Musselwhite Gold Mine

Mining and Processing

The mining method predominantly in use at Musselwhite is sub-level blasthole stoping with backfill. The sub-level blasting stoping method is excavated using three methods: standard AVOCA, modified AVOCA and transverse longhole. (AVOCA is a mining methodology used to extract steeply dipping, narrow ore bodies or veins.)

Musselwhite Mine is a mechanized mine employing rubber-tired diesel equipment for all phases of mining operations, and access to the underground workings is provided by a system of ramps. The main ramp extends from the portal to the 3,750 metre level in the PQ Deeps zone. Ore extracted from the PQ Deeps zone is hoisted by an internal winze to the 280 metre level. From the truck loadout on 280, ore is transferred to a dumping point at the 460 metre level, and thereafter conveyed to surface.

The Musselwhite carbon-in-pulp processing facility was constructed in 1996 and began operations in 1997. Mill throughput is currently limited to approximately 1.1 Mtpa by mine production, which is the current life-of-mine plan requirement. Average gold recovery has been above 95% over the last 15 years of operation.

Opportunities

Musselwhite is estimated to have at least six years of mine life remaining based on its existing 1.5 million ounces of Mineral Reserves and 506,000 ounces of Mineral Resources. In addition, numerous opportunities exist to optimize production, including:

Production increases & efficiency improvements:

• Idle mill capacity filled by incremental development ore
• Additional mining horizon in PQ deeps providing access to higher grade feed 

Productivity & equipment

• Newer, lower-emission fleet, reducing ventilation demands and constraints
• Greater equipment availability, reliability, and disciplined rebuild schedule supported by OEM expertise

Innovation & optimization

• Optimized ventilation systems allowing more concurrent mining activitieses are quartz-vein type hosted in mafic volcanic rocks and silicate facies iron formation, with subordinate mineralization hosted in biotite and amphibolite schists.

Exploration and Geology

The project is located on a 65,000 hectare land package that provides significant potential for exploration and expansion. Orla Mining was advancing a three-pronged exploration strategy with the objective of expanding the resource base to support production and extend the mine life:

• Test mine trend extensions: Deep directional surface drilling to test the down-plunge extension of the mine trend one kilometre beyond historical surface drilling
• Replace and expand underground resources: Underground drilling for reserve, resource, and inventory definition to support production and growth
• Identify satellite deposits: Near-mine surface drilling to evaluate targets for potential shallow open-pit satellite deposits within a 10 km-radius of the mill

The North Caribou Greenstone Belt (NCGB) comprises nine volcanic-dominated assemblages formed during two major magmatic phases. Gold occurrences have been identified in seven of the nine assemblages of the NCGB. Most gold occurrences are quartz-vein type hosted in mafic volcanic rocks and silicate facies iron formation, with subordinate mineralization hosted in biotite and amphibolite schists.

Mineralization at Musselwhite is predominantly found in sub-vertical high strain zones in the favourable silicate facies of the Northern Iron Formation, and to a lesser extent the oxide facies in both the Northern and Southern Iron Formation. Significant mineralization is also locally hosted in mafic volcanics and garnet-biotite schists in the West Limb deposits. In addition to the main hosts of mineralization, anomalous gold concentrations also occur property-wide and within all the major lithologies.