Rio Tinto Announces US$652 Million Investment in Continued Pre-Feasibility Studies on Deep Porphyry Copper Deposit in Arizona

Rio Tinto Announces US$652 Million Investment in Continued Pre-Feasibility Studies on Deep Porphyry Copper Deposit in Arizona

Monday, August 4th 2008

Rio Tinto has announced an investment of US$652 million (Rio Tinto share US$341 million) to support continued pre-feasibility studies on a large, tier-one copper deposit at its Resolution Copper Mining LLC (RCML) operation in Superior, Arizona.

Pre-feasibility studies are expected to be completed by 2012 with production at the new mine expected to start by 2020, eventually ramping up to 500,000 tonnes per annum of copper.

Rio Tinto is a significant global copper producer with high quality assets and an interest in four of the world’s ten largest undeveloped copper deposits, including Resolution*. In 2007, copper was the biggest contributor to Rio Tinto with underlying earnings of US$3.479 billion.

“Rio Tinto’s copper operations are in the first quartile of the cost curve and we are well positioned to take advantage of strong global demand, driven by continued growth in China and other emerging economies,” said Bret Clayton, chief executive, Rio Tinto Copper. “Resolution is an exciting prospect with an expected long mine life.”

Resolution Copper announced on May 29 that it had completed sufficient drilling on the deep porphyry copper deposit to report an Inferred Resource of 1.34 billion tonnes containing 1.51 per cent copper and 0.040 per cent molybdenum. Pre-feasibility work scheduled over the next four years includes dewatering a former mine site and sinking an exploratory shaft to 2170 meters below the surface, as well as preparing numerous studies to evaluate technical, legal and environmental issues and to prepare a mining plan. The plan will include an examination of geohydrology, transportation and infrastructure needs, and will confirm the best approach to constructing the proposed underground mine.

The total cost to complete studies of the deposit, determine the safest and most efficient mine development approach and evaluate all associated costs will be about US1 billion. Before these studies can be completed and the mine developed, Resolution Copper needs to own and manage surface lands above the mine and in the immediate surrounding area. In return for this land, Resolution Copper will transfer to the US government over 5,500 acres of high-priority conservation lands. Passage of the Southeast Arizona Land Exchange and Conservation Act, currently under review in the US Congress, will accomplish this goal, and will also benefit the Town of Superior, the region and the state of Arizona.

About Resolution Copper

Resolution Copper Mining (RCM) is a limited liability company owned by Resolution Copper Company (55%), a Rio Tinto plc subsidiary, and BHP Copper, Inc. (45%), a BHP-Billiton plc subsidiary. Resolution Copper Company, part of the Rio Tinto Group, is the manager of RCM. The project is located in the historic mining district about five kilometres east of Superior, Arizona.

* The other three major undeveloped copper resources in which Rio Tinto has an interest are La Granja in Peru, Oyu Tolgoi in Mongolia and Pebble in Alaska.

About Rio Tinto

Rio Tinto is a leading international mining group headquartered in the UK, combining Rio Tinto plc, a London and NYSE listed company, and Rio Tinto Limited, which is listed on the Australian Securities Exchange.

Rio Tinto’s business is finding, mining, and processing mineral resources. Major products are aluminium, copper, diamonds, energy (coal and uranium), gold, industrial minerals (borax, titanium dioxide, salt, talc) and iron ore. Activities span the world but are strongly represented in Australia and North America with significant businesses in South America, Asia, Europe and southern Africa.

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