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Gold/Mining/Energy : Global Platinum & Gold (GPGI) -- Ignore unavailable to you. Want to Upgrade?

To: d:oug who wrote (13401)	10/9/2000 6:28:58 AM
From: d:oug	Read Replies (1) \| Respond to of 14226

Focused blasts of sound may be the key to extract precious metals. DISCOVER MAGAZINE - discover.com OCTOBER 2000 HIGHLIGHTS FEATURES 20 Species We Might Lose 20 Things That Won't Change 20 Ways the World Could End 20 Young Scientists to Watch 20 Things That Will Be Obsolete in 20 years 20 Ideas That Will Rule Research in the Next 20 Years 20 of the Greatest Blunders in Science in the Last 20 Years What You'll Need to Know In 2020 That You Don't Know Now Focused blasts of sound may be the key to... ... procedure that dispenses with chemicals entirely; ... water and precisely controlled pulses of sound. As a sound wave travels, it creates a ripple of expansion and compression: a low-pressure pulse followed by a high pressure pulse... Tiny bubbles that can sometimes form in water and other liquids react to this change in pressure. The low pressure pulse expands the bubbles and the high pressure pulse makes them contract. With certain sound waves, the contraction caused by the high pressure part of the sound wave can be strong and fast enough to make the bubble collapse in on itself, creating a surprisingly large concentration of energy. Called cavitation, this process is powerful enough that it can damage things like ship propellers and water pipes, eventually eroding them away. Engineers therefore usually try to create cavitation-proof designs, but this goal is hampered by the unpredictable nature of cavitation. ... does not see cavitation as a bad thing. "It's such a fascinating energy manifestation, but we are removing it because we don't understand it and we can't control it," he says. "If you think of fire, any fire is devastating, but if you contain it you can do some good cooking." ... has found a way to control when and where cavitation will occur. Along with a strong sound pulse that causes the bubbles to expand and contract, he uses a weaker background sound wave that destabilizes the bubbles so that they collapse at a lower pressure; the result is that they release... ... is placed in water, tiny bubbles... to form around them, because they repels water. ... sound system blasts these microbubbles; when they collapse, they literally explode the... "It's like micro-jackhammers," he explains. "It chisels away the... and throws it up." The process can strip the... in a few seconds, and the particles can then be filtered out of the water. Although the bubbles have enough energy to destroy the...