The mineralisation observed at surface and in the drill core along the trend of the Alpala Deposit is considered as a classic porphyry copper-gold system and exploration has been designed with this in mind as a primary target. The site team is continuously engaged in advancing the understanding of the porphyry systems at Cascabel and exploration also keeps in mind the potential for surrounding economic porphyry deposits within a 1-2 km radius of the Alpala Deposit, as well as the potential for discovery of epithermal and skarn deposits peripheral to these porphyry systems throughout the Cascabel Project area.

Porphyry deposits are characterised by disseminated, veinlet- and fracture-controlled copper-iron sulphide minerals distributed throughout a large volume of rock in association with potassium silicate, sericitic, propylitic and, less commonly, advanced argillic alteration in porphyritic plutons and in the immediate wall rocks. In porphyry systems, there exists a close spatial and temporal link between volumetrically-small causative intrusions and broadly dispersed magmatic-hydrothermal alteration and mineralisation. Porphyry copper deposits are large (commonly hundreds to thousands of million tonnes) and low to medium in grade (0.3 to 1.5% copper). The majority of gold-rich porphyry deposits occur in the circum-Pacific and commonly contain 0.3 to 1.6 g/t gold.

Porphyry systems are causal to different deposits including:
-Porphyry deposits centred on the parent intrusion and its surrounding host rocks;
-Epithermal and skarn deposits peripheral to porphyry deposits;
-Carbonate replacement and sediment hosted deposits with increasing distance from the parent intrusion.

Mineralisation is seen across the six main intrusive bodies and the porphyry-related vein types to a varying degree. Early-formed hydrothermal magnetite occurs within early AB- and B1-type veins, and as monomineralic veinlets, disseminated grains and replacements of hornblende. Magnetite is variably converted to metallic haematite and pyrite in the upper part of the deposit where chlorite-epidote altered intrusions and volcaniclastic rocks are moderately to strongly affected by feldspar-destructive alteration.

The earliest formed sulphide mineral observed in drill-core consists of abundant chalcopyrite and rare bornite in B-type veins. Chalcopyrite most commonly forms after, and surrounds, cubic and massive pyrite in C- and D-type veins. It also occurs in anhydrite-rich veins and B-type veins that have been re-opened by later vein types. Late-stage bornite is in textural equilibrium with pyrite and chalcopyrite in C- and D-type veins, which suggests that these later-stage veins formed at a lower temperature and a higher sulfidation state than chalcopyrite in early-stage B-type veins (Einaudi et al., 2003).

The bulk of the copper mineralisation is hosted within the B-veins. Chalcopyrite-rich, C-type sulphide veins also contain significant amounts of metal and may be associated with elevated gold grades. Mineralising fluids are believed to have been introduced during the emplacement of the QD10 and to a less extent the QD15 intrusive. These defined two broad mineralising events at Alpala.

Quartz- and sulphide-vein abundances are recorded by SolGold during core logging and allow for the correlation with the final assay grades. This correlation illustrates a strong important to B-type veining to the mineralising system, particularly below 2% Cu. Therefore B-type vein abundance can be used as an analogy for the mineralisation boundaries during modelling.

The mine plan uses the block caving method which is considered to be the appropriate method due to the size, grade, ground conditions and depth of the Alpala deposit. High level studies have highlighted some areas of the deposit that may be mined using other bulk underground methods, such as sublevel caving, but that these are small and not material to the plan at this early stage of study.

The conceptual mine plan considered in PEA consists of two phases. In the first phase, the highest value material is targeted. Mining criteria are more conservative with column heights restricted to ~500 m and a relatively even draw across each footprint to ensure even cave propagation. In the second phase, lower value, but potentially economic material is mined, along with more aggressive mine planning assumptions, with taller columns and a greater variation of draw heights within a column.

Grinding Circuit
The grinding circuit is proposed as a conventional SAG mill / Ball Mill / Pebble Crusher (SABC) configuration for treatment of competent ores at elevated throughput. It should be noted that the pebble crusher may be required only in later years.

