Purification of Materials Non-Electrically Conductive in the Solid State and Electrically Conductive in the Molten State with Electric Induction Power

An induction furnace for melting and purify a composition non-electrically conductive in the solid state and electrically conductive in the molten state, the induction furnace comprising:

• a crucible having a cylindrically shaped interior volume at least partially lined around the crucible's interior wall and bottom with a susceptor material where the ratio of the diameter of the interior volume to the fill height of the interior volume is at least 8 to 1;
• at least one gas inlet penetrating into the bottom of the crucible;
• at least one gas dispersal element disposed in the bottom of the interior volume of the crucible for dispersal of a gas flowing through the at least one gas inlet;
• at least one induction coil surrounding the exterior height of the crucible from at least the fill height to at least 25 percent below the susceptor material in the crucible's bottom;
• at least one alternating current power source having an output connected to the at least one induction coil;
• a sealing structure for establishing vacuum environment over the surface of the material in the interior volume;
• and
• a frequency controller for adjusting the heating frequency of the output current from at least a susceptor heating high frequency for magnetic flux coupling with the susceptor material to at least a molten material heating low frequency for magnetic flux coupling into the interior volume of the crucible, and for supplying a modulating low frequency of the output current from at least between zero and 2 Hertz.