US-focused Resolution Copper has completed the $200-million rehabilitation and deepening of its historic No. 9 Shaft in Arizona.

Originally constructed in 1971 by Magma Copper Company and used as a production shaft until the mid-1990s, the refurbished shaft now reaches a final depth of 2 103 m – nearly five Empire State Buildings tall – with a diameter of 6.7 m. It is the second-deepest single-lift mine shaft in the US, behind only Resolution Copper’s No. 10 Shaft at 2 118 m.

The No. 9 Shaft, rehabilitated and deepened from 1 463 m, now connects to No. 10 Shaft to serve as ventilation and access for future underground development. Together, the shafts form the backbone of the next phase of underground work, laying the foundation for future copper production to strengthen the domestic supply of critical minerals.

“Completing the No. 9 Shaft is a huge milestone and a testament to the dedication and expertise of our underground team and contracting partners,” said Vicky Peacey, president and GM of Resolution Copper. “While ongoing litigation continues to stall development, we are ready to advance this important copper project, enabling thousands of high-paying jobs, billions in economic development for rural Arizona, and access to a domestic supply of copper essential to American security and modern infrastructure. The sooner the litigation delays stop, the sooner this project can move forward, and the sooner Arizona and the nation will benefit.”

The shaft project also achieved two years without a single medical injury or lost-time incident. Crews drilled nearly 4 420 m, poured 430 m³ of concrete, and installed about 128 m³ of shotcrete.

“Achieving this safely for more than two years without a recordable injury shows the professionalism and dedication of everyone who worked underground to bring No. 9 back to life in a modern way,” said operations manager Rob Tobin.

Redpath USA led the sinking and construction work, with Globe-based Oddonetto Construction supporting concrete and logistics operations.

Resolution Copper, operated by a joint venture between Rio Tinto (55%) and BHP (45%), aims to develop one of the largest undeveloped copper deposits in North America.