Graphite occurs naturally in the Earth’s crust in schist and gneiss
metamorphic rocks. The graphite can have a microcrystalline
structure and flaky morphology, displaying a polymorphic phase with
hexagonal and rhombohedra layers. Based on its structure
properties, graphite is applied in a variety of technological
applications including lithium-ion batteries, fuel cells,
two-dimensional grapheme, electronics, fiber optics, electrical
vehicles, and so forth.
Mining
Graphite ore is mined using excavating machines that carry dump
trucks with raw ore.
The entire extraction process follows a mining plan, facilitating
the selection of the most suitable ore for final products.
Homogenisation
The deposition of this ore on the feeding plant is systematised to
form feeding piles in layers.
The goal is to reduce the natural variability of the ore.
Mechanical Concentration
The ore is subjected to successive grinding and a mechanical
process separating impurities from the graphite. The mechanical
concentration aims for maximum recovery of the graphite present in
the ore, preserving its physical features.
Chemical Concentration
The chemical concentration is used to remove the remaining
impurities in the previously graphite mechanically concentrated.
Nacional de Grafite uses and treats the residues of the chemical
concentration in order not to pollute the environment.
Filtering and drying
After the chemical concentration, the graphite is washed
extensively with demineralised water, reaching a neutral pH. The
remaining moisture is removed in Press-type filters and rotary
dryers.
