Highlights

This project included the custom fabrication of a 500-1,000-mm pilot-scale rotary drum screen inclusive mesh wash water manifold, oversize/undersize catchments, and pumps.
Data logging was implemented to automate the process and to generate trend analysis over time.
Training of operators onsite was implemented to handover pilot-plant operations to the owner for six weeks.

Challenge

The plate-like nature of graphite particles creates entrained fines and often blinds the apertures of standard screens. As the value of graphite is largely correlated to flake size, it is integral that large-flake graphite particles can be recovered without fracturing or loss to the environment. Screening efficiency is directly related to the product value and revenues from sales.

Additionally, flotation froth can create a colloidal matrix which can inhibit screening performance; this project implemented a series of customizations to the process to ensure that this issue could be combatted.

Solution

By employing a highly turbid environment and reverse mesh washing, the rotary drum screen solution was able to ensure oversize streams were free of entrained fines. Results were generated at 500-75-micron so that process design could be initiated with reasonable basis for mass-water balances and equipment sizing.

Benefit

Screening efficiencies were measured ~90% with employing the mechanical and process techniques described in this project; a massive improvement to historical standards experienced by the graphite industry which range from 60-70%. There are numerous cases where graphite concentrate has not been sized correctly and hence is not saleable to the marketplace. Many projects have had to manually re-size the concentrate stockpiles at significant operating cost and time.