Table 5 – Comparison of simulation and post-installation survey results Stream TPH Au Au Recovery Cu Cu Recovery (g/t) (%) (%) (%) Survey 3.93 34.78 33.35 21.58 11.51 SK240 Concentrate Pre_Sim #1 3.14 41.56 31.96 13.29 5.74 Pre_Sim #2 1.70 76.58 31.89 24.14 5.65 Survey 22.66 9.00 49.68 27.40 84.16 Cleaner 3 Concentrate Pre_Sim #1 22.34 9.60 52.50 29.09 89.39 Pre_Sim #2 22.44 9.57 52.56 28.99 89.47 Survey 26.59 12.81 83.03 26.54 95.67 Final Concentrate Pre_Sim #1 25.48 13.54 84.46 27.14 95.13 Pre_Sim #2 24.14 14.29 84.45 28.65 95.12 Pre‑simulation 1 (Pre_Sim #1) predicted a lower copper concentrate grade (13.29%) compared with the grade measured during the post‑installation survey (21.58%). This discrepancy was expected, as the simulation was based on performance data from the SK0.25 pilot unit rather than from a full‑scale cell. In addition to the considerable difference in scale between the pilot and installed units, the froth recovery characteristics observed in the pilot plant were not representative of those achieved in the full‑scale SK240. As a result, the pilot‑based model was unable to accurately predict full‑scale concentrate grade performance. However, the simulation results demonstrated that concentrate grade could be improved by adjusting the froth recovery factor (Pre‑Sim #2). This sensitivity analysis indicated that the model responded strongly to changes in froth recovery, highlighting the importance of accurately characterising full‑scale froth behaviour to improve predictive performance. Post-installation: Modeling and simulation to optimise performance A further objective of the campaign was to recalibrate the JKSimFloat model to support future simulations and optimisation of the Ernest Henry Operations flotation circuit. At this stage, the simulation work focused on identifying strategies to enhance overall flotation efficiency. The following simulation scenarios were evaluated to identify opportunities for improvement: • Increased residence time in the rougher banks. • Increased residence time in the Cleaner 1 bank. • Increased mass recovery in the Cleaner 1 bank. • Increased mass recovery in the Cleaner 3 bank. • Redirection of Cleaner 1 Bank 1 concentrate to the head of Cleaner 3. • Redirection of Cleaner 1 Bank 1 concentrate to the head of Cleaner 3, combined with increased mass pull in the Cleaner 1 bank. • Redirection of Cleaner 1 Bank 1 concentrate to the head of Cleaner 3, combined with increased residence time in the Cleaner 1 bank. • Increased mass pull in the SK240 flash flotation cell. • Increased mass pulls in both the SK240 cell and the Cleaner 1 bank. The simulated gold and copper recoveries for each scenario are presented in Figure 6, which illustrates the step change in recovery relative to the original base‑case performance.
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