Your browser is out of date.

You are currently using Internet Explorer 7/8/9, which is not supported by our site. For the best experience, please use one of the latest browsers.

"Scalping" of Coal Slag in the Manufacture of Roofing Granules

Black roofing granules are now being made from water-quenched furnace slag, which was formerly a waste product. Slag, as received from the power company, is dried in a rotary, direct oil-fired drier and then passed to a 2-roll crusher. The crusher operates closed-circuit with a Kason VIBROSCREEN Circular Vibratory Separator to produce –3/8" feed to a classification plant that removes needle-shaped particles and delivers final granules of required size.

Method and results
Only 1% of the roll crusher product is +3/8", but plant layout required a compact unit capable of very high capacity. A 24" diameter Kason unit was designed for the service and accepts product at a rate of 25 TPH, rejecting +3/8" completely free of undersize. Feed material has a bulk density of approximately 100 lbs per cubic foot, and the Kason's capacity exceeds 10 TPH per square foot of screen cloth.

1. The Kason's capacity on this application far exceeds that possible on any other type of vibrating screen.
2. A screening capacity of 25 TPH is handled with a floor space requirement of 2.5 square feet, and headroom of 23". Total power requirement is 1/3 HP.
3. The Kason transmits no vibration to supporting structures, and since the model for this service only weighs 140 pounds, installation is extremely simple.

  • Epoxy-coated carbon steel construction.
  • Standard discharge spout for oversize fraction and 2 oversized discharge spouts at 180° for product.
  • Stainless steel screens with 3/8" clear opening.
  • Capacity on 24" in. model is 25 TPH; other models available for capacities exceeding 100 TPH.
Kason Application Data No: 5