This article has multiple issues. Cyclone technology had already been iron making process pdf successfully in different industrial, chemical processes
This article has multiple issues. Cyclone technology had already been iron making process pdf successfully in different industrial, chemical processes and designers at Hoogovens thought it might be a strategy for improvement for their process.
However, at the time they couldn’t get it to work properly and the experiment was quickly abandoned. The first serious revival came in 1986, when Hoogovens sought a method of producing steel without having to produce iron ore agglomerates such as pellets and sinter. At that time the desire was mostly a cost-cutting measure in order to make the process cheaper in trying economic times. The trying times did not last however and the project was put on the back burner until the early 1990s. West that produced cokes from coal were reaching the end of their economic life.
Hoogovens started putting more effort into the cyclone technology as a solution to this problem and a test facility for the cyclone part proved capable of producing twenty tons of pig iron per hour. The steep drop in prices of commodities around 1999 caused the project to be halted. ULCOS consortium was founded as a result and in the period 2005-2007 the cyclone technology was selected as one of four high-potential technologies. A theoretical answer was found to the earlier problems of the post-cyclone part of the cyclone furnace in the form of a Smelting Reduction Vessel and the Rio Tinto Group had industrial-scale experience with the required process, called HIsmelt. An agreement between them and ULCOS added the HIsmelt technology to the cyclone furnace and the result was the HIsarna process. The pilot plant has a capacity of producing 65,000 tons of pig iron per year.
A first campaign of experiments was completed in spring 2011, which was followed by three more successful experimental campaigns. The most recent campaign finished in June 2014 and a new campaign is scheduled for 2016. The HIsarna process is a smelting reduction process with two directly coupled process stages in which the production of liquid pig iron takes place. The HIsarna plant is shaped like a wine bottle: a “bottle” at the bottom and a thin “neck” at the top. The molten iron droplets then drip down the furnace wall to the place where the “neck” widens into the “bottle”. Here the droplets fall from the wall into the molten slag, which sits on top of the liquid iron bath in the bottom of the furnace. Between the cyclone and the slag layer, oxygen is injected through water cooled lances to generate heat by partly combusting the gasses being released from the final reduction reaction step that takes place in the slag.
Powder coal is injected into the slag layer, again through water cooled lances. Both layers can be tapped individually and the pig iron can be used immediately in the remainder of the basic oxygen steelmaking process. In a technical sense, the advantage of the HIsarna process is that it removes the step of creating iron ore agglomerates and coke to create a porous burden for the blast furnace. In the traditional process one cannot use powdered coal alone since the strength of the coke is required to support the burden. By comparison, in HIsarna, the powder form of the coal and ore are an advantage because the increased surface area improves the speed and quality of the reduction reaction in the cyclone. The main advantages of the process are derived from those mentioned above, however: the fact that the separate steps of creating ore agglomerates and cokes disappear from the process makes the process more energy efficient and reduces its carbon footprint.