Question

The method mining suitable for the extraction of coal seams with dirt bands is

• A. Board and Pillar method
• B. Longwall method
• C. Slicing method
• D. Hydraulic Mining

Hint:

Longwall mining is a highly mechanized and systematic method.
This high degree of control allows for "selective mining," where the cutting machine can be precisely positioned to either avoid cutting a waste band or to handle it separately, thus improving the quality of the mined coal.

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
We need to identify the mining method that is well-suited for extracting coal seams that contain one or more layers of non-coal material, known as "dirt bands" or "partings".

Step 2: Detailed Explanation:
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Board and Pillar method (or Room and Pillar): This method involves driving a series of entries (rooms) into the seam, leaving behind pillars of coal to support the roof.
While it is flexible, selectively mining around or excluding a dirt band within the extraction height can be difficult and inefficient, often leading to dilution (mixing waste rock with coal).
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Longwall method: This is a high-production method where a large block of coal (a "panel") is extracted in a single, continuous operation.
A machine called a shearer cuts coal from a long face (up to 400m).
Modern longwall shearers are very adaptable.
They can be programmed to cut at specific horizons, allowing them to selectively cut the coal sections while leaving the dirt band either in the roof or the floor, if possible.
Even if the band must be cut, it can be handled more systematically than in room and pillar.
This ability to manage in-seam waste makes longwall a suitable method.
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Slicing method: This refers to methods for extracting very thick seams by taking them out in horizontal or inclined "slices".
While it can handle thick seams, it doesn't inherently offer a better solution for thin dirt bands than other methods.
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Hydraulic Mining: This uses high-pressure water jets to break and transport coal.
It is not selective and would mix the coal and dirt band together, making it unsuitable.

Step 3: Final Answer:
The longwall method is highly suitable for extracting coal seams with dirt bands due to the selective cutting capabilities of modern shearers.
This corresponds to option (B).