Ajax is an alkalic copper-gold porphyry deposit hosted within the Iron Mask Batholith. Mineralization extends to depths exceeding 700 m, widths exceeding 1,000 m, and has a strike length that exceeds 2,000 m. The mineralization in the project area is associated with structural corridors of highly fractured and albite-altered sections of Sugarloaf Diorite (SLD) and Sugarloaf Volcanic Hybrid (SVHYB) units.


The Iron Mask Batholith is host to more than 20 known mineral deposits and occurrences. Copper-gold mineralization within the Iron Mask Batholith is associated with the younger intrusive phases of CHMZ and SLD. Mineralization is generally localized along major fault zones, at the contacts with the older PHD and IMH units and associated with albite and potassium feldspar alteration.

The mineralization in the project area is associated with structural corridors of highly fractured sections of SLD and SVHYB phases of the Iron Mask Batholith. Chalcopyrite is the dominant copper mineral and occurs as veins, veinlets, fracture fillings, disseminations and isolated blebs in the host rock. Concentrations of chalcopyrite rarely exceed 5%. Accessory sulphide minerals include pyrite and molybdenite.

Copper mineralization in the Ajax area consists predominantly of chalcopyrite and is hosted primarily in the SLD and SVHYB units. This mineralization appears to have greater concentration within the Sugarloaf units near the contact with IMH. Some mineralization is also seen within the IMH, MAFV, PXPP and PICR units near the contacts with Sugarloaf units, but mineralization drops off quickly with increasing distance from the contact. Chalcopyrite occurs as blebs and disseminations, in fractures, veinlets and micro-veinlets, as well as in occasional breccias and vugs with calcite. High-grade copper mineralization (>1.0% Cu) is confined to chalcopyrite vein systems. High-grade mineralization can extend several metres from the vein structure. Low-grade copper mineralization (0.10% to 0.50% Cu) is generally associated with the SLD-IMH contact. Drilling on the Ajax property has shown that mineralization extends to depths exceeding 700 m, widths exceeding 1,000 m and has a strike length exceeding 2,000 m.

Sulphide mineralization at Ajax also consists of pyrite and molybdenite. Pyrite is ubiquitous, occurring with chalcopyrite but also peripherally to the copper mineralization. Molybdenite is occasionally observed in SLD and SVHYB units, associated with potassium feldspar ± carbonate veins. Tetrahedrite has also been observed in trace amounts. Secondary copper oxides bornite and chalcocite occur infrequently.

Very minor amounts of the copper oxides malachite and azurite occur near surface. Native copper has also been observed locally.

As albite alteration was a precursor to mineralization, not all altered areas are mineralized. Where albitization is intense and texturally destructive, typically no copper mineralization is present. Intense albitization is interpreted to have rendered the SLD impermeable to mineralized fluids.

There are three copper mineralization/albite relationships:
- High-grade copper with weak to moderate albitization
- Low-grade copper with high albitization
- Barren copper with high albitization.

Gold mineralization is common and has a significant correlation with copper, but is very finegrained and visible gold has not been observed in the core. Gold mineralization increases slightly in areas where strong albite alteration occurs (Wardrop, 2009). It is common for gold concentrations to be directly correlated with copper concentrations. It is infrequent for gold mineralization to occur without associated copper; however, in areas of moderate to strong potassium feldspar alteration, this can occur. Variable gold-copper ratios throughout the deposit suggest a series of pulses of gold-copper mineralization were emplaced. Spatial distribution of copper-gold ratios has pointed to at least three phases of mineralization in the Ajax West Pit but possibly only one in the Ajax East Pit (Bond, 1988). In addition, northwest trending faults seem to be offsetting copper mineralization and concentrating gold, possibly due to later remobilization along structures.

Minor palladium mineralization is associated with copper near the contacts of the IMH and SLD units (Wardrop, 2009). Minor amounts of silver have also been found.

The proposed mine plan envisages a conventional open pit operation producing 65,000 t/d of ore to the processing facility. The pit has been designed to be developed in seven phases. The ultimate pit will be approximately 2.7 km in an east-west direction and approximately 1.3 km in a north-south direction.

Two stockpiles will be utilized to maximize the discounted cash flow of the project. A mid-grade stockpile and a low-grade stockpile will be constructed to store lower grade ore and will be reclaimed and processed later in the mine life.

A conventional truck and shovel fleet will be used to mine 15 m benches. Drilling and blasting will be required. Horizontal drains are proposed as the primary means to depressurize the pit slope. In-pit water will be removed by way of ditches, pipes, sumps, pumps, and booster pumps.

Four mine rock storage facilities (MRSFs) for waste rock are planned for the Ajax Site. The east mine rock storage facility (EMRSF) will be constructed east of the ultimate pit. Similarly the south mine rock storage facility (SMRSF), will be located south of the ultimate pit. The tailings embankment will be constructed in two parts using run-of-mine rock, the north and east sections. A north extension and buttress for the main tailings embankment called the west mine rock storage facility (WMRSF) will be constructed to increase storage capacity, reduce haul costs, and to increase the stability of the TSF Embankment. A backfill storage facility is also planned once Phase 6 of the interim pit phases has been completed.

The ultimate pit will be developed through a series of seven interim phases.

The first two phases focus on the extraction of high grade ore with a low strip ratio in the area of the existing West pit. Phase 3 further expands the existing East pit and takes advantage of a low strip ratio to maintain an uninterrupted ore release during the mining of Phase 2. Phase 3 also allows for development of Phase 4 which combines the existing West and East mining areas into a single pit. Phase 5, 6 and 7 are push backs to the Northeast and advance the pit towards the ultimate pit limits. Pit backfilling can only commence once Phase 6 has reached the maximum depth of the ultimate pit. Phase 6 completes the Western extent of the ultimate pit.

