste generated during the process (Jena et al. 2012).
Coal reactivity and selection for solid-based pre-reduction of sponge iron
Published in International Journal of Coal Preparation and Utilization, 2020
S. Van Wyk, H.W.J.P. Neomagus, J.R. Bunt, R.C. Everson
Solid-based (coal-based) direct reduction of iron ore utilizes coal as a reduction medium inside a rotary kiln to produce sponge iron, which is then further reduced in an electric arc furnace to produce iron metal. During direct pre-reduction, the iron ore is directly reduced without melting the ore. This makes it less energy intensive than conventional blast furnace operations due to the lower operating temperatures (<1200°C) (Feinman 1999; Mashhadi, Rastgoo, and Khaki 2008; Sutherland 2000). In 2015, solid-based direct reduction accounted for 20% of the world direct reduced iron (DRI) production, which is used for the manufacture of steel for construction purposes and the automotive industry (MIDREX 2015). In South Africa, there are numerous rotary kiln-based DRI plants, with a combined capacity that could contribute up to 12% of the global production of coal-based DRI in 2015 (MIDREX 2015). Due to the depletion of South African coal reserves, alternative coals have to be identified and implemented for pre-reduction processes, which could lead to lower pre-reduction inside the rotary kiln, if the selection is not done properly (Hartnady 2010; Sutherland 2000). It is preferred that coals utilized for pre-reduction have certain characteristics to ensure favorable conditions within the kiln. These coals should typically have a low ash yield (5–25 wt.%) and sulfur content (<1 wt.%), a moderate amount of volatiles (25–30 wt.%), and a high initial deformation temperature (>1300°C) (Chatterjee 2010; Mashhadi, Rastgoo, and Khaki 2008; Sarangi and Sarangi 2011; Sutherland 2000). In this study, nine coals that meet the desired requirements, and which are commercially available in the Highveld, Witbank, and Ermelo coalfields, were investigated.