June 30, 2025 - Core Natural Resources, Inc. has provided an update on its ongoing efforts to resume longwall operations at its Leer South mine following a combustion-related event at the mine in mid-January. Consistent with the previously provided timeline, Core personnel and regulatory officials re-entered the sealed area of the mine on June 10^th, and thereafter re-established ventilation to the full mine, restored hydraulic pressure along the longwall face, and conducted an extensive evaluation of the major equipment and infrastructure. As expected, the longwall was largely unaffected by the combustion event and major components and systems remain in good condition.

On June 26^th, after more than two weeks in the mine, the operating team found it necessary to evacuate the mine and begin restoring pumpable seals to the affected area in the wake of an increase in carbon monoxide levels. The Core team is working closely with federal and state officials on a plan to recover and reposition the longwall equipment in an effort that is expected to be completed within four months.

“The Core team continues to do an admirable job of addressing the situation at Leer South in a safe and efficient manner, and we want to again thank federal and state regulatory officials for their invaluable assistance,” said George J. Schuller Jr., Core’s senior vice president and chief operating officer. “While recent developments are expected to delay the restart of the longwall, we are encouraged by the condition of the mine and related infrastructure, and optimistic about the prospects of resuming longwall production during the fourth quarter.”

“Core maintains a property damage / business interruption insurance program and placed insurance carriers on notice immediately after the Leer South event occurred earlier this year,” said Mitesh Thakkar, Core’s president and chief financial officer. “Core has kept the carriers updated on developments to date and anticipates an insurance recovery in excess of $100 million.”

Core is reiterating its 2025 coking coal sales volume guidance despite the delayed restart of the Leer South mine and expects to provide a more detailed update on ongoing efforts at Leer South in its second quarter earnings release in early August.

About Core Natural Resources, Inc.

Core Natural Resources, Inc. (NYSE: CNR) is a world-class producer and exporter of high-quality, low-cost coals, including metallurgical and high calorific value thermal coals. The company operates a best-in-sector portfolio, including the Pennsylvania Mining Complex, Leer, Leer South, and West Elk mines. With a focus on seaborne markets, Core plays an essential role in meeting the world’s growing need for steel, infrastructure, and energy, and has ownership interests in two marine export terminals. The company was created in January 2025 via the merger of long-time industry leaders CONSOL Energy and Arch Resources and is based in Canonsburg, Pennsylvania.