Graphite Products

Flake graphite is a naturally occurring mineral. Like diamond, it is a form of elemental carbon, but the two allotropes (forms) of carbon have very different properties. Whereas diamond is very hard and transparent, graphite is soft, lubricious and metallic grey in appearance. Annual production is over 600,000 tons. Synthetic graphite is also available and a more recent variant is graphene where the individual sheets in graphite have been separated. When it comes to graphite, there are five main classifications.

Crystalline graphite: this is mined at high purity and occurs in thicker veins.

Amorphous graphite: the name is a misnomer because the product is not amorphous but is actually still crystalline but with lower purity and smaller particles.

Flake graphite: this occurs in low purity and flotation is used to purify and concentrate it.

Synthetic graphite: formed by high temperature calcination of carbonaceous starting materials. This leads to a porous product with lower electrical conductivity.

Expandable graphite: the graphite sheets have another substance inserted between them. Upon heating, that substance, often sulfuric acid, escapes rapidly and expands the graphite in much the same way that popcorn expands when heated.

Graphite is widely used for three main reasons:

Substantial applications for graphite include pencils, electrodes, lubricants and high temperature applications such as crucibles for molten metals. The nuclear industry uses graphite for moderator rods in reactors. They are also used for the brushes in electric motors, an application that has taken off with the prevalence of electric vehicles. Additionally, batteries for such vehicles contain graphite in the electrodes.

Expandable graphite is a very effective intumescent flame retardant meaning that upon exposure to the heat of a fire, the plates expand creating a foam that protects the substrate by diluting the fuel source and by forming an insulating barrier. The onset temperature of expansion can be tailored to the application.

Pyrolytic graphite is a special type known for its strong diamagnetic properties meaning that it is repelled from a magnet, making levitation possible.

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