Abstract
Magnesium is recovered from partially oxidized scrap alloy by combining refining and solid oxide membrane (SOM) electrolysis. In this combined process, a molten salt eutectic flux (45 wt.% MgF2–55 wt.% CaF2) containing 10 wt.% MgO and 2 wt.% YF3 was used as the medium for magnesium recovery. During refining, magnesium and its oxide are dissolved from the scrap into the molten flux. Forming gas is bubbled through the flux and the dissolved magnesium is removed via the gas phase and condensed in a separate condenser at a lower temperature. The molten flux has a finite solubility for magnesium and acts as a selective medium for magnesium dissolution, but not aluminum or iron, and therefore the magnesium recovered has high purity. After refining, SOM electrolysis is performed in the same reactor to enable electrolysis of the dissolved magnesium oxide in the molten flux producing magnesium at the cathode and oxygen at the SOM anode. During SOM electrolysis, it is necessary to decrease the concentration of the dissolved magnesium in the flux to improve the faradaic current efficiency and prevent degradation of the SOM. Thus, for both refining and SOM electrolysis, it is very important to measure and control the magnesium solubility in the molten flux. High magnesium solubility facilitates refining whereas lower solubility benefits the SOM electrolysis process. Computational fluid dynamics modeling was employed to simulate the flow behavior of the flux stirred by the forming gas. Based on the modeling results, an optimized design of the stirring tubes and its placement in the flux are determined for efficiently removing the dissolved magnesium and also increasing the efficiency of the SOM electrolysis process.
Similar content being viewed by others
References
R.E. Brown, Fourth International Symposium on Recycling of Metals and Engineered Materials, ed. D.L. Donald Jr., J.C. Daley, and R.L. Stephens (Warrendale, PA: TMS, 2000), pp. 1317–1329.
G. Hanko, H. Antrekowitsch, and P. Ebner, JOM 54 (2), 51 (2002).
T.M. Pollock, Science 328, 986 (2010).
B.L. Mordike and T. Ebert, Mat. Sci. Eng. A 302, 37 (2001).
W.W. Jian, G.M. Cheng, W.Z. Xu, H. Yuan, M.H. Tsai, Q.D. Wang, C.C. Koch, Y.T. Zhu, and S.N. Mathaudhu, Mater. Res. Lett. (2013).
United States Automotive Materials Partnership (USAMP), Magnesium Vision 2020: A North American Automotive Strategic Vision for Magnesium (Southfield, MI: United States Council for Automotive Research USCAR, 2006).
L. Riopelle, JOM 48 (10), 44 (1996).
A. Tharumarajah and P. Koltun, J. Cleaner Prod. 15, 1007 (2007).
S. Bell, B. David, A. Javaid, and E. Essadiqi, Final Report on Refining Technologies of Magnesium, Report No. 2003–2019(CF) (Ontario, Canada: Davis Laboratories, 2006).
O. Wallevik and J.B. Ronhaug, U.S. patent 5,167,700 (1 December 1992).
H.E. Friedrich and B.L. Mordike, Magnesium Technology: Metallurgy, Design Data, Applications (Berlin: Springer, 2006), p. 638.
S.D. Cramer and B.S. Covino, ASM Handbook, Volume 13A: Corrosion: Fundamentals, Testing, and Protection (Materials Park: ASM International, 2003), p. 693.
T. Zhu, N. Li, X. Mei, A. Yu, and S. Shang, Magnesium Technology 2001, ed. J.N. Hryn (Warrendale, PA: TMS, 2001), pp. 55–60.
X. Guan, P.A. Zink, U.B. Pal, and A.C. Powell, Metall. Mater. Trans. B 44, 261 (2013).
P. Chartrand and A.D. Pelton, Metall. Mater. Trans. A 32, 1385 (2001).
A. Krishnan (Ph.D. dissertation, Boston University, 2006).
E. Gratz (Ph.D. dissertation, Boston University, 2013).
A.S. Dworkin and M.A. Bredig, J. Phys. Chem. 75, 2340 (1971).
E. Gratz, S. Pati, J. Milshtein, A. Powell, and U. Pal, Magnesium Technology 2011, ed. W.H. Sillekens, S.R. Agnew, N.R. Neelameggham, and S.N. Mathaudhu (Warrendale, PA: TMS, 2011), pp. 39–42.
U.B. Pal, D.E. Woolley, and G.B. Kenney, JOM 53 (10), 32 (2001).
A. Krishnan, U.B. Pal, and X.G. Lu, Metall. Mater. Trans. B 36, 463 (2005).
U.B. Pal and A.C. Powell, JOM 59 (5), 44 (2007).
U.B. Pal, JOM 60 (2), 43 (2008).
A.D. Kirshenbaum, J.A. Cahill, and C.S. Stokes, J. Inorg. Nucl. Chem. 15, 297 (1960).
Flow in a bubble column reactor, COMSOL Multiphysics Model Gallery, No. 2160, 2008, http://www.comsol.com/showroom/documentation/model/2160/.
Acknowledgements
This material is based on work supported by the Department of Energy under Award No. DE-EE0003454. The authors would like to thank Dr. Peter A. Zink and Dr. Eric Gratz for helpful discussions.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Guan, X., Pal, U.B. & Powell, A.C. An Environmentally Friendly Process Involving Refining and Membrane-Based Electrolysis for Magnesium Recovery from Partially Oxidized Scrap Alloy. JOM 65, 1285–1292 (2013). https://doi.org/10.1007/s11837-013-0659-3
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11837-013-0659-3