SAGUENAY, Que. -- Rio Tinto says it's investing $250 million in its Vaudreuil alumina refinery in Quebec to extend the life of the operation past 2022.

The company says work on the refinery, located in the Saguenay region of the province, will include construction of a filtration plant and optimization at a site to manage bauxite residue.

The residue, also known as red mud, is what's left over after extracting the alumina from the bauxite and can include small amounts of toxic metals like arsenic and lead.

Rio Tinto says it's also looking to identify ways of getting value out of the residue, which in general is mostly made up of iron oxide, titanium dioxide, silicon oxide, and undissolved alumina.\

The company says the Vaudreuil refinery, built in 1936, supports more than 1,000 jobs and generates about $135 million in annual regional economic benefits.

The investment announcement in the Vaudreuil refinery comes as a strike continues at the ABI aluminum smelter in Quebec, 75 per cent owned by Alcoa and 25 per cent by Rio Tinto.