Indispensable twin metals critical to US
Niobium-tantalum; closely related metals with vital properties
Last updated 6/22/2020 at 11:08am
With nearly indistinguishable characteristics, niobium and tantalum are considered the "indispensable twins" among the 35 minerals and metals considered critical to the United States.
"Niobium and tantalum are transition metals that are almost always found together in nature because they have very similar physical and chemical properties," the U.S. Geological Survey wrote in a 2018 paper on the twin metals.
While nearly identical twins, they each have their own set of unique characteristics that make them vital to a wide array of products used in the defense, energy, high-tech and medical sectors.
"The leading use of niobium is in the production of high-strength steel alloys used in pipelines, transportation infrastructure, and structural applications," USGS penned in its report. "Electronic capacitors are the leading use of tantalum for high-end applications, including cell phones, computer hard drives, and such implantable medical devices as pacemakers."
Niobium and tantalum share one more quality that places these indispensable twins firmly on the list of minerals and metals the USGS has deemed critical to the security and economic wellbeing of the United States – you cannot find a good substitute for either without sacrificing performance and increasing costs.
Like the majority of the 35 critical minerals and metals, Alaska has the potential to be a domestic source of both niobium and tantalum.
Niobium's toughness, resistance to corrosion and high melting point makes it an important alloy to steel that is used in situations where durability is vital. That is why around 75 percent of this metal is used as an alloy in high-strength steel used in pipelines, transportation, and structural applications.
Niobium's extreme resistance to heat makes this metal an important ingredient for iron-, nickel- and cobalt-based superalloys that need to stand up to high temperatures.
Roughly 20 percent of the niobium consumed in the U.S. is used to make high-temperature superalloys used in parts that go into jet engines, rockets, gas turbines and turbochargers.
Adding to its résumé of "super" properties, niobium is among the most powerful superconducting metals.
Superconducting magnets made from niobium-germanium, niobium-tin and niobium-titanium alloys are used in a range of important devices, from imaging equipment to particle accelerators.
The magnetic resonance imaging (MRI) scanners, which use niobium superconducting magnets, along with radio waves and a computer to create a detailed image of the inside of a human body – is among the applications of this critical metal's special characteristics.
Niobium superalloy magnets also play a crucial role in the Large Hadron Collider, a 27-kilometre (17 miles) circular tunnel deep under the border between Switzerland and France that physicists use to collide particles together at near the speed of light. These high-energy collisions of protons help scientists investigate dark matter, antimatter and other secrets of the universe.
Magnetic fields guide and squeeze the particle beams, creating a more powerful collision. Niobium-titanium magnets currently being used to provide these powerful magnetic fields are being replaced with even more powerful niobium-tin magnets.
International scientists are now floating the idea for the Future Circular Collider, a 100-kilometers (62 miles) successor that would be 10 times more powerful than the Large Hadron Collider. This massive US$27.5 billion project, including initial and upgrade costs, would need a whole lot more niobium and a slew of other metals considered critical to the United States.
Beyond its "super" characteristics, niobium is also hypoallergenic and inert, making it a good candidate for uses inside the human body, such as pacemakers and prosthetics.
Niobium is also one of the few metals that can be heated to produce a wide array of iridescent colors. The heat creates anodized oxide layers on the surface of niobium that creates this color changing effect by diffracting the light that bounces off it.
This ability, coupled with being hypoallergenic, makes it a popular for creating colorful jewelry, especially for body-piercing.
While tantalum shares many of niobium's characteristics, its exceptional capacity to store and release energy is this twin's superpower. Due to this unique ability, more than 50 percent of the tantalum consumed in the United States was used in capacitors and high-power resistors for the electronics sector.
"Major end uses for tantalum capacitors include automotive electronics, mobile phones, and personal computers," the USGS penned in its 2018 minerals report.
Because it is so good at storing and releasing energy, tantalum capacitors and resistors can be exceptionally small. This is crucial in the shrinking of modern electronics, such as cell phones and hard drives, and medical devices, such as hearing aids.
Tantalum oxides are also used to make lighter weight glass camera lenses that produce a brighter image.
In addition to traits that set it apart from its twin, tantalum shares many of niobium's characteristics and is often used for similar applications. Being substantially more expensive, however, tantalum typically imbues its properties as a coating on other metals.
One such parallel is devices going inside the human body, where tantalum-coated blood vessel stents, plates, bone replacements, suture clips and wire are often used.
