Core Natural Resources Recovers, Restarts Key Mine After 11-Month Halt

CANONSBURG, PA – December 18, 2025 – Core Natural Resources (NYSE: CNR) announced today it has successfully resumed longwall mining at its pivotal Leer South metallurgical mine, marking the end of a difficult eleven-month shutdown that has weighed heavily on the newly-formed coal giant's finances throughout 2025. The restart, coupled with stabilizing performance at another key mine, positions the company for a significant operational and financial recovery heading into the new year.

The announcement represents a critical turning point for Core, which was created in January 2025 through the landmark merger of industry titans CONSOL Energy and Arch Resources. The company's inaugural year was immediately tested when operations at the West Virginia mine were halted on January 13, 2025, after a combustion event was detected in a sealed, previously mined section.

"On behalf of the entire board and management team, I commend the operations team for making safety their highest priority in the successful recovery, repositioning, and restart of the longwall system," said Jimmy Brock, Core's chairman and chief executive officer, in a statement. "Leer South is a highly strategic asset, and we fully expect this world-class operation to execute at a high level in 2026 and beyond."

The Long Road to Recovery

The path to restarting Leer South was a complex and methodical process underscoring the inherent risks of underground mining. The incident was not a sudden explosion but a smoldering fire deep within a worked-out area, requiring a delicate and safety-focused response. The company spent months working in close collaboration with federal, state, and local regulatory bodies, including the Mine Safety and Health Administration (MSHA).

Initial re-entry efforts began on June 10, 2025, allowing teams to re-establish ventilation and inspect the mine. Critically, the major longwall mining equipment—including 209 massive hydraulic roof shields, the face conveyor, and the shearer—was found to be in surprisingly good condition despite the prolonged inactivity. However, the recovery hit a snag later that month when elevated carbon monoxide levels were detected, prompting an immediate evacuation and the decision to temporarily reseal the mine. This setback pushed the restart timeline into the fourth quarter.

Throughout the process, the company's operational leadership emphasized a safety-first approach. "The Core operations team has displayed tremendous professionalism, dedication, and – most importantly – the highest commitment to safety throughout this process at Leer South," stated George Schuller Jr., Core's senior vice president and chief operating officer. Following the successful recovery of the equipment, the affected area was permanently sealed, a standard industry practice designed to inert the atmosphere and eliminate any future risks from the original combustion event.

A Year of Financial Headwinds

The operational challenges at Leer South, along with a difficult geological transition at its West Elk mine in Colorado, created significant financial headwinds for Core throughout 2025. The company reported a net loss of $69.3 million in the first quarter and another $36.6 million loss in the second. These figures were burdened by direct costs for fire suppression and idle mine expenses at Leer South, which amounted to $21.2 million in Q2 and another $18.4 million in Q3.

The metallurgical segment's costs per ton rose, reflecting the loss of production from one of its most efficient mines. The company managed to post a small net income of $31.6 million in the third quarter, aided by an initial insurance recovery of $19.4 million related to the Leer South incident. Core has stated it expects total insurance recoveries for property damage and business interruption to ultimately exceed $100 million, which will provide a substantial financial cushion and offset a portion of the losses incurred.

Forging a Giant Amidst Crisis

The operational crisis at Leer South unfolded just as Core Natural Resources was navigating the complex integration of its two predecessor companies. The merger was designed to create a world-class producer of both metallurgical coal for steelmaking and thermal coal for power generation, with a diversified portfolio of low-cost mines and an extensive logistics network, including ownership in two East Coast export terminals.

Management projected the combination would generate annual synergies between $110 million and $140 million. Despite the operational difficulties, the integration process appears to have exceeded expectations on this front. By mid-2025, Core had increased its annual synergy target to a range of $150 million to $170 million, citing greater-than-expected efficiencies in administrative costs, procurement, and logistics. However, some market analysts have noted that while SG&A synergies are materializing, the anticipated margin growth from combining the powerful asset bases has yet to fully translate to the bottom line, partly due to the operational issues in 2025.

A Brighter Outlook for 2026

With its two major longwall mines now poised for consistent production, Core's leadership is forecasting a sharp turnaround. The company expects a "significant step-up" in financial performance for 2026, driven by a confluence of positive factors. The primary driver is the resumption of high-volume, low-cost production from Leer South. This will be complemented by improved productivity at the West Elk mine, which has completed its transition into a new, more favorable coal seam.

Financially, the company's bottom line will see a multi-faceted boost. The cessation of the heavy fire-suppression and idling costs, which dragged down earnings in 2025, will provide immediate relief. Furthermore, the expected influx of substantial insurance payments and the full-year benefit of the increased merger synergies are projected to significantly enhance profitability and cash flow.

This recovery comes as the global metallurgical coal market remains a cornerstone of industrial production, even as demand forecasts for the broader coal sector suggest a period of stability rather than rapid growth. By restoring its operational capabilities, Core Natural Resources is reasserting its position as a reliable supplier to the global steel industry and aims to finally demonstrate the full strategic and financial power envisioned by its formative merger.