Zafranal represents a classic example of an Andean style porphyry copper, gold, and molybdenum deposit.

Porphyry copper-gold mineralization occurs within a large roughly east-west trending hydrothermally altered zone that is more than 7 kilometres in length and as much as 1.7 kilometres in width in a north-south direction. Copper occurs within veins and stockworks and as disseminations in both the Zafranal Main zone and Victoria deposits. At the Zafranal Main zone deposit, primary (hypogene) mineralization is overlain by zones of secondary enrichment mineralization. Copper mineralization has been categorized, based on copper solubility, into leached, mixed, oxide, supergene and primary zones.

Zafranal Main zone.
Drilling on the Zafranal Main zone has demonstrated continuous mineralization over a strike length of at least 2,500 m, widths of between 500 to 800 m, and over a vertical range of up to 1,000 m. The types of copper mineralization are described as follows:

Leached cap and secondary enrichment

The large altered and mineralized area at Zafranal has a subdued colour anomaly. The deposit has been intensely leached with a well-developed leached cap over the top of the supergene-enriched horizon at depth. Very little hypogene sulfide mineralization is present in outcrop, having been strongly leached and/or altered. At surface all forms of sulfides are absent except for occasional pyrite along with chalcopyrite in some more silicified rocks where acid ground waters could not invade the rock and oxidize and leach it.

The best supergene enrichment zone is generally associated with phyllic alteration consisting of a sericite + quartz + chlorite/biotite + clays + pyrite assemblage. The thickness of this zone can reach up to 150 m – averaging 75 m throughout the deposit – with grades up to 7% Cu.

Copper oxides of chrysocolla, neotocite, malachite and azurite generally occur above the main supergene enriched blanket and below the leached cap. This type of oxide copper mineralization is associated with an intense phyllic alteration (sericite + quartz + clays). Oxide mineralization can be up to 50 m thick. The leached cap itself is 30 m to 200 m thick. The copper-oxide zone defines former supergene enrichment zones (paleoblanket) preserved within the oxidized leach zone.

Primary sulfide mineralization

Hypogene mineralization occurs as veins, stockworks, and disseminations in the Zafranal diorite and microdiorite units. The Zafranal diorite at surface contains consistent background copper amounts (typically between 1,000 ppm and 1,500 ppm Cu) and typically presents the highest surface geochemical anomalies on the property. At deeper levels higher-grade hypogene mineralization is closely associated to the intrusive contact with the cross cutting microdiorite. The overlying enriched blanket is much smaller than the underlying hypogene mineralization, though with much higher grades.

Primary sulfide mineralization at the Main zone is hosted mainly by the microdiorite and the Zafranal diorite. This primary mineralization is related to a potassic alteration zone with a quartzsecondary biotite-chlorite assemblage. Chalcopyrite is by far the most abundant copper species here and occurs both as disseminations and in veinlets. A- type and B-type veins (quartzchalcopyrite-pyrite and quartz-chalcopyrite-molybdenite respectively) are abundant at Zafranal and average copper grades range from 0.15% to 0.5% Cu, locally increasing up to 1% Cu.

Victoria zone

Mineralization at Victoria is predominantly hypogene and occurs as a tabular body parallel to the main foliation, suggesting that it predates or is contemporaneous with the principal deformation event. Chalcopyrite occurs both as fine-grained disseminations and as patches associated with veins and stockworks. Mineralization within the Victoria zone measures approximately 900 m along strike and up to 500 m width and drilling encountered it down to depths of up to 400 m below surface.

To assess reasonable prospects for eventual economic extraction, it was assumed that the Zafranal deposit would be mined utilizing open pit mining methods under a conceptual scenario of 55,000 tonnes per day production using conventional flotation to produce a concentrate grading 28% copper with credit for gold.

The proposed Zafranal mine will develop two open pits (Zafranal Main and Victoria) with a combined area of 2.47 km2 . The final pits will be 2.6 km long and 1.0 km wide and shall reach a maximum depth of 554 m.

The Zafranal Main pit has two exits on the south side and two on the north side to provide access to the, primary crusher, stockpiles and waste dumps. The main pit is 2,500 m long in the east- west direction and 1,000 m wide in the north-south direction. The pit bottom is at 2,280 m elevation, at the western end. The highest wall is about 456 m on the northeast side. The total area disturbed by the main pit is about 250 hectares.

