The Jakarta-based Adaro also generated $210 million from its domestic mining, while other revenues accounted for $73 million. Coal prices declined last year amid a global supply glut from Africa and the U.S.—where the industry faces both harsh Washington regulations and steep competition from an emerging natural gas sector.

Slowing demand from China, Indonesia’s largest export market, also pushed coal prices lower. The archipelago nation sits atop more thermal coal than any other country and was one few nations to emerge unscathed by the global recession—largely thanks to its coal, metal and mineral exports.