ROM Ore Receiving & Primary Crushing
Ore will be dumped directly into the 450 tonne capacity covered dump pocket that allows for a two-truck approach at the dump pocket. Large rocks, not passing the 1,500 mm by 2,800 mm (60” by 110”) primary gyratory crusher, will be broken with the permanently installed hydraulic rock breaker.

An apron feeder, equipped with a variable frequency drive, situated below the primary crusher surge pocket will draw crushed ore (P80 = 150 mm) and transfer the crushed material to the coarse ore stockpile feed conveyor which in turn transfer the ore to the coarse ore stockpile.

A dry dust collection system will control dust emissions from the primary crusher plant. Exhaust hoods are provided at drop points to control fugitive emissions and chemical suppression systems are included at locations where captured dust collector fines are reintroduced into the process.

Crusher performance will be monitored by a particle size camera located on the stockpile feed conveyor.

Secondary Crushing
Coarse ore is transferred from cone crusher screen feed conveyor number one to cone crusher screen feed conveyor number two which discharges to a feed bin at the head of the cone crusher screening circuit. The bin has a live capacity of 360 tonnes, providing approximately 3.5 minutes of live storage in front of the screening plant. Individual belt feeders draw off each of the two discharge points on the bin and feed a 4.2 m by 8.5 m double-deck, vibrating screen.

The cone crusher feed conveyor will be equipped with a feed metal detector to protect the cone crushers. Any metal detected will activate the cone crusher feed diverter chute and material will be diverted to an outside bunker. A belt scale and particle size camera will monitor material on the belt generating data for both process control and metallurgical accounting.

Material will be drawn from the cone crusher feed bin by two belt feeders, each equipped with variable frequency drives, and coarse ore will be delivered to the two 900 kW MP1250 cone crushers. Feed will be controlled to the crusher to ensure a choke-fed situation is maintained.

Secondary crushed material is returned to the head of the screening circuit. Each area, the cone crusher building and the cone crusher screening area, will have a dedicated dry dust collection system to help control ambient dust levels in each facility.

Tertiary Crushing
The tertiary crushing circuit will consist of two HPGR units and two HPGR screens in a closed circuit configuration and will crush material to a particle size acceptable to the grinding and flotation circuit.

In order to mitigate the effects of freezing the 360 tonne HPGR feed bin will have steep tapered walls, be of mass flow design (i.e., no dead material) and will be located inside the secondary and tertiary crushing building to ensure the bin surface area is heated. Twenty-five millimetre thick liners will line the inner walls of the bin.

Two 2.4 m diameter roll class HPGRs will receive the F80 of 45 mm fine ore feed and reduce it to a P80 of 15 mm. A level sensor above each HPGR will control the HPGR belt feeder rate to ensure the HPGR is choke fed. A discharge chute under each opening will receive the HPGR discharge and direct it onto the HPGR screen feed conveyor for classification by the screening system.

Ball Mill Grinding Circuit
Milling of crushed ore down to the target size (P80=214 µm) will be accomplished in two parallel ball mill trains, each operating in closed circuit with a cluster of hydrocyclones. Each circuit will be capable of treating 1,472 t/h of new feed. HPGR screen undersize (new feed) will be combined with ball mill discharge and process water in a 281 cubic meter cyclone feed pumpbox and pumped by a 2,000 kW cyclone feed pump to a cyclone cluster consisting of twelve (ten operating, two standby) 840 mm diameter cyclones. Cyclone underflow, at 78% solids by weight flows by gravity to the ball mill feed chute and into a 7.9 m Ø by 13.4 m dual pinion drive grinding mill. The drives are powered by two variable frequency drives, 9,000 kW, low synchronous motors.

Both ball mills will be equipped with a ball mill magnet positioned on the ball mill discharge, capturing any ball chips exiting the mill and preventing this tramp metal damaging the downstream cyclone feed pumps. Collected chips will be discharged to a ball mill scats bunker.

Primary Regrind
Additional regrinding to 20 µm is required to fully liberate the copper bearing material. This is discussed below. A vertically stirred mill operating in closed circuit with a set of cyclone cluster, at a recirculating load of 250%, has been selected as the appropriate technology to achieve the 40 µm grind.

Secondary Regrind
Horizontal stirred mill has been selected as the appropriate technology for the Ajax secondary regrind application in order to reduce the grind size of the first cleaner concentrate to a P80 of 20 µm.

Cyclone underflow, at 50% solids by weight, passes over a trash screen and discharges to the secondary regrind feed pumpbox and is pump to the horizontal stirred. The mill will be powered by a 1,120 kW motor.

The Ajax process plant is designed to process 23,725,000 dry tonnes of a copper-gold ore annually, or 65,000 t/d, producing approximately 250,000 dry tonnes of concentrate per year. The process design allows to produce a combined copper-gold concentrate at 25% Cu and 16.4 g/t Au.

The processing plant will consist of stage-wise crushing and grinding, followed by flotation processes to recover and upgrade copper from the feed ores. A gravity circuit will be included within the flotation circuit to enhance overall gold recovery. The the flotation concentrate will be thickened, filtered, and sent to the concentrate stockpile for loadout and subsequent shipment to smelters.

The final flotation tailings will be thickened and pumped into a tailings storage facility (TSF). Main process water will be recovered from the tailings thickener overflow in conjunction with reclaimed water from the barge at the tailings pond in TSF to the plant. Fresh water will be used for pump ........