November 2015    Print this article

GRAPHITE

Dominic Fragasso
Ministère de l'Énergie et des Ressources naturelles

Graphite is one of two minerals composed entirely of carbon (C), the other being diamond. Even though diamond and graphite have the same composition, their atoms are arranged very differently. Diamond consists of exceptionally solid carbon tetrahedra in which each atom is connected to four other atoms, making it the hardest substance. On the other hand, graphite consists of hexagonal rings arranged in thin, stacked sheets that are weakly bonded to each other, creating a structure with low strength.

  

Comparative table of properties

Diamond

Graphite

Hard

Soft

Transparent

Opaque

Electrically non-conductive

Electrically conductive

Abrasiv

Lubricant

Clean feel

Greasy feel

Very valuable

Moderately valuable

Physical properties and applications

Graphite is the only non-metallic electrically conductive mineral. It has high thermal and electrical conductivity, a greasy texture and high solidity of structure along the horizontal axis and weak along the vertical axis, which gives it very interesting physical properties. People have used it to write since ancient times, and it takes its name from the Greek word “graphein,” meaning “to write.”

Graphite is primarily used in metallurgy and in the manufacture of refractory materials (crucibles, moulds, alloying element foundries), mainly due to its high melting point (3,927 °C). It is also added to molten steel to increase the carbon content and meet quality standards for hardness. Graphite is also used as a coating at foundries during casting to ease the separation of the object cast from the mould after the hot metal has cooled.

Graphite is very useful in the automobile industry in manufacturing brake linings and brake shoes. Its greasy texture also makes it useful in manufacturing lubricants that work over a wide temperature range. 

Because it is highly conductive, graphite is increasingly used in the manufacture of cell phone electrodes, various computer parts, zinc-carbon batteries, electronic motor brushes and, more recently, in manufacturing lithium-ion batteries for electric vehicles.

China recently started making a new generation of nuclear reactors known as pebble-bed reactors using a technique developed in Germany. These new nuclear reactors use the uranium contained in balls of pyrolitic graphite1, which acts as a moderator. These reactors require 300 tonnes of graphite at start-up, and 60 to 100 tonnes per year after that.

Three types of mined graphite

Generally, there are three principal types of natural graphite, each occurring in deposits of different origins, and the price of the resource depends on shape and size.


        FLAKE                            AMORPHOUS                       VEIN            

Flake graphite, which accounts for 49% of world production, is composed of well-formed crystals and is easily identified. It has a high level of purity (85%–99% C) and gains the best market prices.

Amorphous graphite is cryptocrystalline form in which the crystals are so small they cannot be seen by the naked eye. It is less pure (60%–90% C) than flake graphite and attracts the lowest market prices.

Vein graphite is much rarer and accounts for only 1% of world production. The degree of crystallization ranges from very fine crystals to coarse flakes up to 1 cm across. It is marketed as lump graphite. Sri Lanka is the only country mining vein graphite, and is the only place in which a market price exists.

Origin and mode of formation

Graphite forms in nature in four ways, each producing a different type.

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1- Metamorphic: advanced metamorphism Flake graphite

2- Metamorphosed
3- Contact metasomatic Amorphous graphite

4- Hydrothermal vein Vein graphite

Metamorphic deposits form by the concentration and crystallization of the carbon present in silica-rich rocks and carbon-rich sedimentary rocks during a phase of metamorphism that can affect an entire region. These deposits contain flake graphite. In Québec, the Grenville orogeny formed graphite deposits associated with gneiss, quartzites and schists in the Côte Nord region (Lac Knife, Lac Guérêt), and those associated with graphitic marbles in the Mont-Laurier (Lac-des-Îles) and Gatineau regions.

Metamorphosed deposits form by contact metamorphism of sediments rich in carbonaceous organic matter (bitumen, coal). The rocks associated with these deposits are quartzites, schists, phyllites and metagraywackes. Contact deposits also include metasomatic “skarn” deposits that develop at the contact between carbonate and plutonic rocks through the crystallization of organic carbon or the reduction of the original CO2. Contact deposits contain amorphous graphite.

Hydrothermal vein deposits originate as CO2-rich post-magmatic fluids. They are generally associated with stratiform flake graphite that enriches the vein graphite. The fluids produce amorphous and flake graphite that are highly heterogeneous in terms of purity, nature and crystal size. Hydrothermal vein deposits notably include the very pure deposits of Sri Lanka. In Québec, this type of deposit is found in the Outaouais region (the former Miller and Walker mines).

World production, trading and markets

In 2012, the world production of graphite was 1.01 Mt (Roskill). China is by far the leading producer, with 89% of amorphous graphite production and 58% of flake production for a total of 710 kt. Sri Lanka is the only producer of vein graphite, with 3.5 kt.

Other producers are, in order: North Korea (130 kt), Brazil (75 kt), Canada (25 kt), India (15 kt), Russia (12 kt), Mexico (8 kt), Ukraine (8 kt) and Norway (8 kt).

Trading between countries follows a fairly consistent trend, with China exporting large volumes to the European, Japanese and American markets, which represent countries that produce very little natural graphite. The United States also sources its graphite from Brazil, Mexico and Canada. Canada exports nearly all its production to European markets.

