Raman Structure Investigations of CaO-MgO-Al 2 O 3 -SiO 2 -CrO x and Its Correlation with Sulfide Capacity
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has been known that the addition of polyvalent cations to a slag system leads to structural relaxation in the silicate matrix, and consequently, would result in a change in slag properties. In the past decades, influence of Fe2+ and Fe3+ on the structure of silicate melts has been investigated in view of its implications in ferrous and non-ferrous metallurgy. Due to the presence of Fe2+ and Fe3+, the thermophysical and thermochemical properties were found to vary along with the ratio of Fe2+/Fe3+. With the rapid improvements in instrumentation, structure investigations of silicate melts were focused upon by means of techniques like Raman spectroscopy, IR, MO¨ssbauer spectroscopy, as well as X-ray near edge spectroscopy (XANES). For example, Nagata et al.[1] have investigated by MO¨ssbauer spectroscopy the change of oxidation states and coordination structures of iron ions in liquid CaO-SiO2-Fe2O3 slags during the equilibration process.
LIJUN WANG, Associate Professor, YAXIAN WANG, QI WANG, Master Students, and KUOCHIH CHOU, Professor, are with the State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, Beijing 100083, P.R. China, and also with the School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083, P.R. China Contact e-mail: [email protected] Manuscript submitted on June 25, 2015. Article published online September 28, 2015. 10—VOLUME 47B, FEBRUARY 2016
With regard to chromium in slags, the information is somewhat limited with respect to in thermochemical and thermophysical properties. In the present work, an attempt has been made to understand the impact of the redox equilibrium ratio of Cr2+/Cr3+ on the slag structure, which, in turn, would be reflected in macrothermochemical property of the slag system. In the present work, sulfide capacities of the same slag system are compared with Raman spectroscopy results, and the structure-property link is discussed. CaCO3 powder (supplied by Sinopharm Chemical Reagent, AR grade) was calcined at 1373 K (1100 C) for 6 hours to decompose any carbonate and hydroxide. SiO2, MgO, Al2O3, and Cr2O3 (all from Sinopharm Chemical Reagent, AR grade) were heated at 873 K (600 C) for 6 hours to remove moisture and stored in a desiccator with phosphorus pentoxide as the dehydrant. These components were mixed in required proportions and ground together in an agate mortar. The compositions of the slag samples are presented in Table I. One gram of sample was used for each experimental run. The slag samples in Pt crucibles were positioned in alumina sample holders (90 9 20 9 15 mm) and put into the temperature even zone in horizontal MoSi2 furnace. Mixture of each sample was equilibrated with purified Ar-CO-CO2-SO2 gas at 1873 K (1600 C) for 6 hours and quenched subsequently. The transparent slag samples thus synthesized were subjected to LECO and Raman spectrum analysis. The quenched slag was subjected to Raman spectroscopy measurements. Raman spectroscopy analysis was carried out on a micr
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