Taca Taca has porphyry copper-gold-molybdenum mineralisation located in the southern half of a 50 km long Ordovician batholith, which forms the Sierra de Taca Taca mountain range. The Taca Taca mineralisation is hosted by plutonic rocks of granitic composition together with lesser dacite, dolerite, and rhyolite intrusions. The porphyry is characterised by kilometre-scale zones of hydrothermally altered rocks that grade from a central potassic core to outer phyllic and argillic zones. Phyllic alteration is most pervasive across the deposit and is closely associated with mineralisation.

Mineralisation is comprised of supergene (chalcocite) and hypogene (chalcopyrite) zones. A sub-surface leached horizon of varying thickness overlies the supergene and hypogene mineralisation. Mineralisation is disseminated and in fractures, veinlets, and quartz vein stockworks.

The leached horizon is largely depleted of copper mineralisation except for a zone of chalcocite-rich ore perched within the leached material to the east of the deposit. In addition, a zone of supergene gold mineralisation, close to surface, is present above the thickest portion of leached material.

Hypogene copper sulphides are mostly chalcopyrite with lesser bornite, chalcocite, covellite, and digenite. The mineralisation is broadly zoned with a chalcopyrite-bornite-molybdenite core yielding to a stronger pyritic halo around the outer edges. Supergene zones are mostly secondary sulphides formed by enrichment within a discontinuous blanket underneath the leached cap.

Supergene mineralisation is often variably mixed with hypogene mineralisation and is often due to deep-seated alteration along structures and host rocks. Fine-grained black chalcocite and lesser covellite are the main secondary copper sulphides.

Mineralisation remains open at depth and around several peripheral areas of the deposit.

The Taca Taca deposit grades, geometry, and depth make it suitable for conventional, large-scale, bulk open pit mining methods involving blasthole drills, diesel hydraulic excavators, electric shovels and off-highway haul trucks.

Open pit mining would proceed in phases from an initial starter pit, supplying pre-strip development waste for site infrastructure and construction, and ore onto stockpile for process plant commissioning. The average and maximum material movements over this three year timeframe are 32.9 Mbcm and 43.3 Mbcm, respectively. There is a pronounced peak in material movements over the next ten years as the first three pit phases are completed and mining proceeds into the fourth phase. The average and maximum material movements over this period are 91.9 Mbcm and 95.7 Mbcm, respectively. Thereafter, the average and maximum material movements reduce to 42.3 Mbcm and 65.2 Mbcm, respectively.

In-pit ore crushing and conveying
Also subject to further work during the engineering phase, there is the possibility that in-pit crushing and conveying (IPCC) of ore could be adopted.

Features of the mining and production schedule are as follows:
• Mining commences in Year -3 starting with the pre-strip period, whilst processing commences in Year 1. The Project life (processing years) is 32 years.
• 240.1 Mt of waste is mined in the three year pre-strip period, during which time 17.4 Mt of ore is mined onto a stockpile for subsequent active and longer-term reclaim.
• The total material mined over the life of operations amounts to 4,543.0 Mt (1,737.0 Mbcm) of which:
- 1,758.5 Mt is ore with average grades of 0.44% Cu, 0.012% Mo and 0.09g/t Au, and
- 2,784.5 Mt is waste
• The overall life of mine strip ratio (waste tonnes: ore tonnes) is 1.6 : 1.
• The direct feed ore to the plant is 1,390.4 Mt at an average grade of 0.50% Cu, whilst 57.1 Mt at an average grade of 0.43% Cu is ore reclaimed from active stockpiles, and 311.0 Mt at an average grade of 0.15% Cu is ore (marginal ore) reclaimed from longer term stockpiles (mostly in Years 27 to 32).
• The total ore mined includes 39.0 Mt of ore grading 0.46% Cu from the near-surface “leached cap”, of which over 15 Mt is mined to stockpile during the pre-strip years. Most of this ore is then processed over the following three years.
• There is a small area in the north west of the ultimate pit design that crosses over into a joint venture concession. The encroachment occurs between Years 5 and 15 and involves 1.7 Mt of ore and 47.5 Mt of waste.
• The Inferred Mineral Resource that is mined as waste amounts to 69 Mt at an average grade of 0.31% Cu (i.e., about 2.5% of the total waste mined). This material is encountered in the mining schedule after Year 6, and following completion of mining phases 1 and 2.
• The crusher feed ramps up from Year 1 at 30 Mt, to 40 Mt in Year 2, at which level it remains until Year 6. The feed rate then rises to 50 Mt in Year 7, and thereafter to 60 Mtpa until Year 32.
• In terms of total plant feed (after mining dilution/recovery):
- the average copper grade is 0.72% Cu for the first six years when processing at up to 40 Mtpa,
- then 0.45% Cu to Year 27 when processing at up to 60 Mtpa,
- and finally 0.15% Cu for the remaining five years of Project life when reclaiming from longer term stockpiles
• Before the final five years of marginal ore reclaim, the total plant feed is 1,476.3 Mt at an average grade of 0.50% Cu.

