The Sciences

6 Times We Tried to Extract Gold from Seawater

Traces of gold in the world's oceans have captivated ambitious minds for more than 100 years. We're still seeking new, inventive ways to extract the precious metal.

By Marisa SloanMar 16, 2022 11:10 AM
Gold nuggets
(Credit: Junjira Limcharoen/Shutterstock)

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Many of the prospectors seeking to strike it rich during the California Gold Rush traveled thousands of miles by foot, wagon or horseback. But for us modern-day millionaire hopefuls, any old coastline just might do the trick.

That's because in 1872, British chemist Edward Sonstadt discovered scant traces of gold in seawater. At that point, scientists already knew about the silver, copper and lead hidden within the world’s oceans — but nothing yet as valuable as gold. Sonstadt suggested that large tanks could be used during high tide to trap and extract wealth from the seas (estimated to be about 65 milligrams of gold per ton of seawater).

Today, some experts argue that seawater extraction could become a more attractive alternative to current gold mining practices and future deep-sea gold mining — a scheme to collect the gold and other metals that shoot out of hydrothermal vents, often located more than a mile below the surface, and build up on the seafloor. Although mining in international waters is expected to begin in 2025, and the International Seabed Authority has so far issued more than 30 contracts for the exploration of deep-sea mineral deposits, experts argue that doing so will irreparably damage ocean ecosystems that are already struggling to combat climate change.

Unfortunately, Sonstadt's calculations were generous. A 1990 study published by MIT scientists instead found that there’s only about 1 gram of dissolved gold (worth around $63 today) for every 100 million tons of water in the Atlantic and Pacific Oceans. If you do the math, that’s at least a few hundred billion dollars floating around out there, depending on the estimated volume of the world’s oceans. At such low concentrations, however, it probably wouldn’t pay off to extract it with the technologies available to us today.

Of course, that hasn’t stopped researchers, rebel inventors and at least one convincing con artist from trying.

The 'Gold Accumulator'

Prescott Ford Jernegan, a Massachusetts pastor with money troubles, contracted typhoid in the summer of 1896. While recovering, he claimed to have had a fever-fueled dream of turning seawater into gold; thus, a scam was born.

Jernegan teamed up with childhood friend Charles Fisher, a trained diver, to attract investors for his “Gold Accumulator” invention later that year. Standing on a pier in Providence, Rhode Island, Jernegan lowered a zinc-lined bucket filled with mercury into the water and claimed to activate a battery that provided the electrical current necessary to extract gold. Unbeknownst to the investors, however, Fisher was beneath the water — replacing the original mercury with previously purchased, mercury-infused gold.

“There is enough gold in the waters of Long Island Sound to pay off the National Debt and leave a larger gold reserve in the Treasury than the Government has yet possessed,” Jernegan wrote in a pamphlet about his new Electrolytic Marine Salts Company. By 1898, the successful company had raised nearly $1 million (about $34 million today), constructed a series of the zinc bucket inventions at a secluded grist mill in Maine, and hired more than 100 unwitting employees to run the scheme.

Things fell apart when a fellow conspirator, private investigator William Phelan, felt cheated of his share of the wealth and published what he knew of the scam in the New York Herald. By the time investors came around to investigate, both con artists had fled — Jernegan and his family set their sights on Europe while Fisher was never heard from again.

War Reparations

During World War I, German chemist Fritz Haber directed a team of scientists on the front lines, helping to weaponize chlorine gas and other chemical agents. Haber was never put on trial for war crimes, however, and was even awarded a Nobel Prize in 1918 for the invention of the Haber-Bosch process. The chemical method turned nitrogen into fertilizer for crops and later kick-started the chemical weapons industry implemented in the second World War.

During the subsequent decade, Haber secretly attempted to recover gold from seawater to help pay off the massive war reparations Germany owed. He estimated that 65 milligrams of gold could be extracted per metric ton of seawater, and he and his colleagues worked hard to develop a method that relied on costly electricity and massive centrifuges. Despite the steep investment, Haber assured a high profit margin.

After Germany greenlit a two-year plan to survey the amount of gold in the world’s oceans, however, Haber discovered that his initial calculations were off by 1,000 percent; the energy-intensive effort to extract this meager amount of gold wasn’t financially viable after all. When Haber died of cardiovascular failure shortly after fleeing Germany (due to his Jewish heritage) in 1933, he still blamed himself for this miscalculation.

