DEPOSIT TYPES
Gold-copper deposits within the SW Pacific Magmatic Arcs have been classified into three main groups by Corbett and Leach (Corbett and Leach, 1997; Corbett, 2009):
• Porphyry-related (including gold skarn).
• High sulphidation gold-copper.
• Low sulphidation (including sediment-hosted replacement).

Telescoping may overprint the varying styles of low sulphidation gold mineralization upon each other or upon the source porphyry intrusion.

Hydrothermal porphyry-related activity in the Kainantu area may have been protracted and associated with more than one intrusive phase (17 Ma to younger than 7 Ma). According to Corbett (2009), while the accepted wisdom is that porphyry Cu-Au mineralization in the Kainantu region is related to Elandora style porphyry intrusions, the coincidence of prograde alteration (Kokofimpa area; K-feldspar alteration) with Akuna-style diorite intrusions suggests alteration and mineralization may have been initiated at an earlier Akuna age and continued to an association with Elandora intrusions. The presence of Elandora clasts within advanced argillic alerted breccias, is consistent with a protracted history of activity. The (17-13 Ma) extended age of Akuna intrusions provides for batholitic intrusions to be overprinted by the mineralized phase recognised herein and distinguished from the younger (9-7 Ma) Elandora-style intrusions. Corbett (2009) recommends limited age dating is conducted once field relationships are established.

These exploration models as used by HKL and Barrick emphasized the epithermal and porphyry geological setting, which is broadly correct, at least spatially. But these models were later refined by Espi and others (2006) who recognized that the high grade quartz-Au-telluride veins with common percent Cu grades and significant W and Bi (e.g. Irumafimpa and Kora) were likely to be a significant separate event not directly connected to a porphyry Cu-Au source. The term “intrusion-related lodes” was introduced to describe this mineralization style. The consistent Au-Te association is interpreted to indicate an alkalic intrusion source at depth. Felsic dykes observed adjacent to some of the mineralised veins could be derived from such a source and may serve as a useful exploration guide.

MINERALIZATION OVERVIEW
Mineralization on the property includes gold, silver and copper occurring in low sulphidation epithermal Au-telluride veins, Au-Cu-Ag sulphide veins of Intrusion Related Gold Copper (“IRGC”) affinity,less explored porphyry Cu Au systems and alluvial gold.

The Kora-Irumafimpa (including Eutompi and Kora North) vein deposit has been demonstrated from K92 Mining’s drilling results to be a continuous mineralised structure. The April 2020 Mineral Resource Estimate reported in Section 14 of this report has produced a Kora Consolidated Resource comprising the Kora, Kora North and Eutompi deposits. Mining is currently taking place at Kora North. In addition,there remains a Mineral Resource at Irumafimpa areathat has had some modern mining activity(2007-2009). The deposit occurs in the centre of a large mineralized system approximately 5km x 5km in area that has been partly delineated by drilling and comprises several individual zones of vein and porphyry-style mineralization. Peripherally,exploration activities have also identified further areas of vein and porphyry-style mineralization.

Other less advanced prospects on the property include epithermal Au veins similar to Irumafimpa, IRGC veins similar to Kora, porphyry Cu-Au systems, skarn Cu, Pb and Zn mineralization and alluvial gold.

Proposed Mining Method
Although longhole stoping represents a considerably larger scale of mining than cut and fill, it is still a relatively selective mining method which allows extraction of high grade, yet relatively narrow, ore zones. The longhole stoping method is based on drilling and blasting ore in vertical rings from drives spaced 20m apart vertically, floor-to-floor, forming stopes 25m high. Stope widths will range from 3m to 15m and strike lengths will vary depending on localised ground conditions.

The average stope width generated using the MSO program is 5.2m, with most stopes less than 8m in width and only 8% of the shapes being greater than 8m wide.

Stopes will be extracted along strike initially in a bottom-up sequence with each stope progressively backfilled for stability and to provide a working base for the next stope above. The Avoca method would be used to limit the strike length of the open stope to maintain stability of the side walls and backs. Stopes will be progressively backfilled from the opposite end to where the stope is being blasted and loaded out.

Where access is not available to both ends of a stope the Modified Avoca method will be used. This method involves tight filling the stope against the ore face after each firing has been loaded out. The next ore blast can be fired against the tight-placed fill, or the fill can be partly mucked out to provide expansion space for the blast. Although Modified Avoca requires less lateral development, it has a lower productivity rate and higher filling costs.

Currently, development waste rock or “mullock” is used to backfill the stopes. However, K92ML is planning to construct a paste fill plant that will use filtered tailings from the processing plant to deliver paste fill to the mine.

Once the paste fill plant is operational, unconsolidated mullock fill will be replaced by cemented paste fill. This will provide greater flexibility in stope sequencing as well as in drilling and blasting. With cemented paste fill, stopes can be mined in a top-down direction as well as bottom-up. Top down mining in combination with paste fill will reduce the risk of self-propagation within the clay gauge zone versus bottom-up mining techniques; the risk will be mitigated by providing a beam of engineered fill overhead.

Although cemented paste fill offers greater stope scheduling flexibility, the preparation work prior to filling, plus cement curing time post-filling, will increase overall filling cycle times.

STOPE DESIGN
AMDAD used the MSO module in CAE Studio 3 to prepare a conceptual stope design for Kora. MSO automatically produces stope shapes from the resource block model that are economically optimised within specified geometrical and design constraints. Design parameters are shown in Table 55.

