Corbett and Leach classified gold-copper deposits within the southwestern Pacific magmatic arcs into three main groups (Corbett and Leach, 1997; Corbett, 2009):
• Associated with porphyry (including gold skarn).
• Gold-copper of high sulphidation.
• Low sulphidation (including replacement in sediments).

Telescoping may superimpose different styles of low-sulfide gold mineralization on top of each other or on parent porphyry intrusions.

Hydrothermal porphyry activity in the Kainantu area may have been protracted and associated with more than one intrusive phase (17 Ma to younger than 7 Ma). Porphyry Cu-Au mineralization in the Kainantu region is associated with Elandora-type porphyry intrusions.

The exploration models emphasized an epithermal and porphyry geological setting, which is generally correct, at least spatially. But these models were later refined and it was recognized that the high-grade quartz-gold-telluride veins with the usual Cu percentages and significant W and Bi contents (e.g., Irumafimpa and Kora) were probably a significant isolated event that was not directly related to associated with porphyry Cu- Source. The term "intrusion-related lands" has been coined to describe this type of mineralization. The consistent Au-Te association is interpreted to indicate an alkaline intrusion source at depth. Acid dikes observed adjacent to some mineralized veins may be derived from such a source and may serve as a useful ex ........

The underground mine has been operated by K92 since October 2016 and has a current processing throughput of 400,000 tpa. The FS targets an expansion to a peak processing rate of 1,200,000 tpa with a 7-year mine life.

The Stage 3 Expansion mine plan considered in the DFS is designed as an incline access operation with a series of ore passes for efficient material movement between sublevels and the twin incline for material transport to surface. The DFS mine plan initially employs a long hole open stoping mining method utilizing Avoca and modified Avoca mining methods, which are currently employed at the mine. Upon construction of the paste fill plant, the mining method transitions to long hole open stoping with paste fill in Q2 2024.

Long hole open stoping has been successfully executed at both the Kora and Judd deposits, with the first long hole stope mined in Q1 2020 at Kora and Q4 2021 at Judd. The Avoca methods involve backfilling from the overcut sublevel while the long hole stope is advanced from the undercut sublevel to limit the strike length of the open stope. By limiting the strike length of the open stope, the method is designed to maintain stability of the stope walls and backs and increase the ultimate strike length extracted. The application of cemented paste fill provides improved geotechnical conditions for less dilution and higher mining recovery factors, greater operating flexibility through the ability to mine above and below paste fil ........

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