Positive Preliminary Economic Assessment For Mason Copper Project

TORONTO - Hudbay Minerals Inc. reported on the preliminary economic assessment (PEA) of its 100%-owned Mason copper project located in Nevada. “The Mason PEA demonstrates the success of Hudbay’s consistent growth strategy and our team’s ability to create value from accretive acquisitions of high-quality copper projects in mining-friendly jurisdictions,” said Peter Kukielski, President and Chief Executive Officer. “We added Mason to our development pipeline portfolio in 2018 and have since leveraged our integrated core competencies of exploration, mine planning and project development to demonstrate that Mason is a quality long-term development project in our robust organic growth pipeline.”

The Mason project is a large greenfield copper deposit located in the historic Yerington District of Nevada and is one of the largest undeveloped copper porphyry deposits in North America. Mason’s measured and indicated mineral resource estimates are approximately twice the size of Hudbay’s Constancia and Rosemont deposits. Hudbay views the Mason project as a long-term option for future development and a strong component of its pipeline of long-term growth opportunities in mining friendly jurisdictions.

The 2021 Mason PEA contemplates a 27-year mine life with average annual copper production of approximately 140,000 tonnes over the first ten years of full production. At a copper price of $3.10 per pound, the after-tax net present value using a 10% discount rate is $519 million and the internal rate of return is 13.7%. The valuation metrics are highly sensitive to the copper price and at a price of $3.25 per pound, the after-tax net present value using a 10% discount rate increases to $773 million and the internal rate of return increases to 15.4%.

The Mason deposit is a large tonnage, copper-molybdenum deposit and is planned to be a traditional open pit shovel/truck operation with a copper sulphide mineral processing plant producing commercial grade copper and molybdenum concentrate. The plant is designed to operate at a throughput rate of 120,000 tonnes per day. Mining operations in the pit are designed to be performed from 15 and 30-meter-high benches using large-scale mining equipment including 10 5/8-inch diameter rotary blast hole drills, 74 cubic-yard electric mining shovels, a 55 cubic-yard hydraulic shovel, a 37 cubic-yard front-end loader and 290-tonne capacity haul trucks. During the 27-year operation, the mine plan achieves peak mining rates until year 13, then reduces by about half of the original mining rate from year 14 to 20 as the strip ratio drops. The remaining seven years assumes the processing of rehandled ore from stockpiles.

The concentrator design consists of conventional crushing and milling, followed by rougher and cleaner froth flotation, and is a similar flowsheet to that used at Hudbay’s Constancia mine in Peru. The proposed site layout assumes the plant will be located to the northwest of the open pit, northeast of the waste rock facility and east of the tailings management facility. Haul trucks will dump ore at the primary crusher, which will feed the concentrator via overland conveyor.

Operating costs were developed by Hudbay based on a bottom-up approach utilizing price quotes from suppliers and local costs for labour. Mine operating costs were validated against actual costs at Constancia and other similar projects and operations.

The PEA and mine plan were based on a revised resource model which was used to publish Hudbay’s first compiled updated resource estimate for Mason. The resource model was constructed using the same methods Hudbay applied at Constancia. Based on this new model, including resource classification criteria calibrated on historical performance at Constancia, control of grade over-smoothing in the central zone of the deposit and the use of a lower cut-off grade, the measured and indicated resources increased to 2.2 billion tonnes at 0.29% copper, from 1.4 billion tonnes at 0.32% copper previously.

There is opportunity to further enhance the project economics through exploration for higher grade satellite deposits on Hudbay’s prospective land package in Nevada, including Mason Valley. The Mason Valley property hosts several historical underground copper mines that were in production in the early 1900s. Much of the Mason Valley property is located on Hudbay’s wholly owned private lands and contains highly prospective skarn mineralization. Mason Valley presents a similar opportunity to Hudbay’s Copper World property in Arizona, where the company has recently announced the discovery of four mineral deposits in a historical mining district. Historical drilling and production records from the past producing mines at Mason Valley indicate the mineralization is high grade and starts at or near surface. In 2015, Metal Bank Limited optioned the Mason Valley property and conducted a limited campaign of nine reverse circulation drillholes at the Bluestone prospect with the objective to define the extent of the high-grade copper mineralization. Two notable holes intersected 42 meters of 1.51% copper and 34 meters of 0.61% copper, both starting from surface.

The company also owns the Blue Hill copper oxide deposit located 1.5 kilometers northwest of the Mason deposit, which was not included in the 2021 PEA and may present an opportunity to add an oxide component to the Mason project design in the future.

Hudbay continues to compile and interpret historical data relating to its land package near Mason. Once this is done, the company expects to complete a geophysical survey to refine the exploration targets in preparation for a potential initial drilling campaign later this year. The company will also continue to advance its local stakeholder engagement program while advancing trade-off studies to support future pre-feasibility work on the project.