CASE STUDY NO. 9650
KEY WORDS MINERAL WOOL, SHOT BRIQUETTES, REUSE
Thermafiber, LLC
3711 W. Mill Street Extended
P.O. Box 237
Wabash, IN 46992
Contact: David A. Leyda, Plant Engineer; Arnold E. Cly, Plant Engineer.
Tel: 219-563-2111. Fax: 219-563-7022.
Summary
The waste material called "shot," produced during manufacture of mineral wool, is reclaimed through a new process and reintroduced as raw material, reducing landfill disposal by 13,000 to 14,000 tons per year.
Action
Thermafiber converts slag from steel mills into mineral wool, which is used in various applications as insulation, as a constituent of acoustic ceiling tile, etc. In the proprietary production process, Thermafiber introduces silica sand to the blend of raw materials. During production, about 25% of total input becomes waste--shot--resembling grains of sand. Previously, all this waste was landfilled, a quantity estimated at 13,000 to 14,000 tons per year.
Thermafiber has adopted a system (perfected at Besser Mill, Alpena, Mich.) which allows the waste to be reintroduced into the production process in a manner compatible with heating and dwell-time requirements. Waste shot is mechanically pressed into briquettes measuring about 4 by 5 inches and approximating an octagonal shape to optimize heat flow melting. Briquettes must be cured for a period before they can be returned to production as raw material.
Thermafiber estimates that it now saves 25% in raw material costs as well as the cost of trucking to a disposal site and tipping fees. Company officials say they have known about the briquetting process for some time but only recently, when the necessary equipment became available at an affordable price, did it become cost effective.
Payback
The company considers its cost data proprietary but has calculated payback at less than 2 years.
Additional benefit
Reuse of shot has reduced the overall volume of material sent to landfill from
Thermafiber by 90-95% and has significantly advanced the prospects for reaching the goal
of 50% waste disposal reduction in the county by 2000.