Ottawa is giving $12 million to help a company extract magnesium from the waste of closed asbestos mines despite warnings from Quebec's public health officers that the province's workplace protections are still lacking.

The federal funding for Alliance Magnesium comes a day after Ottawa unveiled its national ban against the use, import or export of deadly asbestos, which carves out an exemption for mining residues.

Alliance Magnesium has developed technology to extract magnesium from the more than 800 million tonnes of asbestos tailings near the now-closed mines in the Quebec towns of Thetford Mines and Asbestos.

Company president Joel Fournier tells The Canadian Press the technology involves destroying the asbestos left in the tailings in acid, and says workers are well protected during the process.

However, the public health directors of all 18 Quebec health regions warned Environment Minister Catherine McKenna earlier this year that exempting mine residues from the asbestos ban was risky without proper workplace safety standards in place.

The Quebec standard, they say, allows for asbestos exposure that is 10 times greater than the national standard and 100 times greater than standards in many European countries.