Fiber-optics, solar drive germanium demand
Vital optics metal already a byproduct of mining Red Dog zinc
Last updated 6/22/2020 at 11:03am
In addition to being a past producer and a future source of most of the 35 minerals and metals considered critical to the United States, Alaska currently contributes a globally significant amount of one of these vital metals – germanium.
While not a widely known metal, germanium has optical qualities that make it an important ingredient in fiber-optics, infrared optics, electronics and solar energy systems.
"The extensive use of germanium for military and commercial applications has made it a critical material in the United States and the rest of the world," the United States Geological Survey wrote in a report on critical minerals published at the beginning of 2018.
Due to this criticality, the United States and China have included germanium in their stockpile programs and the European Union included germanium in a list of raw materials of critical concern for its member countries in 2010.
Like many other critical metals, germanium is not mined as a primary metal.
"As a byproduct metal, the supply of germanium is heavily reliant on zinc production," the USGS penned in its report.
Alaska happens to be home to the world's largest producing zinc mine, Red Dog, and the concentrates shipped from there contain noteworthy quantities of germanium.
"Worldwide, primary germanium was recovered in Canada from zinc residues (concentrates) shipped from the United States (specifically, the Red Dog zinc-lead mine in Alaska and a previously idled zinc mine complex in Tennessee); in China, from zinc residues and coal from multiple sources; in Finland, from zinc residues (concentrates) originating in Congo (Kinshasa); and in Russia, from coal from domestic sources on Sakhalin Island in Sakhalinskaya Oblast'," the USGS penned in its critical minerals report.
While germanium is an intrinsic semiconductor, the metal has several optical qualities – transparent to the infrared electromagnetic spectrum, can be formed into glass, has an exceptionally high refractive index and low chromatic dispersion – that drives most of its demand.
Roughly half of the 27,000 kilograms (59,525 pounds) of germanium consumed in the United States during 2018 was used in the infrared imaging devices widely used by the military and law-enforcement agencies.
"Infrared optical devices improve a soldier's ability to operate weapon systems in harsh conditions effectively, and they are increasingly used in remotely operated unmanned weapons and aircraft," the USGS inked in its germanium report. "Infrared optical devices are also used for border patrol and by emergency response teams for conducting search-and-rescue operations."
An extraordinarily high refractive index – the ability to bend light – is an important characteristic germanium lends to fiber-optic cables.
"Germanium is added to the pure silica glass core of the fiber-optic cable to increase its refractive index and minimize signal loss over long distances," the USGS explains.
This property is strengthened by germanium's low chromatic dispersion – the scattering of light passing through a medium.
"Chromatic dispersion is a serious consideration in long-haul optical fibers. Its effect is essentially to stretch or flatten the initially sharply-defined binary pulses of information. This degradation makes the signals (1s and 0s) more difficult to distinguish from each other at the far end of the fiber," M2 Optics Inc. CEO Kevin Miller explains.
The growing need to send and receive data continues to drive the demand for more fiber-optic cable and the germanium that goes in it.
Solar power generation and electronics are the other big drivers for growing germanium demand.
"Germanium substrates are used to form the base layer in multijunction solar cells, which are the highest efficiency solar cells currently available," according to the USGS.
These solar arrays, which have three layers of cells that use germanium and other critical metals, are much more expensive to build than the typical photovoltaic cell that primarily uses silicon to convert light into electricity.
The high-efficiency of the germanium infused solar cells make them preferred for space applications such as the Mars rovers.
"The solar cells are stacked in three layers on the rover's solar arrays and, because they absorb more sunlight, can supply more power to the rover's re-chargeable lithium batteries," NASA Jet Propulsion Laboratory explains on technologies to power space missions.
USGS said recent research could make similar high-efficiency solar arrays commercially viable on Earth, a potential driver for future germanium demand.
"Solar powerplants that use concentrator technology composed of lenses or mirrors that focus high concentrations of direct sunlight onto germanium-based multijunction solar cells have emerged as viable sources for large-scale renewable energy generation," the geological survey wrote.
Red Dog germanium
Due to being a byproduct metal that is credited to the refinery extracting the germanium from the zinc and lead concentrates, it is hard to pinpoint exactly how much germanium is produced at Red Dog each year.
Indicators are, however, that Red Dog's germanium production are significant in relation to the global market of this critical mineral.
Teck Resources Ltd. – which operates Red Dog and owns Trail Operations in southern British Columbia where zinc and lead concentrates from the Northwest Alaska mine are refined – is one of the world's largest integrated germanium producers.
The Trail refinery offers a wide variety of high-quality germanium products, including germanium dioxide and fiber optic grade germanium tetrachloride.
While Red Dog is not Trail's only supplier, USGS said the majority of the germanium the refinery produces likely comes from there.
"Most of the germanium produced at metallurgical facilities at Trail, British Columbia, Canada, likely comes from sphalerite concentrates from the Red Dog district," the geological survey wrote.
While the quantity of germanium produced at Trail is guarded, it is considered globally significant.
A partial force majeure – unforeseeable circumstances that prevent someone from fulfilling a contract – on germanium output from Trail early in 2018 pushed germanium prices up 31 percent, from US$1,757/kg in January to US$2,300/kg in March.
Repairs to the damaged facilities at Trail were expected by the end of 2018, which allows the refinery to resume germanium production.
The critical mineral has maintained a price of around US$2,200/kg into 2019.
Teck announced plans in 2018 to extend the life of the Red Dog Mine out to at least 2031, based on the 57.6 million metric tons of reserves averaging 13.6 percent (13.9 billion pounds) zinc, 3.9 percent (2.5 billion lb) lead and an undisclosed amount of germanium in the deposits currently being mined.
Aktigiruq, a large and high-grade zinc target roughly five miles northwest of the current operations, could extend the life of Red Dog 25 to 50 years deeper into the 21st Century.
Part of the same group of sphalerite-rich sedimentary exhalative (SEDEX) deposits that is currently being mined at Red Dog, Aktigiruq likely means Alaska will be a global germanium source for decades to come.
Germanium at Bornite
While zinc deposits are the primary source for germanium and Red Dog is among the richest such stores on Earth, carbonate hosted copper deposits also sometimes have a germanium component to them and there is one such deposit in Alaska that could be a source of this critical metal in the not too distant future.
Although germanium is known to be found in carbonate hosted zinc-lead deposits, not a lot is understood about potential associations with this style of deposit carrying mostly copper. The critical metal, however, has a known affinity for chalcopyrite, a copper mineral, which raises the possibility that a large carbonate hosted copper deposit, such as the Bornite deposit at Trilogy Metals Inc's Upper Kobuk Mineral Projects in Northwest Alaska, could be a future germanium source.
With 6.4 billion lb of high-grade copper, Bornite has long been as a world-class deposit of this energy metal. Now this carbonate-hosted deposit is being investigated for its critical metals potential.
Roughly 77 million lb of cobalt has already been identified at Bornite and the deposit is known to also carry germanium and gallium.
To find out more about the distribution of these critical minerals and to investigate the deposit's potential for rhenium, Trilogy Metals has entered into a technical assistance agreement with USGS.
The work carried out under this study is providing Trilogy a better understanding of the potential of recovery critical minerals as a by product of mining the billion of pounds of copper at Bornite and is providing USGS information it can apply to other deposits in Alaska as it continues to seek potential domestic sources of the metals considered critical to the United States.