- Optimised pilot flowsheet produced a 6.0% Li2O concentrate at 79% lithium recovery
- Final process design completed for the Definitive Feasibility Study
- Further testing will continue over the next six months targeting further optimisation and improvements to the flow sheet and operating parametres
Approximately 5.5 tonnes of mineralised pegmatite ore was collected during the Phase 3 drilling program in December 2017. The diamond drill core was assayed and stage-crushed to the appropriate particle size to feed the pilot plant. Two composite pilot plant feed samples have been prepared to represent Years 0 to 5 and Years 5+ of the operation.
The pilot plant operated for over 100 hours at a feed rate of 50 kg/hour and produced over 400 kg of spodumene concentrate. The pilot plant flowsheet included grinding, de-sliming, magnetic separation, mica and spodumene flotation (see Figure 2 in link below). The optimised pilot flowsheet was able to achieve a concentrate grading 6.0% Li2O at a 79% recovery. The pilot program has confirmed the final process flow sheet and operating parametres for the Definitive Feasibility Study ("DFS").
In addition, prior to the pilot plant operation, a number of batch and locked-cycle testing programs were run to confirm the optimal conditions for the final pilot testing program. The results were similar to historical testing programs incorporated into the Pre-Feasibility Study, including:
- Batch flotation testing - up to 6.0% Li20 concentrate grade at 82% recovery; and
- Locked cycle testing - composite 1 achieved 5.85% Li20 concentrate grade at 84% recovery and composite 2 achieved 5.86% Li20 concentrate grade at 83% recovery.
Dan O'Neill, Managing Director, commented "The Company is pleased with the excellent results achieved during the program, enabling the final design of the plant for the DFS. The program assists in de-risking the metallurgical parametres for the plant construction, commissioning and ramp-up periods. Over the next six months, the Company will continue to undertake further testing targeting improvements to the operating parametres of the plant, including a testing program at the McGill University".
Pilot Program Overview
The objectives of the piloting program were to produce a 6% Li20 concentrate at recoveries of greater than 80% and confirm:
- Finalisation of the flowsheet and processing parameters for spodumene concentrate production developed during the Pre-Feasibility Study;
- Produce engineering data for equipment sizing and plant design; and
- Generation of spodumene concentrate for downstream lithium carbonate testing and marketing purposes.
Approximately 5.5 tonnes of mineralised pegmatite ore was collected during the Phase 3 drilling program in December 2017 (see Figures 4, 5 and 6 in link below). The diamond drill core was assayed and stage-crushed to the appropriate particle size to feed the pilot plant. Two composite pilot plant feed samples have been prepared to represent Years 0 to 5 and Years 5+ of the operation - see Table 1 in link below.
An 80 kilogram sub-sample of each composite was used for batch and locked-cycle-testing. Over 40 batch flotation tests were completed assessing variations in grind size, reagents and dosages, and with and without the use of mica flotation. The optimal batch flotation test conditions produced a 6.0% Li20 concentrate grade at an 82% recovery.
Based on the optimal batch flotation conditions, the two composites were subject to locked cycle flotation testing. The two results included:
- Composite 1 achieved 5.85% Li20 concentrate grade at 84% recovery; and
- Composite 2 achieved 5.86% Li20 concentrate grade at 83% recovery.
Based on the optimal flotation conditions from both the batch and locked cycle testing program, the pilot plant program was designed. The two composites were campaign processed through the pilot plant which operated at 50 kg/hour and produced over 400 kg of spodumene concentrate. The pilot plant flowsheet included grinding, de-sliming, magnetic separation, mica and spodumene flotation. The best campaign run produced a 6% Li20 concentrate at a 79% lithium recovery. During each campaign the test conditions were modified with the aim of maximising the recovery and concentrate grade. As a result there was some variability in the results over the total program. Figure 1 (see link below) compares the batch, locked-cycle and continuous pilot plant grade-recovery curves. Pilot plant results on the optimized flowsheet resulted in 71-76% lithium recovery for Composite 1 and 73-79% recovery for Composite 2.
Ongoing Testing Programs
Concentrate and tailings samples from the pilot plant were sent to Pocock Industrial Inc. in Salt Lake City, Utah for thickening (flocculent screening, static and dynamic settling) and filtration testing. The data produced will be used to size the industrial equipment for the solid-liquid separation.
The information collected from the piloting program will be incorporated into the Definitive Feasibility Study which is expected to be completed late 2Q 2018.
Sayona will continue process optimisation work through a collaboration with Prof. Kristian Waters who specializes in mineral processing at the McGill University in Montréal, Québec. A research project has commenced at the University to further explore the key findings from the pilot plant.
To view tables and figures, please visit:
About Sayona Mining Ltd
Sayona Mining Limited (ASX:SYA) (OTCMKTS:DMNXF) is an Australian-based, ASX-listed (SYA) company focused on sourcing and developing the raw materials required to construct lithium-ion batteries for use in the rapidly growing new and green technology sectors.
The Company's primary focus is the development of the Authier Lithium deposit in Quebec, Canada however exploration for additional lithium deposits is also ongoing in the Authier region and in the Pilbara of Western Australia where the Company has an extensive lithium exploration package of tenements.