Graphite Investing

Types of Graphite: Amorphous, Flake and Vein

The graphite space can be tough for investors to navigate. Getting a grasp on it involves knowing a little about the different types of graphite.

Charlotte McLeod • October 7, 2015

Speaking to the Investing News Network (INN), Riddle said that when those in the graphite space refer to “good” flake size, they’re usually referring to “a graphite deposit or graphite mine [that] is projected to have a high percentage of its total graphite concentrate with flakes greater than 80 mesh — and preferably including some +50 mesh and even possibly some +35 mesh.”

He added that it’s important to consider whether a company has reached those numbers after flotation “because a lot of times during flotation graphite mines break down the flakes in order to get the purity level required by the market.”

In terms of how purity fits into the mix, Riddle said that in general, “the higher the purity of the graphite concentrate, the higher the average realistic FOB mine selling price tends to be.” Essentially, a purer product will likely require less processing, and thus will cost the producer less money to make.

Overall, then, it would appear that large-flake, high-purity graphite is the most desirable product for a company to have. However, Andrew Miller of Benchmark Mineral Intelligence has explained that the equation is not always that simple. “Quite often because of the niche requirements of each industry … they have very specific criteria. For some industries purity is more important, and for other industries flake size is more important,” he told INN.

For instance, for the spherical graphite industry “purity and the shape of the particle are both key factors.” Meanwhile, for the refractories industry flake size is the overriding price influencer. “It’s not … clear cut,” Miller noted. “There’s no exact perfect grade out there — but there’s a need to tailor what you produce for the market.”

Uses

As mentioned, Tesla and other companies are expected to require large amounts of flake graphite for their lithium-ion battery megafactories. That’s because flake graphite is an important component of lithium-ion battery anodes.

Currently there’s no telling exactly how much graphite these companies may require. Though Tesla has now signed two lithiumsupply deals, it has yet to secure graphite supply; data on the other megafactories is also scarce.

That said, predictions have definitely been made about how much graphite Tesla’s gigafactoy will require. For instance, Benchmark Mineral Intelligence has said that if it reaches its target capacity of 35 GWh by 2020, it may need 25,000 tonnes per year of lithium, 112,500 tonnes per year of flake graphite, 45,000 tonnes per year of spherical graphite and 7,000 tonnes per year of cobalt.

However, it’s important for investors to remember that flake graphite has applications other than lithium-ion batteries. For instance, fuel cells use even more graphite than lithium-ion batteries, and some expect them to replace combustion engines as a more efficient means of converting fuel to energy. Fuel cells of all sizes are also making their way into the personal electronics sector and even into the utilities sector, where they can be used to provide emergency power to hospitals or turn methane gas into electricity at wastewater plants.

Flake graphite is also an essential part of vanadium-redox battery technology, with nearly 300 tonnes of flake graphite required per 1,000 megawatts of storage. The unique properties of vanadium and graphite combined allow for the long-term storage of excess energy.

Pebble-bed nuclear reactors, which use uranium embedded in fist-sized graphite balls, are another example of how important graphite is becoming to the energy sector. Just one 100-GW pebble-bed nuclear reactor requires 300 tonnes of graphite to start initial production, followed by an additional 60 to 100 tonnes per year for continual operation.

Amorphous graphite

Amorphous graphite is found as extremely small, crystal-like particles in beds of mesomorphic rocks like coal, slate and shale, and its carbon content depends on that of its parent material. When found in coal it is the result of the thermal metamorphism of coal, and is referred to as meta-anthracite. However, unlike coal, amorphous graphite is not used as fuel as it is difficult to ignite.

According to Riddle, amorphous graphite that is marketable today typically ranges in purity from 70 to 90 percent. “You can’t afford to upgrade it if you are to be cost effective,” he said.

Uses

Amorphous graphite is used in the refractories industry to manufacture crucibles, ladles, molds, nozzles and troughs that can withstand very high temperatures, particularly the casting of steel. Indeed, the electrodes used in many electrical metallurgical furnaces, including the electric arc furnaces used in steel processing, are manufactured from graphite. Furthermore, in the production of steel itself, graphite is used as a carbon raiser to strengthen steel. It’s also used in blast furnace linings for the production of iron because of its high thermal conductivity.

Aside from the refractories industry, amorphous graphite is also used in brake linings, gaskets and clutch materials. Additionally, amorphous graphite is used in foundry facing mold wash, where it helps ease the separation of casted objects from molds. Finally, low-quality amorphous graphite, mostly from China, is used to make pencil lead.

Vein graphite

Vein graphite, also referred to as lump graphite, is believed to have hydrothermal origins and occurs in fissures or fractures, appearing as massive platy intergrowths of fibrous or needle-like crystalline aggregates. Vein graphite is believed to originate from crude oil deposits that through time, temperature and pressure were converted to graphite. Riddle said that the veins “are extremely small and range between 5 and 10 centimeters wide;” generally they have a purity level of 70 to 99+.

Graphite in this form is found all over the world, but is only currently mined in Sri Lanka.