Mining and commodity trading giant Glencore (LON:GLEN) has kicked off the process to sell its Australian copper mine in Cobar, New South Wales, and its Lomas Bayas copper mine in the Atacama desert in Chile.
According to the BBC, Glencore said it has received a number of unsolicited expressions of interest for the mines and that potential buyers can bid to purchase "either one or both of the mines and may or may not result in a sale".
Cobar produces roughly 50,000 tonnes copper concentrate per year while the Lomas Bayas open pit's output is 75,000 tonnes of refined copper. Together the mines could fetch anything between $500m and $1 billion.
These mines are over and above the asset sales, share offerings and other money raising efforts detailed by the Swiss-based company as part of its plans to reduce its crippling debt load by $10 billion over the near term.
Glencore is also said to be in advanced talks to sell future production of by-product precious metals at three of its copper mines in Chile and Peru.
The firms involved in the negotiations are said to leading streaming companies Franco-Nevada Corp (TSE:FNV), Silver Wheaton (TSE, NYSE:SLW), Royal Gold Inc. (TSE:RGL) and two other unnamed miners.
The deals involve Glencore's Collahausi mine in Chile, as well as Antamina and Antapaccay copper mines in Peru.
Collahuasi, one of the world's largest copper mines, produced around 470,000 tonnes of copper last year, or about 8% of Chile's total output.
In the first half of 2015, production at the mine - a joint project of Glencore, Anglo American (LON:ANGLO) and several Japanese firms - fell 10% compared to the previous year, impacted by maintenance at a processing mill and other factors.
Antamina mine, located in Peru's central Ancash state, is the country's top copper producer by output, and it also yields zinc, lead, and silver.