Abstract
A stepwise carbochlorination-chemical vapor transport (SC-CVT) process is proposed for the rare earth extraction and separation from a mixed bastnaesite-monazite concentrate based on thermodynamic and kinetic analysis using carbon as reductant, chlorine gas as chlorination agent, SiCl4 as defluorination agent, and AlCl3 as vapor complex former. Between 500 °C and 800 °C, apparent activation energy of the carbochlorination within 2 hours changed from 22 to 16 kJ/mol roughly for the initial half hour and final 1 hour, respectively, in the absence of SiCl4; but these values reduced to 15 and 2.1 kJ/mole under 2 kPa of SiCl4 gas. The rare earth chloride yield for 2 hours was 56 to 88 mol pct in the absence of SiCl4 and 92 to 99 mol pct in the presence of SiCl4; but carbochlorination at above 1000 °C yielded a large amount of acid-insoluble residue. This, together with the negligible equilibrium vapor pressure of ThCl4 at below 600 °C, suggests that carbochlorination of the mixed concentrate at temperatures as low as 500 °C in the (Cl2 + SiCl4) atmosphere is suitable for rare earth extraction and thorium-free volatile by-product release, which is different from the conventional Goldschmidt process at 1000 °C to 1200 °C. The CVT reaction of the carbochlorination product was performed at 800 °C for 0.5 hours in the (Cl2 + SiCl4 + AlCl3) atmosphere and then at 1000 °C for 6 hours in the (Cl2 + AlCl3) atmosphere along different temperature gradients, leading to complete thorium removal and efficient rare earth separation, respectively. Their combination allows an efficient and environmentally conscious extraction and separation of rare earth elements from the mixed concentrate.
Similar content being viewed by others
References
C. Zhou: J. Alloys Compounds, 1993, vol. 192, pp. 111–13.
C.K. Gupta and N. Krishnamurthy: Int. Mater. Rev., 1992, vol. 37, pp. 197–248.
G. Adachi: Science of Rare Earths, Kagakudojin, Kyoto, 1999, p. 30.
L. Bai, L. Zhang, and L. Wang: Chin. Rare Earths, 2001, vol. 22, pp. 76–78.
W. Brugger and E. Greinacher: J. Met., 1967, vol. 19, pp. 32–35.
K. Murase, T. Ozaki, K. Machida, and G. Adachi: J. Alloys Compounds, 1996, vol. 233, pp. 96–106.
T. Ozaki, T. Miyazawa, K. Murase, K. Machida, and G. Adachi: J. Alloys Compounds, 1996, vol. 245, pp. 10–14.
T. Ozaki, K. Machida, and G. Adachi: Metall. Mater. Trans. B, 1999, vol. 30B, pp. 45–51.
Z.-C. Wang, J. Yu, and Y.-L. Yu: Bull. Chem. Soc. Jpn., 1996, vol. 69, pp. 2369–74.
Z.-C. Wang, J. Yu, Y.-L. Yu, and Y.-H. Sun: J. Alloys Compounds, 1998, vol. 264, pp. 147–50.
J. Jiang, T. Ozaki, K. Machida, and G. Adachi: J. Alloys Compounds, 1998, vol. 264, pp. 157–63.
T. Ozaki, J. Jiang, K. Murase, K. Machida, and G. Adachi: J. Alloys Compounds, 1998, vol. 265, pp. 125–31.
Z.-C. Wang and Y.-H. Sun: Chem. Lett., 1997, vol. XX, pp. 1113–14.
Y.-H. Sun, Z.-C. Wang, and L. Guo: J. Alloys Compounds, 1998, vol. 269, pp. 88–91.
Y.-H. Sun, Z.-C. Wang, and L. Guo: J. Alloys Compounds, 1999, vol. 285, pp. 73–76.
Y.-H. Sun, Z.-C. Wang, and L. Guo: J. Rare Earths, 1999, vol. 17, pp. 178–81.
Y.-H. Sun, L.-Q. Zhang, Z.-C. Wang, and L. Guo: J. Alloys Compounds, 2000, vol. 306, pp. 146–50.
Z.-C. Wang, Y.-H. Sun, and L. Guo: J. Alloys Compounds, 1999, vol. 287, pp. 109–13.
I. Barin and O. Knacke: Thermochemical Properties of Inorganic Substances, Springer-Verlag, Berlin, 1973, pp. 116, 162, 163, 170, 174, 219, 221, 284, 293, 295, 394, 683, 689, and 744.
I. Barin, O. Knacke, and O. Kubaschewski: Thermochemical Properties of Inorganic Substances, Supplement, Springer-Verlag, Berlin, 1977, pp. 101, 351, 649, and 727.
O.G. Polyachenok: Russ. J. Phys. Chem., 1966, vol. 40, pp. 1203–07.
Z.-C. Wang and L.-S. Wang: Inorg. Chem., 1997, vol. 36, pp. 1536–40.
Z.-C. Wang and L.-S. Wang: J. Alloys Compounds, 1998, vol. 265, pp. 153–59.
S. Boghosian and G.P. Papatheodorou: in Handbook on the Physics and Chemistry of Rare Earths, K.A. Gschneidner, Jr. and L. Eyring, eds., Elsevier Science B.V., Amsterdam, 1996, vol. 23, pp. 435–96.
J. Jiang, T. Ozaki, K. Machida, and G. Adachi: J. Alloys Compounds, 1997, vol. 260, pp. 222–35.
D.R. Gaskell: Introduction to Metallurgical Thermodynamics, 2nd ed., Hemisphere Publication Corporation, Washington, DC, 1981, pp. 288–91.
Handbook of Chemistry and Physics, 74th ed., D.R. Lide, ed., CRC Press, Boca Raton, FL, 1993–94, pp. 6-68–6-70.
H. Schäfer: Angew. Chem. Int. Ed. Engl., 1976, vol. 15, pp. 713–27.
Z.-C. Wang, Y.-W. Tian, H.-L. Yu, and J.-K. Zhou: Metall. Trans. B, 1992, vol. 23B, pp. 666–69.
Z.-C. Wang, Y.-W. Tian, H.-L. Yu, X.-H. Zhang, and J.-K. Zhou: Metall. Mater. Trans. B, 1994, vol. 25B, pp. 103–09.
J. Szekely, J. W. Evans, and H. Y. Sohn: Gas-Solid Reactions, Academic Press, New York, NY, 1976, pp. 68–70, 73–88, 109–31, and 232–35.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Wang, ZC., Lei, PX., Chi, MY. et al. Rare earth extraction and separation from mixed bastnaesite-monazite concentrate by stepwise carbochlorination-chemical vapor transport. Metall Mater Trans B 33, 661–668 (2002). https://doi.org/10.1007/s11663-002-0018-1
Received:
Issue Date:
DOI: https://doi.org/10.1007/s11663-002-0018-1