Market Outlook and Operational Insights

Annexure 2: Material Assumptions to support Production Target for Clark deposit Criteria Mineral Resource estimate as a basis for the production target Study status Cut-off parameters Mining factors or assumptions Commentary • • 69% Indicated and 31% Inferred Mineral Resources support a mine life of 70 years (Table 3). The Mineral Resource estimate was declared as part of South32's Annual Report published on 9 September 2022 and is available to view on www.south32.net. South32 confirms that the inclusion of 31% tonnage from Inferred Mineral Resources is not the determining factor of the project viability. The project forecasts a positive financial performance when using 69% tonnage from Indicated Mineral Resources. South32 is therefore satisfied that the use of Inferred Mineral Resources in the determination of the Production Target is reasonable. A selection phase of the pre-feasibility study has been completed for the Clark Deposit in compliance with the Association for the Advancement of cost engineering (AACE) International Class 5 estimate standard within an accuracy range of +/- 35%. A technically achievable and economically viable mine plan has been determined by the study team. Material modifying factors have been considered and are included in this section of the report. Clark is a polymetallic deposit which uses an equivalent Net Smelter Return (NSR) value as a grade descriptor. NSR considers the remaining gross value of the in-situ revenue generating elements once processing recoveries, royalties, concentrate transport, refining costs and other deductions have been considered. The elements of economic interest used for cut-off determination include manganese (Mn), silver (Ag)and zinc (Zn). The cut-off strategy employed at Clark is to optimise the NPV of the operation. An NSR cut-off grade of US$160/tonne was used in the development of mineable stope shapes. Primary access to the orebody will be through a single decline. Ventilation raises will be established to provide ventilation to the working areas. Paste backfill will be produced in a surface backfill plant and distributed underground via a backfill reticulation system. The mining method applied is longhole open stoping with paste backfill. This is the preferred mining method based on a combination of productivity, cost, resource recovery and risk of surface subsidence. The mining dilution is applied based on rock dilution or fill dilution dependent on the location of the stope being mined. Dilution factors are applied on a stope-by- stope basis using incremental dilution widths applied to the stope geometry Geotechnical recommendations based on deposit geology have been used to develop the stope shape dimensions. Due to the continuous nature of the orebody the mining recovery factor in primary stopes is 105% to account for overbreak into ore in the adjacent secondary stopes. The mining recovery factor in the secondary stopes is 85%. Inferred Mineral Resources are incorporated into the stope designs and contribute to the overall weighted grades and NSR of the stope. Inferred Mineral Resources contribute approximately 31% of the total planned tonnes. A risk assessment was completed to understand the incremental value contributed by addition of Inferred Resources and to confirm project viability without considering revenue from Inferred Resources. The proposed mining method with modifying factors applied supports a single- stage ramp-up to a life of mine average of 0.6Mt per annum. 57

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