Copper

Rio Tinto (ASX:RIO) and Ivanhoe Mines said they are unprepared to renegotiate their investment in Mongolia's Oyu Tolgoi project. The two miners formally responded to a letter from the Mongolian government inviting them to a discussion of potential changes to the deal.

Ivanhoe and Rio also sent letters to the members of Mongolia's National Security Council requesting support for the 2009 standing agreement.

Mongolia wants to up its stake in Rio Tinto (ASX:RIO) and Ivanhoe Mines' Oyu Tolgoi copper project to 50 percent from 34 percent. But under the agreement with Rio, such an increase is possible only after 30 years.

"We have sent the proposal to Ivanhoe to renegotiate the timeframe for us to increase the government stake," said Mongolia's Minister of Mineral Resources and Energy Dashdorj Zorigt.

Rio Tinto (ASX:RIO) and Anglo American are planning to sell their stakes in South Africa's Palabora mining so they can focus on bigger assets. The two companies currently own about three quarters of Palabora Mining Co.

Rio said it will sell its 57.7 percent stake in Palabora while Anglo American said it will sell its 16.8 percent stake. According to Liberum, South Africa's largest copper producer contributed 8 percent of Rio's mined copper output in the first half of 2011.

Oz Minerals (OZM) has released information that it expects gold production to increase over the period to 2012 while production costs expected to fall due to increased production. The company's shares jumped almost 4 percent on the announcement by Terry Burgess, the Chief Executive of OZM.

The company expects gold production to rise from previous guidance of between 80,000-90,000 ounces to 110,000-120,000 ounces a year. Copper guidance over the same period was unchanged at 100,000-110,000 tonnes a year.