You’ve probably heard the term “mineshaft” before if you’ve ever been near a mining operation. Although this usage isn’t absolutely accurate, laypeople frequently use the word to refer to any subterranean tunnel used for mining. A mining shaft, then, is what? To find out more about this unusual and audacious excavation project, continue reading.
What does “Shaft” mean in mining?
Shaft mining is a form of excavation that allows access to an underground ore deposit from above. The term “shaft” refers to vertical tunnels dug underground for mining and engineering purposes. When the opening originates on the surface, the ensuing tunnel is known as a shaft. A sub-shaft is a vertical tube that begins underground and extends upwards. The depth changes based on the project. Civil engineers typically design shallow shafts for public projects such as sewer tunnels. Deeper shafts are sunk to access subsurface mining reserves.
What is the purpose of a mine shaft?
Shafts provide access to ore and are dug for ventilation and to ensure the proper flow of air throughout an existing mine. Mine shafts can also be dug for storage. Compressed air, water, and fuel may be stashed in an empty shaft compartment for easy access in the event of an emergency.
Mine Shaft Compartments and Components
Here are the major components that make up a shaft mine.
Surface Facilities
Equipment on the ground surface is covered by a building referred to as the “head frame.”
Within this building, you’ll typically find a sheave wheel or hoist motor that lifts loads of ore through the shaft and storage bins to contain ore and other materials until they can be transported to another facility. Beneath these facilities is the collar, a massive support structure made of reinforced concrete.
Shaft Liner
Shaft lining provides several important safety functions within the mine. Its smooth surface improves ventilation and air flow. It also prevents loose earth, rocks, and other material from falling down the shaft.
Shaft lining may be used when boring through soft earth and rock to provide support to the shaft. The shape of the shaft and the ground conditions around the mine will determine whether or not a liner is used.
The square-shaped, smaller shafts used in North and South America frequently go without lining, while larger, circular shafts typically have a shaft lining made of concrete. During ground support installation on the surface, a temporary lining of shotcrete may be installed through robotic application.
Shaft Sets
The multiple compartments of a mine shaft are called shaft sets. These sets are usually made of steel and are made up of horizontal members called buntons and vertical members called guides. Steel shaft guides come in two varieties: hollow structural sections and top hat sections.
Top hats are preferred because they have increased stiffness over hollow sections and a simpler installation process. They also make use of wire ropes rather than steel guide beams, which are more flexible and easier to replace. The largest compartment in a shaft mine is typically used for moving workers, heavy equipment, and loads of ore. Miners descend and ascend through the shaft in a mine cage, which is similar to an elevator you’d find in a skyscraper.
These cages are equipped with multiple safety systems to ensure workers can be safely evacuated in case of unexpected failure. Horizontal tunnels, called drifts, are used for drainage in shaft mining. These drifts form an important part of the structure. Without proper drainage, water can well up inside the mine and damage the mining components and equipment.
The place where a shaft meets the main ore body is called the shaft station, inset, or plat. Drifts typically fan outward from the station to facilitate movement beneath the ground. The shaft bottom is the lowest part of the mine. It’s also the most dangerous place to work, so care must be taken to ensure miners spend as little time down there as possible.
Are mine shafts still used?
Because of the many dangers this type of excavation poses to miners, shaft sinking is not widely used in most parts of the world. Canada and South Africa are the only countries that regularly employ this mining technique. However, vertical shafts and drifts are still dug in other forms of mining to ensure proper ventilation and that the miners get enough air. They are also used to move workers, equipment, and ore in and out of the mine.
Reference
What Is a Mine Shaft? (n.d.). An Underground Miner. Retrieved November 11, 2024, from https://anundergroundminer.com/blog/what-is-a-mine-shaft
