Here's the deal on block caving mining methodBlock cave mining is an underground mass mining method that allows for the bulk extraction of large, relatively lower- grade ore deposits with substantial vertical dimension. In block caving, a large section of ore is initially undercut by drilling and blasting, creating a large unsupported roof that will start to collapse under its own weight and instability, The broken ore then breaks apart and falls into a series of pre-constructed funnels, or drawbells, and access tunnels developed underneath the caving rock mass to form ore extraction drawpoints.
I have also read where this can be done for $5-10 a tonne.
Anyone with technical expertise feel free to comment. I'm a number guy (bach of commerce-finance major)