Electrolysis makes titanium, other pricey metals less expensive

Titanium wedding bands. Nice!

These days, our most precious technology is made of tiny amounts of very expensive transition metals—those shiny materials in the middle block of the periodic table, including titanium ($30/kg) and tantalum ($500-2000/kg). However, it seems we’re approaching a breakthrough similar to the Hall-Heroult process, thanks to a British company called Metalysis.

When Charles Hall and Paul Heroult simultaneously and independently determined how to produce aluminum metal via the electrolysis of a molten aluminum salt in 1886, aluminum went from one of the costliest and most prized elements on the periodic table to one of the most common manufacturing materials known. Hypothetically, the Hall-Heroult process would work for other difficult-to-refine metals, if it weren’t for their much higher melting points.

Metalysis, a spinoff of Cambridge University’s Department of Materials Science and Metallurgy and now headed by CEO Guppy Dhariwal, performs electrolysis directly on powdered oxides of tantalum and titanium. The metal oxides (fairly common and fairly cheap—titanium oxide is a popular white pigment and a component of mineral sunscreens) serve as the cathode in the electrolytic reaction, with a carbon anode.

A molten salt, whose temperature hovers around 1000 degrees Celsius, conveys oxygen ions from cathode to anode, converting the anode into carbon dioxide and the cathode into pure metal. (Remember battery chemistry? It’s okay; me neither.)

First performed in 1997, the process has been scaled up to provide 3 to 4 percent of the worldwide tantalum metal supply. If the process scales properly for titanium—Metalysis is shopping around for defunct aluminum smelters to convert for that purpose—the economics of the metals market may change drastically in the near future.

Metal powders alone are deeply exciting for 3D printing enthusiasts, whose current metal options are silver, stainless steel, and sometimes aluminum. Casting the powders into ingots or sheets, as used in traditional industry, would allow their use in automobiles and aircraft, as well as hundreds of other possible consumer products.

[via The Economist / Photo: Bence Fördős/Flickr (CC BY-SA 2.0)]

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