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Group of Microbes Change Dissolved Gold to Solid
option8 writes " National Geographic, has a an article about a newly discovered strain of bacteria that might be used (though, as the article says, not cost-effectively) to harvest gold and other metals from seawater - a longtime fantasy of science fiction."
The microbes might not be economically viable at extracting gold from seawater, but that doesn't mean that they're useless. A clever engineer could probably figure out a way of using the microbes to cheaply process low grade ore. That's currently done using environmentally dangerous processes like cyanide heap leaching (which is as dangerous as you'd expect a process using large amount of cyanide to be) but a microbe that has an affinity for gold could make that type of work much safer and more environmentally friendly. Yes it would take quite a bit of work, but gold is still valuable enough that people are likely to look into it.
There's no point in questioning authority if you aren't going to listen to the answers.
gold as a mineral isnt rare. for instance in sea water. only problem it is distributed widely in solution in minute quantities per gram. I read some years ago about mine dumps leaching metals, the problem was tackled by using some specialised bacteria. so using bacteria to concentrate metals is not new. seabed nodules are made by bacteria which gollect Nickel. but this takes thousands of years. by pumping sea water over beds of bacteria in factories the concentration of gold could be increased.
A lot of bacteria that are found in exotic environments, such as hydrothermal vents, aren't horribly happy when moved far away from those environments. (After all if they were competitive in other places, you'd expect them to show up more widely in the ocean).
The article doesn't say, but they may require high temperature, high pressure, or unusual mineral solutions in order to grow and do their thing. This naturally leads to higher costs, at the very least causing you to pump water through some tank designed to keep them happy. Some of the bacteria used in environmental cleanup etc, are actually genetically modified versions meant to survive in environments other than where the trait developed. Of course on the other hand we might get lucky and they do like sitting on the beach churning out gold.
If it can be made profitable I'm sure someone will do it.
Everyone seems to think these bacteria are simply coagulating dissolved gold metal, something you could do by simply by letting water settle.
They're not.
The bacteria are reducing the gold from an ionized salt form (Ag+) to solid gold. That would take a bit more effort (and a ton of water pollution) for a laboratory to accomplish.
If I remember my early 20th century history correctly (and I might not), Bryant wanted free and unlimited minting of money. This would have made it easier for farmers (his chief supporters) to pay off their debts (small farmers then had the same problems as small farmers now), but would have made inflation rampant.
Bryant would have wanted these microbes because his understanding of economics sucked. His understanding of evolution sucked, too (he was part of the prosecution in the Scopes Monkey Trial). Hell of a public speaker, though
-jon
Remember Amalek.
Metals have been produced from seawater for decades, and very economically, too. There are several which can be practically produced this way. But of that group, the only common *structural* metal which I can think of is Magnesium.
Magnesium hydroxide can be cheaply extracted from brine by precipitation when a cheap alkali is added - usually slaked lime (calcium hydroxide). The magnesium hydroxide becomes the feedstock for electrolytic cells which produce metallic magnesium. This second step is similar to the way that metallic aluminum is produced from aluminum hydroxide, after it is refined from bauxite. At one time, most of the world's magnesium was produced this way, though it may or may not be now - there are other practical sources. It is sufficient to say that the cost of electrolysis for magnesium production greatly outweighs the cost of the hydroxide feedstock, regardless of the source.
Uranium can also be produced from seawater, by various methods, but the cost is very much higher than either current world prices (very low right now) or even historical peak prices. It *is* however, *definitely* not too expensive for breeder reactor usage (breeders yield ~100 times more energy per unit mass of natural uranium). And there is something like 500 - 1000 times more uranium dissolved in seawater than all current, proven reserves in conventional mines.
In addition, I believe several other, non-structural metals are or can be produced from seawater. Rubidium, cesium, strontium, barium are perhaps possible. The amounts available is *usually* vastly larger than mine reserves.
Clearly, calling metal extraction from seawater "science fiction" is quite inappropriate.
-- Mike Greaves