Gold mineralization at Aurizona is typical of orogenic gold deposits formed in regional scale brittleductile structures in supracrustal terranes. The general model for these types of deposits involves the migration of large amounts of hydrothermal fluids (generated during collisional orogenesis) within shear zones. The hydrothermal fluids carry gold in solution until changes in temperature, pressure, reduction potential or pH (traps) facilitate its precipitation. The gold source is likely the country rocks through which metamorphic fluids travel before concentratin in the shear zones.

Mineralization is often continuous to considerable depths in these systems as evidenced with the 2012 drill program, which intersected gold mineralization to a depth of -600 mRL at Piaba. Geological modelling indicates that mineralization defined to date at Piaba is located within the brittle-ductile deformation zone consistent with the model of Groves et al. (1998).

The Piaba deposit has a strike length of 3.3 km and trends east-northeast. The primary gold mineralization is hosted by sheared and veined quartz-diorite. The auriferous zone is associated with intense hydrothermal alteration and quartz veining.

The alteration assemblage associated with gold mineralization is composed of quartz, chlorite, carbonate (ankerite and calcite), tourmaline, alkali-feldspar, sericite, and pyrite. Gold mineralization and alteration are strong to intense, particularly within the centre of the deposit. Quartz occurs in veins and in silicified fronts. Pyrite occurs in quartz veins although it predominantly forms a matrix replacement, particularly at deeper levels. Minor pyrrhotite occurs at deeper levels and arsenopyrite has been rarely observed. Graphite alteration is related to reactivation of the main Piaba chloritic shear zone and is restricted to discrete crosscutting shear zones. No significant base metals occur at Piaba.

Gold mineralization at Piaba resulted from the reaction obtained from the mixing of the auriferous hydrothermal fluids with reducing carbonate fluids along the high permeability zones produced by brecciation of the quartz diorite during movement along the main Piaba shear zone.

The Boa Esperança deposit consists of five auriferous zones (1-20m thick) with a nearly 1 km strike extent. The deposit is hosted within diorite, andesite, and gabbro of the Aurizona Group with small zones of metavolcano sedimentary rocks. The deposit and lithology trend east-northeast and dip 80-90° to the north-northwest. The deposit displays intense weathering with an average depth of oxidation at 45m and weak to moderate hydrothermal alteration. The hydrothermal alteration consists of chloritization, carbonatization, sulphidation, albitization and tourmalinization.

The gold mineralization at Boa Esperança is related to increased silicification sulphidation-sericitizationalbitization and carbonation alteration, increased perce tage of disseminated pyrite (2 to 5%), and a denser network of quartz-carbonate-sulphide veins. This context suggests a hydrothermal origin in a transitional environment ranging between brittle and ductile-brittle that developed at low temperatures, pressures and depths which is consistent with a low greenschist facies metamorphic grade.

The open pit mine develops the resources that are contained within the Piaba and Boa Esperança resource areas.

The Life of Mine Plan mines 19.8 Mt of ore grading 1.52 g/t Au diluted and moves 113.2 Mt of waste. This equates to a 5.7:1 strip ratio. The resources for the Piaba pit phases are based on a cutoff of 0.6 g/t Au for all material to elevate the grade and ounces through the process plant. The Boa Esperança pit used a blended milling cutoff of 0.41 g/t Au for the material within that pit. The schedule uses a high-grade cut-off of 1 g/t Au for all material types to separate high grade from low grade in the mine schedule.

The deposits comprise laterite and saprolite material overlying a zone of transition material which in turn is underlain by fresh rock. The laterite and saprolite require no drilling and blasting. The transition will need light blasting and the rock, normal blasting. Blasting is expected to be accomplished with 127 mm top hammer or down the hole hammer drills on a 6m bench. Benches will be prepared with track dozers.

Ore grade control will utilize the blast holes in the fresh rock and reverse circulation drilling in the saprolite and transition zone and to a lesser degree in the fresh rock. Samples in the ore will be collected each metre and included in the ore control model for mine planning purposes. Drilling will be in advance of the mined benches to allow proper planning.

Equipment sizing for ramps and working benches is based on the use of 63 t rigid frame trucks but the full contract mining may only use 41 t articulated trucks and 30 t rigid body trucks. Single lane access is 17.8m (2 x operating width plus berm and ditch) and double lane widths are 23.5m (3 x operating width plus berm and ditch). Ramp gradients are 10% in the pit for uphill gradients and 8% uphill on the dump access roads. Working benches are designed for 35 to 40m minimum on push backs, although one push back did work in a retreat manner to facilitate access.

