Early investigations of the Thierry Deposit by workers such as Bowdidge (1970), Patterson (1980), and Patterson and Watkinson (1983, 1984) concluded that the ores at the Thierry Deposit had undergone intense modification after their initial deposition as magmatic sulphides. This observation also applies to the K1-1 area.

Any model of mineralized rock genesis at the Thierry Project must take into account the unusual Cu/Ni, Pt/Pd and chalcopyrite pyrrhotite ratios in the rocks. According to Naldrett and Cabri (1976), intrusive complexes similar to those at Thierry Deposit contain sulphides with a coppernickel ratio of 2:1, a platinum-palladium ratio of 1:4, and a chalcopyrite/pyrrhotite ratio of 1:10.These ratios at the Thierry Deposit are approximately: copper-nickel 8:1, platinum/palladium 1:4 and chalcopyrite/pyrrhotite 1:1.

Mineralization at the main Thierry and adjacent K1-1 deposits, is more or less coincident with what is best characterized as a chlorite biotite-hornblende altered mylonitic shear zone (the “CBS shear zone”). The shear zone extends across the ultramafic intrusive along a strike length of about one kilometre and a width up to 50 m. Within the shear zone mineralization is hosted by highly schistose rocks containing stringer sulphides to less schistose ultramafic rocks containing massive stringers or veins and disseminated sulphides. Primary sulphides, listed in approximate order of decreasing abundance are pyrrhotite, chalcopyrite, pyrite and pentlandite. Cubanite, bornite, magnetite and minor ilmenite have also been identified. Violarite and mackinawite have developed from alteration of pentlandite.

Outside of the main mineralized zone, chalcopyrite and bornite occur as stringers as well as finely dissemination sulphides. Bornite is commonly associated with carbonate and quartz veins. Oxidized mineralizations are reported to contain violarite, millerite and bornite.

Copper-nickel-PGE mineralization at the Thierry and K1-1 deposits is hosted within a highly deformed and altered ultramafic sequence. Copper-nickel-PGE mineralization consists of:
- Sulphide matrix breccia;
- Blebs and small stringers, occasionally net textured sulphides; and
-Disseminated sulphides.

The sulphide mineral assemblage consists of chalcopyrite, pyrrhotite, pentlandite and pyrite.

MINING METHODS
The Thierry underground Deposit will be mined by underground long-hole retreat method.

Access to the Thierry Deposit would be via a 6.5 m diameter, concrete lined 965 m (3,160 ft) deep fresh air shaft and a -15% ramp from surface to a depth of 1,260 m (4,130 ft). There will be two shaft loading pocket stations, one at a depth of 475 m (1,550 ft) and a second at a depth of 920 m (3,010 ft). Two hoists would be configured to transport workers and skip mineralized rock between surface and the underground loading pocket levels. Operating materials would be transported to and from the mine via the ramp from surface.

A conceptualized mining plan has been developed using mechanized trackless mining equipment. The primary mining method would be conventional longitudinal long-hole retreat with paste backfill. Above the 490 m (1,610 ft) elevation sub-levels will be developed at 15 m (50 ft) vertical intervals. Below the 490 m (1,610 ft) elevation sub-levels will be developed at 21 m (70 ft) vertical intervals. Drifts in mineralization would be developed to the full length of the Thierry Deposit. These drifts would provide access for the successive operations of slot raise development, blasthole drilling and blasting, and backfill placement. The average thickness of the mineralization is 6.7 m (22.1 ft). Remote-operated underground load/haul/dump (“LHD”) units would remove broken mineralization from the stope and from the excavated drifts in mineralized rock. The stopes would be backfilled primarily with cemented paste backfill, supplemented with waste rock. Initially, mineralization above the 290 m (950 ft) level will be mined and hauled up the existing ramp during the pre-production period, while the shaft is being sunk and commissioned from the start of work to the 35th month. Once the shaft is commissioned both the 475 m (1,550 ft) and 920 m (3,010 ft) Levels will be developed from the shaft.

A steady state production of 4,000 tpd of development and stope production will begin during the 27th month, on a schedule of 350 days per year. Stope mining will proceed upwards from the 290 m (950 ft), 475 m (1,550 ft) and 920 m (3,010 ft) Levels and downwards from the 920 m (3,010 ft) Level towards the end of the mine life, on a retreat basis.

It is estimated that 432 stopes would be mined over the mine life. This would generate an average of 4,000 tpd composed of an average of 3,421 stoping tonnes and 579 tonnes from developing the drifts in mineralization and slot raises. The envisaged underground long-hole mining method for the Thierry Mineral Resource is estimated to experience mining dilution in the order of 20% at diluting grades of 0.59% Cu, 0.10% Ni and 2.20 g/t Ag with negligible Au, Pt and Pd. Mining recovery (extraction) is estimated at 90%.

LONG-HOLE LONGITUDINAL RETREAT STOPING METHOD
The Long-hole Longitudinal Retreat mining method is initially developed with sublevel drifts developed to the full width of the Thierry Deposit mineralization every 15 m (50 ft) or 21 m (70 ft) vertical intervals (“undercuts” and “overcuts”) from the access cross-cuts. A 1.8 m by 1.8 m slot / ventilation / backfill raise is then driven at the end of the sublevel drift.

