Techniques of Underground Mining
Underground mining is a method of extracting valuable minerals or ores that are buried deep within the Earth's crust. It involves accessing underground deposits through shafts, tunnels, and other passages. Various mining techniques are employed to safely and efficiently extract the desired minerals. Here are some of the key techniques used in underground mining:
1. Cut and Fill Mining: Cut and fill mining is a method used in steeply dipping ore bodies involving the removal of ore in horizontal slices from the bottom upwards. Once a slice is extracted, the void is filled with waste material to provide support for the overlying rock and to maintain stability.
2. Room and Pillar Mining: Room and pillar mining is a method where horizontal tunnels or "rooms" are excavated into the ore body while leaving "pillars" of untouched ore to support the roof. This technique is commonly used for mining flat or gently dipping ore bodies.
3. Longwall Mining: Longwall mining is a highly mechanized method used in deeper underground mines. It involves the use of a longwall shearer to extract a long wall of coal or ore in a single pass. The extracted material is then transported to the surface via conveyor belts.
4. Sublevel Caving: Sublevel caving is a bulk underground mining method that uses gravity to extract ore from a series of parallel sublevels. As ore is removed from the lowermost sublevel, the overlying rock collapses into the void, allowing for easy extraction of the ore.
5. Block Caving: Block caving is a cost-effective method used for large, low-grade ore bodies. It involves undercutting the ore body to promote its collapse under its weight. The broken ore is then extracted from draw points located at the bottom of the cave.
6. Shaft Mining: Shaft mining involves the excavation of vertical or inclined shafts to access underground deposits. These shafts serve as pathways for workers, equipment, and ore transportation. Ventilation systems are also installed to provide fresh air to underground workings.
7. Drift Mining: Drift mining involves the excavation of horizontal tunnels, or drifts, into the ore body. Drifts are typically used to access shallow ore deposits and allow for easy transportation of ore and waste material to the surface.
These techniques of underground mining require careful planning, engineering expertise, and strict safety measures to ensure the well-being of workers and the sustainability of the mining operation. By leveraging the appropriate mining method based on the characteristics of the ore deposit, miners can extract valuable minerals efficiently while minimizing environmental impact.