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A method of producing direct reduced iron (DRI) in a shaft furnace, passivated in situ as a result of its high iron carbide content, is presently being commercialised by Danieli & Co.
Electric steelmaking is gaining increasing importance in global steel production. In recent years much effort has been devoted to improving the process and particular attention has been paid to the choice of the most suitable charge mix. The usual raw material is scrap, but for the most demanding steel grades - those required for flat products - it is necessary to supply virgin iron units to control the amount of tramp elements in the liquid steel.
Traditionally pig iron has been used for this purpose but recently direct reduced iron (DRI) and hot briquetted iron (HBI) have shown their competitiveness.
From a chemical point of view, pig iron may be considered as an ideal feedstock because of its high iron content (96%+) and its content of bonded carbon. Nevertheless, its price can be unstable. Moreover there is no provision for an increase in world pig iron production because of the costs required to install new blast furnaces or to upgrade existing ones.
Danieli, exploiting its long expertise in installing EAF based mini mills, and its strong R&D, is ready to introduce a modified DRI material, which it calls, Supermetallic(TM) (abbreviated to SPM). This shares many of the advantages of pig iron, such as high metallisation - and hence high yield, and controlled carbon content. Unlike pig iron, SPM can be the only constituent of the EAF charge and this contributes to its attractive 'Value in Use'.
SPM production is carried out using the patented Danarex(TM) technology. Thanks to the peculiarity of this shaft reactor, it is possible to obtain a fully passivated product safe to store and handle without briquetting, this affording a remarkable saving in production cost.
DRI AS FEED
Presently DRI/HBI provides 13-14% of the world EAF feedstock. This annual consumption is about 43Mt, while the installed world gross capacity for DRI is higher at about 49Mt/y (some plants are running under their nominal capacity and others are shutdown). Assuming the same future share of DRI in EAF feedstock, the expected consumption in 2006 will be 55Mt/y[11] (a 3.8% growth...