The mining newspaper for Alaska and Canada's North
North of 60 Mining News – October 28, 2022
Newcrest Mining Ltd.'s Red Chris and Brucejack mines in British Columbia's Golden Triangle produced 101,636 ounces of gold and 19.2 million pounds of copper during the third quarter of 2022.
The precious and base metals output at the Australia-based company's two Northern BC operations, however, was overshadowed by an Oct. 22 fatality at Brucejack, the newest addition to Newcrest's portfolio.
"This week a colleague and team member from our mining and development contractor, Procon, was involved in a critical incident while working underground at our Brucejack operation," said Newcrest Mining CEO Sandeep Biswas.
Newcrest, which is focused on supporting those impacted by the fatal incident and assisting with the ongoing investigation, has suspended operations at Brucejack until further notice.
"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 added.
Since gaining ownership of Brucejack through its March acquisition of Pretium Resources Inc., Newcrest has been focused on unlocking the full potential of its new high-grade underground gold mine and the district-scale property it is located on.
The initial step of a three-phase plan to accomplish this is the implementation of the Australian mining company's NewSafe safety and critical control management programs to provide a framework for the next evolution of safety at Brucejack.
Despite the introduction of this program aimed at eliminating life-changing injuries and fatalities, the rate of recordable injuries at Brucejack was 7.41 incidents per 1 million hours during the third quarter.
The circumstances around the fatal incident, which occurred after the end of the quarter, have yet to be reported.
In addition to NewSafe, Newcrest continued to advance the three-phase transformation program at Brucejack.
The initiatives under this program include bringing on technologies such as underground mine dispatch and communication systems to improve equipment monitoring; adoption of semi-autonomous and autonomous mining equipment; asset health monitoring systems; and an assessment of 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 Brucejack mill throughput rate 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.
A debottlenecking study to investigate this potential is expected by year's end.
In addition to on-site optimizations at Brucejack, Newcrest is leveraging cost-saving synergies with its 70% owned Red Chris copper-gold mine about 85 miles (140 kilometers) to the north.
The company 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.
Brucejack produced 84,123 oz of gold from ore averaging 7.5 grams per metric ton gold during the third quarter of the calendar year and the first quarter of Newcrest's fiscal year 2023.
Newcrest's original FY2023 guidance for Brucejack was 320,000 to 370,000 oz of gold. The current mine shutdown could cause a lowering of this outlook.
As part of its work to unlock greater value at Brucejack, Newcrest has been carrying out an intensive drill program across its recently acquired high-grade gold property.
The company says the drilling carried out during the third quarter continued to confirm the resource growth potential surrounding the Valley of the Kings deposit currently being mined and at targets across the wider property.
Going into 2021, Valley of the Kings hosted 11.5 million metric tons of proven and probable reserves averaging 8.7 g/t (3.2 million oz) gold and 9.8 g/t (3.6 million oz) silver.
Newcrest has yet to report a new Brucejack resource.
An extensive exploration program carried out by Pretium during 2021 delineated several expansion targets immediately surrounding Valley of the Kings and discovered bonanza-grade gold at exploration targets across the larger property.
Newcrest is following up on this work with expansive drilling at Brucejack, including an 89,000-meter program slated for 2022.
"Brucejack is very early in its mine life and offers significant exploration upside with the land package largely unexplored," Biswas said earlier this year.
Third-quarter drilling at 1080 HBx Zone has expanded Valley of the Kings and confirmed the continuity of the higher-grade mineralization at depth and to the south of the deposit.
Newcrest reports that intercepts of greater than 5 g/t gold were cut in 22 of 44 holes drilled at 1080 HBx during the quarter. Highlights include:
• 70.1 meters averaging 35 g/t (1.1 oz/t) gold in hole VU-4331, including one meter of 2,310 g/t (74.3 oz/t) gold.
• 22 meters averaging 178 g/t (5.7 oz/t) gold in hole VU-4546, including one meter of 3,876 g/t (124.6 oz/t) gold.
Newcrest also reported additional high-grade gold intercepts at Golden Marmot, an exploration target about 3,500 meters north of Valley of the Kings, including:
• 91.5 meters averaging 9.1 g/t gold in hole SU-879, including 1.5 meters of 514 g/t (16.5 oz/t) gold.
• 46.5 meters averaging 16 g/t gold in hole SU-888, including one meter of 488 g/t (15.7 oz/t) gold.
"At Brucejack we returned several high-grade intercepts during the quarter, supporting our views for significant resource growth potential. 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.
Red Chris, which is owned by a joint venture between Newcrest (70%) and Imperial Metals Corp. (30%), produced 19.2 million lb of copper and 17,513 oz of gold during the third quarter.
Both gold and copper production were down from the previous quarter.
The drop in gold production was due to lower recoveries and mill throughput, and the roughly 13% drop in copper output was due to lower-grade ore and mill throughput.
Mined grades for copper and gold are expected to decrease with mining now complete in phase five of open pit mining.
Newcrest, however, continues to make progress on its plans to convert Red Chris to an underground block cave mining operation.
A prefeasibility study published about a year ago details a block cave mine at Red Chris 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.
As of Oct. 12, Newcrest had extended the development of a 3,500-meter exploration decline to 2,181 meters, and the first ventilation raise bore has begun.
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 to offset inflationary cost pressures on the block cave operation.
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.
During the third quarter, Newcrest had up to seven drill rigs focused on the discovery of additional zones of higher-grade mineralization, including targets outside of this resource.
The company reports that all 27 holes drilled during the quarter cut gold-copper mineralization.
Highlights from drilling at East Ridge include:
• 222 meters averaging 0.44 g/t gold and 0.61% copper from a depth of 818 meters in hole RC808.
• 334 meters averaging 0.35 g/t gold and 0.5% copper from a depth of 1,276 meters in hole RC819.
• 312 meters averaging 0.49 g/t gold and 0.49% copper from a depth of 1,296 meters in hole RC820.
• 278 meters averaging 0.74 g/t gold and 0.44% copper from a depth of 1,658 meters in hole RC820.
• 284 meters averaging 0.75 g/t gold and 0.63% copper from a depth of 1,295 meters in hole RC835.
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
"The results of our East Ridge discovery at Red Chris continue to expand the higher-grade footprint," said Biswas.
With the 20,926 meters of drilling during the third quarter, Newcrest has completed 286,300 meters of drilling at Red Chris since acquiring a 70% interest in the mined in August 2019. The Australian company plans to complete nearly another 30,000 meters during the fourth quarter.
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