It’s common for underground mining to include the construction of underground tunnels and chambers. Surface mining is less costly, while underground mining might be more expensive and risky.
There are just a few places where this kind of mining is used: narrow veins of gold or other wealthy resources. The ability to drill underwater in underground mines gives them an edge over surface mines.
Underground mining is possible if the following conditions are met:
- The ore body is thick enough to be extracted successfully from an open-pit mining operation.
- To pay expenses, the orebody’s quality and grades should be more than enough.
- It should have a less footprint on the landscape than open-pit mining.
In this post, we are going to explain how underground mining works. Including hard rock mining works as well as the soft rock mining done underground. Let’s begin!
What Is the Process of Mining Underground?
Driving heavy machinery below, breaking up rocks, and dumping them into a tank or vat below ground are the most common mining methods. In contrast, current technology and procedures have made it possible to execute the whole surgery above ground.
Many new techniques have been developed in recent years to make this process simpler and safer. Underground mines may continue to perform their critical role for years to come because of new technology that allows for the safe transportation and storage of all minerals, including soil and rock.
If that is the case, you must thoroughly investigate the many advantages and disadvantages of such an option before deciding whether or not it is good for you.
Underground mining will continue as long as there are minerals in the Earth’s crust. Gold panning, iron ore panning, petroleum exploration, limestone, coal mining, slate mining, and many other businesses all use underground mining.
This is a very stable industry because of the constant need for previously mined resources, such as coal. Understanding how this all works whether you wish to establish your own business or work for an existing one. With a bit of practice, you should be able to handle the tasks. Before mining, you will need to learn as much as you can about the process from experts in the field.
Underground hard-rock mining
There are hard-rock and soft-rock subterranean mines. Therefore, underground mining is divided into hard rock mining and soft rock mining. Respectively. “Hard” minerals, including gold, silver, iron, copper, zinc, nickel, tin, and lead, are often found in “hard-rock” ore deposits that are excavated using underground mining methods. I will explain how hard rock mining works.
There are many processes used to create and remove hard rock, even within the hard-rock category itself. Traditional charge-and-blast methods may be used, or a machine known as a continuous miner can be used in their place.
Miners excavate an access ramp to the deposit and extract ore in a pattern of holes (rooms) and pillars (roof supports) for flat ore deposits with no elevation variation (pillars). The continuous miner forms an excavated chamber of 20 to 30 feet (6 to 9 meters), which leaves a rock pillar in situ to maintain the “roof” in place. Created pillars and chambers may be seen in this process of mining minerals. The pillars are drilled through in the last run, enabling the roofs to fall behind the machine as it exits each area.
An access ramp is drilled from the surface down to the lowest point of the ore deposit, which is then filled up with rock. Using a drill, an operator may then make a horizontal cut through the ore, forming a drift.
No roof support is required in the hardest rock, but when drilling advances in weaker rock, bolts may be installed in the roof.
A platform for the next drift is created after the drift is completed and backfill, or waste material, is spread into the open drift. The drill drives over this backfill as it makes another slash through the ore with the drill bit. When the drill pierces the ore deposit’s uppermost layer, the process repeats again.
Drilling two neighboring access ramps and cutting two adjacent drifts, known as drift and fill, may also be employed in larger deposits. As opposed to a procedure like room and pillar, cut and fill doesn’t have the support devices necessary for hard rock.
When it comes to softer materials like coal, the room-and-pillar method is a natural fit. For low-grade ore, block caving, the least prevalent form of hard-rock mining, is usually the only option.
It entails digging a hole in the deposit’s bottommost ore body and then using blasting to cause the deposit’s roof to cave in. Once support is removed, gravity takes control, fracturing and collapsing the ore above the explosion site. The ore that has fallen to the ground is removed from the mine and processed there.
Underground Soft-Rock Mining
A longwall and a room and pillar technique are the two most common methods used in soft-rock mining. Coal salt uranium, phosphate, and oil shale are all found in soft-rock deposits.
The room-and-pillar method is used to remove the majority of coal. Longwall mining, on the other hand, is gaining in favor at a rapid pace.
Longwall mining is a very effective method of extracting minerals. Ore deposits may be sliced up to 600 feet (182 meters) long using a longwall machine rather than drilled through.
These slices fall into a conveyor belt, where they are transported to a haulage shaft and lifted out of the mine. During longwall mining, the machine’s roof supports lie between the top of the longwall miner and the room’s ceiling. The region behind the machine collapses and fills in the excavated space as the machine moves into the ore.
Up to 90% of the ore may be recovered using the longwall technique. An average recovery rate from the room-and-pillar strategy is about 50 percent.
Shorter cuts are performed when the ore deposit is thin. It is known as “shortwall mining” when referring to this particular form.
TNT and other explosives are still used to break up ore, but only to a limited extent — less than 5 percent of US mining output [source: Great Mining]. As a result of this, underground mining is getting more and more efficient.
As a result, fewer miners are placed in harm’s way when working deep below the surface. Though it is not the most secure place, an underground mine is still as lucrative as it seems.
Underground Mining Equipment
Heavy-Duty Mining Trucks
At the mines, heavy-duty vehicles are needed to transport supplies. They may be powered by either a mechanical engine or an electric drive.
These high-duty mining vehicles feature extra-large tires that can withstand the weight of massive cargo while traversing rough terrain.
There are several enormous mining dozers that can move a lot of material. In addition to wheels or tracks, these dozers may work in a broader range of surfaces, as well.
Excavators are also referred to as mining shovels. They were developed from an old steam shovel design. To move the shovel through hard materials, hydraulics are often used.
Electric Rope Shovel
With an electric rope shovel, a complex of pulleys and ropes propel the shovel forward. Because these versions are powered by electricity rather than hydraulics, they can operate more efficiently and last longer than hydraulic shovels.
For mines, road access isn’t always an option. They are transporting materials and hauling out mined commodities still need roads in the vicinity. Motor graders, which are employed to execute surface activities near mines, are responsible for constructing and maintaining these roads.
With a bucket connected to the boom, draglines are enormous excavators. For mining and overburden removal, the bucket is dropped and scraped down a flat surface. The bucket may be swung at the end of the dragline to drop its contents at a specific area.
Motor graders and wheel tractor scrapers have a lot in common. Unlike a grader, a scraper is fitted with a bin for collecting debris from the ground.
Loaders and Trucks
Underground mining trucks and loaders must function in constrained places. Inside a mine, these vehicles are unable to generate any pollution. Underground mining needs the use of specialized mining vehicles.