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The effect of carbon in slag on steel reoxidation by CaO-SiO 2-Al 2 O 3-MgO-MnO-Fe t O slags
| Content Provider | Semantic Scholar |
|---|---|
| Author | Kim, Jaehwan Shim, S.-C. |
| Copyright Year | 2004 |
| Abstract | There has been an increasing demand for ultra-clean highgrade steels with minimum amounts of inclusions. The reduction of oxide inclusions is performed by flotation into the slag phase and by prevention of Al reoxidation in steel during ladle refining operations. Steel reoxidation by reducible oxides in slag, such as FetO and MnO, induces the formation of fine inclusions, which are not easily floatable during the refining stage. Therefore, for the production of ultra-clean steels, it is important to decrease the activity of the reducible oxides causing the steel reoxidation. In ladle refining processes, (FetO + MnO) content in slag should be lowered less than 1 wt% for the effective desulphurization and the suppression of the steel reoxidation. This brings about an increase in production cost and processing time because of the excessive injection of raw materials. Decreasing the activity coefficients of FetO and MnO is an alternative solution for controlling the activities of the reducible oxides while maintaining high (FetO + MnO) content. The slag phase will contain a certain degree of carbon. Previous research confirms that carbon in Cr2O3 containing slag reduces the activity coefficients of FetO and MnO1. It is necessary to investigate in more detail the activity behaviours of reducible oxides in carbon containing slags to minimize steel reoxidation. However, studies on carbon containing slags have focused mainly on solubility and stable forms of carbon in slag2–6. To date there have been no reports on the effect of carbon in slag on the activities of FetO and MnO. So, in this work, the thermodynamic equilibria between CaO-SiO2-Al2O3-MgO-MnO-FetO slag systems and liquid iron were been carried out in MgO crucible at 1873 K varying the carbon content in slag. The activity coefficients of FetO and MnO, which affect the steel cleanliness, will be discussed, stressing the effect of carbon in slag. To clarify the stable form of carbon in slag, XPS (X-ray photoelectron spectroscopy) was introduced. Park et al. showed the possibility of XPS application for the analysis of carbon in iron ore7. From the XPS results, we will ascertain the dominant parameters affecting the activity coefficients of FetO and MnO. Finally, this paper will suggest an application method of the present results to actual ladle refining processes in order to enhance the steel cleanliness under the condition of high (FetO + MnO) content. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://www.saimm.co.za/Conferences/Slags2004/044_Suk.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