In the chemical industry, tantalum's corrosion resistance makes it useful as a lining for pipes, tanks, and vessels
Wholly dependent on others
While deposits of both niobium and tantalum are found in the United States, it has been nearly six decades since either of these critical minerals have been produced domestically.
"Primary production of niobium or tantalum in the United States has not been reported since the late 1950s; therefore, the United States has to meet its current and expected future needs by importing primary mineral concentrates and alloys, and by recovering them from foreign and domestic alloy scrap," USGS inked in an information sheet on the indispensable twins.
As a result, the U.S. imported an estimated 11 million kilograms (24.3 million pounds) of niobium, valued at US$310 million, to meet the needs of U.S. manufacturers in 2018.
Accounting for roughly 72 percent, Brazil was by far the United States' largest source for niobium. Canada (18 percent), Russia (3 percent) and Germany (2 percent) accounted for most of the balance.
While tantalum consumption in the U.S. is a little more than 10 percent that of niobium, the high price this energy storing metal fetches makes up the differential.
According to the USGS, about 1.17 million kg (2.6 million lb) of tantalum, valued at US$310 million, was used in the U.S. last year.
Brazil, at 35 percent, shipped the most tantalum ore and concentrates to the U.S. in 2017. Rwanda (31 percent), Australia (15 percent) and Congo (8 percent) were other sources of tantalum minerals.
When it comes to tantalum metal, China, at 40 percent, was the United States' largest supplier last year. Germany (18 percent), Kazakhstan (17 percent and Thailand (11 percent) were other countries that supplied America's growing tantalum metal requirements.
Because the U.S. is wholly dependent on foreign sources for both niobium and tantalum, it is vulnerable to potential supply disruptions from swings in the metal markets, such as the recent downturn that interrupted operations at several mines, and global economic instability that could create supply problems.
"Other possible disruptions include war, civil unrest, political changes, natural disasters, environmental issues and market manipulation," the USGS penned in its niobium-tantalum paper. "For example, rebel sales of 'conflict coltan' (coltan is a niobium-tantalum mineral) in the Democratic Republic of Congo, amidst a civil war, have led to discussions about supply-line transparency and traceability as tools for excluding illegal columbite-tantalite while keeping the market open for legitimate, small-scale artisanal mining in central Africa."
An improved global economy – coupled with continued economic development of BRIC (Brazil, Russia, India and China) countries – is expected to drive up the competition for niobium and tantalum.
"Niobium and tantalum are considered critical and strategic metals based on the potential risks to their supply (because current production is restricted to only a few countries) and the significant effects that a restriction in supply would have on the defense, energy, high-tech industrial, and medical sectors," according to the USGS.
Alaska is home to potential domestic supplies of both indispensable metals.
Twins found at Kougarok
The Kougarok prospect about 90 miles north of Nome on the Seward Peninsula is one Alaska locale where both niobium and tantalum are known to exist.
Situated on the north side of Kougarok Mountain, this prospect is best known for its tin, another of the 35 metals considered critical to the United States.
While an official resource estimate is not available for Kougarok, work carried out by Anaconda Mining Company in the 1980s has outlined potentially large and critical mineral-rich deposits at Chuck's dike, Main plug and Roof greisen, the main targets identified so far.
The richest tantalum and niobium concentrations were identified in Main plug. According to preliminary calculations, this portion of the larger Kougarok prospect hosts 1.4 million metric tons averaging 0.45 percent (12.6 million lb) tin and 0.1 to 0.3 percent (2.8 million to 8.4 million lb) combined niobium and tantalum.
Navigator Exploration Corp. and Chapleau Resources, Ltd., which optioned Kougarok in 2001, took a closer look at the prospect's tantalum potential. These explorers found elevated tantalum values across the wider prospect area.
One hole drilled outside of Main plug cut 31.5 meters averaging .033 percent tantalum. The niobium values of this hole were not reported.
Numerous other tin deposits are found on the Seward Peninsula, making this region of western Alaska highly prospective for the niobium and tantalum that is associated with the specialized granites that host this critical metal.
Placer niobium at Tofty
The Tofty tin belt, a 12-mile-long stretch of the Manley Hot Springs district in Interior Alaska, is an area rich in placer tin deposits and intriguing clues of at least a third of the 35 minerals and metals critical to the United States have been found.
