Forming part of the LaRonde Complex, the 7,000-tonnes/day LaRonde mine and processing facility has produced over 6 million ounces of gold as well as valuable by-products. The LaRonde mine still has 3.0 million ounces of gold in proven and probable mineral reserves (15.3 million tonnes grading 6.00 grams of gold per tonne) as of December 31, 2021.
LaRonde achieved commercial production of its deep extension (that is, below level 245) in November 2011, where most of its ore is now mined. LaRonde currently has a mine life lasting through to 2032. Below approximately 2.8 km depth, the LaRonde mine divides into two parallel lobes called the “East mine” and the slightly offset “West mine”.
The LZ5 mine is on the Bousquet property, approximately 2.5 km west of the Penna Shaft on the LaRonde mine property. Previous property owners had partly exploited the deposit by open pit. Following the completion of a positive internal technical study, LZ5 was approved in February 2017 for development. The full permits were received in 2017, and commercial production was achieved on June 1, 2018.
LZ5 has proven and probable mineral reserves of 852,000 ounces of gold (12.8 million tonnes grading 2.07 grams per tonne gold) as of December 31, 2021. Mineral reserves and mineral resources from the adjacent, 100%-owned Ellison property were included in LZ5 mineral resources and mineral reserves beginning in 2020. The LZ5 mine is expected to maintain a production rate of approximately 3,000 tpd through 2032.
The entire LaRonde Complex hosts 3.8 million ounces of gold in proven and probable mineral reserves (28.1 million tonnes grading 4.21 grams of gold per tonne) as of December 31, 2021.
During 2021, the LaRonde Complex produced 379,734 ounces of gold and 738,000 ounces of silver plus by-product zinc and copper, and is forecast to produce 380,000 ounces of gold in 2022.
Geology
The LaRonde property is located in the southern portion of the Archean-age Abitibi volcanic belt, within the Bousquet Formation of the Blake River Group of volcanic rocks. The LaRonde and LZ5 deposits occur at the eastern end of the east-west-trending Doyon-Bousquet-LaRonde mining camp, which includes the Mouska, Doyon, Bousquet 1 and Bousquet 2 gold deposits. The most important regional structure is the Cadillac-Larder Lake fault zone, located approximately 2 km south of the LaRonde property.
The LaRonde deposit is a gold-rich volcanogenic massive sulphide deposit with significant silver, zinc and copper credits. LaRonde lenses were formed mainly by sulphide precipitation from hydrothermal fluids on the seafloor and by replacement below lenses. The stacking of the LaRonde lenses is the result of successive volcanic events, intercalated by cycles of hydrothermal activity associated with reactivation of synvolcanic faults.
The LZ5 deposit, in contrast, is composed of gold-rich disseminated to stringer sulphide mineralization with a significant silver credit.
Mineralization
At the LaRonde mine, gold-copper and zinc-silver mineralization occurs in the form of massive and disseminated sulphide lenses. The presence of silver and base metals adds considerably to the value of LaRonde’s gold ore, reducing the total cash cost to produce each ounce of gold on a by-product basis. Five different mineralized horizons are known to exist adjacent to the Penna Shaft. The zinc-silver mineralization with lower gold values, common in the upper mine, grades into gold-copper mineralization within the lower mine. The predominant base metal sulphides are chalcopyrite (copper) and sphalerite (zinc).
Zone 20 North contains the majority of the mineral reserves and mineral resources at the LaRonde mine. The Company believes that Zone 20 North is one of the largest gold-bearing massive sulphide mineralized zones in the world and one of the largest known mineralized zones in the Abitibi region of Ontario and Quebec. Zone 20 North extends from 700 metres below surface to at least 3,700 metres below surface, and remains open at depth. With increased access on the lower levels of the mine (i.e., below Level 245 and from the internal shaft on levels 257 and 278), the broad transformation from a zinc/silver orebody to a gold/copper deposit was effectively completed in 2017. However, the development of the West mine area, between Levels 278 and 314, provided access to a new zinc/silver rich sector beginning at the end of 2017.
The LZ5 horizon consists of a 4- to 30-metre-thick horizon of disseminated to stringer sulphide mineralization containing 5% to 20% pyrite and traces of chalcopyrite with rare millimetre-wide grains of visible gold. The LZ5 horizon has a large geological footprint and has been estimated to contain a mass of more than 26 million tonnes. The LZ5 horizon can be followed over 900 metres of east-west strike length over the Bousquet property and another 400 metres on the Ellison property for a total strike length of 1,300 metres. LZ5 has been traced vertically for almost 1,000 metres, and it shows a steep dip to the southwest. In an enlarged area of LZ5, there is gold enrichment near the margins of the economic envelope. LZ5 includes two high-grade portions named Zone 5 Footwall and Zone 5 Hanging Wall.
