In Seawater, Researchers See an Untapped Bounty of Critical Metals – by Jim Robbins (Yale Environment 360 – May 15, 2024)

Researchers and companies are aiming to draw key minerals, including lithium and magnesium, from ocean water, desalination plant residue, and industrial waste brine. They say their processes will use less land and produce less pollution than mining, but major hurdles remain.

Can metals that naturally occur in seawater be mined, and can they be mined sustainably? A company in Oakland, California, says yes. And not only is it extracting magnesium from ocean water — and from waste brine generated by industry — it is doing it in a carbon-neutral way.

Magrathea Metals has produced small amounts of magnesium in pilot projects, and with financial support from the U.S. Defense Department, it is building a larger-scale facility to produce about 200 tons of the metal a year. By 2028, it says it plans to be operating a facility that will annually produce more than 11,000 tons.

Magnesium is far lighter and stronger than steel, and it’s critical to the aircraft, automobile, steel, and defense industries, which is why the government has bankrolled the venture. Right now, China produces about 85 percent of the world’s magnesium in a dirty, carbon-intensive process.

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