Mineralisation at the Caravel Copper Project is hosted by a highly deformed Archaean granite and considered to originate as a large porphyry copper system.

The granite host rock, the inferred premetamorphic mineral assemblages and general scale and style are all consistent with the porphyry copper model. The broader geological setting is also consistent with a porphyry style of mineralisation, with the 30km mineralised trend following the margins of granite batholith of similar scale, referred to as the Wongan Batholith.

Outhwaite (2017) describes in detail age dating work and the tectonic history of the project area. Host granites and associated mineralisation have been dated at around 3.0 Ga, with subsequent deformation and metamorphism around 2.7 Ga, coincident with the regional deformation and gold mineralisation at Kalgoorlie and the wider Yilgarn goldfields, as well as the Boddington gold deposit.

Copper occurs almost exclusively as chalcopyrite sulphides associated with quartz veins. Copper grade is largely determined by the frequency and thickness of the veins, which may be semi-massive chalcopyrite up to several cm thick, though mostly the sulphide veins are more attenuated and in the range of mm thick following the main foliation. The frequency of veins or sulphide bands also varies on the scale of meters and tens of meters, where copper grades may range up to 0.6% over thicknesses of tens of meters with lower grades or waste in between. Molybdenite, pyrite and pyrrhotite may also accompany the chalcopyrite, though in much lower amounts. Garnet, sillimanite and magnetite are also commonly associated with mineralisation, possibly as products from metamorphism of the primary alteration assemblages.

The mineralised zones have undergone higher strain than adjacent barren granites in the footwall. In the higher strain zones, the mineralised veins have been transposed into the dominant foliation.

The transposed veins, aligned with the main foliation, have then undergone further folding, as part of the regional deformation event that created the overturned fold, which defines the west and east limbs of the Bindi deposit. Higher grade shoots of mineralisation are associated with the northwest plunging fold hinges of the Bindi antiform and the southeast synform, as illustrated. The same folding may be observed in core as illustrated.

At the regional scale, the Wongan Batholith lies on a major boundary between the Boddington and Lake Grace domains of the SW Terrane of the Yilgarn craton. Relatively little research has been undertaken on this significant boundary, which appears to be a 3.0 Ga Archaean magmatic arc that has subsequently closed when the SW Terrane collided with the Yilgarn, resulting in the regional 2.7 Ga deformation event. The Caravel deposits are believed to have formed in the volcanic arc that developed on this margin during subduction convergence prior to that collision event.

Mining parameters
To determine the most appropriate bench height, block size and loading equipment, a trade-off study was completed by Orelogy. Results showed the best combination to be 500t excavators loading 180t capacity trucks on 5 metre flitch heights, and blasting on a 10 metre bench height. With a selective mining unit of 12.5 x 12.5 x 5m, the overall ore loss and dilution are estimated to be 4.4% and 4.7% respectively. Grade control of ore will be by RC drilling at 15 metre centres on 30m benches.

Pit optimisations were carried out to identify and quantify potential mining inventories within optimal pit shells. The open pit optimisation was undertaken utilising Dassault Systèmes Australia (Geovia) WhittleTM software, which generates a series of nested pit shells using “Revenue Factors” based on a set of financial and other parameters such as costs and metal prices. The pit shells giving the highest undiscounted cashflow values for a given set of optimisation parameters were selected for scheduling. The aim of the mine production scheduling was to generate a practical, realistically achievable schedule which maximises value within the applied constraints that:
• Meets mill feed requirements;
• Includes ramp-up considerations for mine operations as well as the processing plant;
• Avoids excessive and unachievable vertical advance rates.

A life-of-mine annual production schedule was completed based on a throughput of 12Mtpa of ore for the first 5 years, with a ramp-up to 24Mtpa commencing in Year 6. The schedule envisages the Bindi deposit will be mined during the initial stages of the Project with mining at Dasher commencing post Year 14.

Starter pits were generated to ensure early access to higher-grade ore whilst minimising waste stripping. The starter pits at Bindi account for the first 5 years of mining, during which 59Mt of ore (at 0.31% Cu) will be delivered to the mill for processing at a strip ratio of 0.43:1. A total of 92% of material in the production schedule for the first five years is in the Indicated Resource classification and 8% is in the Inferred category. Inferred Mineral Resources are not the determining factor in project viability and do not feature as a significant proportion early in the mine plan.

Over the 28 year project life, the Bindi and Dasher deposits will produce 576Mt of ore (at an average grade of 0.25% Cu) and a strip ratio of 1.1:1. Mining of the current resources is assumed to finish in year 25 at which point the mill will process material from the accumulated low-grade stockpiles. A total of 75% of the overall material in the production schedule is currently in the Indicated resource classification category, while 25% is Inferred (including 0.2% Unclassified).

Primary crushing
A large 54 – 75 gyratory crusher capable of treating 12Mtpa will be utilised for primary crushing. Ore will be direct dumped from the mine by haul trucks or by front end loader into a feed pocket and crushed in the gyratory crusher. Crushed ore will be extracted by apron feeder and discharged to the crushed ore stockpile via the crusher discharge conveyor.

Grinding
The basis for the mill selection was to use single 16 MW twin pinion-driven mills. Twin pinion mills due to their lower supply and install cost when compared to either Gearless Mill Drives (GMD) of similar size, or two mills. The discharge from the 11m diameter SAG mill will feed a 7.9m diameter ball mill in closed circuit with a cyclone cluster. Pebbles from the SAG mill will be recycled back to the through the mill via a cone crusher.

Caravel has modified the process flowsheet from the 2019 Scoping Study as part of trade-off studies (to a scoping level) for Phase 1 of the PFS, with the circuit modified to incorporate a Semi Autogenous Grinding (SAG) Mill with pebble crusher comminution circuit in preference to the High Pressure Grinding Roll (HPGR) envisaged previously. This change aims to provide a faster return on capital, higher throughput and the opportunity for pebble rejection. The study also produced a site layout suitable for start-up operations and future expansion, with an equipment flowsheet for treating the ore at 12Mtpa which will then be effectively replicated when the plant is expanded to 24Mtpa from year 6 onwards.

Flotation
Cyclone overflow from the ball mill will report to a copper flotation circuit consisting of roughing, regrind and three stages of cleaning with scavenging. Tailings from the flotation circuit will be pumped to the tailings thickener.

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