The company that owns the Tara zinc mine in Co Meath has identified a new mineralisation that will see the capacity for production continue well into the next decade.
Boliden had indicated that the lifespan of the mine was limited to 2020, but the decision to extend the tailings dam could see production continue at current levels until 2026.
The new investment, totalling €33m, will be conditional on obtaining the necessary permits.
Tara accounts for half of Boliden's production of zinc concentrate.
"Tara's exploration work in the last few years has been successful, and the capacity of the tailings dam is now limiting the life-of-mine to 2020," Mikael Staffas, the President of Boliden Mines, said.
"New exploration successes, increased productivity, and high zinc prices make extending the mine's lifespan a profitable option, so we have decided to expand the tailings dam with a capacity until 2026."
The mine, which is located just outside of Navan, is Europe's largest and the world's ninth largest zinc mine.
It currently employs over 600 people.