Abstract: A feeder system for uniformly dispensing particulate raw batch material at a constant flow rate from a high temperature environment. A rotating, height adjustable disc is located below an outlet of a raw material hopper which gravity feeds particulate raw material to the disc surface. The raw material then falls off the disc edge at a constant rate as the disc rotates and is then caught by a receiving means which transports the raw material to a processing area outside of the high-temperature zone. The amount of a given material dispensed depends on the separation distance between the disc and the hopper, the speed of rotation of the disc, and the diameter of the disc surface. Means for rotating the disc, as well as means for adjusting the separation between the disc and the hopper are provided outside of the high temperature environment and are adapted for use in vacuum systems, especially in conjunction with a furnace apparatus for growing crystals from a melt.