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, Volume 11, Issue 1, pp 437–451 | Cite as

Thermochemical Aspects of Boron and Phosphorus Distribution Between Silicon and BaO-SiO2 and CaO-BaO-SiO2 lags

  • Jafar SafarianEmail author
Open Access
Original Paper
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Abstract

In the production of solar grade silicon by metallurgical route the distribution of B and P between slags and liquid silicon is the most important key issue. The equilibrium and thermochemistry of reactions between liquid silicon and BaO-SiO2 slags and up to 10% BaO-containing CaO-BaO-SiO2 slags is studied through experimental work and using thermodynamic calculations. It is shown that the distribution coefficient of B (LB) is higher for the CaO-BaO-SiO2 slags than that for BaO-SiO2 slags and it is not significantly affected by temperature and composition changes of the slags. In contrast, the distribution coefficient of P (LP) is higher for BaO-SiO2 slags than that for the CaO-BaO-SiO2 slags, and it is higher at lower temperatures. The chemical activities of the dilute solutions of Ba in liquid silicon, and the dilute solutions of B2O3, P2O5 and BaO in the slags are calculated. Moreover, the reaction mechanisms for B, P, Ba and Ca transport between liquid silicon and the slags are explained.

Keywords

Silicon Boron Phosphorous Barium Calcium Slag Distribution coefficient 

Notes

Acknowledgements

The present research has been supported by Research Domain 3-Recycling and Refining and Society in SFI Metal Production (a Norwegian Center for Research-driven Innovation in metal production) through project number 237738.

