Abstract: Mineral wool produced from fly ash wherein at least 70% to 80% by weight of the mineral wool consists of fibrous strands having a diameter greater than 3 to 5 microns and less than about 7 to 15 microns.

Abstract: A system for converting fly ash into mineral wool including an airtight chamber enclosing a molten stream from a spinner and providing an adjustable access to a bin for receiving shot and including an airflow device for drawing air from the bin, through the adjustable access, past the spinner, and into an accumulator, with the adjustable access being operable to selectively limit the rate of flow of the air to thereby control the average weight of fibrous strands entering the accumulator is also disclosed. The quality of accumulated strands is also controlled through a system including a spinner for converting a molten stream into an output of fibrous strands and shot, a cyclone, and a collector with conduit means delivering fibrous strands from the spinner to cyclone and from a light fiber vortex exit or the cyclone to the collector. Preferably, the cyclone includes a variably positionable vortex exit tube. Methods are taught using the above-identified apparatus to generate a high quality mineral wool.

Abstract: A high temperature electronic furnace wherein a product-containing vessel has a product exit orifice, a plurality of electrodes are located in the vessel to define primary current paths adjacent the orifice, a control electrode is positioned in the vessel for defining an additional current path adjacent the orifice and a circuit for energizing the primary electrodes with multiphase current and for time-sharing the multiphase current with the control electrode. The degree of time-sharing is made responsive to the temperature of product passing through the orifice and/or the rate of flow of product passing through the orifice. In addition, the control electrode is moveably positioned with respect to the orifice, with the position of the control electrode being dependent upon the temperature of product passing through the orifice and/or the rate of flow of product through the orifice.