In-pit ore crushing and conveying
Subject to further work during the engineering phase, there is the possibility that in-pit crushing and conveying (IPCC) of ore could be adopted.

Preliminary mining studies for the Taca Taca Project indicate that IPCC could have limited applicability due to the geometry of the orebody (specifically the conical shape and significant depth) and the configuration of the cutback phases. Whilst production schedule and cashflow scenarios have been run with and without IPCC, the relative economics are not readily distinguishable at this stage of Project engineering. For this Technical Report, the ultimate and phased pit designs plus the associated production schedule, assume no IPCC.

Process design basis and design criteria summary
The comminution circuit would comprise a conventional SABC circuit, with secondary crushing of the SAG mill feed required to increase the throughput from the initial 40 to 60 Mtpa. The grinding circuit would consist of two trains each of 30 Mtpa capacity operating to process 60 Mtpa of ore. Each circuit would be designed to treat 3,750 tph of material from a feed size of 80% passing 130 mm to product size of 80% passing about 180 µm.

Following delivery of run of mine (ROM) ore from the pit, the concentrator circuit would comprise:
• primary crushing in three 63 x 130 gyratory crushers, with a fourth crusher to suit the 60 Mtpa throughput
• secondary crushing of mill feed to a P80 of 75 mm, ahead of the crushed ore stockpile
• the secondary crushing circuit would not be installed until the throughput increases to 60 Mtpa (Year 8)
• conveying of crushed ore to the coarse ore stockpile
• a coarse ore stockpile with 12 hours of live capacity (90,000 t)
• SAG and ball milling of crushed ore, with size classification by means of hydrocyclones
- two grinding circuits would be installed, each comprising a 28 MW SAG mill and two 22 MW Ball mills, for 60 Mtpa processing capacity
- the target grind size would be 80% passing 180 µm
• a gravity recovery circuit on ball mill cyclone underflow for coarse gold recovery
• pebble crushing on scats generated from the SAG mills
- two MP 1250 crushers would be installed for this duty.

The Taca Taca processing feed would be both supergene (plus mixed) and hypogene (sulphide) primary ores. Primary ores are defined as those containing more than 50% of the copper present as chalcopyrite. Consequently, when treating primary ores, significant amounts of secondary sulphides will be present in the feed, and there may also be some tarnished minerals.

The preferred process route follows that of conventional porphyry copper-molybdenum concentrators common throughout South America, but including a sulphidising flotation circuit, using sodium hydrosulphide (NaHS) for sulphidising oxide and tarnished minerals. When treating primary ores with low acid soluble copper, the same circuit will be used, but the NaHS addition would be switched off.

A gold recovery circuit would not be constructed to treat the auriferous oxide cap during the pre-strip phase of mine development. However, this material would be stockpiled separately from waste material and subject to ........