Patrick Atkins says there is plenty of aluminum in landfills — more aluminum than we can produce by mining ores. He is the director of energy innovation at Alcoa, a large aluminum manufacturing firm. He thinks the same is probably true of gold and copper, which are used in the circuit boards of computers and electronic gadgets. One ton of scrap from discarded PCs contains more gold than can be produced from 17 tons of gold ore--and humans throw away 20 million tons of electronic waste a year. Landfill mining is a fascinating sleeper of an idea that's actually been around for decades.It attracted serious interest in the early 1990s, when the EPA came out with new regulations that forced small communities to close their local dumps. Towns such as Newbury, Massachusetts; Edinburg, New York; and Naples, Florida, tried mining their junk piles for metals and rubber, and burning the leftovers for energy. But as market rates for metals fell in the mid-1990s, the whole notion no longer seemed economical. Now, though, with commodity prices high and a wealthy player like Alcoa sniffing around the dump, landfill mining looks like an idea whose time is finally arriving.
Much of the technology for landfill mining is already proven. As in the 1990s trials, screens and sieves could separate the soil from the waste. The standard techniques of the recycling business would come into play: shredding the waste into very small pieces and using magnets to pull out the ferrous metals. Then comes a new approach, pioneered by recyclers in the past few years, using rotors of magnets that spin very quickly, creating an "eddy current" with a strange electrical effect that makes aluminum and other nonferrous metals levitate and eject from the rest of the heap because they are both lightweight and conductive. If Alcoa gets involved, it could use its highly secretive, proprietary process of "fractional crystallization" for separating alloys from each other, such as copper from aluminum.
The separation process isn't cost effective yet. But factor in the energy savings: Alcoa is probably the world's largest purchaser of electricity, and it takes only 5% as much energy to recycle aluminum as it does to produce it from ore. Then add some further innovative thinking and collaboration among companies, such as creating software to simulate the physical environments before the digging and mining take place, and Atkins says landfill mining would become economical.
The idea is one of a number of creative approaches that look at environmental problems as holding the seeds of their own solutions, says Truman Semans of the Pew Center on Global Climate Change. He puts it in the same category as using tapped-out, abandoned oil wells to bury the carbon dioxide produced by burning coal, a promising way to let both the United States and China take advantage of their huge coal supplies without exacerbating global warming. "It's finding value in otherwise nasty or unused resources," he says. Landfill mining will probably follow the same trajectory that recycling did, Semans says. While still an infant industry and not yet efficient enough, it will need some initial support from tax breaks, subsidies, and government policies, but eventually, it will become cost effective on its own.
In the meantime, of course, landfills across the country swell and fester. Even with newly mandated plastic linings and such, they're really not much different than putting your trash in Hefty bags and burying it in the backyard. Eventually, the bag tears or leaks, and the soil gets contaminated. Why not keep those big dumps clean by mining the treasure within?