Thermodynamics of Boron Removal from Silicon Using CaO-MgO-Al2O3-SiO2 Slags
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OriginalversjonMetallurgical and materials transactions. B, process metallurgy and materials processing science. 2018, 49 (4), 1699-1708. 10.1007/s11663-018-1250-7
Slag reﬁning is one of few metallurgical methods for removal of boron from silicon. It is important to know the thermodynamic properties of boron in slags to understand the reﬁning process. The relation of the distribution coeﬃcient of boron to the activity of silica, partial pressure of oxygen, and capacity of slags for boron oxide was investigated. The link between these parameters explains why the distribution coeﬃcient of boron does not change much with changing slag composition. In addition, the thermodynamic properties of dilute boron oxide in CaO-MgO-Al2O3-SiO2 slags was determined. The ratio of the activity coeﬃcient of boron oxide and silica was found to be the most important parameter for understanding changes in the distribution coeﬃcient of boron for diﬀerent slags. Finally, the relation between the activity coeﬃcient of boron oxide and slag structure was investigated. It was found that the structure can explain how the distribution coeﬃcient of boron changes depending on slag composition.