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.
Article PDF
Similar content being viewed by others
Explore related subjects
Discover the latest articles, news and stories from top researchers in related subjects.Avoid common mistakes on your manuscript.
References
Schei A, Tuset J, Tveit H (1998) Production of high silicon alloys. Trondheim, Tapir Forlag
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 92:418–424
Safarian J, Tranell G, Tangstad M (2012) Processes for upgrading metallurgical grade silicon to solar grade silicon. Energy Procedia 20:88–97
Hopkins RH, Rohatgi A (1986) Impurity effects in silicon for high efficiency solar cells. J Cryst Growth 75:67–79
Liaw HM, Secco D’Aragona F (1983) Purification of metallur- gical-grade silicon by slagging and impurity redistribution. Solar Cells 10:109–118
Suzuki K, Sugiyama T, Takano K, Sano N (1990) Thermodynamics for removal of boron from metallurgical silicon by flux treatment. J Jpn Inst Met 54:168–172
Weiss T, Schwerdtfeger K (1994) Chemical equilibria between silicon and slag melts. Met Mat Trans B 25b:497–504
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 49:777–782
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 179–184
Krystad E, Tang K, Tranell G (2012) The kinetics of boron removal transfer in slag refining of silicon. JOM 64:968–972
Dietle J (1987) Metallurgical ways of silicon meltstock processing. In: Silicon for photovoltaics, vol 2, pp 285–352
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 21:1402–1406
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 104:229–234
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, 1178–1184
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 118:497–505
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 94:2085–2090
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:571–83
Safarian J, Tranell G, Tangstad M (2015) Boron removal from silicon by CaO-Na2O-SiO2 slags. Metall Mater Trans E 2E:109–118
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:1063–1079
Safarian J, Tangstad M (2011) Phase diagram study of the Si-P system in Si-rich region. J Mater Res 26:1494–1503
Safarian J, Kolbeinsen L, Tangstad M (2012) Thermodynamic activities in silicon binary melts. J Mater Sci 47:5561–5580
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– 116
Tyurnina ZG, Lopatin SI, Shugurov SM, Stolyarova VL (2006) Thermodynamic properties of silicate glasses and melts, I. System BaO-SiO2. Russ J Gen Chem 76:1522–1530
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 32:533–542
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 47:68–82
Rein RH, Chipman JJ (1965) Activities in the liquid solution SiO2,-CaO-MgO-Al2O3 at 1600°. Trans Metall Soc AIME 233:415–425
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 2013:326
Safarian J, Tangstad M (2012) Vacuum refining of molten silicon. Metall Mater Trans B 43B:1427–1445
Yoshikawa T, Morita K (2005) Thermodynamic property of B in molten Si and phase relations in the Si-Al-B system. Mater Trans 46:1335–1340
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.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
Open Access This 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.
About this article
Cite this article
Safarian, J. Thermochemical Aspects of Boron and Phosphorus Distribution Between Silicon and BaO-SiO2 and CaO-BaO-SiO2 lags. Silicon 11, 437–451 (2019). https://doi.org/10.1007/s12633-018-9919-8
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s12633-018-9919-8