Glencore claims Mt Isa mine assets are no longer viable due to declining ore grades and geological constraints.

Glencore has announced that it will end production at the Mt Isa Mines underground copper operations in Queensland, Australia in H2 2025 after 60 years in operation. The operation is composed of the Enterprise, X41 and Black Rock underground mines in addition to the copper concentrator. At the same time, it will close its Lady Loretta zinc mine 140km north-west of Mt Isa. Glencore also confirmed that the Mount Isa Mines’ other metals assets including the copper smelter, George Fisher Mine, zinc-lead concentrator, and lead smelter in Mt Isa, along with the copper refinery in Townsville, will all continue operating.

Glencore revealed that the past six years have been especially challenging with falling production and declining grades making the Mt Isa Mines operation increasingly uneconomical. Despite this, the mines produced 191.6kt Cu-in-cathode in 2022 and the operation is the country’s second-largest copper producer. Glencore had explored the option to extend the life of the underground copper mines, but this was not feasible due to mines reaching the end of life.

Australia is an important contributor to global copper production. According to the USGS, Australia accounts for just over 10% of the world’s copper reserves and an estimated 4% of mine production in 2022. The Mt Isa operation is not unique in struggling with the combined impacts of declining ore grades and rising production costs, with some of the world’s largest copper mines suffering from dwindling reserves. As a result, producers are slowing production and initiating large, capital-intensive projects to move operations underground. BHP was recently reported to be considering such measures at its Escondida operation in Chile to counter the effects of declining concentrator feed grades in future.

Copper will play an integral role in the energy transition and supporting technologies. In the face of such challenges to the industry, considerable investment will be required to avoid a widely anticipated future market deficit.