How do they start a mine shaft? My town is riddled with ex-mines, many from centuries ago. Before the advent of TNT and mechanical diggers, was it just a case of them digging straight down? How would miners go about starting a completely new shaft today?
Many mines I have seen enter the ground where it is sloped fairly steeply. A likely scenario is that due to erosion, there was an outcropping of whatever they were mining for (or something that indicated it’s presense) and they just started digging into it.
Before machinery many mines were known as drift mines, where an outcropping of mineral was followed into the rock, and worked along the seams. Later on, when vertical lifting equipment was cheap and reliable enough, people would also drill core samples, or else just guess, and then start digging down.
I’m a consultant to a client who is working on building a new mine on their property right now. They have taken numerous core samples to map out where they think the most likely highest density of coal is, with the best qualities, and when they find the right entry point they are going to start digging a very long set of shafts down at an angle (I think about 20 degrees) until they hit the main seam about 120m below the surface.
As an aside, about 70% of coal (by mass) in the US is produced from surface mines, and I think this rises to 80% worldwide. I’d need to check my notes to see.
By making a gap of course.
:: ducks & runs ::