GILLETTE, Wyo. (AP) — U.S. regulators plan to finish reviewing a proposed coal mining joint venture in the first half of 2020.

Peabody Energy Corp. and Arch Coal Inc. seek to merge operations in Wyoming and Colorado. The St. Louis-based companies operate some of the world's largest coal mines in northeast Wyoming.

The companies expect to save $120 million a year over the first 10 years of working together.

Peabody officials disclosed the Federal Trade Commission review timeline in an earnings call Tuesday. CEO Glenn Kellow calls the joint venture the centerpiece of Peabody's future U.S. coal operations.

The U.S. coal industry is struggling with decreased demand as utility companies rely more on natural gas and renewable energy to generate electricity.

The Gillette News-Record reports Peabody posted a third-quarter loss of $74 million.