http://www.miningaustralia.com.au/home
Are we entering the last age of the open cut mine? Is the end of open pit mining near? Speaking to a number of sources, the answer is clearly no, but as grades decrease and deposits become deeper, the increase of underground mining will continue apace as older open cut mines are worked out and new, deeper deposits are discovered.
Underground mining will soon count for a much larger proportion of total mining. According to a Rio Tinto seminar in 2010, in 2009 underground operations accounted for 26 per cent of all copper production, however Rio forecast that by 2025 underground operations would account for 40 per cent of global copper production.
This included major copper producers such as Chile and Australia, where massive open cut pits are the norm. But this is not to say open cut mining has been uneconomical. Surface mining has been, for some time, the most economical form of mining in Australia.
Underground contract mining specialist Pybar’s group business development manager David Noort told Australian Mining “open cut mines have been, economically, the most viable, which has been due to relatively near surface expressions”.
With wide open spaces and often remote locations, it has been the more cost effective form of mining, but globally it has already started coming to an end, with Noort explaining that “many of these higher grade expressions close to the surface have already been discovered, so we are left chasing ore down”.