The apparatus includes a furnace having a furnace chamber (14), a port (16) in fluid communication with the furnace chamber having an inclined lower wall (18), and a bi-directional induction unit (24) mounted to the inclined lower wall for inducing flow in molten material in the port. A retractable channel plate assembly (26) is selectively positionable in the port to define an extraction flow channel (28) for the molten material between the channel plate assembly and the inclined lower wall. A drive arrangement (64) moves the channel plate assembly into and out of the port and the control of a control system (74) which includes a sensor system (78) for measuring the level of the molten material in the port and a feedback system for providing information regarding the position of the channel plate assembly. A method of operating the apparatus is also disclosed.