Vale's Voisey's Bay nickel mine in Labrador had leaked glycol earlier this week, CBC News reported.
Glycol is used to cool Voisey's Bay power plant and heat the facility, Vale told the news agency.
The leak has now been contained and cleanup has begun, the Brazilian company said.
"There was no risk to employees and our initial assessment shows it was contained to surface areas with no impact to any water bodies," company spokesman Jeffrey Lewis told CBC in a statement.
Vale said it would report the leak to regulatory agencies.
Work was temporarily suspended on Wednesday but has no resumed, he added.
The leak was said to have impacted the on-site medical clinic, but Vale did not expand on this.
Vale began work to transition from open-pit to an underground mine in 2018, extending mine life by 15 years.
The company produced its first ore at the extension in June 2021. The underground mine is expected to produce 40,000 tonnes of nickel in concentrate at a peak production rate of 2.6Mt per year.
The metals are processed at the hydrometallurgical facility in Long Harbour, Newfoundland.
Vale has been producing nickel from Voisey's Bay since 2005.