The Meliadine mine is located near the western shore of Hudson Bay in the Kivalliq District of Nunavut, about 25 km north of Rankin Inlet and 290 km southeast of our Meadowbank mine. Meliadine includes seven gold deposits, six of which are part of the current mine plan. The 98,222-hectare property covers an 80-km-long greenstone belt.
Facilities at the Meliadine mine include the main camp and the exploration camp. The main camp is located approximately 1.8 km north of the Tiriganiaq deposit and began operation in 2017. It consists of 14 wings of modular trailers that can accommodate approximately 700 personnel.
Commercial production began at Meliadine in May 2019. The Company anticipates that mining at Meliadine will be carried out through several underground mining operations and open pits over a mine life extending to 2032. There are numerous opportunities to create additional value at Meliadine, both at the mine and on the large regional land package.
Geology
Archean volcanic and sedimentary rocks of the Rankin Inlet greenstone belt underlie the property. The rock layers have been folded, sheared and metamorphosed. They trend west-northwest, dip steeply to the north, and have been overturned. The rock units are truncated by the Pyke Fault, a regional structure that extends the entire 80-km length of the property.
Mineralization
The Pyke Fault and associated secondary structures (i.e., the Lower Fault) appear to control gold mineralization on the property. Along the fault is a series of oxide iron formations that host six of the seven known Meliadine mine deposits. The deposits consist of multiple lodes of mesothermal quartz-vein stockwork, laminated veins and sulphidized iron formation mineralization. The northern, magnetite-rich Upper Oxide iron formation hosts the Tiriganiaq zone, the largest deposit to date with a strike length of approximately 3.0 km at surface and a known depth of 800 metres, as well as the Wolf North and Discovery zones. The southern, weakly magnetic Lower Lean iron formations contain the F Zone, Pump, Wolf Main and Wesmeg deposits. Normeg is hosted by mafic volcanics and is located between the Wesmeg and Tiriganiaq zones.
The deposits are all within 5 km of Tiriganiaq except for Discovery, which is 17 km east-southeast of Tiriganiaq. Each of these deposits has mineralization within 120 metres of surface, making them potentially mineable by open pit methods. They also have deeper mineralization that could potentially be mined with underground methods, which are currently being considered in various internal studies.
At December 31, 2021, Meliadine was estimated to host 3.7 million ounces of gold in proven and probable mineral reserves (19.2 million tonnes grading 5.93 g/t gold) mostly at underground depth, as well as 2.2 million ounces of gold in measured and indicated mineral resources (18.0 million tonnes grading 3.88 g/t gold) and 2.3 million ounces of gold in inferred mineral resources (11.7 million tonnes grading 6.09 g/t gold).
Mining
Mining at Meliadine will be carried out through 12 open pits and two underground mining operations. Underground access is by decline, with long-hole mining methods. Each stope is backfilled, with cemented pastefill and/or cemented rockfill used in primary stopes and dry rockfill for the secondary stopes. A conventional truck/shovel operation is used for the open pits. Mining at Tiriganiaq in 2021 was carried out from both underground and an open pit.
At the Tiriganiaq open pit, pre-commercial gold production was 24,057 ounces in 2021.
A saline water treatment plant treats underground dewatering water; the Company received the necessary approval to discharge the treated saline water to Hudson Bay commencing in the third quarter of 2019.
In 2020, the Company applied for permits to construct and operate a waterline to discharge treated saline effluent directly to Hudson Bay. Discussions with NIRB continued through 2021 and, in early 2022, the updated Project Certificate was received. By replacing the discharge saline water to sea currently done by truck, the waterline is expected to reduce costs and the environmental impact. The construction of the waterline is expected to start in the second quarter of 2022 and to be completed in time for the 2024 discharge season.
In 2021, the Company completed the works at the new wash bay, the oxygen expansion (third line), the relocation of the former water-treatment works into the newly constructed water treatment complex and initiated construction of the building for the new saline effluent treatment works within the water treatment complex.
In 2022, the Company expects to complete the saline effluent treatment works, as well as complete the in-ground works for the power plant expansion, install the structure for the power plant expansion and install the structure for the fourth filter press and CIL expansion works.
Processing
Initial ore processing commenced in early February 2019 using low-grade stockpiles. The mill employs a conventional gold circuit comprising crushing, grinding, gravity separation and cyanide leaching with a carbon-in-leach circuit, followed by cyanide destruction and filtration of the tailings for dry stacking. Metallurgical recoveries are expected to average 96%.
In 2021, milling rates averaged approximately 4,698 tpd. The Phase 2 mill expansion remains on track to be completed in mid-2024 and is expected to increase throughput to approximately 6,000 tpd in 2025.
Exploration
In 2020, the Company completed conversion drilling programs at the Tiriganiaq, Wesmeg and Discovery deposits as well as delineation drilling at Tiriganiaq for the open pits and for the underground. In addition, the Company completed exploration drilling mostly at Tiriganiaq, with limited holes targeting extensions of Normeg, Wesmeg and Discovery.
Positive results from drilling at the Discovery deposit during 2020 led to an initial probable mineral reserve for Discovery at December 31, 2020, of 363,000 ounces of gold (2.1 million tonnes grading 5.41 g/t gold) at underground depths, including mineralization accessible by crown pillar mining methods. The Discovery mineral reserves and mineral resources at year-end 2021 are included in the total mineral reserves and mineral resources for Meliadine.
The Company believes the Discovery deposit could be developed into a satellite mining operation to provide ore feed to the existing mill facility at the Meliadine mine, and completed an internal technical evaluation of Discovery in early 2021. Drilling at Discovery in 2021 continued to test the deposit's main plunge as well as the parallel ore shoot to the west at depth with an aim to expand the mineral resources.
At the Meliadine mine in 2022, the Company expects to spend approximately $8.4 million for 27,300 metres of capitalized drilling with a focus on conversion drilling at the Tiriganiaq, Normeg, Wesmeg and Pump deposits, as well as exploration drilling of the Tiriganiaq, Wesmeg, Pump and F-Zone deposits, which are all open at depth.