Patent ID: 8460629

Claim:
A method of melting and purifying a composition non-electrically conductive in a solid state and electrically conductive in a molten state, the method comprising: depositing a charge of the composition in the solid state in a crucible at least partially lined with a susceptor material; melting the charge of the composition by inductive heating of the susceptor material from a susceptor heating magnetic flux established by the flow of a susceptor heating high frequency current in at least two induction coils surrounding the exterior height of the crucible, and from a molten material heating magnetic flux established by the flow of a molten material heating low frequency current in the at least two induction coils subsequent to melting the charge to form a molten mass in the crucible, the susceptor heating high frequency current and the molten material heating low frequency current supplied from an alternating current power source; containing the molten mass in a vacuum environment; supplying one or more reaction gases to the bottom of the molten mass for reaction with one or more impurities in the molten mass to form one or more gas reaction impurities while supplying a modulating low frequency current to the uppermost one of the at least two induction coils from the alternating current power source to establish an electromagnetic wave action at the surface of the molten mass and the molten material heating low frequency current is supplied to the remaining of the at least two induction coils below the uppermost one of the at least two induction coils from the alternating current power source; and extracting the one or more gas reaction impurities from the vacuum environment.