Graphite Purity and Beneficiation
Graphite is a crystalline mineral with a soft, greyish-black appearance and metallic lustre. It has an extremely low specific gravity and is a highly lubricating material with excellent chemical inertness and corrosion resistance. It has a wide range of applications and performance properties including lithium-ion batteries, fuel cells, two dimensional graphene, water purification, electronics, fiber optics, spintronics, refractories, electrical products, and electric vehicles.
Traditionally, graphite is mined by both open pit and underground methods. After extraction, graphite needs to be processed. The process is known as beneficiation.
The first step is to separate the ore into different sizes, based on their relative carbon/gangue content. This is done via comminution, followed by various techniques such as hydrometallurgical (flotation) and pyrometallurgy.
Beneficiation of flaky graphite ores requires several grinding-flotation steps to prevent large flakes from being destroyed during regrinding and to allow for the recovery of valuable minerals. However, this process also results in a large amount of middling, which affects the quality of the graphite concentrate.
Another method is to use dense media separation, or DMS. DMS uses a dense media to trap gangue minerals, and they float off with the graphite. This process can be a more cost-effective method than the more expensive multi-stage grinding-flotation technique, because it is much simpler and requires fewer personnel.
In addition, DMS is the most efficient industrial gravity-based separator for worldwide coal cleaning. Moreover, it can be used to clean other mineral concentrates and abrasives.