As stated, the Trench 4 developed f

As stated, the Trench 4 developed flow sheet was also used in the Variability Testwork.However, once more detailed mine schedules were developed towards the end of the FStestwork, this showed that the ROM would not have “excess Ca” so calcite flotation would nolonger be required. With the removal of calcite flotation for the final design flow sheet, theflow sheet was simplified after the completion of testwork to a SAG mill rejecting a coarsebarren oversize with a final product grind size of -125 μm.Key testwork steps and outcomes are summarized below:• Initial beneficiation circuit definition identified that scrubbing did not use power inputefficiently. Scrubbing was not sufficient to obtain the desired lithium upgradeeconomically. This necessitated the change to testing and characterising SAG millgrinding. SAG mill grinding still produced a “rejectable” coarse barren oversize• Based on the PFS testwork and the understanding of the ore at the time, calciteflotation was continued in the FS testwork. Calcite flotation was conducted with bothTrench 4 and Variability Testwork samples• Beneficiation testwork on 14 Variability Testwork composites, using the selectedflowsheet from the Trench 4 based testwork, indicated overall lithium recovery (fromore to leach solution) ranged from 77.9% to 91.2%, and averaged 83.8%, for 10 of the14 composites. In these 10 composites beneficiation Li recovery averaged 91.8%(88.5 to 95.2%) and extraction from beneficiate to leach solution averaged 91.3%(88.1 to 95.7%)• Extraction testwork confirmed a robust roasting recipe consistently achieving >90%lithium extraction. Impurity removal successfully reduced levels of fluoride, caesiumand rubidium from the PLS• Locked cycle testwork proved stable operation and a robust flow sheet, as well as theability to produce battery grade lithium carbonate and remove key impurities. Overalllithium recovery from the extraction circuit during locked cycles was between 87% and91%. Therefore the lithium recovery in the process is expected to be higher than theprocess design value of 82.8%, which accounts for other plant losses• Extraction testwork on three production composites successfully followed the processflow sheet. Impurities were removed and battery grade lithium carbonate wasproduced for each of the three composites. The purity of the three refined lithiumcarbonates, expressed as percent lithium carbonate, were 99.82% (Composite A),99.80% (Composite B) and 99.85% (Composite C).The testwork results served as inputs to the process design criteria, which were used todevelop the mass balance.A detailed description of the testwork conducted can be found in Appendix 5.1.5.2 PHASE 1: Beneficiation Testwork5.2.1 Testwork ROM Feed GradeA beneficiation and extraction flow sheet was developed based on a Trench 4 feed sample.Trench 6 was only assayed but not used for testwork.The Trench 4 source report, Trench 4 full head assay and Trench 6 full head assay can befound in Appendix 5.2, Appendix 5.3 and Appendix 5.4 respectively.