Graphite has chemical inertness and corrosion resistance as well as good thermal and electrical conductivity. At present, flake graphite, the most common graphite form, has a high world market share. Crystalline flake graphite is a plate-like particle of hexagonal structure with irregular fragment edges. Graphite has a layered structure, in which carbon atoms in the monoatomic layers share a strong covalent bond, but the relatively weak π-π bonds connect the layers.
In the graphite structure, gangue minerals have the characteristics of accumulation between layers, stacks or clusters. These impurities can coexist with the graphite flake, either adhering to the surface of the graphite flake or being trapped by adjacent graphite flakes. Therefore, it is essential to study the release of impurities from graphite.
Ri Ho Chol, a section head at the Faculty of Mining Engineering, has succeeded in converting graphite flotation concentrate GFC into high purity graphite from laboratory scale to pilot scale through flotation, alkali roasting and acid leaching processes.
In GFC, carbon content was 85.6%, and quartz and hematite were the main gangue minerals. The high-grade flotation concentrate with 95% carbon content was produced by low pulp concentration flotation. And the silicate mineral was converted to the soluble salt at 500℃ by alkali roasting. The soluble roasting products and other impurities such as hematite were dissolved by acid, and the carbon content of the produced high purity graphite was higher than 99.8%.
You can find the details in his paper “Effective purification of graphite via low pulp concentration flotation-low temperature alkali roasting-acid leaching route: From laboratory-scale to pilot-scale” in “Minerals Engineering” (SCI).
© 2021 KumChaek University of Technology