Introduction

Recycling aluminum alloys has been shown to provide major economic benefits.  As a result, it is appropriate for the aluminum industry and the U.S. as a whole to identify, develop, and implement all technologies that will optimize the benefits of recycling.

This paper will focus primarily on alloy design for optimizing the reuse of recycled metal; this is both the most forward looking area as we move toward a more recyclefriendly world, and the most overlooked for its potential in maximizing the recycle loop.  Some specific approaches to alloy design for recycling are put forth, and some specific compositions for evaluation are proposed.  Options for moving forward to further capitalize on the advantages of aluminum recycling are also addressed.

Background

Aluminum recycling in North America is a mature, well-developed economy.  Aluminum recycling gained momentum after World War II following rapid economic and industrial growth, and especially after the introduction of the aluminum beverage can with its easy-open end.  While today’s recycling metals markets also include ferrous metals like iron and steel, and nonferrous metals like copper and brass, aluminum recycling is the engine of recycling economics. Today an increasing amount of the aluminum going into producing new aluminum alloy products is coming from recycled products.  Choate and Green have illustrated that much of the increase is coming from recycled automotive components.  In 2005, for the first time, recycled scrap coming from automotive products is expected to exceed that coming from used beverage cans (UBCs).  The Aluminum Industry Roadmap illustrates the importance of these trends and efforts to address the technology from primary production to finished products, and Fielding’s recent article in Light Metal Age illustrates how one segment of the industry, the extrusion business, is approaching the challenge. 

The increase in recycled metal becoming available is a positive trend, as secondary metal produced from recycled metal requires only about 2.8 kWh/kg of metal produced while primary aluminum production requires about 45 kWh/kg produced.  It is to the aluminum industry’s advantage to maximize the amount of recycled metal, for both the energy-savings and the reduction of dependence upon overseas sources (now about 40% of U.S. consumption).  Increasing the use of recycled metal is also quite important from an ecological standpoint, since producing aluminum by recycling creates only about 4% as much CO2 as by primary production.

The significant economic advantages of aluminum can recycling have also been demonstrated in a joint study of a representative American community by Secat, Inc., the Center for Aluminum Technology (CAT), and the Sloan Industry Center for a Sustainable Aluminum Industry (CSAI), all of which are located at the University of Kentucky in Lexington. For each 1% increase in the amount of aluminum cans recycled, the economic savings to the U.S. economy is $12 million/year.  It was shown that this could approach $600 million to offset the U.S. trade balance if all available aluminum cans could be recycled.  

Savings such as these are significant enough to support the construction of new recycling plants, adding a significant number of high-paying jobs.  The additional recycling also contributes to energy savings of 1 trillion BTU/year.  Such major impacts have the potential to significantly decrease our reliance on overseas sources of primary aluminum metal.

   Today, much recycled aluminum must be “sweetened” with more costly and energy-intense primary metal before it is reused in order to meet the performance requirements of most alloy and product specifications. The result is that, in most cases other than beverage cans, recycled metal tends to be used primarily for lower grade casting alloys or wrought products. While a modest amount of this will always be acceptable, the full benefits of a recycle-friendly world can only be realized when the recycle loop is closer to a closed loop for a number of product lines. These observations lead to the conclusion that as an industry we need to be looking forward to every opportunity for maximizing the advantages of what we are calling a recycle-friendly world.  In the discussion that follows, we will begin to develop the characteristics of such a world, and then to identify and address the technological challenges of optimizing that environment.