Mining the Sea

Chemists located the treasure long ago, and the knowledge that many valuable elements, including gold, are found in sea water has nourished a long dream of riches. But try as they would, no seawater miners could recover precious metals in practical quantities. Germany's famed Chemist Fritz Haber spent years after World War I trying to extract gold from the ocean to pay off his country's war reparations. He failed, and finally gave up the struggle. But in Angewandte Chemie (Applied Chemistry) another German chemist tells how he took a long step toward success, using subtle modern techniques.

Copper Blue Blood. While Professor Ernst Bayer of Tubingen University was still a graduate student, he began to study the ability of marine animals to concentrate some of the rare metals found in sea water. The sea squirt, Phallusia mamillata, for example, has 1,000,000 times more vanadium in its blood than the water it lives in; the deep blue blood of the octopus has 100,000 times as much copper. If sea squirts and octopuses can do the trick, asked Bayer, why shouldn't human chemists?

From octopus blood he extracted hemocyanin, a protein that picks up copper because its molecule has a structure that a copper ion fits into neatly, like a key into a lock. But proteins are hard to handle and almost impossible to synthesize, so Bayer looked for simpler compounds that would do the same job. After many tries, he put together a black granular material that picks up copper and uranium only. When this "chelating agent" worked well in the laboratory with simulated sea water, Bayer took it to Naples, put it in a glass column and ran 100 liters (26.42 gal.) of real sea water through it. Then he flushed the chelating agent with dilute hydrochloric acid. Analysis proved that the acid had picked up 450 micrograms of copper and 50 micrograms of uranium, the precise amounts present in 100 liters of Bay of Naples water.

.000000049 Oz. His achievement was impressive, but Bayer had his eye on the much more difficult feat of capturing the ocean's gold. He concocted another chelating agent with an appetite for gold and went back once more to Naples. There he put a pinch of the new compound in 100 liters of sea water and shook the mixture mechanically for twelve hours. Then he filtered out the chelating agent and washed it with acid. The result: 1.4 micrograms of gold (.000000049 oz.), the exact amount in 100 liters of Naples sea water.

Dr. Bayer himself is not much interested in the practical aspects of ocean gold mining, but he suggests that his method be tried in more favorable places where the water contains more gold than the Bay of Naples. Placed in a stream of sea water that is being pumped through a power-station condenser or a desalinization plant, the chelating compound would work quietly, collecting gold that could be extracted at intervals by washing with acid.

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