Mining
Access to LaRonde’s underground mining operation is through the 2,250-metre-deep Penna Shaft, which was completed in March 2000 and remains the deepest single-lift shaft in the Western Hemisphere. The internal Shaft No.4 extends 823 metres to 2,858 metres depth to provide access to even deeper ore at the lower part of the orebody, and has been at the centre of the LaRonde mine extension project initiated in 2006.
Two mining methods are used at LaRonde: longitudinal retreat with cemented paste backfill; and transverse open stoping with paste or unconsolidated backfill. In addition, to address concerns regarding the frequency and intensity of seismic events encountered at the lower levels of the LaRonde mine, a hybrid of these two methods has been used.
The risk of more frequent and larger seismic events has increased as the Company mines deeper at LaRonde. Over the years, the Company has continued to adapt and manage the risk. The Company continues to adjust the mining methods, ground support and protocols to address seismic activity in the deeper portions of the mine.
Below approximately 2.8 km depth, the LaRonde mine divides into two parallel lobes called the East mine and the slightly offset West mine. In 2021, the Company commissioned the 278 Level cooling plant in the East mine. In 2022 the Company expects to commission the new booster fans at the 275 Level and start the construction of the new cooling plant for the West mine.
The LaRonde Complex has been successful at incrementally implementing automation for its production activities and is increasingly relying on this technology. In 2021, at the LaRonde mine, 27% of the production mucking was done in automated mode with operators based on surface, compared to an initial objective of 17%. In 2021, at the LZ5 mine, 23% of the production mucking was done in automated mode with operators based on surface, compared to an initial objective of 20%. In 2022, the Company has set targets of 30% of the production mucking at LaRonde and 23% of the production mucking and hauling at LZ5 to be done in automated mode, while also working on remote production drilling. Infrastructure continues to be developed to provide further access to mine LaRonde 3 (below level 311 at the LaRonde mine, or below 3,100 metres depth).
At Zone LR11-3 (which is at the past producing Bousquet 2 mine), the dewatering of the old workings and the development continued according to plan in the fourth quarter of 2021. Production from LR11-3 is expected to begin in late 2022.
LZ5 is mined from underground ramp access. The mining methods are longitudinal retreat with paste backfill, and transverse open stoping with paste or unconsolidated backfill. With a production rate above 3,200 tpd during the second half of 2021, the site has demonstrated the benefits from automated equipment and is now targeting to maintain this mining rate of 3,200 tpd in 2022.
Processing
Ore is processed at the LaRonde mineral processing complex, which includes copper and zinc flotation as well as precious metals recovery and refining. The processing plant produces doré bars containing gold and silver, as well as zinc and copper concentrates that carry valuable gold and silver credits.
The plant has a daily capacity of 7,000 tonnes of ore and has been expanded four times since it opened in 1988. In addition, a dedicated 2,000-tonnes/day carbon-in-leach processing facility has treated ore trucked from the LZ5 mine and refined its concentrates into doré bars. This plant formerly treated ore from the now closed Lapa mine.
In 2019, the Company was granted a revision to the Certificate of Authorization at the LaRonde Complex, which allowed for the processing of ore from LZ5 through the LaRonde mill circuit. As a result, the Company began reporting the operational parameters from both the LaRonde and LZ5 mines on a combined basis as the LaRonde Complex starting in 2020.
The LaRonde plant also treats concentrate pulp trucked from the Goldex mill. The material is sent to the LaRonde leaching/carbon-in-pulp circuit for gold recovery along with LaRonde residual pulp.
The construction of the drystack tailings facilities is progressing on schedule. The installation of the mechanical equipment has started and the filter-press assembly is underway. The drystack tailings facility is expected to be operational by the end of 2022.
Exploration
At the LaRonde Complex in 2022, the Company expects to spend approximately $12.0 million for continued development of exploration drifts from the LaRonde 3 infrastructure towards the west below the LZ5 mine workings and for 43,500 metres of drilling into multiples targets including Zone 5, Zone 6, Zone 20N and the recently discovered Zone 20N Zn South with the aim of adding new mineral reserves and mineral resources to extend the mine life of the LaRonde Complex into the 2030s.
The rehabilitation work of track drift 9-0, the enlargement of track drift 215 and the development of exploration drift 290 continued to progress in the fourth quarter of 2021. Initial drilling targeting mineralized zones beneath the past producing Bousquet mine is ongoing from the drill stations rehabilitated so far on track drift 9-0 and initial results are expected later in 2022.