Investigations of the Dephosphorization of Liquid Iron Solution Containing Chromium and Nickel
- PDF / 575,557 Bytes
- 8 Pages / 593.972 x 792 pts Page_size
- 40 Downloads / 187 Views
RODUCTION
THE problem of reducing the phosphorus level in iron solutions containing chromium and nickel has been studied by numerous investigators[1–13] because chromium steels may be produced using iron ores containing chromium compounds as charge materials. However, in such cases, the problem of removing phosphorus from the metal bath during the refining process arises. The dephosphorization of liquid iron in the presence of high Cr concentration is important not only for stainless steels but also for the production of low-phosphorus ferrochrome. In conventional stainless steel technologies, the phosphorus problem is generally related not only to metallic charge materials, such as scrap or alloys, but also to the low quality of slag-forming materials, mainly lime. Independently of, sometimes problematic charge materials, new technological techniques coming into focus recently have solved the high phosphorus problems. In stainless steel technologies such as duplex, which comprises an electric arc furnace (EAF) and argon oxygen decarburization (AOD) converter, and triplex, which consists of an EAF and AOD-lance (AOD-L)/metal refining process-lance (MRP-L) converter and vacuum oxygen decarburization (VOD) plant, the phosphorus problem seems to be mainly caused by the quality of scrap and lime. But the most up-to-date trends in MIROSLAW KARBOWNICZEK, Professor, and ELZBIETA KAWECKA-CEBULA, Assistant Professor, are with the Department of Metal Engineering and Industrial Computer Science, AGH University of Science and Technology, Krakow 30-150, Poland. Contact e-mail: [email protected] JAN REICHEL, Senior Researcher, is with SMS Siemag AG, Du¨sseldorf 40237, Germany. Manuscript submitted October 11, 2010. Article published online January 14, 2012. 554—VOLUME 43B, JUNE 2012
stainless steel production—aiming at the reduction of production costs—substitute steel scrap by hot metal coming from the reduction of iron-chromium ores, which requires more extensive dephosphorization. For the dephosphorization of a liquid iron solution containing chromium, the slag should exhibit good dephosphorizing properties, as either chromium or chromium oxides, which enter the slag during the refining process and decrease the dephosphorization efficiency of the process to an appreciable extent. The best dephosphorizing properties cause slags to be formed on the base of oxides and halides of barium or calcium.[2–4,7–10,12] The phosphate capacity of the slags containing barium compounds is higher, so the dephosphorization becomes more effective. As barium compounds are more expensive, whereas those of calcium are more available, the slags based on CaOCaF2 are now mainly considered. In most metallurgical processes, it is important to assure the low viscosity of slags to enable the rapid transport of mass and heat. One of the most common means of decreasing the viscosities of slags and their melting temperatures is the addition of some fluorite to the slag.[14] It is especially important for cases of the dephosphorization or desulfurization[15] of pi
Data Loading...
