Excellent metallurgical testwork results
Mali Lithium (ASX: MLL) has announced excellent progress in the metallurgical testwork currently underway and designed to optimise the results obtained from the Pre-Feasibility Study (PFS) published in July last year.
The final results of this program will confirm the process design selected as part of the Definitive Feasibility Study (DFS). Results have exceeded expectations with 80% overall recovery achieved from a combination of High Pressure Grinding Rolls (HPGR) and flotation.
Definitive flotation work and variability testwork is now underway. Actual plant performance is likely to be less than achieved in the lab but this is an excellent indication that the 70% recovery assumed in the PFS will be materially improved.
High Pressure Grinding Rolls (HPGR)
A representative bulk sample of Goulamina ore at a grade of 1.7% Li2O was reduced to -4mm top size using High Pressure Grinding Rolls (HPGR) at the Nagrom laboratory in Perth, Western Australia. HPGRs are increasingly being used for crushing hard, abrasive rock such as pegmatite ores. HPGR comminution is a proven alternative to conventional crushing equipment, offering superior availability and reduced maintenance.
Liberation of spodumene particles is crucial to achieving high flotation recoveries. The HPGR crushing principle typically enhances liberation, as opposed to conventional cone crushing, by applying force to compress the ore into a small space.
This selectively breaks particles at the mineral/reject interface thus allowing improved liberation and recovery. Results of HPGR tests at different pressing forces were better than expected resulting in evenly sized reduction to the required size of 4mm at low grinding pressures.
The HPGR crushed bulk sample at -4mm was then used for flotation testwork at Nagrom Laboratories after being ground to a P80 of 106 microns. The first stage of the program is designed to establish baseline parameters which will be used for optimisation, variability and de-risking further flotation testwork.
Four different reagent schemes were tested and were informed by the rapidly evolving practice at Western Australian Spodumene operations.