Redesigning success: Inside Musselwhite’s bold stope overhaul that ended failures, increased output, and redefined deep mining performance

At the AusIMM Underground Operators Conference 2025 in Adelaide, Newmont Principal Advisor, Technical Planning Systems Ismail Ozen delivered a rare blend of candour and insight as he unpacked the dramatic turnaround of stope performance at Musselwhite Mine.

Rather than showcasing triumphs, he began by outlining failure: “We experienced four significant stope failures in PQ Deeps in 2021 and early 2022,” he told delegates. “It was clear we needed a reset—fast.”

Located 500 km north of Thunder Bay, Ontario, Musselwhite is a long-running fly-in/fly-out gold mine that has produced more than 6 million ounces over its 25+ year history.

At its core lies the PQ Deeps (PQD) orebody, a structurally complex zone with variable dip angles and foliated hanging wall rock. As Ismail explained, this deep, high-stress seismically active ore zone had become the site of recurring transverse stope failures—some propagating across multiple levels, causing extensive delays, collapses and production losses.

But what followed was one of the most rigorous optimisation programs in Canadian underground mining. The result: recovery lifted to 95 percent, daily production increased, and failure events were eliminated.

When Everything Fails

The failures weren’t isolated—they were systemic. “Hanging walls caved in. Undercuts collapsed. Recovery was chaotic. The whole stoping system needed to be rebuilt,” Ismail said.

Flat-back geometries, massive toe shots and large unsupported spans were at the heart of the issue. Compounding the problem, stope sequencing had drifted away from geotechnical best practices, while the backfill system was plagued by months-long delays. The mine’s access and infrastructure, situated in the hanging wall, further limited design flexibility.

“We weren’t just dealing with weak rockmass,” said Ismail. “We were working against our own legacy designs.”

Rewriting the Rules: A New Stope Design

The solution began with a simple but radical step: eliminate all rectangular flat-back stope shapes. Instead, the team introduced angled shoulders to increase confinement and reduce stress concentrations. Primary and secondary stopes were differentiated in design, and massive toe shots were replaced by more controlled, arched firing patterns.

“Those big undercuts created huge back spans and set off failure chains,” he explained. “So we changed everything from how we shaped the stopes to how we sequenced the blasts.”

T-Drifts Over Wing Slashes

A major breakthrough came with the replacement of wing slashes—used to widen stopes from crosscuts—with T-drifts: stable crosscuts extending through the orebody. This not only reduced unsupported span exposure but also improved drilling precision and allowed stope drilling with production rigs rather than jumbos.

“The old method was creating voids we couldn’t control. The T-drift redesign eliminated that risk entirely,” Ismail said.

Ground Control: Going Deep

Musselwhite’s ground control was rebuilt from the ground up—literally. Cable bolt length was increased from five to ten metres, with orientation now matched to the rock’s foliation. In some areas, support density doubled.

Shotcrete arches were added, QA/QC on support materials was tightened, and installation was guided by high-resolution geotechnical scanline mapping.

“We stopped using cookie-cutter support layouts,” said Ismail. “Now every zone gets support tailored to the actual stress regime and foliation angle.”

Stress Management Through Blasting

To manage stress concentrations in the deeper levels of the mine, Ismail’s team introduced pre-conditioning rings in the footwall and buffer rings in the hanging wall.

Pre-conditioning rings were drilled densely and blasted ahead of stope production to create a stress-relief curtain, improving fragmentation and reducing strain transfer.

Buffer rings, installed just inside the hanging wall edge, absorbed blast energy and minimised overbreak.

“These rings allowed us to mine with precision in areas where failure risk had previously been too high,” he said. “It’s the biggest game changer in our high-stress zones.”

From Skepticism to Success: Double-Lift Stoping

With confidence building, the team trialled double-lift stoping—a bold move in an environment previously plagued by collapse. The 58-metre-high trial stope achieved 97 percent recovery and less than 5 percent dilution.

“When I suggested it, the team thought I’d gone mad in the -40 degree weather,” Ismail joked. “But it worked. And now it’s used for most of the primary stopes at the lower levels.”

Numbers That Tell the Story

The turnaround is evident in the metrics:

• Daily production increased from 600–700 t/d to nearly 2,000 t/d in peak stopes.
• Redrill rates dropped from 20 percent to below 10 percent.
• Recovery improved from as low as 70 percent in 2021 and 2022 to over 95 percent.
• Dilution, once averaging 30 percent, fell to under 10 percent, with several stopes achieving 5 percent or less.

“Best of all, we’ve had zero stope failures since implementing these changes,” said Ismail.

Lessons for the Industry

Ismail concluded his presentation with a direct message to peers facing similar structural challenges.

“If you’re mining from the hanging wall, with variable dips and seismicity, don’t accept failure as normal. Redesign your geometry. Improve your sequencing. Take ground control seriously. We didn’t invent a new method—we just did the fundamentals, properly, every single time.”

His talk stood out not just for the technical insights, but for its honesty. “This wasn’t about being clever—it was about discipline, and about putting the right systems in place. And above all, collaboration between tech services and operations made it work.”

Musselwhite’s story is a powerful reminder that transformation underground often begins with the courage to stop, reassess—and do things differently.