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Kinetics Analysis of Boron Removal from Silicon through Reactions with CaO-SiO2 and CaO-SiO2-Al2O3 Slags
Ist Teil von
Metallurgical and materials transactions. B, Process metallurgy and materials processing science, 2018-12, Vol.49 (6), p.3171-3185
Ort / Verlag
New York: Springer US
Erscheinungsjahr
2018
Link zum Volltext
Quelle
Alma/SFX Local Collection
Beschreibungen/Notizen
Different types of slags have been used to refine silicon, particularly for removing boron impurity from metallurgical grade (MG) silicon. Although a number of slags have been used for silicon refining, there is limited information about boron removal kinetics, particularly during the refining reaction with CaO-SiO
2
-Al
2
O
3
slags. This article investigates the boron removal kinetics using the CaO-SiO
2
-Al
2
O
3
slag systems in the temperature range 1773 K to 1873 K (1500 °C to 1600 °C). All the results obtained in the present study provide a strong indication that the rate limiting step of the slag-silicon reaction kinetics was mass transport in the liquid slag. It was also shown in the study that as the reaction temperature is increased, the mass transfer coefficient is also increased. At any particular reaction temperature, adding alumina in the CaO-SiO
2
slag was shown to decrease the mass transfer coefficient, which is consistent with the substantially higher viscosity of the alumina bearing slags over the CaO-SiO
2
slag. The mass transfer coefficients were determined to be between 1.23 × 10
−6
and 2.82 × 10
−6
ms
−1
, with activation energies between 64 and 109 kJ/mol, respectively.