The Pricing of Natural Graphite and the history of natural graphite

In the 4th millennium B.C., during the Neolithic Age in southeastern Europe, the Mariţa culture used graphite in a ceramic paint for decorating pottery.

Some time before 1565 (some sources say as early as 1500), an enormous deposit of graphite was discovered on the approach to Grey Knotts from the hamlet of Seathwaite in Borrowdale parish, Cumbria, England, which the locals found very useful for marking sheep.

During the reign of Elizabeth I (1533–1603),  Borrowdale graphite was used as a refractory material to line moulds for cannonballs, resulting in rounder, smoother balls that could be fired farther, contributing to the strength of the English navy. This particular deposit of graphite was extremely pure and soft, and could easily be cut into sticks.  Because of its military importance, this unique mine and its production were strictly controlled by the Crown.

The Pricing of Natural Graphite

Graphite prices are a function of 2 factors – flake size and purity – with large flake (+80 mesh), high Carbon (+94%) varieties commanding premium pricing.

Graphite Prices

There is a posted price for Graphite which provides a guideline with respect to longer term trends but transactions are largely based on direct negotiations between the buyer and seller. Prices exceeded USD$1,300/t in the late 80s but crashed to USD$600 -$750/t in the 90s as Chinese producers dumped product on the market. During this period there was essentially no exploration and as a result there are very few projects under development.

Graphite prices started to recover in 2005 and with average growt rates of 5% per annum over the past decade. They are currently well over USD$1,300/t with premium product rumoured to be selling at up to USD$3,000/t as the supply of large flake, high carbon graphite is tightening. Price appreciation is largely a function of the commodity super cycle and the industrialization of emerging economies as new, high growth applications such as Li-ion batteries are only beginning to have an impact on demand and consumption. Graphite prices have not yet experienced the price appreciation of other commodities and graphite must still be considered an overlooked and undervalued commodity in the context of the current super cycle.

Future Growth

New applications such as lithium-ion batteries, fuel cells and nuclear power have the potential to create significant, incremental demand growth in the future. For example, it takes 20 to 30 times more graphite than lithium to make lithium-ion batteries. The use of lithium-ion batteries is growing rapidly in consumer electronics, and they are now becoming popular in power tools and motor scooters, and growth will continue with the increased use of hybrid and fully electric vehicles. Each hybrid electric car uses about 22 pounds of graphite, while a fully electric auto uses about 110 pounds.

Types and varieties of Graphite

The principal types of natural graphite, each occurring in different types of ore deposits are:

There are three distinct types of natural graphite which occur in different kinds of ore deposits:

  1. Flake Graphite
  • Less common form of graphite
  • Carbon range of 85-98%.
  • Priced ~4X higher than amorphous graphite
  • Used in many traditional applications
  • Desirable for emerging technology graphite applications (e.g. Li-ion battery anode material)
  • Crystalline small flakes of graphite (or flake graphite) occurs as isolated, flat, plate-like particles with hexagonal edges if unbroken.
  • When broken the edges can be irregular or angular;
  1. Amorphous Graphite
  • Most abundant form of graphite
  • Comparatively low carbon content of 70-80%
  • No visible crystallinity
  • Lowest purity
  • Not of suitable quality for use in most applications
  1. High Crystalline Graphite (vein, lump or crystalline vein)
  • Only extracted from Sri Lanka
  • Carbon content of 90-99%
  • Scarcity and high cost restricts viability for most applications

4. Lump graphite (or vein graphite) occurs in fissure veins or fractures and appears as massive platy intergrowths of fibrous or acicular crystalline aggregates, and is probably hydrothermal in origin.

5.Highly ordered pyrolytic graphite refers to graphite with an angular spread between the graphite sheets of less than 1°.

*Synthetic graphite is a manufactured product made by high-temperature treatment of amorphous carbon materials. In the United States, the primary feedstock used for making synthetic graphite is calcined petroleum coke and coal tar pitch. This makes it very expensive to produce — up to 10 times the cost of natural graphite – and less appealing for use in most applications. The name “graphite fiber” is sometimes used to refer to carbon fibers or carbon fiber-reinforced polymer.

What is Graphite ?