The mine schedule is based on mining eight phases in Piaba Main, one phase in Piaba East and the single phase in Boa Esperança. The final schedule is based on 8,000 t/d limit of hard rock to the mill. The Study schedule advances mining in the pre-strip period and builds a substantial stockpile. Full contract mining is assumed for all pre-production and production periods. Dewatering and ore control will be handled by the Trek mining team while all other mining functions will be the contractor responsibility.

Seven years of mining are required to complete the current design. Peak material movement occurs in Years 2 and 3 with 32.4 Mt and 32.2 Mt of material being moved respectively. Years 4 onwards drop in the overall material movement required with only minor movement required in Year 7. This is when the stockpile will be depleted.

The LOM schedule delivers 19.8 Mt of ore grading 1.52 g/t Au to the mill over the approximately 7-year mine life. Waste tonnage totaling 113.2 Mt is stockpiled in the North, West, South and East WSF. The overall strip ratio is 5.7:1.

A combination of conventional gravity concentration and leach/CIP cyanidation process is proposed for the expansion of the Project. The upgrades to the process plant will comprise crushing, grinding, gravity concentration, leach/CIP cyanidation process and gold recovery from the loaded carbon to produce gold doré. The majority of installed and uninstalled equipment that was proposed for the Phase 1 expansion will be completely installed and commissioned. With the upgrade, the process plant will be capable of processing the fresh ore at a nominal process rate of 8,000 t/d.

A hybrid leach/CIP circuit is proposed with the new larger leach tanks providing leaching capacity and the existing tanks used in CIP duty. This will enhance the elution circuit performance by increasing the gold loading on the carbon. Modelling of the leach/CIP circuit will be required to confirm this assumption however previous test work suggests the leach kinetics should make the different ore types amenable to leach/CIP.

The main design work for the Project is to upgrade the comminution circuit to be capable of processing various mill feeds from the saprolite, transitional and fresh rock mineralization zones at a nominal processing rate of 8,000 t/d. The comminution circuit was developed based on the grindability test results, engineering experience, the topography of the plant site and operability of the system. The size selection of the grinding mills was based on the amenability of the ore to grinding, as determined through previous test programs. The proposed comminution circuit includes primary crushing by a jaw crusher and a SABC circuit.

The process plant will consist of the following main processing facilities:
• A crushing and ore storage facility, including a feeder, a primary jaw crusher, a crushed ore surge bin and related conveying systems.
• An SABC grinding circuit, including a SAG mill, a ball mill, a pebble crusher and related pumping and pebble handling systems.
• A gravity concentration circuit with intensive leaching, including an ACACIA leaching reactor, an electrowinning cell and related equipment.
• Cyanide Leach/CIP circuit and related gold recovery and carbon handling circuits, including pre-leach thickening, leach and CIP tanks, acid wash and elution, carbon reactivation, gold electrowinning and melting.
• Cyanide destruction.

The ROM ore will be trucked to the plant site and will either be directly dumped into a hopper located at the east edge of the receiving pad or to the ROM stockpiles on the storage pad. The crushing circuit consists of a vibrating feeder, a jaw crusher and apron feeder. The crusher product particle size will be approximately P80 150 mm.

The crushed ore will be transported by conveyor to a 70 t surge bin and then reclaimed and fed to the SABC grinding circuit to reduce the crushed ore to a particle size of P80 100 µm. During normal crusher operation, the surge bin is maintained in an overflow state. The overflowing ore is conveyed to a crushed ore stockpile for eventual reclaim by front end loader (FEL) during crusher outages.

The SAG mill in the SABC circuit will be in a closed circuit with a pebble crusher while the ball mill will be in a closed circuit with cyclones. A percentage of the cyclone underflow will report to two centrifugal gravity concentrators. On average, approximately 30 to 40% of the gold in the ROM ore is estimated to be recovered from the centrifugal gravity concentration circuit. The intensive leach unit will solubilize the gold from the gravity concentrate, while the gold in the pregnant solution will be recovered by electrowinning.

The cyclone overflow from the SABC circuit will flow by gravity to the pre-leach thickener where the slurry will be thickened for downstream cyanidation. The underflow of the thickener will be cyanide leached in the upgraded leach/CIP circuit to recover the remaining gold that has not been recovered by the gravity circuit.

The loaded carbon from the CIP circuit will be washed by diluted acid solution and eluted by the Anglo American Research Laboratory (AARL) elution process. The gold in the pregnant solution will be recovered by electrowinning. The barren solution will be recirculated back to the elution circuit. The gold sludge produced in the electrowinning cells, together with the gold sludge from the intensive leach circuit, will be smelted to produce gold doré bullion.

The residue from the leach circuit will be sent to a cyanide destruction circuit employing a sulphur dioxide / air process to destroy the residual weak acid dissociable (WAD) cyanide.

The treated residue slurry will then be pumped to the TSF.