Aeon Metals Limited updated on the progress of the Pre-Feasibility Study (PFS) for its 100%-owned, world-class Walford Creek Copper- Cobalt Project (Walford Creek Project) in north-west Queensland. The updated Mineral Resource estimate is currently in the final stages of validation and review and
is expected to be released before month end. The updated Mineral Resource estimate is expected to feature an increase in Measured classification tonnage following the CY2021 infill drilling. The updated Mineral Resource estimate combined with the study work undertaken to date is expected to facilitate the declaration of a maiden Ore Reserve estimate with the release of the PFS. Targeted throughput remains unchanged at 3 Mtpa, as does the preferred mining methods (conventional truck and shovel open pit, and transverse retreat longhole open stoping underground). During the CY2021 drill season, 13 of the holes drilled for metallurgical testwork were also logged for geotechnical data. The results are being used to refine the open pit and underground geotechnical parameters and will form the basis of the geotechnical recommendations for mining. No further geotechnical work is expected to be required as part of any subsequent Feasibility Study. This updated Mineral Resource estimate is to be used to update open pit mine and underground stope designs in conjunction with a new mine schedule optimisation and operating cost estimate refinement. This schedule optimisation will also include updated metal prices, exchange rates, metal premia and metal recoveries based on the ongoing testwork program. Overall mine designs, waste dump designs and surface infrastructure are expected to remain largely the same as those developed previously. The Scoping Study was based on a substantial body of previous testwork that focussed on the selective flotation of base metal and pyrite concentrates. Due to this very advanced starting point, the testwork on bulk flotation has proceeded both quickly and smoothly. The primary grind size has increased since liberation is now driven by sulphide /non-sulphide mineral separation rather than the more challenging separation of the individual metal sulphides from each other and the non-sulphide gangue. Flotation and comminution testwork has been completed for all ore types, representing both open pit
and underground ore which will be mined within the first 10 years of operation. Further flotation testwork is scheduled to be completed for the later mine life ore type of Amy. Bulk flotation is followed by oxidative leaching to extract the key metals into solution. The leach testwork program is nearing completion with leach optimisation of most ore types and blends now well understood. A remarkable feature of the pressure leaching at modest temperature of 150° C and 15 atmospheres of pressure is the relative insensitivity of leach operation to the variations in composition and mix of the flotation ore types. Pressure leaching conditions are well defined using both smaller scale batch and larger scale continuous autoclave configurations. The objective of the larger scale testwork is to confirm leach conditions for the expected bulk concentrate composition over the initial 10 years of the life of mine. The larger scale testwork also generates larger volumes of pregnant leach solution for downstream testwork. Metallurgical testwork for the solid /liquid separation, copper solvent extraction and impurity removal stages are nearing completion. Solid /liquid separation will employ filters rather than the counter- current decantation proposed in the Scoping Study. This has several advantages including lower capital cost, improved metal recovery, higher solution tenors, lower water usage, and dry stacked tailings (smaller tailings footprint, facilitates co-disposal with mine waste and reduces environmental risks). While a range of autoclave operating conditions were studied to optimise valuable metal extraction, the selection of the current design leach conditions does not result in significant silver or lead extraction to the pregnant leach solution. While no lead extraction and saleable production was incorporated into the Scoping Study, saleable silver production was included as a lesser source of revenue ­ this will be absent in the PFS. This will also however result in the removal of the capital and operating costs associated with the previously assumed silver circuit. The Scoping Study contemplated the production of zinc metal by electrowinning. Subsequent analysis suggests that the production of zinc sulphate is both simpler and has the potential to yield a premium to LME zinc metal pricing. The primary market for zinc sulphate is as a trace element additive to
fertiliser. Currently all of Australia's domestic consumption of zinc sulphate is imported from overseas, typically China.