Mining and Milling Process
Graphite is mined around the world by both open pit and underground methods. While flake graphite and amorphous graphite are both mined open pit and underground, lump (vein) graphite is only minedunderground in Sri Lanka. Open pit mines employ heavy equipment (i.e. front end loaders, bulldozers) to scoop up the ore, which is usually put in trucks (Euclids) and moved to the plant. Underground graphite mines employ drilling and blasting to break up the hard rock (ore), which is then moved by mine cars pulled by a locomotive, or moved by automotive vehicles, to the surface and then to the plant. In less-developed areas of the world such as China, the ore is often mined by pick and shovel and transported by mine cars pushed by labourers.
The great majority of world flake graphite production is crushed and ground and then beneficiated by flotation. Treating graphite by flotation typically requires a series of flotation cells to obtain a purer and purer concentrate. In the milling process, the incoming graphite products and concentrates can be ground before being classified (sized or screened), with the coarser flake size fractions (below 8 mesh, 8-20 mesh, 20-50 mesh) carefully preserved, and then the carbon contents are determined. Air classification using winnowers is also used to capture coarser flake and increase the head grade of feed to be subsequently concentrated.
Following beneficiation standard blends can be screened from the different fractions, each with a certain flake size distribution and carbon content. Custom blends can also be made for individual customers who want specific flake size distributions and carbon content. Rough graphite is typically classified, ground, and packaged at a graphite mill; more complex or high-purity formulations are treated, mixed and packaged at an upgrade facility. Environmental impacts from graphite mills consist of air pollution including fine particulate exposure of workers and also limited soil contamination from powder spillages. Workers normally wear dust masks during the production process to avoid worker exposure to the fine airborne graphite.
Preliminary Pilot Plant and Base Plant Process Flow Diagrams (PFD).
Proposed Pilot Plant Flowsheet .pdf
Crushing Circuit Process Flowsheet .pdf click here
Grinding and Rotation .pdf
Dewatering Blending & PKG Process Flowsheet .pdf click here