Barrick Gold reported progress on projects with the potential to contribute up to 1.1 million ounces (oz) of gold production at Cortez, Goldrush, Lagunas Norte and Turquoise Ridge. The company has also initiated a prefeasibility study to evaluate the construction of an underground mine at Lama, on the Argentinean side of the Pascua-Lama project. Optimization work in Chile remains under way.
All of Barrick’s projects must pass a rigorous, independent peer review process led by its evaluations team. The projects are measured against a 15% rate of return, using a long-term gold price of $1,200/oz. Once they are deemed worthy, they are ranked, prioritized, and sequenced to optimize capital spending over time, allowing the company to anticipate and plan for funding requirements.
The Cortez Underground Expansion project will develop underground mining into Deep South area, below currently permitted levels. The Deep South project, located within the Lower Zone of the Cortez Hills underground mine, remains on track to contribute average underground production of more than 300,000 oz/y between 2022 and 2026.
Development of the range-front twin declines that will provide access to the lower zone of the mine began in the fourth quarter of 2016. For the first time, the mine is using a roadheader to bore the tunnels rather than traditional drill-and-blast techniques. The expansion will enable the company to access approximately 1.9 million oz of proven and probable reserves in the Deep South zone, of which more than 80% is oxide.
The permitting process, which began in 2016, is expected to take approximately three to four years, including the preparation of an Environmental Impact Statement. A record of decision is expected in 2019 or 2020. Dewatering and development work could begin as early as 2019 or 2020, with initial production from Deep South commencing in 2022 or 2023. Barrick expects to complete the feasibility study by the end of 2017, which will focus on processing, backfill and stope sequencing to optimize free cash flow.
The Goldrush project continues to advance according to schedule, with the potential to become Barrick’s newest mine in Nevada by 2021. Average annual production for the first full five years of operation is expected to be approximately 450,000 oz of gold. Goldrush is expected to have a mine life of 21 years, with first production as early as 2021, and sustained production in 2023. The initial capital costs are estimated at $1 billion and the project now has 9.6 million oz of measured and indicated gold resources, and 1.9 million oz. of inferred gold resources.
During 2016, Barrick obtained the necessary permits for the construction of twin exploration declines. The twin decline portal access site has been cleared, and work is expected to begin on the portal pad in the first quarter of 2017.
Barrick is evaluating a sequenced approach to extend the life of the Lagunas Norte mine by optimizing the recovery of carbonaceous oxide ore contained in existing stockpiles, followed by extraction and processing of refractory ores.
The prefeasibility study for the Refractory Ore project contemplated an initial capital investment of approximately $640 million for the installation of a 6,000-metric-ton-per-day (mt/d) grinding-flotation-autoclave and carbon-in-leach processing circuit to treat refractory material. Once ramped up, the circuit has the potential to produce an average of 240,000 oz of gold per year.
Over the past year, Lagunas Norte has developed a process to treat certain carbonaceous oxide material already stockpiled at the mine through heap leaching, helping to bridge the gap between processing of oxide and refractory materials. This has created an opportunity to first construct a grinding and carbon-in-leach processing circuit that would treat the remaining carbonaceous oxide material at the site. This would allow the company to defer the construction of the flotation and pressure oxidation circuits required for treating refractory ore, optimizing the timing of capital expenditures.
Construction of these facilities could begin in late 2018, with first production in 2020. Construction of the refractory ore processing facilities (flotation and pressure oxidation circuits) could begin as early as 2020, with first production in 2023.
Barrick continues to advance an expansion at its 75% owned Turquoise Ridge mine. Through the development of a third shaft, the mine has the potential to increase output to an average of 500,000 oz/y. Turquoise Ridge recorded its highest-ever level of production in 2016, producing 355,000 oz of gold. Average throughput increased by 40%, from 1,500 mt/d in 2015, to 2,100 mt/d in 2016. Improvements in mining intensity and reliability have been driven by upgrades to underground ventilation systems, increasing top cut mining widths, greater equipment standardization, and better maintenance.
The company is evaluating whether to construct a third production shaft, instead of installing a new ventilation shaft, which was previously contemplated as the second phase of the mine expansion. All necessary permits for a third production shaft are already in place.
At the end of 2016, the Turquoise Ridge mine had 4 million oz of gold in reserves (75% basis) at an average grade of 15.1 g/mt—the highest reserve grade in the company’s operating portfolio, and among the highest in the entire gold industry, Barrick said.
Barrick has initiated a prefeasibility study to evaluate the construction of an underground mine at Lama. The study will evaluate the use of low-cost bulk mining methods, including sub-level cave and block cave mining, designed to target higher-value ore on the Argentinean side of the border in the initial stages of the operation. Initial ore processing at Lama would be undertaken using one of three partially completed processing streams at the site, with a capacity of approximately 15,000 mt/d. Existing infrastructure could be scaled up to 25,000 mt/d at a later date. An underground mine would reduce the surface footprint of the operation and would be less susceptible to weather-related production interruptions during the winter season.