What the F Is Tantalum?

Title inspiration from Amazon's Jack Ryan.

Spotlight:

• What is tantalum and its history
• Tantalum's essential role in electronics
• Where tantalum is mined and produced
• The supply risk of tantalum

Have you heard of the myth of Tantalus? The Greek king is best known for his punishment in the deep abyss of Tartarus, where he was made to stand in a pool of water beneath a tree budding with berries on low-hanging branches. The fruit was forever above his reach and the water would always recede if Tantalus bent to take a drink.

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How tantalizing.

But this isn't a lesson in Greek mythology. This is simply an exercise in introducing the origin of tantalum—a grey, hard, and heavy metal that is highly resistant to corrosion and also classified as a "rare earth element." And rare it is: tantalum averages only 2 parts per million in the earth's crust.

A Brief History on Tantalum

In 1802, one Anders Gustav Ekeberg reported a new metal at Uppsala University in Sweden. Tantalum gained its name from the Greek myth because it presented a "tantalizing problem" when trying to dissolve it in acid.

Due to this inability to break the metal down with acid, further analysis determined tantalum as identical to niobium—an already discovered metal.

What was not known at that time was that tantalum and niobium often occurred together and were very similar on a chemical level. Not until 1846 was it realized by Heinrich Rose that tantalum and niobium could be separated through a process and proven as two, separate elements.

However, Rose's sample of tantalum was still not pure. Not until 1903 was pure tantalum obtained by one Werner von Bolton.

While the excitement was certain from obtaining a new and pure element, little did the folks in 1903 know just how critical a role the metal would play in the manufacturing of portable electronics.

What Is Tantalum?

Okay, but what exactly is this grey metal that is named after a tortured, mythological Greek king?

Tantalum is sometimes, although rarely, found uncombined in nature. Yet it primarily occurs as columbite-tantalite, which features other metals such as niobium. Tantalum is also obtained commercially as a by-product of tin extraction. Two birds with one stone, as some may say.

The grey, corrosion-resistant tantalum does not have a known biological role and is non-toxic. The metal is naturally solid at room temperature and has extremely high melting and boiling points of 3017 and 5455 degrees Celsius, respectively. Only three other metals have higher melting points.

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Tantalum has extreme tensile strength that is about twice that of high-strength alloy steels. Acids and alkalis are virtually harmless to the metal, as well.

But enough of the chemical jibber jabber. Let's move on...

Why Tantalum Is Essential to Electronics

The primary use of tantalum is in the production of electronic components. The metal has the highest known ability of all metals to store electricity. That sounds important.

The surface of tantalum comprises an oxide layer, which acts as an insulating (dielectric) barrier. Due to this insulating layer, tantalum is often used in a very thin layer to coat other metals and create a high capacitance in a small volume.

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This low volume, high capacitance layer of tantalum makes for quite the tantalizing capacitor. And tantalum capacitors are an attractive option for portable electronics like mobile phones. The metal also is used as electrodes for neon lights and AC/DC rectifiers as it has good rectifying properties.

Yet tantalum's use surpasses consumer electronics and also veers into medical uses. This special, grey metal causes no immune response in mammals: making it a very useful metal for surgical implants. Tantalum in the form of metal plates is used as a bone replacement. In the form of foil or wire, tantalum is used to connect torn nerves. If woven into gauze, the metal is useful in the binding of abdominal muscle.

Camera makers also require tantalum oxide to make special glass with a high index of refraction for camera lenses. And aerospace manufacturers often rely on tantalum to make aircraft and missile parts.

It's easy to understand the namesake of this rare earth mineral. Tantalum truly offers a tantalizing option for many industries.

Where Is Tantalum Sourced and Produced?

The important element is often found in specialized or highly fractionated granitic rocks and their related pegmatites. For the non-geologist, let me translate: tantalum is found in rocks made of granite and the crystals that form on said granite rocks.

Tantalum also occurs in tin deposits and can be sourced from tin slags.

As said above, tantalum is often combined with niobium and other traces of elements such as gold and manganese. To separate tantalum, a solvent extraction process is used to extract the metal into a powder, where metallurgy techniques are then used to form the powder back into metal. Electrolysis of fused salts or reduction of fluoro complexes with reactive metals like sodium is also used to separate tantalum from niobium and other elements.

The current major producer of tantalum is Brazil, with Australia right behind them. Before the economic crisis in 2008, Australia, Canada, and Mozambique were primary producers of tantalum. Yet since the crisis, each country has either shut down or had intermittent production in its main mining operations for the rare metal.

The largest operating mine for tantalum is located in Nazareno, Brazil. The mine has the capacity to produce up to 220 tons of tantalum per year. This equates to around 15% of the global production.

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Supply Risk for Tantalum

The Royal Society of Chemistry rates tantalum as a high supply risk with a score of 7.1 out of 10 (with 10 being the highest risk). The rate is based on the figures featured in the graph below. With its low crustal abundance, low recycling rate, and difficulty for substitution, it's no wonder tantalum offers a high supply risk.

A medium substitutability means it is possible for the metal to be replaced, but the replacement likely creates an economic or performance impact.

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Tantalum is about as abundant as uranium—making it fairly rare. And its current recycling rate creates some angst about the future availability of this critical element. At current rates, it is estimated that tantalum supply will be wiped out in less than 50 years. That's a major blow to miniaturized electronics.

Increased recycling is a major need.

As the supply continues to dwindle, many electronics manufacturers may find themselves stuck between a rock and a hard place.

Or, better yet, between a fruit tree and a pool of water.