Hundreds of demonstrators have gathered near Panama's governmental offices in recent weeks to protest the contract.

Major construction works will begin after the rainy season which is about to start, and will take three years to complete.

By mid-October, the throughput is planned to be increased steadily towards a goal of achieving steady state operations of 4,500-5,000 tpd by the end of 2023.

The overall message from the Australian government's commodity outlook is that evenly balanced risks translates into still robust volumes, but at lower prices.

Inventories of copper in LME-registered warehouses have surged 141% in the past three months.

Nearly 90% of union members voted to approve the agreement.