The tin potential of the Tofty area became readily apparent to the early placer miners that discovered gold in this area about 90 miles northwest of Fairbanks.
Niobium is also present in the gold- and tin-rich placers mined in this area. Pan concentrates from the tailings at Idaho Gulch and Miller Gulch, gold producing creeks in the area, turned up 0.2 to 7 percent niobium bearing minerals.
It has been estimated that the placer tailings in the upper portion of Idaho Creek contain roughly 100,000 pounds of niobium.
While investigating the lode source of the prolific tin found in the streams of the Hot Springs District, the Alaska Division of Geological and Geophysical Surveys found interesting quantities of many of the minerals and metals considered critical to the United States, including bismuth, chromium, gallium, manganese, niobium, rare earth elements, scandium, strontium, tantalum and vanadium.
About 60 miles north of the cassiterite-bearing streams at Tofty, Ucore Rare Metals has found that the rare earths-rich placer deposits on its Ray Mountains property contain appreciable amounts of tin and other critical minerals.
Concentrates from gravity separation of placer samples collected at Ray Mountains returned up to 50 percent tin; 10 percent rare earths; and 0.01 to 1 percent tungsten, tantalum and niobium.
"The Ray Mountains project has select areas rivaling HREE (heavy rare earth element) content at our Bokan property, and the remarkable advantage of collateral tin, niobium and tantalum mineralization which enhances prospective values per ton." Ucore President and CEO Jim McKenzie said, referring to the company's Bokan Mountain property in Southeast Alaska.
A definitive lode source of the 100-meter-deep bed of critical mineral-bearing gravels at Ray Mountains has yet to be found.
Niobium with rare earths
It is also common for niobium to be found alongside the suite of lanthanide minerals know as rare earth elements and Alaska holds a lot of potential as a domestic source of this suite of critical minerals.
Ucore's Bokan Mountain project on Prince of Wales Island in Southeast Alaska hosts the most advanced rare earth deposit in the state.
"REE prospects at Bokan Mountain may have the greatest immediate potential for development of an REE resource in the state," USGS penned in its 2017 report on Alaska's critical mineral potential.
A rare earth mine here has the potential to provide a by-product supply of niobium, along with zirconium and tantalum.
The Dobson Ridge deposit at Bokan Mountain hosts 4.79 million metric tons of indicated resource averaging 0.6 percent (63.54 million lb) total rare earth oxides.
Dobson Ridge, however, is only one of numerous REE occurrences radiating from Bokan Mountain. Back in the 1980s, the U.S. Bureau of Mines estimated that these occurrences contain some 374 million lb of rare earths plus yttrium; another 638 million lb of zirconium, another critical metal; 96 million lb of niobium; and an unquantified amount of tantalum.
While this resource estimate does not comply with modern reporting standards, it does provide a sense of the critical minerals at Bokan Mountain and similar rare earth targets found across Alaska.
A stretch of Southeast Alaska, extending 200 miles northwest from Bokan Mountain, is known to host additional rare earth prospects such as Salmon Bay at the northern end of Prince of Wales Island.
Where to find the twins
The good news for explorers seeking niobium and tantalum in Alaska is the two deposit types – tin-bearing granites and REE-bearing intrusive rocks – are typically found close to each other across the state.
Working with the Alaska Division of Geological & Geophysical Surveys, USGS has identified 10 areas of Alaska that are highly prospective for tin-rich granites that typically also host tantalum, niobium and a suite of other critical minerals.
Besides the Kougarok area on the Seward Peninsula and the swath of Alaska's Interior that hosts Tofty and Ray Mountains, the other regions that are good hunting grounds for tin, niobium and tantalum are:
• Northern Alaska Range, an area arcing about 220 miles west from Tok;
• Western Alaska Range, a 15,000-square-mile region centered on the Revelation Mountains that shows very high potential;
• Yukon-Tanana, a large swath of Interior Alaska extending from the Yukon-Alaska border to the Roy Creek REE prospect north of Fairbanks;
• Kuskokwim-White Mountains, which stretches about 500 miles southwest from Yukon-Tanana;
• Darby Hogatza, an area of know uranium and REE occurrences that arcs 200 miles east from the Seward Peninsula; and
• Porcupine, an area centered on Spike Mountain in far northeastern Alaska.
The areas that show promise for tin-bearing granites are also great places to look for rare earth deposits, all of which could provide domestic sources for the indispensable twins – niobium and tantalum.