May 5, 2012 – Blackhawk Colorado, United States – (Kazor.com) - Two of the biggest mining firms in the world, Rio Tinto PLC and BHP Billiton Ltd are teaming up to invest over USD 4 billion to boost their copper output, according to their announcement on Tuesday. Rio and BHP have staked their investment on a high copper demand worldwide as they approve plans for USD 4.5 billion expansion...