Graphite Processing Flowsheet
Graphite is a crystalline allotrope of carbon, a semimetal, a native element mineral and a form of coal. Graphite is used in many industrial applications because of its metallic properties (thermal and electrical conductivity) as well as its nonmetallic properties, such as chemical inertness, lubrication, and high thermal resistance.
Typically, graphite is mined from metamorphic rock such as gneiss, marble, and schist. However, it may also be found in organic-rich shale deposits or coal beds.
It has been suggested that the flakes of graphite are formed from fractures or fissures in the earth’s crust, caused by the pyrolosis of carbon-bearing gases like methane or carbon dioxide. These fractures are then filled with vapor, which forms the carbon flakes we know as graphite.
The resulting spherical crystals are often polished to create a high-purity product with better conductive qualities for use in battery anode materials. Spherical graphite is typically produced primarily in China and is sold at a premium to traditional large-sized flakes.
Typical graphite processing flowsheets include some initial comminution and flotation to increase the total graphitic carbon content (TGC). This is followed by further grinding to enhance impurity rejection prior to screening into different flake sizes. The screened flake sizes are usually bagged and then blended to meet customer specifications. The purity of the screened flake is a key initial differentiator for the final product. The product is then shipped to market. This process requires an investment in capital, personnel and equipment to meet all required purity objectives.
