Stacking uses for Alaska STAX graphite
Batteries, stealth coatings, semiconductor diamonds top list Metal Tech News Weekly Edition – May 20, 2020
Last updated 6/27/2020 at 6:09am
The adoption of electric vehicles and renewable energy is driving increased demand for graphite, a major ingredient in lithium-ion batteries. Graphite, however, is high on a list of 35 critical minerals and metals not mined in the United States.
Graphite One Inc. would like to shift America's reliance on foreign countries such as China for its graphite needs by developing a mine at Graphite Creek, a world-class deposit of graphite with some properties that make it uniquely suited for batteries and other high-tech applications.
Located about 35 miles north of the famous gold mining town of Nome, Alaska, Graphite Creek already hosts 8.2 million metric tons of graphite in 10.95 million metric tons of measured and indicated resources averaging 7.8 percent (850,534 metric tons) graphitic carbon; and 91.89 million metric tons of inferred resource averaging 8 percent (7.34 million metric tons) graphitic carbon.
Already large, this resource represents roughly a half-mile section of thick layers of graphite that extend at least 11 miles across the company's property. With enough graphite in this small section to support 40 years of mining, there is no real need to do the drilling required to add further resources.
A 2017 scoping level economic assessment outlines plans for a mine at Graphite Creek that would produce roughly 60,000 metric tons of 95% graphite concentrate per year and a separate processing facility to refine these annual concentrates into 41,850 metric tons of the coated spherical graphite used in lithium-ion rechargeable batteries and 13,500 metric tons of purified graphite powders annually.
Those purified powders may go into some interesting high-tech and industrial products – stealth coatings, synthetic semiconductor diamonds and fire suppressing foams, to name a few – thanks to some unique properties of the Graphite Creek graphite.
"We are excited about the potential for value-added applications which identify flake graphite from Graphite Creek as a unique resource," said Graphite One President and CEO Anthony Huston.
Need for STAX graphite
The anodes in lithium-ion batteries are packed full of graphite that has been rolled into potato-shaped spheres and coated in a hard carbon shell that protects the anode material. So, any graphite deposit that wants to supply the rapidly growing lithium-ion battery sector must have graphite that can be transformed into this semi-spherical shape – typically large flakes that can be rolled.
When testing Graphite Creek material, Graphite One was pleasantly surprised to find that much of the graphite in its Alaska deposit is naturally spherical and possessed other unique attributes.
The company coined the acronym STAX to describe the distinctive spheroidal, thin, aggregate, and expanded properties of the graphite in the Graphite Creek deposit – characteristics that may make the material well-suited for numerous high-tech, renewable energy and military applications.
Graphite One believes the uniqueness of STAX graphite could provide a major competitive advantage by delivering U.S. manufacturers with a domestic supply of high-end graphite products, at lower costs and with superior performance.
Of course, the naturally occurring spherical graphite is of particular interest because the lithium-ion batteries that require this form of the carbon allotrope is expected to be the biggest driver for graphite demand in the coming years and decades.
In a May 11 report, World Bank Group forecast that EVs and renewable energy sources such as wind and solar could drive a 500% increase in the annual demand for battery minerals such as graphite, lithium, and cobalt.
Without a domestic source for graphite, U.S. battery manufacturers will be forced to rely heavier on overseas sources for the anode mineral or export their lithium-ion battery manufacturing to countries that have the materials.
During a 2019 testimony before the U.S. Senate Energy and Natural Resources Committee, Benchmark Mineral Intelligence Managing Director Simon Moores said America is not doing enough to secure reliable sources of graphite and other lithium-ion battery materials.
"We are in the midst of a global battery arms race in which the U.S. is presently a bystander," the global battery materials authority said.
"Those who control these critical raw materials and those who possess the manufacturing and processing know-how, will hold the balance of industrial power in the 21st century auto and energy storage industries," he added.
Fortunately for the U.S. and Graphite One, preliminary tests found that more than 74 percent of the STAX flake graphite could be turned into spherical graphite needed for batteries without milling.
This is a monumental achievement considering that only about 40 percent of the best-performing flake graphite found in any other known deposit can be converted to spherical graphite, even with the use of high-end processing equipment.
The shape would be of little consequence if the material did not perform well in batteries and STAX graphite as the anode in lithium-ion cells demonstrated a first discharge capacity at or near the theoretical maximum for natural, uncoated spherical graphite.
Discharge capacity is a measure of a battery's energy storage capability once first charged.
The first-discharge capacity of the best-performing cell using STAX graphite equaled the theoretical maximum and most of the cells were within 1 percent. The largest deviation from the theoretical maximum was 3 percent.
