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📢 文末扫码进裙，免费领取双语精读讲义 Urban mining: Goldbugs at work Bacteria can help recover precious metals from electronic waste The Economist Science & technology Nov 11, 2024 | 791 words | ★★★★☆ Gold mining can be a dirty business. Even with relatively rich deposits, usually found in remote areas, you need giant excavators, huge crushing machines, lots of water and highly toxic chemicals, like acids and cyanide, to extract just ten grams of gold from a single tonne of ore (there are 31 grams in a troy ounce). At current rates, that is worth over $800. A different sort of pay dirt, however, offers the prospect of a much greater return for urban miners: the printed circuit boards (PCBs) found in rapidly growing mountains of electronic waste. Estimates vary, but a tonne of PCBs could contain 150 grams or more of pure gold, which, because it does not tarnish, produces stable electrical connections. There are also other valuable materials used alongsi
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