The ReCYN™ pit designs, scheduled in the ‘ReCYN™ Optimised Plan’ Prober® run, showed an increase in resource and ore tonnage at all sites, as shown in Table 5 below. The biggest change in the pit designs between the two cases was an increased tolerance for higher cyanide-soluble copper (CuCN) ore, with areas not deemed economic in the base case pit optimisation included in the ReCYN™ shapes. This was particularly evident in the deeper south west areas at both Ramba Joring and Tor Uluala, and, to a lesser degree, the north west of Purnama. This result was due to both the silver uplift in recoveries, as well as to some degree the reduced sensitivity to cyanide-soluble copper in the ReCYN™ pit optimisation.
Table 5: Change in outcome between ‘Base Case Optimised Plan’ Prober® Run and ‘ReCYN™ Optimised Plan’ Prober® Run.
Delta in Run outcome between Base Case and ReCYN™ EO Runs
Ramba Joring
Tor Uluala 17.4% 21.3% -2.7% 11.1% 138.3%
Total 1
Purnama
Barani
Total Material Movement (Mt)
9.3%
13.5% 19.6% -9.3%
27.1% 34.4% -6.7%
17.6% 19.7% -6.1% -3.0% 43.0% 10.0% 26.7% +7.9kt 9.6%
Processed Tonnes (Mt)
11.6% -5.5% -1.2% 10.4%
Average Au g/t of ore Processed Average Ag g/t of ore Processed Average CuCN ppm of ore Processed Average SXS % of ore Processed
1.8% 0.1% 6.4% 8.1%
7.0%
108.3% 13.2% 22.2% 62.5% +2.5Kt 21.2%
6.4% 4.2%
19.5% 15.4% 65.4% +1.4kt 11.2%
Au Product (MOz) Ag Product (MOz)
18.2% +4.0kt
43.1% +0.0kt -0.2%
Copper Cathode Product (t)
LOM NPV of site before Period Costs 1
5.5%
1 Includes feed and product contribution from existing stockpiles not separately itemised
Overleaf, Figure 9 shows the effect on the pits of redesigning in GEOVIA Whittle™ for ReCYN™. Redesigning the pits on the ReCYN™ process. The benefits of the silver uplift and reducing sensitivity to Cyanide-soluble copper, showed significant increases in ore levels to most pits, while the overall mine life was extended by an extra two years. Average Cyanide-soluble copper in the crusher feed increased markedly, as previously-discarded high Cyanide-soluble copper ore becomes economic in the pit design and the lessening of focus on Cyanide- soluble copper in the grade control, given the revised CIL costs in pit optimisation and no CIL Cyanide- soluble copper maximum feed limit. Average Gold Grade processed slipped slightly. This result was due to both the longer sustainable operational life-reducing average grade and the focus slightly adjusting to silver, given the revised recovery outcomes. Figure 10 on page 25 shows average Gold, Silver, Cyanide-soluble Copper and Sulphide Sulphur (SXS) for both key Prober® runs. Later mine life in the ReCYN™ pit schedules show high SXS and Cyanide- soluble copper. This results as the high Cyanide-soluble copper areas of Ramba Joring, Purnama and Tor Uluala, newly deemed economic with the ReCYN™ pit optimisation, are mined out. Overall Cyanide usage has increased from 49.5kt in the ‘Base Case Optimised Plan’ to 73.1kt in the ‘ReCYN™ Optimised Plan’ Prober® run given a larger ore feed and more intensive cyanide usage to increase silver recovery. However, Cyanide required to be purchased externally has dropped by 25.7%, from 49.5kt to only 36.8kt, with the remainder of the Cyanide required recovered via the ReCYN™ process.
ReCYN™ Case Study – Martabe Operations
23
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