References

  1. 1.
    Schei A, Tuset J, Tveit H (1998) Production of high silicon alloys. Trondheim, Tapir ForlagGoogle Scholar
  2. 2.
    Braga AFB, Zampieri PR, Bacchin JM, Mei PR (2008) Review: new processes for the production of solar-grade polycrystalline silicon. Solar Energy Mater Solar Cells 92:418–424CrossRefGoogle Scholar
  3. 3.
    Safarian J, Tranell G, Tangstad M (2012) Processes for upgrading metallurgical grade silicon to solar grade silicon. Energy Procedia 20:88–97CrossRefGoogle Scholar
  4. 4.
    Hopkins RH, Rohatgi A (1986) Impurity effects in silicon for high efficiency solar cells. J Cryst Growth 75:67–79CrossRefGoogle Scholar
  5. 5.
    Liaw HM, Secco D’Aragona F (1983) Purification of metallur- gical-grade silicon by slagging and impurity redistribution. Solar Cells 10:109–118CrossRefGoogle Scholar
  6. 6.
    Suzuki K, Sugiyama T, Takano K, Sano N (1990) Thermodynamics for removal of boron from metallurgical silicon by flux treatment. J Jpn Inst Met 54:168–172CrossRefGoogle Scholar
  7. 7.
    Weiss T, Schwerdtfeger K (1994) Chemical equilibria between silicon and slag melts. Met Mat Trans B 25b:497–504CrossRefGoogle Scholar
  8. 8.
    Teixeira LAV, Tokuda Y, Yoko T, Morita K (2009) Behaviour and state of boron in CaO-SiO2 slags during refining of solar grade silicon. ISIJ Int 49:777–782CrossRefGoogle Scholar
  9. 9.
    Jakobsson LK, Tangstad M (2012) Distribution of boron and calcium between silicon and calcium silicate slags. In: Downey JP, Battle TP, White JF (eds) International Smelting Technology Symposium (Incorporating the 6th Advances in Sulfide Smelting Symposium). TMS, pp 179–184Google Scholar
  10. 10.
    Krystad E, Tang K, Tranell G (2012) The kinetics of boron removal transfer in slag refining of silicon. JOM 64:968–972CrossRefGoogle Scholar
  11. 11.
    Dietle J (1987) Metallurgical ways of silicon meltstock processing. In: Silicon for photovoltaics, vol 2, pp 285–352Google Scholar
  12. 12.
    Cai J, Li JT, Chen WH, Chen C, Luo XT (2011) Boron removal from metallurgical silicon using CaO-SiO2-CaF2 slags. Trans Nonferrous Met Soc China 21:1402–1406CrossRefGoogle Scholar
  13. 13.
    White J, Allertz C, Forwald K, Sichen D (2013) The thermodynamics of boron extraction from liquid silicon using SiO2-CaO-MgO slag treatment. Int J Materials Research 104:229–234CrossRefGoogle Scholar
  14. 14.
    Luo DW, Liu N, Lu YP, Zhang GL, Li TJ Removal of boron from metallurgical grade silicon by electromagnetic induction slag melting. Trans Nonferrous Met Soc China 21, 1178–1184Google Scholar
  15. 15.
    Tanahashi M, Shinpo Y, Fujisawa T, Yamauchi C (2002) Distribution behaviour of boron between SiO2 saturated NaO0.5-CaO-SiO2 flux and molten silicon. J Min Mat Proc Inst Japan 118:497–505Google Scholar
  16. 16.
    Johnston MD, Barati M (2010) Distribution of impurity elements in slag-silicon equilibria for oxidative refining of metallurgical silicon for solar cell applications. Solar Energy Mater Solar Cell 94:2085–2090CrossRefGoogle Scholar
  17. 17.
    Safarian J, Tranell G, Tangstad M (2013) Thermodynamic and kinetic behaviour of B and Na through the contact of B-doped silicon with Na2O-SiO2 slags. Metall Mater Trans B 44B:571–83CrossRefGoogle Scholar
  18. 18.
    Safarian J, Tranell G, Tangstad M (2015) Boron removal from silicon by CaO-Na2O-SiO2 slags. Metall Mater Trans E 2E:109–118Google Scholar
  19. 19.
    Safarian J, Tang K, Olsen JE, Andersson S, Tranell G, Hildal K (2016) Mechanisms and kinetics of boron removal from silicon by humidified hydrogen. Metall Mater Trans B 47B:1063–1079CrossRefGoogle Scholar
  20. 20.
    Safarian J, Tangstad M (2011) Phase diagram study of the Si-P system in Si-rich region. J Mater Res 26:1494–1503CrossRefGoogle Scholar
  21. 21.
    Safarian J, Kolbeinsen L, Tangstad M (2012) Thermodynamic activities in silicon binary melts. J Mater Sci 47:5561–5580CrossRefGoogle Scholar
  22. 22.
    Zhang R, Mao H, Taskinen P (2016) Thermodynamic descriptions of the BaO-CaO, BaO-SrO, BaO-SiO2 systems. CALPHAD: Comput Coupling Phase Diagrams Thermochemistry 54:107– 116CrossRefGoogle Scholar
  23. 23.
    Tyurnina ZG, Lopatin SI, Shugurov SM, Stolyarova VL (2006) Thermodynamic properties of silicate glasses and melts, I. System BaO-SiO2. Russ J Gen Chem 76:1522–1530CrossRefGoogle Scholar
  24. 24.
    Tyurnina ZG, Stolyarova VL, Lopatin SI, Plotnikov EN (2006) Mass spectrometric investigation of the vaporization and thermodynamic properties of components in the BaO-SiO2 system. Glas Phys Chem 32:533–542CrossRefGoogle Scholar
  25. 25.
    Boulay E, Nakano J, Turner S, Idrissi H, Schryvers D, Godet S (2014) Critical assessment and thermodynamic modeling of BaO-SiO2 and SiO2-TiO2 systems and their extensions into liquid immiscibility in the BaO-SiO2-TiO2 system. CALPHAD: Comput Coupling Phase Diagrams and Thermochemistry 47:68–82CrossRefGoogle Scholar
  26. 26.
    Rein RH, Chipman JJ (1965) Activities in the liquid solution SiO2,-CaO-MgO-Al2O3 at 1600°. Trans Metall Soc AIME 233:415–425Google Scholar
  27. 27.
    Jakobsson LK (2013) Distribution of boron between silicon and CaO-SiO2, MgO-SiO2, CaO-MgO-SiO2, and CaO-Al2O3-SiO2 slags at 1600° C, PhD thesis. NTNU 2013:326Google Scholar
  28. 28.
    Safarian J, Tangstad M (2012) Vacuum refining of molten silicon. Metall Mater Trans B 43B:1427–1445CrossRefGoogle Scholar
  29. 29.
    Yoshikawa T, Morita K (2005) Thermodynamic property of B in molten Si and phase relations in the Si-Al-B system. Mater Trans 46:1335–1340CrossRefGoogle Scholar

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© The Author(s) 2018

Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

Authors and Affiliations

  1. 1.Norwegian University of Science and Technology (NTNU)TrondheimNorway

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