The underground operation is expected to achieve commercial production in the December quarter.

"Borden opens a new gold mining district in Ontario and profitably extends operations at the Porcupine complex near Timmins," said president Tom Palmer, who is set to also become CEO on October 1 to succeed retiring Gary Goldberg.

Borden ore will be taken 180km to be processed at Newmont's Timmins mill, where the Porcupine operations produced 275,000 ounces last year.

The Canadian and Ontario governments both granted C$5 million (US$3.8 million) towards Borden's electrification, to support the company's vision of a "safer, greener mining industry".

Palmer said the mine's electric underground fleet would eliminate diesel particulate matter from the underground environment and lower greenhouse gas emissions.

"This will help reduce energy costs, protect employee health and minimise impacts to the environment," he said.

The company said it had successfully built 11 new mines, expansions and projects on four continents on or ahead of schedule and at or below budget over the last six years, including the Tanami power project in Australia earlier this year.

Newmont shares are up about 18% year-to-date, having recovered from a dip following the Goldcorp merger in April and as the gold price has strengthened on geopolitical and global economic concerns.