The property hosts a wide variety of deposit types from volcanogenic polymetallic type to syn-orogenic to late-orogenic gold mineralization.

The Bachelor Lake gold mineralization is related to brittle deformational features and dilatational zones (stockwork) and to brittle-ductile shear zones. The Bachelor Lake gold deposit can be either classified an “orogenic lode gold deposit” or an “intrusion related gold deposit”. The gold distribution appears to be controlled by both structural and lithological features (e.g. the rhyolite being more fractured compared to the agglomerate) (Y. Buro, personal communication, 2004).

The Bachelor Lake gold mineralization has also been interpreted to be associated with the late-tectonic granitic to granodioritic intrusion (O’Brien pluton located east of the deposit and associated dykes documented at the mine). The link between the late intrusive rocks and the gold distribution can be interpreted as either:
• The result of a litho-structural relationship (i.e. lithological contrasts), or
• As a magmatic process (intrusion-related, oxydized magma).

According to Buro (1984) and Lauzière (1989), the O’Brien granodioritic stock probably provided the concentrating mechanisms through heat and hydrothermal solutions. The late phase dykes related to the O’Brien stock were introduced later than the shearing event, and the gold mineralization event has been bracketed between the occurrence of these late dykes and the earlier granodioritic phase (Lauzière, 1989). The high fluorine content of the hydrothermal biotite in the ore zone alteration correlates with that of magmatic biotite within the intrusive phases. There is probably a direct genetic link between the O’Brien stock and the gold mineralization.

In this perspective, the Bachelor Lake gold deposit may well correspond to the new class of gold deposits introduced by Robert (1997) in the southern Abitibi Belt:
Syenite-Associated Disseminated Gold Deposit. In this class of deposits, the ore bodies usually consist of zones of disseminated sulphides and variably developed stock works associated with intensely altered wall rocks. The mineralization, with sharp to diffuse limits, is defined by a decrease in sulphide content, gold grades and intensity of stock work fracturing (Robert, 2001).

From a descriptive point of view, Brisson and Guha (1993) have documented two main types of gold mineralization occurring in the Bachelor Lake area and in the Wachigamau Member:
1. Gold-bearing quartz veins with gold isseminated sulphides in wall rocks, and
2. Disseminated gold-bearing sulphide zones.

During the last drilling program, these ifferences have been recognized and can be illustrated as the B and Main Zones. These zones were interpreted as contemporaneous disseminated gold-bearing sulphide zones, the B Zone just superseding the Main Zone formation. In both types, the mineralization is characterized and dominated by pyrite. Gold is:
• Native and is in close association with pyrite; or
• Free in quartz predominant veins.

The mineralization is found in close association with hydrothermal alteration zones (silica-hematite alteration) which have been superimposed on the regional metamorphic minerals.

The orebody has very competent host rocks and low cost longhole stoping is a good choice for the mining method.

Once the stopes were identified, it was possible to determine the development needed to mine these stopes. The width of the mineralized zones varies considerably. Some are as narrow as 1.2 metres (four ft) and other are more than 9.0 metres (30 ft) wide in some locations. Accordingly, it was decided that the ore should be extracted using sublevel stoping and longhole blasting (54 mm – 63.5 mm [2 ¹/8 inches - 2 ½ inches] blast hole diameter). It should be noted that the dip and continuity of the zones, as well as the quality of the vein walls, also suggest that this method could be used successfully. To obtain a high degree of accuracy (and thereby minimize dilution), the ideal drill-hole length of approximately 13.5 metres (45 ft) was used to determine the sublevel spacings.

The veins will be entirely excavated on every sublevel. This means that the width of a sublevel could also exceed 9.0 metres (30 ft). The walls of the sublevels have to be inclined according to the dip of the vein to minimize dilution. The height, on the other hand, must be kept at 2.74 metres (9 ft) to allow the longhole drilling equipment to have the necessary manoeuvring space. Métanor decided that Cavo 310 mucking machines would be needed to handle all the ore during excavation of these sublevels.

