Abstract
The activities of chromium oxides in a CaO-SiO2-CrO x slag system were determined with the electromotive force (EMF) method by equilibrating with metallic chromium at 1873 K. The effect of slag basicity on the activity coefficients of CrO and CrO1.5 was analyzed. The results showed that increasing the slag basicity increased the activity coefficient of CrO; however, the effect on that of CrO1.5 was not significant. The oxidation state of chromium in CaO-SiO2-CrO x slags was systematically investigated at both 1873 and 1863 K. It was found that divalent and trivalent chromium coexists in the slags. Divalent chromium oxide is favored, instead of trivalent chromium oxide, because of low slag basicity and low oxygen potential. It was concluded that the oxidation state of chromium in the slag system varied greatly from almost pure “CrO” to a composition corresponding to Cr3O4. In addition, the thermodynamic data in the slag system were assessed based on the regular solution model to mathematically describe the activities of chromium oxides in the slags. A group of model parameters were obtained. The calculated activities of chromium oxides were comparable to the measured data.
Similar content being viewed by others
References
M.J.U.T. Van Wijngaarden: MINTEK Report No. M365, Council for Mineral Technology, Randburg, Dec. 1988.
E.B. Pretorius and A. Muan: J. Am. Ceram. Soc., 1992, vol. 75 (6), pp. 1364–77.
M.G. Frohberg and K. Richter: Arch. Eisenhüttenwes., 1968, vol. 39, pp. 799–802.
K. Morita, A. Inoue, N. Takayama, and N. Sano: Tetsu-to-Hagané, 1988, vol. 74 (6) pp. 999–1005.
C.W. McCoy and W.O. Philbrook: Trans. TMS-AIME, 1958, Apr., pp. 226–35.
E.B. Pretorius, R. Snellgrove, and A. Muan: J. Am. Ceram. Soc., 1992, vol. 75 (6), pp. 1378–81.
K. Morita, M. Mori, M. Guo, T. Ikagawa, and N. Sano: Steel Res., 1999, vol. 70 (8–9), pp. 319–24.
W. Pei and O. Wijk: Scand. J. Metall., 1994, vol. 23, pp. 228–35.
M. Maeda and N. Sano: Tetsu-to-Hagané, 1982, vol. 68(7), pp. 759–66.
K. Schwerdtfeger and A. Mirzayousef-Jadid: Belton Memorial Symposium Proc., Sydney, Australia, Jan. 10–11, 2000, ISS, Warrendale, PA, pp. 108–19.
Y. Xiao: Acta Polytechnica Scandinavica, 1993, pp. 1–78.
Y. Xiao, M. Reuter, and L. Holappa: Proc. 6th Int. Conf. on Molten Slags, Fluxes and Salts, Stockholm, Sweden-Helsinki, Finland, June 12–17, 2000, S. Seetharaman and Du Sichen, eds., Stockholm, CD Rom, Paper No. 089, pp. 1–77.
J.P.R. de Villiers and A. Muan: J. Am. Ceram. Soc., 1992, vol. 75 (6), pp. 1333–41.
E.T. Turkdogan: Physical Chemistry of High Temperature Technology, Academic Press, London, 1980, p. 10.
M. Iwase, E. Ichise, M. Takeuchi, and T. Yamasaki: Trans. Jpn. Inst. Met., 1984, vol. 25 (1), pp. 43–52.
N.Y. Toker: Ph.D. Thesis, The Pennsylvania State University, University Park, PA, 1978.
F. Körber and W. Oelsen: Mitt. Kais.-Wilh.-Inst. Eisenforschg. Düsseld., 1935, vol. 17 (21), pp. 231–45.
G.W. Healy and J.C. Schottmiller: Trans. TMS-AIME, 1964, vol. 230 (3), pp. 420–25.
J. Lumsden: Physical Chemistry of Process Metallurgy, G.R. St Pierre, ed., AIME, Interscience, New York, 1961, part 1, p. 165.
R.A. Sharma and F.D. Richardson: J. Iron Steel Inst., 1962, vol. 200, pp. 373–79.
J.D. Baird and J. Taylor: Trans. Faraday Soc., 1958, vol. 54, pp. 526–39.
R.H. Rein and J. Chipman: Trans. TMS-AIME, 1965, vol. 233, pp. 415–25.
D.A.R. Kay and J. Taylor: Trans. Faraday Soc., 1960, vol. 56, pp. 1372–86.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Xiao, Y., Reuter, M.A. & Holappa, L. Oxidation state and activities of chromium oxides in CaO-SiO2-CrOx slag system. Metall Mater Trans B 33, 595–603 (2002). https://doi.org/10.1007/s11663-002-0039-9
Received:
Issue Date:
DOI: https://doi.org/10.1007/s11663-002-0039-9