The Prosperity deposit is predominantly hosted in Cretaceous andesitic volcaniclastic and volcanic rocks which are transitional to a sequence of sparsely mineralized, volcanically-derived sedimentary rocks to the south. The andesitic volcaniclastics are comprised of coarse-grained crystal tuff and ash tuff, and thinly bedded tuff with lesser lapilli tuff. The upper eastern portion of the deposit is hosted by subvolcanic units of crowded feldspar porphyritic andesite and thick feldspar and hornblende porphyritic flows.

Gold-copper mineralization within the Prosperity deposit is intimately related to potassium silicate alteration and a later, superimposed sericite-iron carbonate alteration. This is particularly true within a central, east-west trending ovoid zone that hosts the majority of the mineralization.

Chalcopyrite-pyrite mineralization and associated copper and gold concentrations are distributed relatively evenly throughout the host volcanic and intrusive units in the deposit. A sedimentary unit, which is located in the upper southeastern part of the mineralized zone, is sparsely mineralized. Post mineralization porphyritic dikes are essentially barren.

Pyrite and chalcopyrite are the principal sulphide minerals and are accompanied by: minor amounts of bornite and molybdenite; sparse tetrahedrite-tennantite, sphalerite and galena; and rare chalcocite-digenite, covellite, pyrrhotite, arsenopyrite and marcasite. Native gold generally occurs as inclusions in, and along microfractures with, copper sulphides and pyrite. Pyrite to chalcopyrite ratios throughout most of the proposed pit area range from 0.5:1 to 1:1 and rise to 3:1 or higher around the periphery of the deposit which coincides with the propylitic, and locally the phyllic, alteration zones.

Sulphide minerals show the thoroughly dispersed mode of occurrence characteristic of porphyry copper deposits. Sulphides occur in relatively equal concentrations as disseminations, blebs and aggregates in mafic sites, as fracture fillings and as veinlets. Disseminated sulphide mineralization is marginally more prevalent than veinlets in intrusive rocks while in volcanic rocks the reverse was noted.

The Prosperity open pit will be a nominal 525 m deep when complete.

The mine will operate using electric cable shovels and rotary drills. Diesel electric trucks and a support equipment fleet will gradually be increased to match the production schedule that will peak in terms of total production in Year 7 through Year 9 at 200,000 tpd.

The process design is conventional and consists of SAG and ball mill grinding; bulk sulphide flotation, regrind and bulk rougher/scavenger cleaner flotation, cleaner flotation and concentrate dewatering. The concentrator is designed to operate 24 hours per day, 365 days per year.

The Prosperity crushing circuit has been designed to crush on average 70,000 t/d of run-of-mine ore from minus 1,000 mm to 100% passing 350 mm and 80% passing 150 mm at a nominal rate of 4,444 tonnes/hr. The crushing system will consist of a single 1.52 x 2.79 m gyratory crusher operating at 75% utilization per 21 hour day, 365 days per year basis. The primary crusher will be located near the east corner of the ultimate pit boundary.

The primary grinding circuit will be designed to process an average of 70,000 tonnes/day at 90% utilization on a 24 hour per day, 365 day per year basis. The grinding circuit will be designed to reduce the crushed ore from 80% passing 150 mm to 80% passing 170 µm. The grinding operation will consist of a SAG mill and two ball mills.

The bulk flotation circuit will consist of three parallel trains of bulk rougher cells.

Cyclone overflow from each of the three parallel grinding circuits will flow by gravity into a collection box and then split into three equal portions to feed each of the three rows of seven cells. The cells in each row are 200 m3 forced air cells, giving a total of 21 cells for the complete bulk rougher flotation area. This combination of cells provides the power and retention time required for flotation. The tailings from the last scavenger cells in each row are combined as bulk flotation tailings.

The flotation reagent distribution system will permit the addition of flotation reagents, collector, promoter and frother at each cell in the bulk sulphide flotation circuits. Flotation air for all flotation sections will be provided by 6 air blowers (5 operating, 1 stand-by), that will supply air to all flotation cells via a ring-main system. The air supply for each cell will be controlled by valves located at specific locations.

The concentrate from the bulk rougher/scavenger flotation circuit is combined with the bulk cleaner scavenger concentrate as feed to the regrind circuit. In order to provide the liberation required to achieve the design copper concentrate grade and copper and gold recovery in the concentrate, the regrind circuit P80 of 20 µm is required. The regrind circuit is designed with five parallel vertical stirred regrind mills. Each regrind mill circuit consists of a 1,120 kW stirred mill operating in closed circuit with a cluster of seven 250 mm cyclones. The cyclone overflow at 20% solids flows to the bulk cleaner flotation circuit.

The bulk cleaner circuit consists of a single row of four 130 m3 forced air flotation cells followed by a further four 130 m3 forced air bulk cleaner scavenger flotation cells. The bulk cleaner concentrate is pumped to the copper first cleaner flotation circuit while the bulk cleaner scavenger concentrate is returned to the regrind circuit.

The bulk cleaner concentrate is cleaned in three stages of copper cleaning at an elevated pH to produce the final copper concentrate. The tailings from the copper cleaning circuit are returned to the head end of the bulk cleaner flotation circuit.

The copper first cleaner flotation uses six 30m3 forced air flotation cells. The concentrate is pumped to three 30 m3 forced air flotation cells. The copper first cleaner tails are pumped to the bulk cleaner circuit. The copper second cleaner concentrate is pumped to the copper third cleaners and the tailings are returned by gravity to the copper first cleaners.

The copper third cleaners consist of three 30m3 forced air flotation cells. The third copper cleaner concentrate is the final copper concentrate, which is pumped to the concentrate thickener, and the copper third cleaner tailings are returned by gravity to the copper second cleaners.

Final copper-gold concentrate from the cleaner flotation circuit will be pumped to the concentrate dewatering and load-out circuit. The concentrate dewatering circuit will consist of thickening and filtering unit processes.

Concentrate from the cleaner flotation circuit will be pumped to the 16 m diameter high capacity concentrate thickener. The concentrate will be thickened to approximately 60% solids by weight and pumped to one of two 4.88 m diameter x 4.80 m high agitated concentrate stock tanks that will provide approximately 5 hours of total storage capacity. Overflow from the concentrate thickener will flow to a standpipe and will be pumped to the distribution points in the milling and flotation areas.

Concentrate from the stock tanks will be pumped to a 120m2 automatic pressure filter where the moisture content of the concentrate will be reduced to an estimated 8%. Filtrate from the concentrate filter will be combined with the thickener feed and gravity flow to the concentrate thickener feed box.

Concentrate filter cake from the pressure filter will discharge (free-fall) directly onto stockpiles located on floor level below the filters. The concentrate will be reclaimed by a front end loader and loaded directly into bulk concentrate highway transport “B” trailers. The concentrate trailers will report to a weighscale to determine the concentrate load and then proceed to a truck wash station where the under side of the truck-trailer units will be spray washed to remove and recover concentrate residue and spillage prior to exiting the load-out facility. This measure is intended to minimize potential environmental concerns. The truck trailer units will the transport the concentrate to the Gibraltar Concentrate load-out facility for transfer to the CN rail transport system for transport to Vancouver.