How to Extract Gold From Seawater

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It sounds too good to be true but it actually is possible. The total quantity of gold and precious metals dissolved in sea water is really unbelievable. It has been estimated that mankind has mined over 5 billion troy ounces of gold since mining began about 6,000 years ago. In contrast, the concentration of gold in seawater is, according to scientific estimates, that the oceans contain somewhere in the region of 25 billion troy ounces, and that this quantity is increasing steadily as more gold comes out from the earth's core.

There are several ways in which this gold could be extracted, and a number of companies are conducting trials. Distillation would be one method - basically distilling seawater and refining the residue. This is uneconomic as the energy required to boil off the water is considerable, though it is potentially a product of desalination plants with added stages. Besides gold, practically all naturally occurring elements are dissolved in sea water, to some degree.

There is now a more exciting and potentially economic solution - literally. In areas of the sea floor where the earth's tectonic plates are diverging (you may have heard of the Mid-Atlantic Ridge and continental drift for example), there are fissures in the sea bottom into which sea water flows. It is heated in the earth's crust (these mid oceanic ridges are composed of hot soft rock) and minerals dissolve in the water. The mineral-rich water emerges through fumaroles (also known as smokers), and the minerals are deposited, which build chimney-shaped structures.

Researchers have discovered over 300 new species living in this very aggressive environment, where temperatures can reach over 200 degrees centigrade or more and water pressure is as much as 1.5 tons per square inch. These species range from bacteria to clams and giant tube worms.

It is thought that bacteria (also known as extremophiles) play a significant role in the production of the minerals which build the chimneys - sulphur-oxidizing bacteria of the genera Beggiatoa, Thiothrix or Thiovulum may be involved in this process.

Some observers have proposed that it may be possible to genetically engineer these or similar bacteria to extract gold and other precious or strategic elements and compounds from seawater. Bacteria have already been engineered to devour crude oil, so why not gold?

It will be the economics that drive this of course. Some mining companies have already been developing bacteria to help with the further refining of low content gold ore waste left over after traditional gold mining operations (bio-oxidation).

Recent difficulties in the world economy, and even talk of a return to the gold standard, are almost certain to lead to a continuing increase in gold prices (they have been increasing steadily for many years) - probably for at least 10 years - and this will inevitably tip the economic balance of gold mining and refining towards more marginal methods.