"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 classifier to produce –3/8" feed to a Kason classification plant that removes needle shaped particles and delivers final granules of required size.


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 Separator was designed for the service and accepts product at a rate of 25 tons per hour rejecting + 3/8" completely free of undersize. Feed material has a bulk density of approximately 100 Ibs. per cu. ft. and the Kason's capacity exceeds 10 tons/hour/sq. ft. 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 tons/hour is handled with floor space requirement of 2.5 sq. ft. and head room of 23". Total power require. requirement is 1/3 H.P .

3. The Kason transmits no vibration to supporting structures and since the model for this service only weighs 140 lbs. installation was extremely simple.


  • Single deck Kason.
  • 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" model, 25 tons per hour; other models available capacities exceeding 100 tons per hour.

Kason Application Data No: 5