Primary Grinding
Crushed ore will be reclaimed from the coarse ore stockpile, via variable speed apron feeders, directly to the SAG mill feed conveyor which will transport the ore to the SAG mill feed chute. Process water will also be added to the SAG mill, via the SAG mill feed chute. The variable speed SAG mill will operate with a nominal ball charge of 10% v/v. The 125 mm steel balls will be loaded into the SAG mill ball storage hopper via a front-end-loader (FEL). Media will be added to the SAG mill feed conveyor via a dedicated media charger.

The SAG mill feed rate will be controlled to optimise throughput and flotation feed grind size by the plant’s expert control system. The SAG mill feed conveyors will be equipped with a weightometer for metallurgical accounting.

The SAG mill product with a top size of 85 mm will discharge from the mill to a screen. The oversize will be screened and washed over a double deck, vibrating screen. Oversize from the screen decks will discharge to the pebble recycle conveyor which feeds the pebble crusher. The pebble crusher will be operated to maximise power draw and to maintain a set chamber fill level, typically 60%. Self-cleaning electromagnets on the conveying system protect the cone crushers from tramp metal and crushed pebbles will be transferred to a surge bin before being fed proportionately to the SAG mill feed conveyors via belt feeders.

Pebble Crushing
Comminution lines for both Phase 1 and Phase 2 will feed pebbles back to a common pebble recycle conveyor. A self-cleaning metal tramp magnet would be located at the transfer point of the recycle conveyor. SAG mill pebbles will return to the SAG mill feed conveyor.

Secondary Grinding and Classification
Each secondary grinding circuit will consist of two ball mills operating in parallel and in closed circuit with cyclone clusters. The discharge from the SAG mill discharge pump box and ball mill trommel screen underflow will discharge into a cyclone feed hopper, one per ball mill line. Each cyclone cluster will be fed by a cyclone feed pump. During the initial Phase 1 ramp-up, only one ball mill-cyclone cluster may be required.

Each ball mill feed chute receives mill feed dilution water, grinding media and cyclone underflow. The ball mill discharge is screened via a trommel screen. Each ball mill trommel screen undersize will gravitate to the cyclone feed hoppers.

The slurry from the cyclone feed hopper is pumped to a dedicated cyclone cluster. The cyclone overflow will gravitate to a combined cyclone overflow stilling box. Cyclone underflow from each cluster will return to its respective ball mill for additional grinding. Trunnion magnets will remove ball chips from the ball mill discharge, preventing a build-up of chips.

Auxiliary equipment in the grinding section of the plant will include a common kibble crane to service each ball mill. There will be a single ball storage bunker for both Phase 1 and Phase 2. Each ball mill has a kibble loading facility and ball charging system. Two ball mill feed chute removal systems and two liner handler systems will be provided which will allow the servicing of two ball mills at the same time. Two liner bolt removal tools will also be provided.

Concentrate Regrind Circuit
The combined rougher and cleaner scavenger concentrate will be pre-classified, via concentrate regrind cyclone clusters. Cyclone underflow constitutes the feed to the concentrate regrind mill. The regrind section consists of series of stirred vertical regrind mills arranged in a conventional closed-circuit configuration with cyclones to produce the required feed size to optimise concentrate grade and recovery.

The concentrator is anticipated to utilise the following principal process areas for the recovery of copper and gold into copper concentrates:
-Crushed ore stockpile and reclaim;
-Secondary crushing (deferred);
-Open circuit SAG milling;
-Pebbles return to pebble crushers (deferred);
-Closed circuit ball milling and classification;
-Copper rougher flotation;
-Rougher concentrate regrind;
-Three stages of copper cleaners and cleaner scavenger flotation;
-Copper concentrate thickening and storage;
-Copper concentrate thickening, concentrate pipeline, filtration and storage;
-Tailings thickening, disposal and decant water return;
Process water storage and distribution;
-Raw water storage and distribution Reagent make-up and distribution;
-High and low pressure air distribution.

Underground ore will be transferred to the coarse stockpile conveyor which deposits the crushed material onto the coarse ore stockpil ........