GEOLOGYGEOTECHMININGPROCESSINGVALUATION/RISKTECHNOLOGIESENVIRONMENTTRAINING Investigation of Alternative Drawpoint Sampling A Sub-Level Cave, Gold-Copper Mine Example Presented by Mark Noppe At IQPC Mine Site Sampling, Brisbane May 2013

Xstract - Excellence from the Outset XstractGroup.com Content Sub-level cave mining Background Granulometry and grade variation Drawpoint sampling Drawpoint test work Test work results Mine reconciliation comparisons Future developments 2

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Xstract - Excellence from the Outset XstractGroup.com Reference “Investigation of Alternative Drawpoint Sampling at Ridgeway Mine, NSW – By G Smart, J Rutter and M Noppe – In: Sampling and Blending Conference Sunshine Coast, QLD, 9-12 May 2005, AusIMM 4

Xstract - Excellence from the Outset XstractGroup.com Sub-level cave mining Blind orebody – top 600 m below surface Large Ore Body Footprint (~350 mE-W x 250 mN-S) Transverse SLC Ore Pass System to Transfer Level with Gyro Crusher and Conveyor to surface Sub-Levels at m –Ring burdens 2.6 m –6 x 4.5 m drives, 14 m spacing –Up to 26 crosscut drives per level 5

Xstract - Excellence from the Outset XstractGroup.com Mineralisation Ordovician porphyry Au-Cu deposit Structurally Controlled – Stock work and sheeted veins – Sub-vertical Monzonite Stock Mineral and Grade Zonation – associated with Quartz Veining – High Grade: Au, Bn (+/- Cpy, Mt) – Low Grade: Au, Cpy (+/- Bn, Mt) – Monzonite: low grade to barren Strong association between quartz veining and Au-Cu grades Bornite decreases, chalcopyrite increases with depth Gold and copper both decrease at depth Visual grade estimation based on vein% is possible Current ore grades g/t Au, %Cu – Gravity gold recovery approximately 20% – Total gold recovery approximately 85% 6

Xstract - Excellence from the Outset XstractGroup.com History Sampling review initiated due to the ongoing manual sampling of the crushed ore conveyor belt 1 full belt-cut sample of kg every 1,000 t as an umpire assay 2 persons required for the task Identified as an OHS risk and a limitation to production Granulometry study to evaluate substituting a smaller, finer sub-sample 7

Xstract - Excellence from the Outset XstractGroup.com Conveyor granulometry 8

Xstract - Excellence from the Outset XstractGroup.com Results of conveyor granulometry study – Au and Cu 9 Au grades +53 mm <mean <-53 mm -10% <mean <+5% Cu grades +53 mm <mean <-53 mm -5% <mean <+5%

Xstract - Excellence from the Outset XstractGroup.com 10 Results of conveyor granulometry study – CuCN and S

Xstract - Excellence from the Outset XstractGroup.com Drawpoint monitoring and sampling Continuous activity every 400 t 24 hrs/day 11

Xstract - Excellence from the Outset XstractGroup.com Drawpoint sampling issues x 30 kg samples per day Manual handling/OHS issues 2 injuries at CVO, 3 injuries at assay laboratory Sample preparation costs Transport logistics Assay turnaround Encouraging results from conveyor granulometry and possible extension to routine drawpoint samples identified 12

Xstract - Excellence from the Outset XstractGroup.com Drawpoint rill material is inhomogeneous Use of sample bunds over previous 18 months had removed personnel from the rill More fines are exposed 13 Which bits to sample?

Xstract - Excellence from the Outset XstractGroup.com Fine versus normal samples 14 Normal (historical) samples 2 x 15 kg Fine fraction sample kg <45 mm For scale, polyweave sacks are 900 x 600 mm

Xstract - Excellence from the Outset XstractGroup.com Screening the fine fraction samples 15

Xstract - Excellence from the Outset XstractGroup.com Drawpoint test work Multiple “normal” samples (12 x 15 kg) and multiple “fine” samples (12 x 12 kg x 45 mm) collected from single sample bund Paired duplicate samples fine versus coarse: – Paired “fine” and “normal” field duplicates collected from 123 locations to determine sampling bias Routine drawpoint sampling changed to fine fraction sampling in mid- January 2005, reconciliation was ongoing 16

Xstract - Excellence from the Outset XstractGroup.com Multiple repeat drawpoint samples – Au x 15 kg normal samples and 12 x 10 kg fine samples per location Mean Au grade of <45 mm samples is % <normal samples

Xstract - Excellence from the Outset XstractGroup.com Multiple repeat drawpoint samples – Cu x 15 kg normal samples and 12 x 10 kg fine samples per location Mean Cu grade of <45 mm samples is -10% +10%

Xstract - Excellence from the Outset XstractGroup.com Paired duplicate drawpoint sampling 123 paired fine/normal duplicate drawpoint samples Mean Au grade of <45 mm is 12-13% lower than normal samples Mean Cu grade of <45 mm is 2-3% lower than normal samples 19

Xstract - Excellence from the Outset XstractGroup.com 5180 level drawpoint sample assays – pre/post sample mass change 20 Sampling protocol changed 10/01/ level = 39% of mine production

Xstract - Excellence from the Outset XstractGroup.com 5205 level drawpoint sample assays – pre/post sample mass change 21 Sampling protocol changed 10/01/ level = 40% of mine production

Xstract - Excellence from the Outset XstractGroup.com Mine reconciliations – pre/post sample mass reduction level = 40% of mine production 5180 level = 39% of mine production

Xstract - Excellence from the Outset XstractGroup.com Drawpoint sample reconciliation with conveyor and mill – pre/post sample mass reduction 23 Expected reconciliation changes -10% Au and -2% Cu

Xstract - Excellence from the Outset XstractGroup.com Future developments Examine in-situ sample preparation (jaw crush to <6 mm? and subsample 3 kg?) In-situ pseudo-assaying of crushed ore using portable XRF technology and the strong copper/gold correlation Ore/waste determination using magnetic properties of the crushed ore 24

Xstract - Excellence from the Outset XstractGroup.com Thank you for your attention For any follow up questions or enquires please contact: Mark Noppe Managing Director & Principal Consultant Xstract Mining Consultants Pty Ltd Offices Brisbane, AustraliaPerth, Australia Phone: Phone: Adelaide, AustraliaNewcastle, Australia Phone: Phone: Ulaanbaatar, MongoliaLondon, United Kingdom Phone: Phone: Xstract - Excellence from the Outset XstractGroup.com