The bulk test produced around 160 kilograms of concentrate of 6.1% Li2O with a 60.1% lithia recovery.
As well as delivering impressive results in terms of lithia recovery, the results also support AVZ's selected definitive feasibility study (DFS) flowsheet.
The completed phase II optimisation work has demonstrated AVZ's laboratory test work is scalable to a full-size operation.
AVZ managing director Nigel Ferguson said: “Our phase two test work is now complete and has delivered exceptional results in terms of lithia recovery and supporting the selected DFS flowsheet.
“Furthermore, the product grade and recovery confirm both the reproducibility of testing and high degree of flexibility in attaining economic graded products.
“Overall, our phase two optimisation work has demonstrated that our laboratory test work is scalable to a full-size operation."
The metallurgical test program aimed to test and confirm the two-stage dense media separation (DMS) flowsheet, quantify the extent of heavy mineral recovery including tin and tantalum minerals, explore fine lithia recovery pathways (flotation) for future plant expansion, and generate verification parameters for the process design criteria.
Bulk sample results
This dense media separation (DMS) test work for phase two is now complete with seven optimisation tests undertaken to maximise product recovery and grade.
Processing of a two-tonne bulk sample produced about 160 kilograms of concentrate.
Around 3% of xenolithic waste was purposefully added to assess the worst-case iron contamination and, even after this inclusion, iron levels were well within the specification of circa 0.72% iron oxide.
Given a mining scenario where these minor xenolithic units will be selectively removed to waste dumps, the company expects that iron levels will be reduced in the final product for sale.
Heavy minerals recovery and lithia flotation
As phase II test work nears completion, the company’s focus is now on by-product (heavy mineral) recovery, including tin and tantalum.
During the DMS process, dense media cyclone (DMC) concentrates were flagged for heavy mineral recovery test work employing conventional gravity recovery techniques.
All heavy minerals, including gangue iron minerals, are proposed to be rejected, and as a result, tin and tantalum by-products may be produced with gravity tailing lithia concentrates.
Ferguson said: “Tin and tantalum recovery test work is progressing very well with some very encouraging intermediate results and we have now produced a -0.5-millimetre gravity product ready for further dressing test work.
“The flotation sighter test work for lithia recovery from fines is progressing well and results are expected mid-March.”
The metallurgical parameters for the proposed flow sheet are now confirmed with the DFS on its way.
AVZ's next milestone is the completion and release of its DFS in March.
Ferguson said: “We eagerly await the completion of our DFS and look forward to its release next month.”