Describe briefly the different factors on which choice of mining is depended What are the major type of long

e major type of long wall method? Which method is more popular and How thickness of the coal seam & Gradient of the coal seam influence to choice the
why? mining method?
The choice of mining method depends on several factors, including:
1. Longwall Advancing Method 1. Thickness of the Coal Seam
1. Type of Ore Deposit: The nature of the mineral deposit (e.g., surface or subsurface,
shape, depth, and orientation) determines whether surface mining (e.g., open-pit, In this method, mining starts near the main intake and return roadways and proceeds The thickness of the seam determines the practicality and economic feasibility of
strip mining) or underground mining is suitable. outward into the panel. extracting coal.
2. Geological Characteristics: Rock strength, thickness of ore body, presence of faults,
Roadways (or headings) are driven to access the coal seam before longwall mining begins. Influence on Mining Method:
and surrounding strata influence mining techniques.
3. Economic Factors: Costs related to extraction, equipment, labor, and processing Suitable for seams where geological disturbances are minimal and where significant coal Thin seams (<1.5 m):
are critical in choosing the method. deposits are located closer to the entry.
Extraction requires highly mechanized methods to ensure productivity, such as continuous
4. Environmental Impact: Methods that minimize environmental disturbance and
2. Longwall Retreating Method : mining.
ensure compliance with regulations are preferred.
Mining begins after the development of the panel has been completed. Roadways
5. Safety Concerns: Methods that ensure worker safety and reduce risks from May not be economically viable in some regions.
are driven outward to the boundary of the panel, and coal is then mined back
collapses, explosions, or toxic exposures are prioritized.
towards the main gate.The panels are typically pre-developed, making the process Moderate thickness (1.5 – 3.5 m):
6. Technology Availability: Advanced machinery and tools often dictate feasible
more systematic and efficient.Can be used in more varied and complex geological
methods of mining. Suitable for both bord-and-pillar and longwall mining methods, depending on other factors
conditions.
7. Mineral Quality and Market Demand: High-quality or in-demand minerals may like geology.
justify costlier mining methods. Thick seams (>3.5 m):
8. Local Regulations: Legal frameworks and permissions in the region affect the choice Which Method is More Popular?
of mining. Multi-slice methods may be used to extract coal in layers (e.g., thick longwall mining).For
extremely thick seams, methods like sub-level caving or slicing are preferred
The longwall retreating method is generally more popular than the advancing method.
2. Gradient (Dip) of the Coal Seam
Reasons for its Popularity:
The gradient affects the movement of equipment, coal, and workers within the
1. Safety: The retreating method ensures that a solid barrier of coal protects the main mine.Influence on Mining Method:
roadways from the stress of mining. This reduces the chances of roof collapse and
Gentle dip (0°-10°):
minimizes risks to miners.
2. Efficiency: As all development is completed before mining begins, operations can Mechanized methods such as bord-and-pillar and longwall mining are typically used due to
continue without interruptions caused by simultaneous roadway development. the ease of equipment operation and coal transportation.
3. Better Ground Control: Panels can be extracted more systematically, leading to
Moderate dip (10°-25°):
improved management of surface subsidence and better roof control.
4. Flexibility: It is more adaptable to varying geological conditions, including thick Continuous mining and longwall mining may still be used, but mining equipment requires
seams and areas with faults or undulations. adjustments to maintain productivity.

Transport may require conveyors, rails, or other aids.

Steep dip (>25°):

Define the following with neat sketch Stook, Bump, Rib pillar & Gallery List two advantage of Long Wall Mining Method. Write a short note on Power support & Definition of Stowing:
AFC
1. Stook Stowing in mining refers to the process of filling the voids or empty spaces created after
Advantages of Long Wall Mining Method extracting minerals or ore from underground mines. This practice helps to stabilize the
A stook usually refers to a frame or support structure for storing or holding materials. In
overlying strata, prevent subsidence on the surface, and maintain safety in the mine.
construction or rural contexts, it might signify a framework for temporarily holding 1. High Production and Efficiency: Long wall mining provides higher coal recovery
materials like straw or grains. compared to other methods, often achieving up to 80%-90%. It is designed for mass Conditions Necessitating Sand Stowing:
production, making it ideal for large-scale mining operations.
Sketch Description: Sand stowing, a specific method of stowing where sand is used as a filling material,
2. Safer Working Conditions: The mechanization and remote operation reduce manual
becomes essential in certain mining conditions, such as:
A triangular or rectangular wooden or metal framework with a base to hold materials. handling of equipment, minimizing exposure to hazards for workers.
1. Prevention of Subsidence:
2. Bump Short Note on Power Support and AFC
In areas where mining activities are close to the surface or near important structures like
A bump refers to a raised portion on a surface. It is often a small protrusion or convexity 1. Power Support: In long wall mining, power supports are hydraulic roof supports
buildings, railways, or water bodies, sand stowing is crucial to prevent ground collapse or
used as a design feature or to prevent objects from sliding. used to prevent roof collapse in the working area. These supports are automated,
surface subsidence.
advancing as the mining progresses. They provide safety for workers and equipment
Sketch Description:
while allowing the mined-out area (gob) to collapse behind. 2. Weak Strata Above the Seam:
A raised, semi-spherical projection on a flat surface like a floor or road. 2. AFC (Armored Face Conveyor): The AFC is a heavy-duty conveyor system installed
If the strata above the seam are weak or friable, leaving large voids after coal or mineral
along the longwall face to transport the mined coal from the cutting area to the belt
3. Rib Pillar extraction can lead to roof falls. Stowing sand into these voids ensures stability.
conveyor. It also acts as a base for the shearer or plow, enabling efficient coal
A rib pillar is a structural member designed as a rib-shaped support, often providing both cutting and transportation in a single operation 3. Environmental Safety:
vertical and horizontal strength to an architectural frame or roof.
To prevent pollution or water contamination from collapsing mines, stowing helps maintain
Sketch Description: ground integrity and protects nearby watercourses.

A longitudinal or semi-arched pillar forming a rib-like shape in a roof or structural frame. 4. Safety in Thick or Steep Seams:

4. Gallery In mines with thick or steep seams, the void left after extraction can become unstable.
Sand stowing prevents uncontrolled collapse, ensuring safety for miners.
In architecture, a gallery is a long, covered space often with open sides used for
observation or circulation. It can also mean an interior passage, balcony, or dedicated 5. Regulatory Requirements:
display area.
Certain regions may have legal mandates to adopt stowing to control subsidence and
Sketch Description: minimize environmental impact due to mining activities.
A long, covered corridor with open railings or windows for light and ventilation. 6. Use of Waterlogged Areas:

In areas prone to water accumulation, sand stowing effectively seals abandoned portions,
preventing water ingress or outflow.

Advantages of Sand Stowing:

It is economical, as sand is often readily available near mining areas.

High packing efficiency compared to other materials.