Please note the following in relation to the mining method modelled by MSO:

• AMDAD applied the geometric parameters in the table above to cater primarily for longhole stoping. However, the stope shapes can also represent 20m high cut and fill panels.
• A 20m stope length was used as an approximation of the 50thpercentile stable longhole stope lengths recommended by OTMS –17m for K1 supported and 25.5m for K2 unsupported. In practice, K1 stopes may be shorter than this while K2 stopes may be longer.
• As the clay gouge zone is currently not defined as a suitable model for application in MSO, the preliminary stope designs have not been constrained to stand off from the gouge. The K1 western extent has been driven simply by grade. In some cases, K1 may combine with KL to form a wider stope, with the gouge zone potentially more centrally positioned within the stope.

The resultant stope shapes, prior to any adjustment, are shown in the following Figures 81to 83. Corresponding estimates of resource tonnes and grade within the stope shapes totalling approximately 8.5Mt,are summarised in Table 56.

Development Concept
The mine plan makes use of existing Irumafimpa development and recent Kora exploration development, and in particular the existing incline, to provide access to the orebody for stope production activities.

As a starting point for the PEA mine plan for 1stJan 2021, K92ML provided AMDAD with its short-term designs for development for the remainder of 2020. The LOM production is also dependent on excavation of the following new development that AMDAD has incorporated in the PEA mine plan

Lateral Development
• A twin incline Haulage-way is being mined from a new portal north of the existing portal at 841mRL.
o Ore from Kora will be delivered via orepass to the new Haulage-way.
o One of the twin drives will be a dedicated haulage drive while the other will facilitate ventilation, drainage and provide a second means of emergency egress.
• A Northern Incline and Southern Incline will extend upwards from the existing development levels to the top of the mineable resource.
• A Central Decline will be developed down from 1142mRL. Once the twin incline Haulage-way is established from the 841mRL portal, the Central Decline can also be mined up and down from 900mRL.
• A footwall drive will be established on each level, with ancillary development including stockpiles, loading bays, access to ventilation and orepass rises and cross-cut orebody accesses to K1, KL and K2 stopes
• Orebody strike-drives for K1, KL and K2
• Miscellaneous development including recesses for sumps, and drill cuddies.

Vertical Development
• A 4.0m diameter raisebored Central Return Air Raise (RAR) will be developed from 1267mRL to surface.
• A Northern RAR and Southern RAR will be develope dto surface to service the upper inclines in conjunction with the Central RAR. These are also 4.0m diameter raisebored raises.
• Two 4.0m diameter raisebored Fresh Air Raises (FARs) will also be developed to surface to service the Northern and Southern Inclines and also to provide fresh secondary air onto each level.
• The Central and Northern RARs will belinked to the lower Central and lower Northern RAR extended below current development to service all development and production associated with the Central Decline.These are mined as 4.0m x 4.0m long hole winzes (LHW).
• A 4.0m x 4.0m LHW FAR system will be developed with the lower section of the Central Decline linking into the Irumafimpa Incline and twin incline Haulage-way.
• A Northern, Central and Southern Orepass System will be developed from the twin incline Haulage-way to the top of the mine. Most ore can be transported down through the Orepass System to 900 level where trucks can be loaded. All ore and mullock below 900 level will be trucked up to the twin incline Haulage-way.

ROM Pad and Crushing
ROM ore will be delivered to an enlarged ROM ore pad. The required seven (7) days storage on the ROM pad will be achieved by small extension of the existing ROM pad for the current plant. Should the current plant and scrubber be recommissioned in the future, then the need for a larger pad can be reconsidered at that time.

ROM ore will be fed over a static grizzly into a crusher bin by a front end loader. Provision has been made for direct truck tipping as well. A static rock breaker has been allowed for in the capital estimate.

An apron feeder will then feed a single toggle jaw crusher to crush to a nominal P80 of 90mm.

The crusher has been sized on 6,500 operating hours per year.

Ahead of the crusher, a finger grizzly will remove fines and reduce the load on the crusher.

One static and one self-cleaning magnet have been allowed for, to capture tramp metal.

Milling
Crushed product will be fed into a SAG mill (6.7m x 5.0m) with installed power of 4MW. The mill motor will have a variable speed drive and will drive through a conventional gear box, pinion and ring gear arrangement.

A plough arrangement on the SAG mill feed conveyor will plough off part of the crushed material for stockpiling and re-feeding to the SAG mill when the crusher is unavailable due to maintenance,etc. Scats from the SAG mill discharge are recycled to the feed with the option to divert to a scats bunker if required. Provision in the layout has been made for a pebble crusher if required in the future.

SAG mill discharge is pumped to a nest of (12) twelve Cavex CVX250 cyclones. It is expected that (10) ten will be operational at any one time. Cyclone overflow (80% passing 75µm) reports to a trash screen and then a flotation conditioning tank ahead of flotation. Fifteen minutes of conditioning residence time has been allowed to remove surges to the rougher flotation bank of cells. Cyclone underflow returns to the mill for further grinding. A cut of the cyclone underflow stream passes over a scalping screen with 2mm apertures and is then split between a flash flotation cell and a 30” Falcon Concentrator. Tails from the flash flotation cell and Falcon concentrator combine with the cyclone underflow balance for further grinding.

The proposed 1Mtpa processing plant uses conventional processing equipment for recovery of valuable sulphides from a copper sulphide deposit.
The processing plant will consist of the following unit processes:

• Ore receiving and single stage crushing
• Grinding and classification
• Flash flotation and gravity circuit for recovery of free gold
• Conventional sulphide flotation
• Concentrate thickening, filtering, drying and load out
• Reagent storage and mixing
• Plant services (compressed air and water)
• Tailings handling

Flash Flotation and Gravity Concentrate
The flash flotation concentrate reports directly to the concentrate thickener. Falcon concentrate gravitates to a new gold room where it is upgraded over two shaking tables before the final concentrate is dried and smelted to produce gold dore bars. The number and size of the Flash Flotation units will be further investigated during the Feasibility Study stage t ........