The Macassa property was first explored in 1931, leading quickly to a gold discovery, and in October 1933 Macassa’s first mill began processing ore. Macassa was in continuous production from 1933 until 1999, when operations were suspended and placed into care and maintenance due to the declining gold price. Macassa resumed operations in 2002, and with the discovery of the high-grade South Mine Complex (SMC), was able to increase production levels significantly above historic levels and make Macassa one of the highest grades gold mines in the world. Successful ongoing exploration drilling continues to extend the SMC mineralization and add to the mine’s mineral reserves and mineral resources in support of extending mine life.
The construction of the #4 Shaft is starting a new chapter in the life of the Macassa mine. Currently running ahead of schedule and on track for completion in late 2022, #4 Shaft project will increase production, lower unit costs, improve working conditions, and increase exploration capacity.
The mine is located in an area with well-developed infrastructure, including a provincial highway, a railway system and a private airport. Macassa ore is processed on-site at the Macassa mill.
Geology & Mineralization
The gold mineralization at Macassa is found along breaks or faults, in veins as quartz filled fractures, as breccias and as sulphide rich (pyrite) zones. There are multiple mineralized breaks, named the ‘04, ‘05, No.6, Kirkland Lake Main and the Kirkland Lake North and South branches. The breaks strike 60 degrees northeast and dip 70 to 80 degrees south in keeping with the Timiskaming trend. The trend of the gold mineralization in the Kirkland Lake camp conforms to the 60 degree westerly plunge of the syenite intrusives.
The SMC was a significant discovery, with the zone having a different character than the zones mined historically at Macassa. The SMC is associated with a cross-over structure that links the ’04 / Main Break with the Amalgamated Break. The mineralization trends parallel to the main structures but has a much flatter dip ranging from 20 to 50 degrees south. SMC mineralization has been found to have greater widths and contain higher grades than the main zones. Considerable potential exists for future exploration drilling to identify additional parallel and stacked zones located above, below and along strike of the known SMC Zone.
Mining
Mining at Macassa is currently underway at an average rate of 1,000 tpd across two mining horizons: the historical Main/’04 breaks and the SMC Zone with access via #3 shaft. Mining is conducted primarily via overhand and underhand cut-and-fill and a small portion of long hole methods. All stopes are backfilled with either paste fill, cemented rock fill or loose waste rock. The Macassa mine was the first mine in the world to use lithium ion battery operated trucks and loaders.
Processing
The Macassa mill was built in 1986 and originally designed for a throughput of 725 tonnes per day. The mill was subsequently expanded to its current capacity of 1,650 tpd. Processing of ore at Macassa starts with crushing and grinding before it enters the leach tanks for cyanidation. Then, it flows through a carbon-in-pulp circuit, followed by a Zadra recovery process. The concentrate is melted in an induction furnace where doré is poured that typically contains 70% to 85% gold, and 5% to 10% silver.
Exploration
Agnico Eagle now controls six of the original producing mines along the Main Break in the Kirkland Lake mining camp. The underground workings of these mines are all interconnected and tie into production areas at the Macassa mine.
The Company plans to continue to work with the historical data to assess the potential of longer-term exploration targets along the Main Break. The near-term focus will be to assess the mineral potential to the east and along the Main Break below the 5800 Level at Macassa and east onto the Kirkland Minerals and Teck-Hughes properties. Any significant discoveries on these properties could provide incremental sources of ore for the Macassa mill.
At the Macassa mine in 2022, the Company expects to spend approximately $20.3 million for 99,900 metres in capitalized drilling and to develop exploration drifts to replace mineral reserves and mineral resources depletion. Another $18.9 million is budgeted for exploration, including $10.4 million for 89,700 metres of exploration drilling to continue to investigate extensions of key targets at South Mine Complex (East, West, Upper and Lower), Main Break, '04 Break, Amalgamated Break and near-surface. The remaining $8.6 million of exploration will be spent developing a 1.3 kilometre exploration ramp from the Near-Surface area in order to access, develop and infill with underground drilling the mineralization on the AK property.
Development Projects
#4 Shaft Project
On January 17, 2018, plans were announced to sink a new shaft at Macassa. The new, 21.5-foot diameter, concrete-lined shaft will offer a number of important benefits to the mine, including: de-risking the operation; enabling more effective underground exploration to the east of the South Mine Complex; improving ventilation and general working conditions in the mine; and supporting higher levels of production and lower unit costs. The new four-compartment shaft will have a total hoisting capacity of 4,000 tonnes per day (ore and waste) and is an important component of the plan to increase production at Macassa with a target to produce approximately 330,000 to 350,000 ounces in 2024. Production levels could potentially increase further once the full benefit of the #4 Shaft is realized.
A significant milestone was achieved in January 2022 when the sinking phase of the project to 6,400 feet was completed. Remaining work includes the construction of the loading pocket and other infrastructure as well as additional development to connect the #4 Shaft to current mining operations. The full project is on schedule for completion in late 2022.
AK deposit
The Company is evaluating the possibility of using the existing Macassa Near Surface Zone infrastructure to access the AK deposit. Preliminary evaluations indicate that mining activities could begin as early as 2024 and production could average approximately 40,000 ounces per year, at total cash cost per ounce of $650-$750. This production is expected to have a positive impact on cash flow generation at Macassa. Permitting work is ongoing and the Company expects to make a production decision later in 2022.
Upper Beaver project
The Upper Beaver deposit is located approximately 27 kilometres from the Macassa mine, and 60 kilometres from the Holt mining complex. The Company is currently reviewing the concept of leveraging the Macassa infrastructure or the Holt Complex infrastructure and the shaft sinking experience at Macassa to enhance project returns at Upper Beaver. With the sinking of the Macassa #4 Shaft now complete, the Macassa internal team and shaft sinking equipment could be used at Upper Beaver and could result in potential savings of tens of millions of dollars.