The mining newspaper for Alaska and Canada's North
The mining newspaper for Alaska and Canada's North
Grows Golden Triangle presence with Brucejack acquisition Mining Explorers 2022 - January 19, 2023
Ultrahigh-grade gold in core from a hole drilled at Newcrest Mining's Brucejack Mine in Northern British Columbia.
An aerial view of Newcrest Mining's high-grade Brucejack gold mine in British Columbia's Golden Triangle.
Core from a highly mineralized intercept encountered during 2021 drilling of the East Ridge discovery on the Red Chris gold-copper project in Northern British Columbia.
Gaining ownership of the Brucejack Mine through the US$2.8 billion buyout of Pretium Resources Inc., Newcrest Mining Ltd. consolidated all the current large-scale gold, silver, and copper production in the Golden Triangle and established Northern British Columbia as a solid foundation for the Australia-based company's growing North American presence.
The high-grade Brucejack Mine adds more than 300,000 ounces per year to Newcrest's annual gold production and created synergies with its 70%-owned Red Chris copper-gold mine in Northern BC that are estimated to be worth around US$15 million per year.
"Through this acquisition and the continued development of our outstanding organic growth pipeline, Newcrest's base case gold production is expected to remain strong until at least 2030, and we have a range of further upside opportunities being progressed across the portfolio," Newcrest Mining CEO Sandeep Biswas said upon the March closing of the Pretium acquisition.
This growth potential includes several opportunities to maximize the long-term potential and value of Brucejack.
"We will pursue efficiencies to simplify mining and increase productivity through a holistic view of the Brucejack operations and orebody," said Biswas. "In parallel, our exploration team will be progressing an extensive drilling campaign across the Brucejack mineral claims which make up one of the largest epithermal footprints we have ever seen."
As Newcrest's exploration team worked to unlock the large and high-grade gold potential at Brucejack, the company continued its two-stage transformation at Red Chris – optimizing the current open-pit mine and then applying the Australian miner's industry-leading block cave mining technology to realize the much larger potential this Northern BC porphyry copper-gold project has to offer.
Like kids in a candy store, Newcrest's Brucejack team wasted no time exploring the golden opportunities this high-grade asset has to offer.
Building on a solid foundation established by Pretium, Newcrest launched a three-phase plan to unlock the full potential of its new high-grade underground gold mine and the district-scale property it is located on.
The initial phase of this plan included the implementation of the Australian mining company's NewSafe safety and critical control management programs for high-risk tasks. Despite the introduction of this program, a contractor at Brucejack suffered a fatal accident in October that resulted in a shutdown of the underground mine during the investigation into the incident.
"There is nothing more important than the safety and wellbeing of those who work with us, and our focus is on providing support to all those impacted during this distressing time as we assist with the ongoing investigation," Biwas said.
Several new technologies being introduced by Newcrest are also focused on improving safety, as well as efficiency and productivity at the underground mine, including:
• Improved underground mine dispatch and communication capabilities.
• Semi-autonomous and autonomous mining equipment.
• Asset management and asset health monitoring systems.
Newcrest is also assessing the potential of using ore sorting technology to upgrade the already high-grade ore at Brucejack.
As it onboards these technologies, the Australian miner is assessing the potential to expand the mill throughput to 4,500 to 5,000 metric tons per day, which is a roughly 18% to 32% boost to the current 3,800 t/d processing rate.
Newcrest believes that much of this mill throughput increase can be achieved by simply eliminating bottlenecks in the current process, making this a potentially low-cost, high-reward gold production initiative.
Newcrest sees no shortage of high-grade ore to feed an expanded mining operation at Brucejack.
"Brucejack is very early in its mine life and offers significant exploration upside with the land package largely unexplored," said Biswas.
Going into 2021, the Valley of the Kings deposit at Brucejack hosted 11.5 million metric tons of proven and probable reserves averaging 8.7 grams per metric ton (3.2 million oz) gold and 9.8 g/t (3.6 million oz) silver.
An extensive exploration program carried out by Pretium during 2021 identified several intriguing expansion targets immediately surrounding Valley of the Kings and discovered bonanza-grade gold at exploration targets across the larger property.
Newcrest carried out a roughly 89,000-meter drill program during 2022 to explore expansion targets around the area currently being mined and the wider potential of a 2.5-mile- (four kilometers) trend of high-grade gold zones that runs across the property.
"At Brucejack, drilling continued to deliver outstanding results in all of our target zones, supporting our views of significant resource growth opportunities beyond the Valley of the Kings deposit," said Biswas.
The Australian mining company encountered bonanza gold in several expansion targets on the south side of Valley of the Kings – 1080 HBx, 1080 Level East, and Bridge Zone:
This includes drilling at 1080 HBx, which has expanded Valley of the Kings and confirmed the continuity of the higher-grade mineralization at depth and to the south of the deposit. Highlights include:
• 70.1 meters averaging 35 g/t gold, including one meter of 2,310 g/t gold (1080 HBx).
