The Indiana-based producer submitted requests for permits, Vigo operations president John Harman told Platts.

Unlike two of the company’s existing operations that sell the majority of their coal to aluminium producer Alcoa, Harman said the proposed Sunna mine had a number of output options, including selling coal to overseas markets.

"It just depends, whatever opportunities present themselves," he said.

"We're pursuing the permits and once we have the permits in hand we would try to develop the market for Sunna.

"If we can bring it online and make money, we'll do that."

If not, Vigo will hold onto the permits until market conditions improve.

The market for traditional high-sulfur Illinois Basin steam coal appeared to have "stabilized”, Harman told Platts.

Increasingly, coal companies in the region were looking to augment sales by exporting coal to Europe, Asia and South America, he noted.

Harman said the Sunna mine would probably produce around 600,000 tonnes a year if approved.

Vigo has six active mines in Illinois and Indiana, producing more than 2 million tons of coal per year.