Over an approximate 20-year mine life, the Santo Tomas project would have total payable copper production (in concentrate) of 4.75 billion lb.

The spill pumped 40,000 cubic meters of toxic mining acid into the Bacanuchi river in Mexico's northern Sonora state.

The Volcanic team discovered significant concentrations of bonanza-grade and visible gold within a 250 x 570-metre zone, at the prospect, notably in quartz veins.

Last week the miner suspended all operating activities at La Colorada after reporting an armed robbery involving two trailers of concentrate.

Researchers emphasized that many mines set to close soon don't have plans for future operations or transitioning to a post-coal economy.

The approval comes after extended negotiations over regulations concerning the Cobre Panama copper mine, which accounts for about 4% of Panama's GDP.

There were no physical injuries to personnel in connection with the incident.