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 (15.2 million tonnes grading 6.12 grams of gold per tonne) as of December 31, 2020.
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 2030. 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 788,000 ounces of gold (11.8 million tonnes grading 2.08 grams per tonne gold) as of December 31, 2020. 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 2029.
The entire LaRonde Complex hosts 3.8 million ounces of gold in proven and probable mineral reserves (26.9 million tonnes grading 4.36 grams of gold per tonne) as of December 31, 2020.
During 2020, the LaRonde Complex produced 349,913 ounces of gold and 684,000 ounces of silver plus by-product zinc and copper, and is forecast to produce 375,000 ounces of gold in 2021.
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 m below surface to at least 3,700 m 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 transformation from a zinc/silver orebody to a gold/copper deposit was effectively completed in 2017. 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 m of east-west strike length over the Bousquet property and another 400 m on the Ellison property for a total strike length of 1,300 m. LZ5 has been traced vertically for almost 1,000 m showing 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 m to 2,858 m 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. The West mine area contributed approximately 19% of the tonnage mined at the LaRonde Complex in 2020. In 2021, the West mine area is expected to contribute approximately 15% of the ore mined and 21% of the gold produced at the LaRonde Complex.
The good performance at the LaRonde mine is partially a result of the automation strategy that has helped to improve productivity and allow continuation of mucking activities during non-entry protocols related to seismicity. In 2020, 13% of tonnes mucked from stopes at the LaRonde mine were done in automation mode. In December 2020, a record 39% of the production mucking at the LaRonde mine was done using automated methods, which included 100% of the production mucking from the West mine area. At LZ5 in 2020, 14% of tonnes mucked and hauled to surface were accomplished in automated mode with operators based on surface. The target for 2021 is to muck over 17% of the total tonnage for the LaRonde Complex using automated methods. The LaRonde Complex automation team will continue optimizing the automated mining techniques, and work is ongoing to perform production drilling using automation.
Infrastructure continues to be developed to provide further access to mine LaRonde 3 (below level 311 at the LaRonde mine, or below 3,100 m depth).
At Zone LR11-3 (which is at the past producing Bousquet 2 mine), development from level 146 of the LaRonde mine continues on schedule and dewatering of the previously mined area is ongoing. The zone is expected to be reached in the second half of 2021 and production activities are expected to begin in 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. In its first year of operation, the mine achieved its designed production rate of 1,975 tonnes/day, and by the fourth quarter of 2020, the LZ5 production rate was 2,987 tpd, essentially meeting the targeted rate of 3,000 tpd.
Given the success in mining the upper portions of the LZ5 deposit (from surface to 330 metres), the extension of mining activities to a depth of 650 metres has been approved, resulting in the addition of 272,000 ounces of gold to the LZ5 mineral reserves at year-end 2020. With this addition, the LZ5 mine is expected to maintain a production rate of approximately 3,000 tpd through 2029. The Company is also evaluating the potential to mine portions of the neighbouring Ellison property from the LZ5 underground infrastructure.
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 adjacent 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.
Exploration
The main focus of the 2020 exploration program at the LaRonde mine was continuing the investigation and conversion of Zone 20 North at depth in both the West mine and East mine areas by extending drill targets down to 3.5 and 3.3 km depth, and exploring the Zone 6 and 7 horizons at depth from the accesses developed toward the west on Levels 146 and 292 to 311. The conversion program also helped to identify a new zinc-rich area of Zone 20 North on the east fringe of LaRonde 3, named the 20N Zinc South Zone, which resulted in new inferred mineral resources at the end of 2020.
The conversion program is expected to continue in 2021 and will investigate the possibility of extending indicated mineral resources down to 3.5 and 3.6 km depth in the western and eastern portions of LaRonde 3, respectively, and on the 20N Zinc South Zone. Drilling into Zone 6, mainly from level 292, is continuing to reinforce the quality of inferred mineral resources down to 3.4 km depth.
Exploration also continued at the adjacent Bousquet property, where the Company is achieving strong operating results at the LZ5 mine and the Zone 11-3 area mine development. Exploration in 2020 targeted historic Bousquet zones, which are showing good potential between 2,000 and 3,000 m depth. Compilation of historic data from the entire Bousquet property also continued.
The Company is developing two new accesses towards the west on levels 215 and 290 which are expected to allow the investigation of historic Bousquet zones at depth from a closer range with better drilling angles. Rehabilitation work will also be completed on the exploration drift at level 9 of the Bousquet 2 mine to allow drilling in late 2021.
Exploration drilling is planned to convert inferred mineral resources to indicated mineral resources on the Ellison property and to investigate the Bousquet Zone 6 horizon.