Graphite One says this ability to reach and closely approach what is currently believed to be the discharge capacity limit, coupled with the capacity to consistently maintain high values on cycling demonstrates the high-performance potential of the STAX graphitic carbon.
"From the time we identified the unique mineralization of our STAX graphite, we've observed a number of potential performance advantages," said Huston.
To further test the advantages STAX has to offer, Graphite One shipped roughly 12,000 pounds from surface sampling at Graphite Creek to a United States-based industrial partner for processing into advanced graphite materials.
Testing by this unnamed partner confirmed that spherical graphite made from STAX material performed well as lithium-ion battery anode and maintained strong performance after 170 charge-discharge cycles. Graphite One said this testing further demonstrates strong potential for STAX as an anode material.
Enhancing alkaline batteries
In addition to a good candidate for a domestic source of lithium-ion battery anode material, the recent testing shows that the unique properties of STAX graphite is well suited for other high-tech, industrial and defensive applications.
To fully take advantage of all the attributes STAX has to offer, Graphite One has opted for a processing flow sheet that purifies the Graphite Creek concentrates in the beginning. While opposite of what is done at other graphite operations, this inverted purification flow sheet would allow the company to redirect all the material that is not ideal for rechargeable battery anode material toward other value-added applications.
Testing carried out by Graphite One's industrial partner found that some of the non-spherical STAX graphite would work well as a conductivity enhancement additive for cathodes in alkaline batteries.
Extensive testing of two STAX products with grades topping 99.99% graphite have shown to work well as a conductivity enhancer in alkaline batteries. Samples of this ultra-high purity graphite has been supplied to a leading battery company for further analysis.
Graphite One said initial feedback has been positive and testing is ongoing.
Putting out fires
Some STAX graphite may also find its way into fire suppression foams.
Thermally purified STAX graphite has been turned into an expandable flake product, which was subsequently formulated into fire retardant foam concentrates.
Testing being carried out as part of a joint project with the Naval Air Warfare Center Weapons Division of the Naval Air Systems Command (NAVAIR) in California has formulated fire retardant foams capable of extinguishing Class B – burning oil, gasoline, diesel, and aviation fuel – fires using expandable STAX graphite.
Graphite One and its unnamed partner have conducted small scale demonstrations highlighting the increased effectiveness of STAX graphite in extinguishing oil fires. Full scale Class B testing per military specifications is slated to take place in the third quarter of this year.
Another potential application that is garnering military interest is the use of graphite in paints and coating that suppress radio waves and infrared. These coatings could also be used for anti-corrosion and ultra-high precision metal working applications.
Technical data from testing ultra-pure STAX graphite dispersed in paints and coatings has been introduced to the Defense Logistics Agency, which is responsible for sourcing materials into America's military supply chains.
Purified versions of STAX material have also been converted into synthetic diamonds with the use of industry-standard technologies that involve high pressure and temperature.
Initially, a 6.5-gigapascal press was used to generate synthetic diamond dust. This is an essential test to validate the ability of STAX material to be converted into synthetic diamonds. Not every graphite precursor can produce diamonds with this method as some lose integrity when under high pressure. STAX graphite, however, successfully formed diamond dust under the lower temperature and pressure conditions that could be used for metal working applications, such as pigments for lapping compounds and ultra-hard coatings on drilling, cutting, and grinding equipment.
The second phase of this development work subjected STAX material to higher temperatures and pressures for longer periods, resulting in the synthesis of gemstone-quality diamonds of three carats and larger.
The next stage of testing will involve doping large synthetic diamonds with elements to produce next-generation semiconductor materials that could replace silicon wafers in critical applications and high-temperature applications.
These semiconductor materials have potential uses in rocketry, heat sinks, new generation electronics, fast-moving aerial systems, and specialty engines. The concept is being reviewed by the engineering community at the U.S. Army Redstone Arsenal in Alabama and Army Research Laboratory in Pennsylvania. Graphite One said its industrial partner is working on delivering prototype samples of new semiconductor devices made from Graphite Creek materials.
"All of the above examples of potential upsides coupled with Graphite One's smart design choices and selection of an environmentally responsible processing flow sheet further support the value of the Graphite Creek deposit and the upcoming PFS that will be unveiled within the next few months," said Huston.
This coming study is expected to detail the engineering and economic parameters of a mine at Graphite Creek and an advanced material processing facility to refine concentrates produced at the mine into the coated spherical graphite used in lithium-ion rechargeable batteries and other graphitic materials for industrial and high-tech applications.