Host rocks to the underground Mineral Resource include carbonaceous metasedimentary rocks, dioritic and dacitic intrusive rocks, and metavolcanic rocks. The majority portion of the underground resource is classified as carbonaceous breccia. The mineralization style is quartz-carbonate-sulfide veins and breccia fillings hosted in a major, district-scale shear zone, typical of orogenic gold deposits.

The shear zone is north to northeast trending and dips moderately to the west. In the underground resource area, the shear zone is overlain by a dioritic intrusive mass and underlain by andesitic metavolcanics rocks. The shear zone and mineralization range in thickness from several metres to over twenty metres. The planned stopesfor the C1 Underground are generally located in areas where the shear zone is thickest and contains the highest gold grades.

Primary and secondary long hole stoping using paste backfill is considered the most practical and economic method for extracting the C1 Underground Mineral Resources.

The design anticipates a nominal 2,500 t/d underground long hole mining operation using cemented paste backfill to allow for maximum extraction of the deposit. Over the potential 9.5-year LOM, a total of 7.1 Mt of mill feed would be extracted at a grade of 2.65 g/t Au.

The mill feed from the C1 Underground would be blended with open pit ore in the proposed 7,400 t/d process plant and no modifications to the process plant are included in this analysis. Over the expected 9.5-year LOM, the C1 Underground is forecast to contribute a total production of 511,000 oz Au.

A large proportion of the tailings generated from the processing of C1 Underground mill feed will be returned underground as paste backfill for the mined-out stopes. Paste fill production is estimated at 5.1 Mt. The remaining tailings (2.0 Mt) will be placed in the existing TSF.

Primary Development
The underground mine will be accessed from a portal to be established in the southwest corner of the open pit. The decline will be driven 5.0 m wide by 5.5 m high, incorporating a roof line back- excavated along the angle of the rock foliation. This heading size is the same as currently used by Equinox for declines at the Fazenda Brasileiro mine.

The main decline will be driven at a maximum grad ........

The crushing section of the plant is part of the original facility. It consists of a jaw crusher followed by a cone crusher, both of which are in open circuit, with the product conveyed to a conical stockpile.

Run-of-mine ore is fed by a front-end loader, from stockpiles on a pad adjoining the crushing plant, and into a hopper in front of the jaw crusher. Ore is withdrawn from the hopper by a vibrating feeder-grizzly, with grizzly oversize feeding the jaw crusher and grizzly undersize dropping to a conveyor that transports the grizzly undersize and the jaw crusher product to a transfer hopper, thence to a second conveyor that feeds a cone crusher. Prior to entering the grinding circuit, a third conveyor takes the crushed ore from the secondary crusher to a crushed ore stockpile.

The grinding section will consist of two mills: a SAG mill and a ball mill operated in series. The SAG mill was part of the original facility; the ball mill is new. The SAG mill, as originally installed, operated as a single-stage SAG mill to produce the final grind size. The new ball mill is a conventional overflow ball mill, and will grind the SAG mill product to the final grind size.

Ore from the stockpile is drawn by two underlying vibrating feeders onto the SAG mill feed conveyor. The SAG mill is equipped with a trommel screen that screens out plus 12 mm pebbles. The pebbles are conveyed back to the SAG mill feed conveyor and are expected to constitute approximately 5% of new feed. Trommel screen undersize will be pumped via new pumpsto the new primary mill cyclones; cyclone underflow will be recycled to the SAG mill, and the cyclone overflow will pass to the ball mill discharge pump box. From the ball mill on, all process equipment is new. The ball mill discharge pumps (one operating, one spare) will pump the combined SAG mill cyclone overflow and the ball mill discharge to the secondary mill cyclones. Cyclone underflow flows to the ball mill feed. Dry lime will be fed from a silo adjoining the ball mill pump box directly into the pump box. Cyclone overflow will flow to a trash screen. Trash screen oversize will be recycled to the ball mill pump box; trash screen undersize will flow to the plant feed sampler and thence to a pump box from which it will be pumped to the RIL circuit.

The original processing plant at Santa Luz was built and placed in operation in mid-2013 and was shut down in September 2014 after 14 months of operation. The plant did not operate well, as a result of both process difficulties and mechanical problems. The new processing facility will incorporate the crushing, crushed ore storage, and SAG mill sections of the original plant. The rest of the plant, with the exception of the refinery, will be new.

The new processing facility will incorporate the crushing, crushed ore storage, and SAG mill sections of the original plant. The rest of the plant will be new, except the refinery. The new facility will process a blend of carbonaceous and dacitic ore, using the following processing sequences:
- Two-stage crushing;
- Two-stage grinding;
- Gravity concentration and intensive cyanidation;
- Pre-aeration and kerosene conditioning;
- RIL;
- Detoxification of leached tailings;
- Containment of tailings ........