During a day's operation, up to 100 gallons of oil and grease from open gears, drive chains, bearings and other sources get washed into wastewater flumes by cooling water. The flumes carry the water to concrete interceptor (descaling) pits located below grade and upstream of the sand beds. The flow rate of the system is about 10,000 gallons per minute.
Over the years, Dave Giancola, plant maintenance engineer at North Star Steel, has tried floating booms, floating suction (pump) skimmers and moving media in the form of tubes and mops to remove the oil and grease - all with no success.
Giancola then turned to Abanaki Corporation, Oil Skimmer Division in Chagrin Falls, Ohio for a solution. After analyzing the situation, Abanaki's belt style oil skimmer, the Grease Grabber® was recommended and tested at North Star Steel. The Grease Grabber makes use of the differences in specific gravity and surface tension between oil and water. This allows the belt skimmer to attract grease, oil and other hydrocarbon liquids as the belt passes through the surface of the water, even under the most turbulent conditions. Because of the skimmer's sleek construction, it was easily installed on the catwalk at the edge of the mill's final interceptor pit.
According to Giancola, 'At first, our personnel were skeptical that the Grease Grabber's smooth belt could really pick up oil and grease. However, it wasn't long before they were seeing it remove 400 - 500 gallons of oil and grease a week from the interceptor pit.'
The only maintenance required has been routine cleaning of the unit's wiper blades, a procedure that takes about 20 minutes a month.