An Eye for Byproducts

According to a 1934 article in the New York Times, a Dow Chemicals plant near Wilmington, North Carolina, reported that it could collect a “three-quadrillion-dollar hoard” of pure gold, silver and other metals from seawater within a decade. The plant, initially constructed to extract the element bromine from seawater for use in gasoline, was the first of its kind.

William Dow, the company’s president, claimed that gold could be extracted just as easily as bromine — he just hadn’t figured out how yet. He outlined a plan in which the gold would initially be extracted in the form of a bromine byproduct, to eliminate the large cost of pumping enormous volumes of seawater. According to Dow, the amount of water already being pumped through the plant each day supposedly contained somewhere between $300 and $1,000 worth of gold ($6,000 and $21,000 in today’s dollars).

In 1941, however, Dow announced that their best efforts had “recovered no more than a pinhead of gold from one ton of seawater,” according to another article in the New York Times. One year later, Columbia professor Colin Fink filed another patent for gold extraction, based on his own bromide extraction process. But once again, there were no reports of success.

The 'Sullivan Generator'

Fast forward to 2012, when a Texas-based inventor named Mark Sullivan marched onto the set of the TV show Shark Tank. He sought a $1 million investment for his conceptual “Sullivan generator,” which he claimed used seawater and the Coriolis force (caused by Earth’s rotation) to produce a steam vortex; this hypothetical hurricane could then be used to turn the generator’s turbines and create clean energy.

To sweeten the pot, Sullivan added that byproducts of the process would include potable water and mineral deposits — such as gold. If the 100-foot-tall Sullivan generator sounds too good to be true, that’s because it probably is. After failing to secure a Shark Tank investor, not much has become of the invention in the decade since.

A Molecular Sponge

Chemists in Switzerland identified a new, gold-grabbing material in 2018. They reported that their molecular “sponge” — a polymer filled with pores that increase its surface area — attracts between 90 and 99 percent of the gold ions in water and can reduce them to shiny nuggets within mere minutes. Even more impressive is its ability to target gold, considering other metals like copper are up to 11,000 times more abundant in seawater.

Speaking of seawater, the material isn’t limited to use in the ocean. According to the study published in the Journal of the American Chemical Society, it could also separate gold from freshwater, electronic waste and even sewage sludge. To recover the gold from the polymer, the chemists heated it to 1,600 degrees Fahrenheit to burn off excess organic material, then treated it with hydrochloric acid. The resulting product was the highest karat gold (23.9 karats) ever reported for gold extracted in this way.

Unlike the other inventions on this list, the ingredients used to create the polymer are inexpensive and readily available. However, the polymer must be periodically treated with ascorbic acid to regenerate it. And when it comes to larger quantities of water — more than 2 gallons, in this case — the researchers achieved the same efficiency only after soaking the material for a few weeks.

Since their discovery, the Swiss team has endeavored to transform the polymer into beads that could be used in filter cartridges for running water. Their new startup, Retreeva, aims to make the metal industry more sustainable by helping jewelry and electronics companies retrieve a portion of the estimated $3.5 billion of gold lost in waste streams during production each year.

Microbial Metalworkers

In recent years, a growing body of research has identified a tiny, rod-shaped bacterium as an ideal candidate for extraction of gold from seawater. Delftia acidovorans was first identified in soil in the Netherlands, but has recently been found in other environments too. Researchers at North Carolina State University, for example, have found D. acidovorans throughout their campus, primarily in sink and shower drains.

These chosen habitats are typically toxic thanks to high concentrations of heavy metals, but the bacterium thrives because it secretes a peptide (known as delftibactin) that neutralizes the charged ions. As a result, gold ions are transformed into nanoparticles that eventually accumulate in cracks and crevices as nuggets. Researchers in Germany recently identified the genes that make this possible and successfully incorporated them into an everyday microbe, E. coli., to recover gold from electronic waste.

If you’re ready to swab a shower drain and head straight to the nearest beach, however, maybe take a step back. So far, the amount of gold extracted in this way is almost nonexistent; scientists aren't exactly whipping up gold bars in the lab, and it's unlikely to be practical at the industry level. On the other hand, geologists could someday search for the bacteria as a quick way to determine whether heavy metals are present in an area.

In truth, we’re probably still a long way off from extracting gold from seawater profitably. And that’s OK — the metal has captured human imagination for thousands of years. Our obsession isn’t likely to waver anytime soon.

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