The new addition will allow Cleveland-Cliffs to further diversify its participation in the steelmaking materials industry.

“When combined with our Australian coking and thermal coal operation, the Sonoma Project, the company will control a 10 million ton position, with the majority being for export," Cleveland-Cliffs chairman, president and CEO Joseph Carrabba said.

“It marks yet another step in the execution of our strategy to deepen Cliffs' exposure to faster growing international markets and further diversify its mineral sales."

PinnOak's operations include two complexes comprising three underground mines: the Pinnacle and Green Ridge mines in southern West Virginia, and the Oak Grove mine in Alabama.

The Pinnacle mine boasts the only longwall plow system in the US, and combined, the mines have the capacity to produce in excess of 7Mt of premium-quality metallurgical coal each year.

“We are excited to welcome the PinnOak team to the Cliffs organisation as they provide a depth of experience and an additional growth platform consistent with the company's strategic objectives,” Carrabba said.