While the financial details of the transaction were not disclosed, Walter confirmed in March that it had successfully negotiated the lease of 75 million tons of recoverable Blue Creek coking coal in Tuscaloosa County.

Terms of the new leases include royalty rates consistent with existing coal lease agreements.

"We are happy with the opportunities these leases present to grow our reserve base and expand our footprint in Alabama," Walter Energy chief executive officer Keith Calder said.

"These reserves are an integral portion of the last remaining block of Blue Creek coal reserves and pave the way for a strategic opportunity to assemble approximately 170 million tons of high quality coking coal reserves for the development of a new underground longwall coking coal mine."

Walter also completed the takeover of the state’s third largest underground operation, the North River steam coal mine in Fayette and Tuscaloosa County. It already owns the state’s two largest mines, the No. 4 and No. 7 operations.

Total consideration for North River included a small cash payment as well as assumption of certain liabilities not material to the company.

Walter said the deal is expected to be neutral to slightly accretive to earnings in the first year.

"The North River steam coal mine has approximately three years of production remaining, all of which is under contract to local utilities," Calder said.

"Importantly, the operation has approximately 350 skilled and experienced miners, whom we'll be very happy to welcome into the Walter Energy Alabama team."