Graphite, archaically referred to as plumbago, is a crystalline allotrope of carbon, a semimetal, a native element mineral, and a form of coal. Graphite is the most stable form of carbon under standard conditions. Therefore, it is used in thermochemistry as the standard state for defining the heat of formation of carbon compounds. Graphite and diamond are the two mineral forms of carbon. Diamond forms in the mantle under extreme heat and pressure. Most graphite found near Earth’s surface was formed within the crust at lower temperatures and pressures. Graphite and diamond share the same composition but have very different structures. Graphite and diamonds are the only two naturally formed polymers of carbon. Graphite is essentially a two dimensional, planar crystal structure whereas diamonds are a three dimensional structure. Graphite is an excellent conductor of heat and electricity and has the highest natural strength and stiffness of any material. It maintains its strength and stability to temperatures in excess of 3,600°C and is very resistant to chemical attack. At the same time it is one of the lightest of all reinforcing agents and has high natural lubricity.

Graphite has a layered, planar structure. The individual layers are called graphene. In each layer, the carbon atoms are arranged in a honeycomb lattice with separation of 0.142 nm, and the distance between planes is 0.335 nm. Atoms in the plane are bonded covalently, with only three of the four potential bonding sites satisfied. The fourth electron is free to migrate in the plane, making graphite electrically conductive. However, it does not conduct in a direction at right angles to the plane. Bonding between layers is via weak van der Waals bonds, which allows layers of graphite to be easily separated, or to slide past each other.

The two known forms of graphite, alpha (hexagonal) and beta (rhombohedral), have very similar physical properties, except for that the graphene layers stack slightly differently. The alpha graphite may be either flat or buckled. The alpha form can be converted to the beta form through mechanical treatment and the beta form reverts to the alpha form when it is heated above 1300 °C.

Graphite is a mineral that forms when carbon is subjected to heat and pressure in Earth’s crust and in the upper mantle. Pressures in the range of 75,000 pounds per square inch and temperatures in the range of 750 degrees Celsius are needed to produce graphite. These correspond to the granulite metamorphic facies.

What is graphite used for?

Natural graphite is mostly consumed for refractories, batteries, steelmaking, expanded graphite, brake linings, foundry facings and lubricants.  Graphene, which occurs naturally in graphite, has unique physical properties and is among the strongest substances known. However, the process of separating it from graphite will require more technological development.

What is the Structures of graphite ?

Graphite has a layer structure which is quite difficult to draw convincingly in three dimensions. The diagram below shows the arrangement of the atoms in each layer, and the way the layers are spaced.

Notice that you can’t really draw the side view of the layers to the same scale as the atoms in the layer without one or other part of the diagram being either very spread out or very squashed.

In that case, it is important to give some idea of the distances involved. The distance between the layers is about 2.5 times the distance between the atoms within each layer.

The layers, of course, extend over huge numbers of atoms – not just the few shown above.

You might argue that carbon has to form 4 bonds because of its 4 unpaired electrons, whereas in this diagram it only seems to be forming 3 bonds to the neighboring carbons. This diagram is something of a simplification, and shows the arrangement of atoms rather than the bonding.

What is The properties of graphite ?

 

  • has a high melting point, similar to that of diamond. In order to melt graphite, it isn’t enough to loosen one sheet from another. You have to break the covalent bonding throughout the whole structure.
  •  Graphite’s high thermal stability and electrical and thermal conductivity facilitate its widespread use as electrodes and refractories in high temperature material processing applications.
  • has a soft, slippery feel, and is used in pencils and as a dry lubricant for things like locks. Graphite and graphite powder are valued in industrial applications for their self-lubricating and dry lubricating properties. You can think of graphite rather like a pack of cards – each card is strong, but the cards will slide over each other, or even fall off the pack altogether. When you use a pencil, sheets are rubbed off and stick to the paper.
  • has a lower density than diamond. This is because of the relatively large amount of space that is “wasted” between the sheets.
  • is insoluble in water and organic solvents – for the same reason that diamond is insoluble. Attractions between solvent molecules and carbon atoms will never be strong enough to overcome the strong covalent bonds in graphite.
  • conducts electricity. Graphite is an electric conductor, consequently, useful in such applications as arc lamp electrodes. The de-localized electrons are free to move throughout the sheets. If a piece of graphite is connected into a circuit, electrons can fall off one end of the sheet and be replaced with new ones at the other end.