Graphite is a soft, crystalline form of elemental carbon. It is one of three allotropic (meaning having the same chemical formula but different physical properties) forms of carbon which exist in nature, the other two being coal and diamond. Graphite is a grey to black, opaque mineral with a metallic lustre. Graphite occurs naturally in metamorphic rocks such as marble, schist, gneiss and phyllite. It is usually found as veins, lenses, pockets and as thin laminae disseminated in metamorphic rocks. Depending on the mode of occurrence and origin, graphite is graded into three forms: flake, crystalline (lumpy) and cryptocrystalline (amorphous).
In nature, graphite is usually found in mechanical association with feldspar, mica, quartz, pyroxene, rutile, pyrite and apatite.
Sample of graphite concentrate from Ancuabe at 98% TGC.
Common Graphite Issues
Graphite exhibits both metallic and non-metallic properties making it suitable for many industrial applications. The metallic properties include thermal and electrical conductivity. The non-metallic properties include inertness, high thermal resistance and lubricity. Natural graphite is in demand, not only for conventional applications such as refractories, lubricants, crucibles, coatings, gaskets, consumer electronics, pencils and advanced polymer systems, but with the emerging applications and green initiatives in nuclear energy, fuel cell and Li-ion battery technologies.
Industrial demand for graphite has been growing at about 5% per annum for most of the last decade due to the ongoing industrialisation of China, India and other emerging economies. However, the major growth potential for the graphite industry is in the increased demand that will be created by a number of green initiatives including Li ion batteries, fuel cells, solar energy, semi-conductors and nuclear energy. Many of these applications have the potential to consume more graphite than all current uses combined.