Current production meets demand, which is growing at 5 to 7% per year. Global demand is expected to double by 2020 with the advent of new technologies such as lithium-ion batteries for electric vehicles and for storing the electricity produced by solar panels, as well as pebble-bed nuclear reactors, computer equipment and cell phones.

Until recently, synthetic graphite supplied the markets with the highest standards in terms of purity and crystal form. Synthetic graphite is produced by pyrolysis (heating) of carbon-rich material, often petroleum coke, followed by graphitization between 2,500 °C and 3,000 °C, to produce nearly perfect graphite crystals. The manufacture of synthetic graphite is very costly, and also very polluting.

Lately, advances in the purification methods for natural graphite have yielded flake graphite concentrate with a purity of more than 99.5% C at a very competitive production cost. This suggests that purified natural graphite could replace synthetic graphite for technological applications. 

The most lucrative market for producers of high-quality natural flake graphite is primarily the lithium-ion battery market. Vein graphite producers aim for the nuclear reactor markets, which requires graphite purified to 99.99% C and a nearly perfect crystal shape that only vein graphite can provide.

Graphite in Québec

Graphite mining in Québec started in the Outaouais and Laurentides regions with the opening of the Miller mine (Keystone mine) at Grenville-sur-la-Rouge in 1845 and the Walker mine at Buckingham in 1876. The former was mined for about 30 years, and the latter was sporadically operated until 1906. At the time, Buckingham was known as “Graphite City”.

When graphite mining began in Québec, it was wrongly called “plombago” because it was thought to contain lead. This belief gave rise to the term “lead pencil” for pencils made with graphite. In fact, pencils are made with graphite and a certain proportion of clay — the more the clay, the harder the pencil. 

In 1989, Stratmin opened a graphite mine and concentration plant at Lac-des-Îles south of Mont-Laurier with an annual production of about 25,000 tonnes. It is still operating today. Part of the production is sold directly to foreign markets (United States, Europe), and the rest is shipped to a plant in Terrebonne where it undergoes other purification processes. Stratmin was bought by Imerys, a French company that specializes in industrial minerals.

The mine at Lac-des-Îles was the only graphite mine in Canada for a long time, and it was only in 2007 that the company Eagle Graphite started up production at the Black Crystal mine at Nelson in British Colombia. This mine produces around 4,000 tonnes of graphite concentrate per year.

Several graphite showings are known in the Grenville Province due to the intense metamorphism that affected the region during its orogeny. The deposits are characterized by large flakes with high levels of graphitic carbon.

The price of graphite reached a peak in 2012 following a long period of stagnation since the turn of the century. From US $1,750/tonne in 2012, it dropped to US $1,300/tonne in 2014 before returning to an upward trend. The rising price explains exploration companies’ enthusiasm for Québec graphite. 

In Québec, two projects have reached the deposit appraisal stage in the mining development process. In the North Shore (Côte-Nord) region, 30 km southwest of Fermont, the Lac Knife project of Focus Graphite published a feasibility study in October 2014. According to the study, the mine could produce 44,300 tonnes of graphite concentrate per year for a period of 25 years. South of the Manicouagan Reservoir, the Lac Guérêt project of Mason Graphite could produce 50,000 tonnes of concentrate per year for 22 years.

There is also one deposit at the calculated tonnage stage. The Mousseau West project of Graniz Mondal in the Mont-Laurier area could soon reach the deposit appraisal stage. In addition, a number of exploration companies are working on their graphite showings in the Outaouais, Laurentides and Lanaudière regions.

Outlook for development of the Québec graphite industry

The announcement in summer 2014 that a battery plant had been commissioned in Nevada for the American electric vehicle company Tesla Motor Inc. raised the hopes of many graphite project promoters in Canada. Nevertheless, no supply agreement has been disclosed since the announcement was made. More recently, in May 2015, another media announcement was made that American graphite giant Asbury Carbons would start building a plant in North Carolina to manufacture value-added graphite products. These announcements suggest there will be increasing interest from American industrials for this commodity over the coming decade. 

In the free market environment, some non-producing countries like Japan and the United States have fared well in the graphite industry. Japan has, until now, used synthetic graphite to manufacture electric batteries. The United States has benefited from the proximity of amorphous graphite mines in Mexico to supply their plants. In a context where natural graphite could become more competitive, this situation will likely change.

On the other side of the Atlantic, the European Union countries have already mined most of their graphite resources and are now dependent on producing countries like China. This led them to add graphite to the list of critical elements for the European industry.

The development of the graphite industry in Québec would consolidate the current market, and could also support the growth of industries related to the manufacture of electric batteries and electrodes for computer equipment and cell phones. Graphite could become vital to the transportation electrification sector. More precisely, the production of electric batteries requires graphite and lithium. The electric battery manufacturing industry also pairs well with other industry like the solar panel industry because it need batteries to store the electricity produced by solar energy.

as  a major producer of electricity, which can supplies power to electrical terminals, as well iron and aluminum, which are used to build automobiles should then be well positioned for the development of electrical vehicles. The province’s wide range of interrelated products provides all the components needed to create a transportation electrification sector. 
Beyond the simple fact that graphite is found in the province, the development of an industry for this resource in Québec will depend on related industries in order to reap the benefits, thereby creating significant added value that will stimulate the economy.

1. Pyrolitic: the chemical decomposition of a substance at elevated temperatures in the absence of oxygen.

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