NICE3: On-Site Aluminum Recycling for Wheel Manufacturers

A joint cost-sharing grant program of:
U.S. Department of Energy's Office of Industrial Technologies and Office of Technical and Financial Assistance
U.S. Environmental Protection Agency's Office of Pollution Prevention

Produced by the National Renewable Energy Laboratory,
a laboratory of the U.S. Department of Energy
1000 Independence Ave., SW
Washington, DC 20586

Machining rough aluminum castings for automotive wheels produces aluminum chips that are contaminated with cutting oils and coolant. To be recycled, these chips must be transported to an off-site processor where the chips are cleaned, melted into an ingot for shipment back to the manufacturer, then remelted into molten aluminum for casting wheels.

AAP St. Mary's makes cast aluminum wheels, and like other aluminum wheelmakers, it produces large quantities of metal chips as a by-product. A $200,000 grant from the NICE3 program, which is sponsored by the U.S. Department of Energy (DOE) and the U.S. Environmental Protection Agency, helped AAP St. Mary's integrate an aluminum chip recycling process into its existing wheel production facility. As a result, the inefficiencies and production costs of the current process have been dramatically reduced.

• Challenge: In the aluminum wheel manufacturing process, approximately 30% of each casting is machined away as chips. These chips must be transported by truck to an outside recycler, who cleans, melts, and makes ingot from the chips. The ingot is then transported back to the manufacturer, who must remelt the ingot for reuse. Each step of this process generates pollution and waste. Transporting the material to and from the recycler uses energy and generates emissions, and the recycling process produces waste cutting oils.

• Solution: AAP St. Mary's is introducing a new, more efficient technology to integrate aluminum chip recycling into its wheel manufacturing process. The technology involves remelting the large volume of aluminum chips on-site, using a new spinning system to separate the chips from cutting oils and a more efficient technology for melting and stirring the molten aluminum. In the process, the new system will reduce the amount of energy, waste, emissions, and expenses associated with the current technology.

  The new chip recycling process involves several steps. First, automated conveyors transport the chips from the machining operation to the remelting operation for recycling. The chips are cleaned and then added to an enhanced melting furnace, which virtually eliminates airborne fumes and dust. In addition, the new melting furnace is more efficient and will reduce the waste of aluminum from the process from 8% with current technology to 1.5%. The cutting oils are collected for reclamation and recycling so that no waste coolant is left for disposal.

  Equipment for the new process has been installed at AAP St. Mary's. Initial tests recycled 130 tons (118 metric tons) of aluminum, which were used to produce three types of wheels on four types of casting machines. All of the resulting wheels -- made entirely from recycled aluminum -- met or exceeded quality standards. AAP St. Mary's is now working to implement the system in full operation.

• Energy Savings: The system allows the aluminum chips to be melted once, not twice, resulting in large energy savings. Consequently, project personnel estimate that energy use will be cut in half. Additional energy savings will result from eliminating the truck transportation of the aluminum waste to and from the recycler. Assuming most U.S. wheel manufacturers will adopt the technology, annual energy savings could climb to 400 billion Btu (422 trillion joules) in 2010.

• Environmental Benefits: Emissions from the old melting technology and gas emissions from the use of trucks and forklifts are completely eliminated with this technology. In addition, the waste cutting oils are completely reclaimed or reused, eliminating the disposal requirement. Waste dross (molten aluminum) volumes are reduced by 75%.

• Economic Savings: Using the proposed technology, AAP St. Mary's will save an estimated $1.92 million in operating and maintenance costs and experience an estimated payback period of 1.6 years. Project personnel estimate that U.S. wheelmakers could save $16 million annually by adopting this technology.

• Applications: All aluminum wheelmakers can benefit from this technology, as well as metal processing and fabricating operations that produce metal chips as a waste or by-product.