The Haile district consists of nine gold deposits within a 3.5 km by 1 km area. Haile occurs within a variably deformed ENE-trending structural zone at or near the contact between metamorphosed Neoproterozoic volcanic and sedimentary rocks. Haile is hosted in laminated siltstones and minor volcanic rocks of the Upper Persimmon Fork Formation and is dissected by barren NNW-striking diabase dikes. Deformation includes brittle and ductile styles with ENE-trending foliation, faults, brecciation, and isoclinal folds.

Foliation intensity increases along sedimentary-volcanic contacts and is strongest in the laminated siltstones where gold mineralization is best developed. Gold-pyrite-silica-rich fluids were preferentially precipitated in more permeable and structurally deformed metasediments. Gold mineralization also occurs in intrusive and volcanic rocks adjacent to faults and shear zones.

The Haile gold deposits occur within a 5 km long by 1.5 km wide ENE-trending structural corridor. Northwest-dipping ore zones dip 30 to 500NW and include the Champion, Small, Mill Zone, Chase, Ledbetter, Red Hill and Snake deposits. Both northwest- and southeast-dipping ore zones occur in the Palomino and Horseshoe deposits along the southeast edge of the district. ENE-striking, 40-600NW-dipping faults focus high-grade zones > 3 g/t Au.

Mineralisation and Alteration

Haile gold mineralization occurs as an en-echelon 5 km long by 1.5 km wide cluster of ........

Haile is being mined using conventional open pit methods and OceanaGold plans to continue with current mining methods. The material encountered at Haile is a combination of soft (Costal Plains Sands [CPS] and saprolite) and hard (metavolcanics and metasediments) rock units.

CPS is loosely consolidated sand which can be mined without the need for drilling and blasting. Mineralization is not present in CPS thus drilling for the purposes of ore control and waste classification is not necessary. Saprolite is mined without blasting where possible. Saprolite is sampled for waste classification to meet the requirements in Haile’s Overburden Management Plan (OMP).

Drilling and blasting are required in all hard rock. Drilling and blasting are performed on 10 m benches. Multiple bit sizes (115 mm, 171 mm, 200 mm) are used depending on material type and application. Blast hole depth is 10 m plus subdrill; subdrill ranges from 1.4 m to 1.9 m.

The number of samples taken per blasthole is material-type dependent. Blastholes in waste are typically sampled twice on 5m intervals (top half and bottom half). Blastholes in ore are typically sampled three times at 3.3 m sample intervals.

Flitch height is variable. Waste is typically mined on a 10 m flitch and ore is typically mined on a 3.3 m flitch. Ore is usually mined with hydraulic backhoe excavators, while the majority of waste is mined with hydraulic shovels. Front-end loaders may be used in eith ........

A relatively compact Run of Mine (ROM) area is provided for storage and re-handling of ore allowing blending to minimize variation of head grade (sulfur and gold) and rock type, into the crusher. Ore is rehandled into the crusher dump pocket by Front End Loader (FEL).

Ore is reclaimed by an apron feeder onto a vibrating grizzly that delivers scalped oversize to the primary jaw crusher to reduce the ore size from RoM to minus 100 mm. Crushed ore is conveyed for surge and storage of the recombined grizzly undersize fines and primary crushed ore in a coarse ore surge bin or diverted on to an open conical emergency stockpile for later reclaim by Front End Loader (FEL) into a reclaim bin.

Ore is reclaimed from either the surge or reclaim bins, separately or simultaneously, using apron feeders onto a SAG mill feed conveyor belt delivering into the SAG mill feed chute.

Ore is milled in the SAG–Ball Mill-Pebble Crusher (SABC) circuit. The SAG mill operates in closed circuit with a vibrating discharge screen and a pebble return circuit incorporating a surge bin and Sandvik CH-440 cone crusher. The ball mill operates in closed circuit with hydrocyclones to produce the desired grinding product size of 75 microns.

Selected flotation reagents are added in the grinding circuit. A portion of the grinding circuit ball mill circulating load is treated in a flash flotation cell with the concentrate going to the regrind circuit. The grinding circuit product passes to a bank of bulk rougher flotation cells to recover the balance of the sulfide mineralization. Thereafter, the combined flash and rougher flotation concentrates are reground in a two-stage circuit utilizing an ETM-1500 tower mill in closed circuit with cyclones to a P80 under 40 microns and then followed by an M10000 Isamill in closed circuit with cyclones to a target P80 of 13 microns.

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