Compressed Air Best Practices - November 2008 - (Page 28) | 11–12/08 Focu Focus Ind stry STEE Focus Industry STEEL & METALS u y M T LS | BY BILL CLEARY, WASTEWATER TREATMENT MANAGER, METALDYNE Challenging Mix of Oil and Glycol Finding the most effective, reliable and economical method for separating and concentrating die lubricant is no easy task for die casting plants — and the situation at the Metaldyne aluminum die casting plant in Twinsburg, Ohio was no different. For more than a decade, Bill Cleary, the wastewater treatment manager, worked with 22 different wastewater treatment vendors, in addition to experts from academia and the United States Department of Energy to find the optimal solution for his plant. The Twinsburg Plan is a world leader in the production of aluminum valve body castings. To facilitate this process, Metaldyne has developed a world-class die casting process that utilizes a specially-formulated die lubricant, an oil and water emulsion, which helps control the temperature of the die as well as the removal of the complex castings during the part ejection process. Each cycle of the highly automated process begins with numerous nozzles spraying a controlled volume of lubricant onto specific locations on the die. Next, molten aluminum, at 1,250 °F, is auto-ladled into the cold chamber and injected into the die under high pressure. The plant’s drainage system collects the waste generated from the casting process, including the die lubricant, as well as detergents from washing operations and glycol from the hydraulic fluid used in the robotic machinery. In addition, some process cooling water and cooling tower bleed are piped into the wastewater treatment system. The total combined wastewater flow is 9,000 to 11,000 gpd, with chemical oxygen demand (COD) ranging from 20,000 to 40,000 mg/l. 28 www.airbestpractices.com http://www.airbestpractices.com
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