• 22 meters averaging 178 g/t gold, including one meter of 3,876 g/t gold (1080 HBx).
• 17 meters averaging 41 g/t gold, including one meter averaging 662 g/t gold (1080 Level East).
• 36 meters averaging 33 g/t gold, including one meter averaging 1,164 g/t gold (Bridge).
Newcrest cut even higher grades on the north side of Valley of the Kings. One such hole drilled in North Block cut 28.5 meters averaging 262 g/t (8.4 ounces per metric ton) gold, including a one-meter bonanza grade subsection averaging 7,400 g/t (237.9 oz/t) gold.
This is similar to Pretium's 2021 drilling at North Block, which included:
• 15 meters averaging 561.5 g/t gold, including one meter averaging 8,400 g/t gold.
• 15 meters averaging 493.2 g/t gold, including one meter averaging 7,360 g/t gold.
At Gossan Hill North, which lies about 750 meters north of North Block, one hole drilled by Newcrest during the first half of 2022 cut 30 meters averaging 28 g/t gold, including one meter averaging 717 g/t (23.1 oz/t) gold.
Newcrest tapped similar high-grade gold at Golden Marmot, an exploration target about 3,500 meters north of Valley of the Kings, including:
• 20 meters averaging 187 g/t gold, including 0.5 meters averaging 6,700 g/t gold.
• 38.5 meters averaging 27 g/t gold, including 0.5 meters averaging 1,925 g/t gold.
"Golden Marmot remains open to the east, north, and south, with the target displaying many geological features of the nearby Valley of the Kings deposit," said Biswas.
While exploring the golden potential Brucejack has to offer, Newcrest is heading underground at the Red Chris copper-gold mine about 85 miles (140 kilometers) to the north.
Operated under a joint venture with Imperial Metals Corp., which owns the remaining 30%, Red Chris is a large porphyry copper-gold operation that is currently being mined from the surface.
A 2021 prefeasibility study, however, details an underground block cave mining operation forecast to produce 4.9 million oz of gold and 1.5 million metric tons of copper from 406 million metric tons of ore over roughly 31 years of mining.
In preparation for this bulk tonnage underground mine, Newcrest is advancing an exploration decline that will provide a platform for underground drilling, as well as to potentially mine higher grade pods ahead of full-scale block caving.
A Red Chris block cave feasibility study, which includes the option for an electrified mine, remains on track for completion in the first half of 2023.
Inflation and global supply chain interruptions are also being considered as part of the feasibility study, and value engineering continues with the objective of offsetting inflationary cost pressures on the block cave operation.
Synergies with its newly acquired Brucejack Mine is expected to help offset some of the increased costs.
Newcrest foresees that streamlining the supply, logistics, travel, and procurement activities between its two Northern BC mines will result in C$20 to $30 million (US$16 to $24 million) in savings each year.
The block cave exploration decline could provide a better vantage for drilling East Ridge, a discovery zone not included in Newcrest's current mineral resource for Red Chris.
As of June 30, the open pit portion of Red Chris hosted 240 million metric tons of measured and indicated resources averaging 0.3 g/t (2.4 million oz) gold and 0.36% (880,000 metric tons) copper; plus 8.5 million metric tons of inferred resource averaging 0.25 g/t (69,000 oz) gold and 0.30% (26,000 metric tons) copper.
The underground portion of Red Chris hosts another 670 million metric tons of measured and indicated resources averaging 0.46 g/t (10 million oz) gold and 0.40% (2.7 million metric tons) copper; plus 180 million metric tons of inferred resource averaging 0.32 g/t (1.8 million oz) gold and 0.3% (540,000 metric tons) copper.
Much of Newcrest's 2022 drilling at Red Chris focuses on East Ridge; highlights include:
• 154 meters averaging 0.46 g/t gold and 0.47% copper.
• 222 meters averaging 0.44 g/t gold and 0.61% copper.
• 334 meters averaging 0.35 g/t gold and 0.5% copper.
• 312 meters averaging 0.49 g/t gold and 0.49% copper.
• 278 meters averaging 0.74 g/t gold and 0.44% copper.
• 284 meters averaging 0.75 g/t gold and 0.63% copper.
"The results of our East Ridge discovery at Red Chris continue to expand the higher-grade footprint," said Biswas.
The East Ridge mineralized corridor is 900 meters long, up to 1,000 meters thick and 125 meters wide, with several smaller pods with higher-grade mineralization
Newcrest has completed more than 300,000 meters of drilling at Red Chris since acquiring a 70% interest in the mine in August 2019.
Over his more than 16 years of covering mining and mineral exploration, Shane has become renowned for his ability to report on the sector in a way that is technically sound enough to inform industry insiders while being easy to understand by a wider audience.
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