Friday, July 20, 2007

nothing is disposable: landfill mining

There is always treasure from trash, the latest idea to make mining landfills economical. So much already disgarded material is in our landfills that it the idea will be both cost effective and more energy effiecient. Novel. North American landfills already contain more aluminum than we can produce by mining ores. It takes only 5% as much energy to recycle aluminum as it does to produce it from ore. Yikes. Landfills also contain gold and copper, used in circuit boards of computers and electronic gadgets. One ton of scrap from discarded PCs contains more gold than that produced from 17 tons of gold ore--and humans throw away 20 million tons of electronic waste a year. Americans dispose of 50 million computers annually; by the end of this decade, the Japanese alone will have trashed 610 million cell phones. Ideas for the extraction include shredding the waste into very small pieces and using magnets to pull out the ferrous metals, using rotors of magnets spinning quickly, creating a current making aluminum metals levitate above the heap (lightweight and conductive) or fractional crystallization a proprietary process from Alcoa (the leading world producer of traditionally strip mined aluminum). Alcoa, thankfully is looking into this practice, not yet having implemented it, but this type of practive will eventually become mainstream.

Via FastCompany

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