Study on Reaction Mechanism of Reducing Dephosphorization of Fe-Ni-Si Melt by CaO-CaF 2 Slag
- PDF / 579,112 Bytes
- 3 Pages / 593.972 x 792 pts Page_size
- 95 Downloads / 152 Views
mportant tasks during the smelting of stainless steel, dephosphorization (de-P) continuously gains much attention, since the conventional oxidizing de-P technique could lead to the oxidation of chrome. In 2013, a new process of producing nickel chrome stainless steel by the electro-silicothemic method was proposed, considering the high SiO2 content in the laterite nickel ore.[1] The high silicon Fe-Ni-Si alloy is prepared first, and then the nickel chrome stainless steel is produced by the reaction between Fe-Si-Ni melt and chrome ore. According to the new process, the reducing de-P is finished in the Fe-Ni-Si melt, which effectively avoid the disadvantages of oxidizing de-P in the presence of Cr. At present, many studies have been done on the reducing de-P of Cr PEI-XIAN CHEN, Doctoral Student, GUO-HUA ZHANG, Associate Professor, and SHAO-JUN CHU, Professor, are with the State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, Beijing, China and also with the School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, China. Contact e-mail: [email protected] Manuscript submitted April 30, 2015. Article published online October 6, 2015. 16—VOLUME 47B, FEBRUARY 2016
bearing steel,[2,3] Fe-Mn-Si alloy,[4,5] and Fe-Cr-Si alloy,[6] etc., whereas there is no related work on Fe-Ni-Si system. Furthermore, detailed discussion is also needed on the de-P mechanism of the high silicon ferroalloy melt. The present investigation was carried out based on these points. The Fe-Ni-Si melts with different contents of silicon were first prepared by smelting Ni-Fe alloy (Ni/ Fe = 0.1, w[Si]95 mass pct) in the medium frequency induction furnace. For each experiment, 2 kg alloy and 0.2 kg CaO-saturated CaO-40 mass pct CaF2 slag were held in the MgO crucible. The melt temperature was controlled to be 1873 K (1600 °C) and monitored by a Pt-6mass pct Ph/ Pt-30mass pct Rh thermocouple sheathed with an alumina tube immersed in the melt. During the experiment, alloy and slag were sampled by the quart tube and steel rod, respectively. X-ray fluorescence (Shimazu, XRF-1800) analyses were used to measure the phosphorus content in the alloy. After being quickly quenched, the slag sample was rapidly crushed and preserved in a desiccator for XRD (PANalytical, PW 3040-X’Pert Pro) analyses to detect its phase compositions. The preliminary experiments were first done in order to determine the reaction time. After adding slag to alloy melt, the change of phosphorus content with time was shown in Figure 1, from which it can be seen that the de-P process was almost finished after reacting for 15 minutes. Therefore, the reaction time was determined to be 20 minutes as investigating the variation of de-P efficiency with silicon content in alloy melt. In this study, the de-P efficiency gdeP was determined as follows, gdeP ¼
w½P0 w½Pf w½P0
100 pct
½1
where the superscripts ‘‘0’’ and ‘‘f’’ represent the content of phosphorus before and after the de-P process, respectively. The composi
Data Loading...
