GB1271493A - Improved treatment process - Google Patents

Abstract

1,271,493. Induction furnaces. STANELCOTHEKMATEON Ltd. 8 May, 1969 [9 May, 1968], No. 21945/68. Heading H5H. A molten charge is supported above the pouring aperture in the base of a crucible by electromagnetically induced forces acting on the charge. When heating is completed, reduction of the levitating magnetic field allows the charge to flow through the aperture. As shown the crucible 1 comprises a diabolo-shaped array of tubes extending between headers 2, 3 split at 5, 6 respectively. Water flows through the tubes from one header to the other. The individual tubes are alternately staggered radially. A helical induction heating and levitating coil 7 surrounds the upper part of the crucible and extends just below the pouring aperture 4 so that currents induced in the crucible and charge produce a levitating force on the charge. The above arrangement of induction coil and crucible may be disposed beneath a pouring aperture in a refractory oxide or graphite crucible which is surrounded by an induction heating coil. In this embodiment, the arrangement merely acts as a valve for the pouring aperture of the crucible. In Fig. 2, not shown, the crucible is hemispherical and constructed from two identical arrays of tubes, each supplied separately with coolant. The two arrays may be separated about a vertical plane. Thus initially in order to retain granular charge the two arrays are held together to prevent escape of the charge, but as the charge melts they may be separated slightly so that when the levitating field of the surrounding heating coil is reduced, the molten charge will be expelled through the crucible bottom. If the charge is initially granular, the aperture of the crucible may be closed by a liquid cooled plug until the charge melts.