Deep mining, also known as underground mining, is a method used to extract valuable minerals, such as coal, from deposits that are too deep below the Earth's surface to be economically or practically reached by surface mining techniques. It involves creating access routes into the earth to reach these deep seams.
Understanding Underground Mining
The core principle of underground mining is to access mineral seams situated far beneath the ground. This is achieved by:
- Opening Access Points: This involves opening one or more portals or shafts into the earth. These openings serve as the main entry points for personnel, equipment, and extracted material.
- Following or Intercepting Seams: The tunnels or shafts are designed to follow or intercept coal seams that are too deep for surface mining methods. This means digging downwards and then horizontally along the seam.
- Mineral Extraction: Once the seam is reached, various techniques are employed to extract the mineral (e.g., coal) from the surrounding rock.
Common Methods in Deep Mining
Different methods are used in underground mining depending on factors like the depth, thickness, and angle of the mineral seam, as well as the strength of the surrounding rock.
One widely practiced method, particularly noted for coal extraction, is:
Room-and-Pillar Mining
This method is generally used for seams that are relatively flat or gently dipping. Here's a simplified look at how it works:
- Creating "Rooms": Miners excavate sections of the coal seam, creating open areas or "rooms."
- Leaving "Pillars": Crucially, sections of the coal seam are deliberately left in place to act as "pillars." These pillars support the roof of the mine, preventing collapse.
- Extraction Pattern: Mining progresses in a pattern that creates a network of rooms separated by pillars.
While Room-and-Pillar is common, other deep mining methods exist, such as Longwall mining, which involves complete removal of large blocks of coal with the roof behind the mining operation allowed to collapse in a controlled manner. However, the foundational aspect remains accessing the deep seam via shafts or portals.
In essence, deep mining requires intricate engineering and careful planning to safely access and extract minerals located far beneath the surface, utilizing specific methods adapted to the geological conditions.