MINE AND STOPE DEVELOPMENT All excavations in waste rock are classified as mine development. All development in mineralization that produces process plant feed is classified as stope development. The life of mine (“LOM”) schedule includes a total of 43,984 m of mine development. In additional there would be 963 vertical m of shaft development and 3,794 m3 of shaft station and loading pocket development.

SHAFT SINKING AND CONSTRUCTION SCHEDULE
P&E estimates it will take 18 months to clear the site of the shaft collar, collar the shaft and install the headframe, hoist room and hoists and commission these installations. Shaft sinking will begin when this is complete. It is anticipated that the shaft will be commissioned 35 months from the start of collaring.

ACCESS RAMP FROM SURFACE
The existing ramp from surface extends down to the 490 m (1,610 ft) Level. From there a new ramp will ultimately be driven at a -15% gradient to the 1,260 m (4,130 ft) Level by a contractor. This access ramp will allow underground mobile equipment, personnel and supplies to travel between levels, as well as to and from surface.

LEVEL DEVELOPMENT
Pre-production level development will start on the 290 m (950 ft) Level once mine dewatering and rehabilitation has reached that elevation. Once the 244 m to 950 m (800 ft to 950 ft) development work is complete, development crews will proceed to develop all levels and sublevels up to the 137 m (450 ft) Level, from the bottom up.

STOPE DEVELOPMENT
Stope development includes both drifting and slot raising in mineralized rock. Stope development will start on the 290 m (950 ft) Level during the 16th pre-production month. Once the 244 m to 950 m (800 to 950 ft) development work is complete, development crews will proceed to develop all levels and sublevels up to the 137 m (450 ft) Level, upwards.

STOPING
Stope production will start on the 290 m (950 ft) Level during the 26th month of pre-production development.

PROCESS PLANT
A conventional process plant and flowsheet has been selected, including crushing and grinding to a 100 µm grind at an annual rate of 1.4 Mtpa (4,000 tpd). This will be followed by a two-product flotation circuit; a 30% copper concentrate containing low nickel and 50% of the PGM, and a nickel-copper concentrate containing 10% metal (8% Ni, 2% Cu) and low PGM. The projected concentrates would be shipped to an off-site smelter. Estimated process recoveries are:
• Copper concentrate: 30% Cu, 0.5% Ni, with 92% Cu recovery, 15% Ni recovery, and 50% Au, Ag and PGM recoveries.
• Nickel-copper concentrate: 8% Ni, 2% Cu, with 40% Ni recovery, 1% Cu recovery and 3% Au, Ag and PGM recoveries.

MINERALIZED PLANT FEED HANDLING
Mineralized material, sized to less than 300 mm, will be hoisted from underground and crushed to -100 mm in a jaw crusher. No crusher will be installed underground, and oversize will be managed underground with rock breakers and grizzlies. The single primary crusher size on surface could be as large as 110 mm by 120 mm (42 in by 48 in) and powered by a 180 kW drive. The crushed feed will be drawn from a mine skip surge bin by an apron feeder discharging to a conveyor equipped with metallic scrap removal magnets. Crusher discharge would be transferred to a 10,000 t capacity covered stockpile, from which material would be drawn by at least three feeders. The stockpile would be manipulated with a front-end loader to reduce stockpile segregation by size and to compensate for freezing.

GRINDING
Conventional SAG and ball mill grinding is proposed. SAG feed will be automatically weighed and grab-sampled for moisture content. With a target grind size P80 of 100 µm, a SAG size of 5.5 m diameter by 4.4 m long and a ball mill size of 5.5 m by 8.4 m long should be suitable. Steel ball consumption could be in the order of 3-4 kg/t with energy draw approximately 25-30 kWh/t. The SAG mill is equipped with a pebble circuit where pebbles are recycled to the SAG feed. Pebble return is expected to be low, at less than 5% of feed. At this low rate, a pebble crusher (gyratory) would not be required but could be installed later. The ball mill will be in closed circuit with two banks of cyclones, with cyclone overflow sent to a flotation conditioner following automatic two-stage slurry sampling.

Less than 5% (200 tpd, 8.3 tph) of the plant feed will report to the regrind mill and to the subsequent flotation circuits.

FLOTATION
A low-grade copper-nickel concentrate is obtained in a rougher-scavenger circuit which will have a retention time of 20-25 minutes. The rougher scavenger tailings will be automatically sampled with a two-stage Vezintype sampler. The rougher-scavenger concentrate is finely ground to be approximately P80 20- 25 µm. This smaller grinding unit could be a rubber-lined ball mill, but a vertical attritiongrinding mill using ceramic grinding media may be preferred. Less than 5% (200 tpd, 8.3 tph) of the plant feed will report to the regrind mill and to the subsequent flotation circuits. The finely ground rougher-scavenger concentrate would be subject to precise flotation reagent conditioning and directed to a copper-nickel separation flotation step, with tailings reporting to a nickel concentration/cleaner circuit. The copper concentrate from the copper-nickel separation step would be subject to at least two copper cleaner stages.

Some caveats to the definiti ........