Aluminum Beverage Cans began to be used in the United States in the early 1960s. In 1968, several aluminum producers, notably Reynolds Metals Company, being aware of the value of the metal in the used beverage cans (UBC), initiated a buy-back recycling program to recover the metal and capture the corresponding energy content. In this recycling campaign, some 24,000 metric tons were recovered in 1972, and this grew to 974,000 metric tons in 1994. Some 10,000 recycling centers were established nationwide during this period. The most successful UBC recycling year was 1997 when 66.5% of all cans produced were recycled and some 2.05 billion pounds of metal were recovered by the industry. Since then, the recycling rate has slipped.
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The benefits of recycling are many: firstly, it is now well established that one saves 95% of the energy by recycling UBC scrap as compared to mining, refining and smelting the metal from the original bauxite ore. In effect, a UBC scrap can be regarded as an extremely pure form of bauxite ore! Secondly, 95% of the environmental emissions associated with metal and can production are also eliminated.
The Aluminum Association, in conjunction with Habitat for Humanity, has formed Cans for Humanity and since 1997 some $4 million has been collected and 92 homes have been built for needy families. However, the unfortunate fact still remains that in the U.S., despite the evident value of the beverage can, almost half of all cans produced are disposed of in a landfill. Many options for the recovery of UBC scrap can be envisioned but all of these probably can be grouped under three main categories:
Option 1. Collection of “clean” UBC.
Increasing can collection in this option involves improving and enhancing the inherent benefit of recycling. The U.S. lacks a population segment that is extremely poor to drive can collection and generally is averse to establishing deposit regulations (can be re-evaluated). As noted above, the Aluminum Can Council has recently been formed with the charter to develop educational messages and programs to encourage UBC collection though school, community and municipal recycling promotions. This option is clearly a minimal cost option as user individuals are the ones who capture and segregate the cans. There is still much room for improvement, as there are some situations where virtually 100% capture should be feasible, e.g. on planes and trains, and yet recycling does not always occur. The use and collection of cans depend on each individual user, and so recycling depends of the individual whims of the total 300 million populations.
We need to stress the need, to develop educational messages to enhance aluminium UBC scrap recycling to prevent these from ending up in a landfill. Specifically, the organization Earth 911 in its evaluation of why can recycling is languishing, stresses the need to educate local government coordinators that there are still more cans to recycle. Also, the organization urges a focus on “smart” recycling, namely to focus on the high value components of the waste stream, i.e. aluminum cans and to a lesser degree, paper.
In their recent article, Das and Hughes describe a comprehensive study being conducted by the University of Kentucky in association with the Fayette County Recycling Center in Lexington, Kentucky. They note a significant difference in individual behavior concerning recycling when individuals are at “home” or are “away from home”. As a result, they propose locating collection bins in key places. Especially, they advocate placing collection bins in all elementary schools. They also point out that the advances made by the industry in can making technology ironically tend to work against increasing the rate of recycling. With the reductions in the thickness of the can walls, it now takes the collection of 33 cans to get 1 lb. of aluminum.
It is strongly recommended that programs be continued and bolstered to educate the public about the benefits of curbside collection and to educate school children about the economic and environmental benefits of recycling.
Option 2: Collection of UBC as commingled waste Increased
In this option when the commingled waste reaches the MRF it is placed on a conveyor belt and the plastic and paper bags are either removed by hand or are blown off. Magnets are used to separate the ferrous materials, glass is removed by a shaker and is subsequently crushed, and the aluminum UBC scrap cans are removed at the end of the belt. In Europe where recycling has traditionally been more accepted, some of the plants are quite sophisticated with automated sorting and picking equipment, magnets for ferrous metals and eddy currents separators for aluminum.
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The problem at this point is that the market for the cans recovered from the commingled waste while it does exist, does not pay the same value as the curbside UBC because of the contamination of the material. The UBC recycling facilities do not want it, and it gets melted with high oxide (dross) losses in the rotary salt furnace and is made into low-grade remelt scrap ingot (RSI). The result is that there is much less incentive for the municipalities to go after the cans in the commingled waste.
The key issue is to improve the cleanliness of the UBC portion of the waste stream and make it more valuable to the remelt operators. Accordingly, the debagging and loosening of materials should be examined from the aspect of reducing contamination.
Option 3 – Recovery of UBC from an existing landfill
This option is certainly the most complicated and costly, and is probably fraught with complex political, legal liability and regulation issues. On the positive side, the total prize is large with some 20 million tons of aluminium UBC scrap estimated to be buried in the nation’s landfills over the past 3 decades.
When a landfill is filled and sealed, decomposition in the sealed volume generates methane under the chemically-reducing conditions. Boring into a landfill will release the methane and this will be counterproductive if the gas is being used as a fuel. Increasingly, this methane is being combusted for steam generation and to heat large institutional buildings. Also, the material recovered from a landfill will certainly be more contaminated than cans retrieved from commingled waste and, as was noted above, these cans are presently not attractive to the remelt operators.
Again, then, there is the need to develop technology to clean and beneficiate the waste UBC. Before attempting to mine an existing landfill it would be important to conduct some surveys of the locality in an attempt to select a landfill with an above average content of UBC scrap. For instance, it would be important to establish the degree of packing or overburden in the areas of the landfill targeted for recycling, the amount of drying and cleaning required for the recovered UBC, the landfill timeline and the potential capital and operating costs, the potential value of the recovered aluminum and the environmental requirements and costs for resealing the landfill following the recovery process.
My Analysis:
I would say that, aluminum UBC waste could be best handled by working with Options 1 and 2. These options are clearly more straightforward and cost efficient than recovery from an existing landfill, Option 3.
The educational messages on the importance of recycling should have a strong thrust toward the younger schoolchildren. The second major idea is that some serious study should be undertaken to explore and develop low cost techniques to beneficiate and clean the UBC scrap recovered from commingled waste. A more important task will be to develop procedures to remove contamination from the UBC scrap.
Finally, it is noted that any technical success in the cleaning of UBC scrap from commingled waste will also be highly relevant to material that may be eventually recovered from landfills. However, it is not recommended that landfill recovery is attempted at this time pending the outcome of more aggressive educational and beneficiation efforts cited under options 1 and 2.