Graphite

What is graphite

Graphite is an industrial mineral with unique physical properties which includes superior thermal/electrical conductivity and generally occurs in one of three forms – Microcrystalline or amorphous, Crystalline lump or vein and Crystalline flake.

An industrial mineral has many unique physical properties:

  • Superior thermal/electrical conductivity
  • Stable wide temperature range
  • Excellent lubrication
  • Malleable
  • Resistant to chemical attack
  • Fire retardant and thermally efficient building products

Graphite and its uses

There are existing traditional uses for graphite; refractories, foundries, lubricants etc which are growing modestly and some new innovations, but this is being swamped by new demand for graphite suitable for use in electric vehicles.

Traditional demand for graphite is largely tied to the steel industry where it is used as a liner for ladles and crucibles, as a component in bricks which line furnaces (“refractories”), and as an agent to increase the carbon content of steel. In the automotive industry it is used in brake linings, gaskets and clutch materials. Graphite also has a myriad of other emerging uses in batteries, thermal management in consumer electronics, lubricants, fire retardants, and reinforcements in plastics.

What is Natural Flake Graphite

Natural Flake Graphite occurs in host rocks such as quartz-mica schist, feldspathic or micaceous quartzite and gneiss. Flake graphite may also occur in metamorphosed carbonate rocks, though these occurrences are currently of little economic significance. Flake graphite deposits are usually strata bound, with individual beds or lenses ranging from 30cm to more than 30m thick, and extending for lengths of two kilometres or more. Ore bodies are normally tabular, occasionally lenticular, and occur locally as irregular bodies in the hinge zones of folds. Most economic deposits of flake graphite are of Archean to late Proterozoic age. These rocks may contain up to 90% graphite, although 10-15% graphite is a more typical grade for an ore body.


Mechanical Shaping – Micronising and Spheronising

The processing route selected for the micronising and spheronising of the graphite flake is a continuous process using pulverisers (mills) in series. Several trains will be used, each train has a capacity of producing spherical graphite between 2,500-3,000tpa each. The trains are identical, with each train containing six micronising and eighteen spheronising mills.

Each spheronising mill is in circuit with an air separator, spheronising cyclone and baghose. The air separator allows for the control of product sizing with the coarse size fraction from the air separator feeding the next spheronising mill in series.

What is Spherical Graphite (SpG)

Spherical graphite (SpG), also known as battery-grade graphite, is the product that is consumed as an anode in lithium-ion batteries. Flake graphite concentrate is processed into ultra-high-purity (>99.95% C) with particle sizes ranging from 10 micron to 25 micron.

These are then used as a battery anode material. It is it’s special electrical conductivity that makes spherical graphite a critical component in anode manufacture. Graphite represents just under 50% of battery minerals in a lithium-ion battery.

The spheronisation process decreases the surface area to allow more graphite into a smaller volume. This creates a smaller, denser, more efficient anode product for the battery. It also increases the rate at which the cell can be charged and discharged.

With the expected growth in demand for lithium-ion batteries for markets such as electric vehicles, demand for spherical graphite is also expected to increase at a rapid pace.

Battery Graphite Market

China is the only producer of commercial quantities of  battery spherical graphite, which requires hydrofluoric (“HF”) acid to achieve 99.95% carbon grade.This is a very toxic chemical. Hubei and Shandong provinces are the largest producing areas and there is increasing pressure on producers due to environmental and occupational health & safety regulations.

HF acid is critical for the production of high purity flake and battery graphite in China.

As global demand for battery graphite rapidly expands, there is an increasing customer requirement for new, more geographically diversified and environmentally sustainable sources of high-quality supply. Feedback from lithium-ion battery anode manufacturers indicates that demand from e-mobility and energy storage markets will continue to grow strongly.

The focus on ensuring responsible and sustainable supply chains which is already evident in cobalt markets, is expected to support the adoption of cost competitive and environmentally friendly products.