The deposits of the Eva Copper Project belong to the IOCG type. IOCG deposits are hydrothermal copper-gold deposits associated with relatively high contents of iron oxide minerals (magnetite or hematite). The hydrothermal fluids are believed to be sourced from magmatic systems; however, mineralization is commonly distal (or spatially distinct) from the causative plutonic rocks. Mineralization can take many forms; however, vein networks, breccias, dissemination, and replacement are the dominant ones. Both structure (fault or fracture systems) and lithology (chemistry and rheology) are key features in localization of mineralization.

There are 12 defined deposits within the Eva Copper Project, ranging in size from 0.7 Mt to over 100 Mt, although only five are being considered for the current mine plan. Deposits are of two types: copper-gold and copper only. The copper-gold deposits are typically structurallyto stratigraphically-controlled, gold-bearing, chalcopyrite mineralization, associated with magnetite and sodic alteration. An oxidized zone from 15 m to 25 m deep commonly overlies the copper-gold deposits. The copper-only deposits are typically stratabound, and sulphide mineralization is predominately bornite or chalcocite, with low chalcopyrite. Some of the copper-only deposits have deep weathering profiles containing native copper and/or other copper-bearing minerals that present metallurgical challenges.

Mineralization within the Project area occurs as primary, sulphide-bearing and non-sulphide copper minerals in two deposit types: breccia, fracture, vein and shear-hosted copper-gold deposits, and stratabound, copper-only deposits. Both these deposit types can have nonsulphide oxide and supergene mineralization at the surface, underlain by primary sulphidebearing mineralization.

While resources of the non-sulphide deposits may be significant, difficulties with conventional flotation copper recovery prevent them from being considered for exploitation at this time within the planned recovery circuit.

Mineralization of the sulphide deposits is associated with regional-scale hematite and albite alteration (red-rock alteration) and localized magnetite alteration. There are five sulphide deposits included in the study, although the Little Eva and Turkey Creek deposits account for more than 90% of the resources. The main copper-bearing mineral is chalcopyrite, although bornite and primary chalcocite are abundant within the Turkey Creek deposit. Sulphide mineralization is controlled by fracture-induced permeability and lithology. In the Little Eva deposit, chalcopyrite occurs as a network of veins and fracture fillings, as well as clots and disseminations within intermediate igneous host rocks. Sulphide mineralization is commonly coarse-grained, resulting in favourable recoveries. Sulphide deposits included in the mine plan typically have a 15 m to 25 m deep oxidized zone with a relatively sharp transition to sulphide mineralization and little or no development of a supergene zone.

Conventional open pit mining methods, which include drilling, blasting, loading, and hauling will be employed at the Eva Copper Project open pits. The Eva Copper Project is estimated to have a two-year construction period, one of which is pre-production mining. Mining activities are based on open pit mining of the Little Eva deposit initially at a rate of 28 kt/d of ore. This higher rate than nominal rate is due to the softness of the initial ores. This primary pit will be supplemented by progressively mining five smaller satellite pit areas at Turkey Creek, Bedford North and South, Lady Clayre, and Ivy Ann to achieve a minimum 9.3 Mt/a mill feed rate.

The mining method involves a 25.3 Mt pre-strip of a starter-pit at Little Eva, which includes 5.3 Mt of ore. To sustain a 28 kt/d production rate during the first five years, stripping will continue at slightly elevated rates for several months after production commences. There will be three pushback pits in Little Eva and two pushback pits in Turkey Creek, while Bedford, Lady Clayre, and Ivy Ann will have one phase of mining.

Drilling will be carried out using conventional drill and blast (D&B) blasthole drills with dieselpowered front shovel excavation, and off- highway dump truck haulage. The main mining fleet consists of two, front shovels with 22-m3 buckets and an operating weight of 400-tonne each matched to ten, 141-tonne off-highway rear dump trucks. This fleet is supplemented by the standard support equipment composed of, but not limited to, track dozers, water trucks, graders, loaders, light vehicles, and service equipment.

Ore haulage from the Ivy Ann and Lady Clayre satellite pits will probably be accomplished using 50-tonne to 100-tonne highway trucks, similar to the trucks that currently haul concentrate on Queensland highways.

Mine waste will be transported to dumps adjacent to each of the pits, and to construct the TSF. Waste will also be used to construct an engineered, creek diversion channel and flood protection bund, and bund around the Little Eva pit. The channel and bund will re-direct wet season water flows in Cabbage Tree Creek away from the Little Eva pit.

The ROM ore will be delivered to the ROM pad where there will be the capability to direct feed from mine trucks to a gyratory crusher with 600 kW of installed power capable of accepting 1-m diameter rock at a rate of 1,713 t/h.