The sublevels will be excavated via service raises between the main levels, which will be used to move workers, equipment, services and broken rock. The raises will be spaced 61 metres (200 feet) apart to keep sublevel working faces clear. Otherwise, a second ore pass system will be installed to reduce mucking distances and attain anticipated mining performances. Alimak raises will be 2.4 m x 2.4 m (8 ft x 8 ft). Conventional raises can be excavated to 2.1 m x 1.8 m (7 ft x 6 ft) but for calculation purposes the raises were also considered to be 2.4 m x 2.4 m (8 ft x 8 ft). The track access drifts will have dimensions of 2.7 m x 2.7 m (9 ft x 9 ft) to allow passage of rail equipment and services. The ore drifts will be excavated without rails using Cavo 320 mucking machines. In narrow zones, the possibility of using a 1.8 m (6 ft) wide scraper and maintaining a slash of 0.9 m (3 ft) in the waste rock will be considered. Rail haulage drifts will be excavated parallel to the ore drifts and draw points will be developed every 10.7 m (35 ft) to effectively recover ore from the stopes.

Presently, Metanor mines and mills some 750 tpd of the Bachelor mine ore. In a nut shell, the mill circuit comprises a 24” x 36” KueKen jaw crusher followed by a 4¼’ Simons standard cone crusher which itself is followed by a 5½’ Simons short head cone crusher. Material crushed and screened to 3/8” is stored in a 1200 tonne fine ore bin.

From the fine ore bin, the mineralized material is ground in a conventional grinding circuit comprising a primary 10’ x 14’, 400 HP rod mill followed by a 10½’ x 9’ x 10’, 525 HP tricone ball mill in parallel with two secondary 6’ x 10’, 150 HP and a 5’ x 10’, 100 HP ball mills, from a feed F80 of 9,525 microns to a final grind P80 of 75 µm. Classification is by a set of 4-15 inch cyclones.

Cyclone overflow reports to a wood chips screen prior to flow by gravity into a 40-foot single tray thickener. Thickener underflow is pumped to a bank of four 22’ x 22’ leaching tanks followed by four 22’ x 22’ CIP reservoirs for a total leaching time of some 50 hours. The tanks interconnected with launders allow slurry to flow by gravity from one tank to the next. Each tank is fitted with impeller mechanical agitators to ensure uniform mixing and dispersion. Oxygen required for leaching is provided by air sparging through the bottom of the agitator shaft into the slurry. The adsorption tanks are each fitted with a woven wire inter-tank screen to retain the carbon. All tanks are provided with bypass facilities to allow any tank to be removed from service for maintenance.

Sodium cyanide solution is metered into the leach feed distribution box as required to maintain the desired cyanide concentration in the circuit. Compressed air is distributed to the circuit and sparged down the shafts of the agitators to allow a high dissolved oxygen profile to be maintained in the circuit. Fresh and regenerated carbon are returned to the circuit at CIP tank 4 and allowed to advance countercurrent to the slurry flow by pumping slurry and carbon from tank 4 to tank 3 to tank 2, and so on. The inter-tank screen in each CIP tank retains the carbon and allows the slurry to gravity flow to the next CIP tank. This counter-current process is repeated until the carbon eventually reaches CIP tank No 1 at which point an air lift is used to transfer loaded carbon to the loaded carbon recovery screen. Loaded carbon is screened and reports to the carbon wash tank. Leached tails pass through a safety screen before being pumped to the tailings pond.

The carbon elution – refining circuit comprises mainly a loaded carbon tank, an acid wash tank, a carbon strip vessel, a bank of electrowinning cells and two Wabi type gold bullion furnaces. Stripped carbon is reactivated in a horizontal kiln, quenched and classified. Classifier oversize is ready to be reused while very fine carbon particles are filtered in a filter press and kept aside to be eventually shipped to a copper-gold smelter.

Tailings from the undersize of the safety screen coupled to other miscellaneous waste streams from the process plant are combined in the tailings collection pump box and pumped to the tailings pond to settle. Supernatant water is allowed to flow by gravity to the polishing pond. Clear water from the polishing pond is finally pumped back to the process water reservoir.