Mining News - Either Teck or the 106-member union, which comprises 24 percent of the mine’s workforce, may still opt for a period of government-facilitated mediation before a strike begins.

“The last offer by the company was rejected and a strike was approved with 92 percent of votes,” said Jorge Flores, the president of the group, called Union 1.

The mine’s remaining unions earlier this year opted to extend their contract for 15 months, leaving negotiations until 2018.

Quebrada Blanca has produced 17,300 tonnes of copper so far this year. Chile is the world’s top copper producer.