To the east of the Main Pit, a small Victoria Pit was designed 950 m long and 500m wide, with the pit bottom at 2,532 m elevation, the highest wall of 180 m to the north and with 47 hectares of disturbed area.

Based on the design throughput, run-of-mine (ROM) ore maximum lump size and ore comminution characteristics, a single gyratory crusher 1,600 mm by 2,400 mm (63” x 95”) or equivalent has been selected for primary crushing run of mine ore at a rate of 3,274 t/h based on availability of 70% for 6,100 hours operating per year.

The primary crushed product size distribution is based on a gyratory crusher operating close side setting (CSS) of 120 mm to produce a product top size of 280 mm and a crusher product size P80 of 91 mm when treating ROM ore with a feed top size of 1,000 mm and an F80 of 450 mm.

Auxiliary crusher equipment includes a rock breaker; the overhead crane described above, and dust suppression system. Water sprays are used to minimise dust at the crusher dump pocket and conveyor transfer points.

The primary crusher discharge conveyor is fitted with a weightometer, belt monitoring systems, and a metal detector to detect tramp metal. From the sacrificial discharge conveyor, the primary crushed ore reports to the crushed ore stockpile. Due to the steep topography between the primary crusher and the rest of the concentrator, the 3.9 km long conveyor that transfers crushed ore from the crusher discharge conveyor to the crushed ore stockpile feed conveyor passes through a 3.6 km tunnel. The crushed ore stockpile has 16 hours of live capacity to ensure stable feed to the SAG mill. The crushed ore stockpile will also provide buffer to allow continuous SAG mill feed during periods of crusher maintenance. Additional dead capacity on the stockpile can be dozed into the reclaim feeders during longer shutdowns.

The grinding circuit consists of two parallel lines of grinding mills, each treating 50% of the concentrator throughput. Each grinding line consists of a single semi-autogenous grinding (SAG) mill with pebble crushing system, followed by a single ball mill operating in closed circuit with a cyclone cluster. The area will be open with all maintenance activities completed using mobile equipment, with the exception of a cyclone cluster jib crane.

The SAG mill feed conveyor transfers ore (along with crushed pebble and grinding media) to the SAG mill feed chute where it is combined with mill feed dilution water and lime slurry to increase slurry pH to approximately 9-10. Each SAG mill is fitted with a twin pinion drive arrangement and is driven by a variable-speed drive comprised of a slip energy recovery (SER) hypersynchronous drive. Both SAG mills are fitted with discharge grates with pebble ports to retain grinding media and larger particles while allowing smaller particles to discharge from the mill. Each SAG mill is fitted with a trommel screen to separate slurry and pebbles. Trommel oversize from each SAG mill reports to a surge bin and pebble crusher via transfer conveyors. Each pebble transfer conveyor is fitted with self-cleaning magnet and each pebble crusher feed conveyor has a metal detector. Tramp metal from each magnet is diverted to a bunker, and remaining metal detected on the pebble conveyor is by-passed to the SAG feed conveyor belt.

Pebble crusher product is conveyed back to the SAG mill feed conveyor. ‘High angle’ pebble conveyors have been used to minimize earthworks and have been deemed suitable based on recent industry feedback. SAG mill trommel undersize gravitates to the primary cyclone feed hopper where it is combined with the discharge from the ball mill.

Each grinding line includes a single variable-speed cyclone feed pump sending slurry to a dedicated cyclone cluster. A rotable spare bare-shaft cyclone feed pump (wet end) is stored on site to allow quick change-out.

Process water for dilution is added to the cyclone feed hoppers before the slurry is pumped to the respective cyclone cluster for classification. Flotation primary collector is also added to the cyclone feed hoppers.

The concentrator associated support facilities and utilities will process run-of-mine (ROM) ore delivered to the primary crusher and produce a copper-gold concentrate for sale. The process encompasses crushing of the ROM ore, grinding, flotation including regrind, and concentrate thickening and filtration to produce copper-gold concentrate that is then transported by road for subsequent shipping to customers. The flotation tailings will be thickened prior to discharge to the tailings management facility (TMF).

The key criteria selected for comminution, flotation, intermediate concentrate regrind and final concentrate and tailings thickening are summarised below:

- Treatment of an average 55,000 dry metric tonnes per day (t/d) for 365 days per year.

- Sufficient plant design flexibility for individual treatment of either of the main ore types tested (whole resource is supergene 47% and hypogene 53%), as tested in the metallurgical test work program, ........