Some mining companies (including BHP and RIO) that have relied mostly on surface mining are now...

|About: BHP Billiton Limited (BHP)|By:, SA News Editor

Some mining companies (including BHP and RIO) that have relied mostly on surface mining are now going deeper, allowing them to continue using mining, processing and transport infrastructure even after the surface deposits are depleted. New technologies and the high price of commodities are making the unusually-deep mines financially feasible, but going deeper isn't without its risks.