The current mining schedule then prioritises the mining of ore sequentially from Little Eva and Turkey Creek. Satellite deposits, which only account for 9% of the Mineral Reserve, will commence mining towards the middle to end of the mine life. The proximity of Turkey Creek to the mill makes it preferable to be mined early in the mining schedule. Further investigation and rescheduling will be carried out prior to project commencement. Mining of ore from the Bedford pits (North and South) is scheduled to commence in years three and four after the process plant commissioning. Lady Clayre pits are scheduled to be mined in year five and Ivy Ann in years six through eight. As noted previously, the satellite pits are quite small compared to the Little Eva pit.

Dewatering of the open pits will be required. A plan of dewatering wells, horizontal drains, and sumps are envisioned. A detailed plan will be developed during the Project’s development period. It has been estimated that the Little Eva pit dewatering will discharge approximately 4,000 m3 /d. This water is slated to be used as make-up water in the processing plant.

The Little Eva processing plant has been designed to produce a marketable copper concentrate with a grade of 25% Cu and containing about 4 g/t Au at a nominal throughput rate of 28,000 t/d in the first five years of production. The processing plant is designed for a throughput of 29,900 t/d. Production for the Years 6 to 12 would be lower at 25,500 t/d as a result of mining ore with an increased hardness. These revised throughputs over the life of the mine are based on the geometallurgical projections of the mine plan developed by Copper Mountain which modelled the ore hardness values obtained from drill hole data distributed across the pit.

The following summary of the unit process descriptions is based on the nominal ore throughput rate of 28,000 t/d (29,900 t/d design).

• The ROM ore primary crushing circuit will use a gyratory crusher with a nominal crushing rate of 1,268 t/h (1,354 t/h design) at the availability of 75%. The crusher is a Metso model 60-89. The crusher will be supplied with ROM using haul trucks. The crushed ore stockpile has a live capacity of 25,000 tonnes. The crushed ore stockpile reclaim system will be equipped with two reclaim apron feeders.
• The primary grinding circuit consists of a SAG-ball mill grinding circuit incorporating cyclones for classification and a pebble crusher for treating oversize SAG mill material. The throughput rate of the grinding circuit will be 1,268 t/h (nominal) and 1,354 t/h design at an availability of 92%. The primary grind product size will have a P80 value of 250 µm.
• The rougher flotation circuit will consist of six 150-m3 flotation cells. The circuit has an overall residence time of 18 minutes. Rougher flotation concentrate will be reground in the regrind circuit. Rougher tailings will be discharged to the tailings thickener.
• The rougher concentrate regrinding circuit incorporates a Vertimill (model VTM1500) and cyclones for classification. The regrind circuit product size will have a P80 value range of 55 µm to 75 µm. A partial underflow stream will be directed to a flash flotation unit producing a final grade copper concentrate with the tailings returned to the regrind mill.
• The regrind cyclone overflow will feed the single cleaner column flotation cell (6.5-m diameter and 19.5-m in height), which will produce the final copper product with a grade of 25% Cu. The cleaner column cell tailings will report to the cleaner scavenger flotation circuit. The column cell concentrate will be the final grade product, and it will report to the concentrate thickener.
• The cleaner scavenger flotation concentrate will be returned to the regrind circuit. The cleaner scavenger tailings will be discharged to the tailings thickener. The cleaner scavenger flotation circuit will have four 70-m3 cells.
• The concentrate thickener will collect the concentrate products from the flash flotation cell and the column cell. The thickened concentrate will be delivered to the concentrate storage tank, and this will feed the concentrate filter press. The filtered copper concentrate will have a moisture value of 9%. The dewatered final concentrate will be loaded onto trucks for despatch to smelters.
• The copper concentrate production will be 219,000 t/a nominal, and 233,000 t/a at the design throughput.
• The concentrate thickener overflow solution will be recovered and used in the grinding and flotation circuit.
• The tailings thickener will combine the rougher and cleaner scavenger tailings for discharging to the TSF as final tailings. Process water will be recovered from the tailings thickener and the TSF for re-use in the plant.
• The process water circuit will provide process water to the grinding circuit and other parts of the plant.
• A fresh water circuit will provide water for reagent make-up, gland service and mill cooling water.
• The reagent preparation section will prepare the flotation collector reagent (PAX) and the frother reagent (MIBC) for distribution to the slurry streams. The reagent dosage rates are respectively 40 g/t and 30 g/t. The flocculant required for the tailings and concentrate thickeners will also be prepared in this section.