Owing to its metamorphic grade, the Borden Gold deposit is markedly different from most known Archean-aged mesothermal gold occurrences. On the basis of visual evidence, which is yet to be supported by detailed petrographic studies, it is believed that the Borden Gold deposit is most closely associated with the disseminated gold sub-class.

The gold mineralization at the Borden Gold deposit occurs as a broad zone of disseminated and fracture-controlled sulphides within a volcano- metasedimentary package of variable composition. The main sulphides are pyrite and pyrrhotite, with the former typically dominating. The mineralization generally consists of low- to moderate-grade gold, with minor silver, and is characterized by a persistent higher-grade core surrounded by a lower-grade envelope. Results to date indicate that the higher-grade core improves in grade towards the southeast where it develops into a High-Grade Zone (HGZ) with average grades typically above 2.5 g/t Au.

The northwest portions of the deposit are characterized by local silicification but lack lithological control and quartz veining; while to the southeast a well-developed hydrothermal system consisting of local quartz flooding and potassic alteration predominates and defines the HGZ. The broad mineralized zone encompasses multiple/variable host rocks, dominated by metasedimentary horizons and subordinate intrusives of acidic to intermediate composition, all of which display feldspathic, chloritic and biotitic alteration. Outcropping in the northwest parts of the deposit, the lower-grade mineralization rarely exhibits visible gold grains, while in the southeast HGZ it is much more common, particularly in the quartz-rich core. A higher-grade core is also consistently present within the lower-grade zone, locally attaining very high grades reminiscent of the HGZ.

The deposit displays continuity and is consistently intersected along strike, reaching a current length of 3.7 kilometres, while remaining open in both the northwest and southeast directions. Structurally, the deposit is described by a consistent northeast dip and, locally, a shallow southeast plunge, which is mostly evident in the HGZ. Mineralization appears to be controlled by a ductile shear zone, which appears much better developed in the HGZ. The mineralized zone is up to 120 m wide, and has been confirmed to a vertical depth of approximately 650 m.

Borden mine is the world’s first all-electric underground mine.
Commercial gold production at Borden began in October 2019.
Production rate of 1,750 to 4,000 tpd ore as annual average; to be developed to a depth of about 800 m below surface and accessed by ramp from surface.

Mining method:
- Sub-level retreat
- Cemented rock fill with waste backhaul from PGM for waste requirement.
- 15m longhole retreat – factored 24% dilution
- ~2000tpd ore @ 7gpt to mill using proven production rates
- 5x5m main haulage drifts
- Diesel trucks & tethered (electric) scoops until quick-charge battery alternate is viable.
- Battery electric equipment.

Overall, the best fit for Borden was a fleet comprised of equipment from Sandvik and MacLean.
• Scoops: Sandvik LH 514 E – tethered electric
• Trucks: Sandvik TH 54-0 diesel - with a firm commitment to a 40 T battery truck
• Drills: Sandvik DD 422i
• Bolters: MacLean MEM 975 Scissor Bolter
• Utility Vehicles: MacLean Cassette Carries and Scissor Lift
• Grader: MacLean conversion of a Cat 12 M2 diesel grader.

Ore from Borden is processed at the existing Dome mill.

Gold is recovered using a combination of gravity concentration and cyanidation techniques. The circuit consists of primary, secondary and tertiary crushing, rod/ball mill grinding, gravity concentration, cyanide leaching, carbon-in-pulp gold recovery, stripping, electro winning and refining.

Gravity gold is recovered by the use of five Knelson CD-30 Concentrators fed from the cyclone underflow. A Consep CS6000 Acacia Reactor is used to intensively leach the Knelson concentrate. The Acacia loaded solution has a dedicated electrowinning circuit. Gravity recovery accounts for up to 45% of the recovered gold, depending on ore type.

The cyclone overflows reports to a 155' thickener where the slurry density is increased to 55-60% solids. The thickener underflow feeds six leach tanks in series, which provide about 32 hours residence time.

Lime is added to the mill discharge pump boxes, thickene ........