Hard rock mining is an underground mining method that is used to mine extremely hard materials, such as those containing ores such as the valuable metals we are going after, specifically gold. The excavation of these hard golds, silvers, diamonds, and other minerals requires a few things that we will be discussing and we will also mention the methods and techniques applied, as they are very different from the placer mining we have been discussing at length. Let us explore.
The first obvious thing you need to work on underground hard rock mining is underground access. There are ways to get this done. There can be what is called a decline, which involves a tunnel with either spirals downward or slowly heads towards the target at a slight angle.
These are started into a rock side or the side of an already dug cave. There will often be load-bearing supports brought in to help keep everyone safe. Another method is just a mine shaft, which is a vertical well-type hole dug next to the body of rock you will be working on. You can also haul the ore out this way as well with buckets. Finally, there are adits, which are horizontal caves or excavations dug level and to the side of ore bodies where you don’t need any kind of ramp or spiral decline.
Safety While Hard Rock Mining
Always consider safety as the foremost important thing when doing anything! If you aren’t alive, you won’t be completing or enjoying your task. Injuries will stop you from your goal as well. So don’t risk it. One of the main concerns of hard rock mining underground is ventilation. You have to have fresh air that is cool enough to work in. It has to be a friendly enough environment or you won’t be productive. It is important to make sure there are no toxic fumes from all of the engines and blasting in the air. Make sure you are wearing a hardhat, safety harness, and dust mask as well.
The last safety point to consider is the ground support that supports the stability of the shafts, tunnels, and cave openings. I won’t go into a lot of detail, but make sure you consider using anchor bolts, grouted rebar and cable, friction stabilizers, and welded wire meshes and even latex membranes. What these serve to do is keep the walls from caving in, quite literally. Its like how grass keeps the soil from eroding on a hill by having its system of roots in place. It serves the same function.
Hard Rock Mining Methods
There are several ways of performing hard rock mining. Of these are the cut and fill, drill and fill, shrinkage stoping, and room and pillar mining. There is also the block caving method that is used in bulk mining situations. The principles of these are all the same. You either cut out or drill out ore, and then fill in predug holes behind you that dump to a lower level of your excavation site where other machinery can hoist the ore out. It is then sorted and filtered and the gold is extracted using all of the smaller methods we’ve discussed. This is a really interesting topic, this hard rock mining, and you should look into it further for more info. You won’t be doing this as a hobbyist though, so don’t worry if you don’t understand it all. Its for big company teams with big pockets.