Mine operator BHP had said earlier in the week that terms had been reached but the union needed to vote on the new pact.

We have managed to defend all of our benefits and we have been able to move forward on the relevant issues that have been long postponed," the union said in a statement, adding that the proposal received 93 percent approval.

The company issued a statement saying the agreement "satisfies both workers and their families, as well as the need for Escondida to be sustainable over time."

The negotiations took place just over a year after the failure of a labor agreement that led to a historic 44-day strike at the mine, which shook the international copper market.