Chrome immobilisation in EAF slags from high-alloy steelmaking - Development of a slag treatment process
EAF slags from stainless steelmaking sometimes have insufficient properties to be used as construction materials for qualified applications. In addition to this, the slags often do not meet environmental requirements due to the leaching rates of chrome. During melting of scrap in the EAF, chrome is oxidised into the slag. Therefore, a reduction step is necessary for both the recovery of chrome and to improve the environmental behaviour of the EAF slag. Nevertheless, it is not possible to reduce all the chrome from the slag in an economic manner. The best practice for oxygen blowing and for reduction of slag in the EAF has been investigated. One possible route to decrease the chrome scorification is the use of carbonated slag formers, thus reducing the oxygen partial pressure in the EAF atmosphere, which has been investigated at another steel shop. Finally, the partners in this research project have developed a method to fix the remaining chrome into stable slag phases after partial reduction of chrome. To meet the demands on a good construction material, the liquid EAF slag has been treated during tapping to improve both the technical properties and the environmental behaviour of the slag by additions which favour the formation of spinel type phases during solidification. To verify the successful results of the laboratory investigations, pilot test runs on an industrial scale have been performed. These operational results at the steel shops confirm the laboratory results. Thus it is possible to treat the liquid EAF slag from stainless steelmaking to produce volume stable construction materials with good environmental behaviour. Even if the slag contains remaining chrome contents, the leaching of chrome is suppressed.
Bibliographic Reference: EUR 22077 EN (2006), 97 pp. Euro: 15
Availability: Katalogue Number: KI-NA-22077-EN-S The paper version can be ordered online and the PDF version downloaded at: http://bookshop.europa.eu
ISBN: ISBN: 92-79-02077-3
Record Number: 200719271 / Last updated on: 2007-07-10
Original language: en
Available languages: en