🧭 Detailed Notes

                        🪨 1. Introduction 

The Bord and Pillar method (also known as the Room and Pillar method) is one of the oldest and most widely used underground coal mining methods in India.
It involves developing a network of roadways (bords) and leaving pillars of coal to support the roof. This method is extensively used due to its simplicity, flexibility, and safety.
DGMS considers this method crucial for mine planning, safety design, and production efficiency in coal mines.

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⚙️ 2. Principle of the Method

• The seam is divided into rectangular blocks (pillars) separated by roadways (bords).
• The size of the pillar depends on depth, roof condition, and seam thickness.
• Once the development is complete, coal extraction is done by depillaring.

🧠 DGMS Tip: The balance between pillar size and extraction ratio determines the mine stability and production safety.

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🧱 3. Layout Features

Component	Description
Bords	Galleries driven parallel or perpendicular to each other.
Pillars	Coal blocks left in place to support the roof.
Panel	A group of pillars worked as one unit.
Barrier Pillar	Left to protect surface or important structures.

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🧩 4. Equipment Used

• Continuous Miner (CM)
• Shuttle Car
• Load Haul Dumper (LHD)
• Roof Bolter
• Conveyor Belt System

DGMS emphasizes mechanization and roof bolting to reduce manual hazards.

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🛠 5. Advantages 

✅ Simple layout and easy to supervise.
✅ Low capital cost compared to longwall   mining.
✅ Suitable for thick and moderately gassy   seams.
✅ Allows selective extraction and ventilation   control.

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⚠️ 6. Disadvantages 

❌ High percentage of coal left as pillars.
❌ Risk of pillar collapse during depillaring.
❌ Not suitable for very deep seams.
❌ Requires strict supervision to prevent roof   falls.

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🧮 7. Formula for Extraction Ratio

Typically, extraction = 40–60% depending on mine conditions.

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🧠 8. DGMS Relevance Bord and Pillar mining is included under Coal Mines Regulations, 2017 (CMR 2017) for safe working design.
DGMS exam questions often test:

• Layout diagrams
• Pillar design
• Extraction ratio
• Roof support systems

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⚡ Quick One-Liners (Revision)

• “Bord = Roadway; Pillar = Coal block left to support roof.”
• “Used for seams < 300 m depth.”
• “Extraction ratio = 40–60%.”
• “Barrier pillar protects surface features.”
• “Depillaring = Pillar extraction stage.”
• “DGMS Circular 02/2010 covers roof control & safety.”

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🧾 Descriptive Model Answer 

Q: Explain the Bord and Pillar method and its importance in mining.
A:
The Bord and Pillar method is a system of working coal seams where pillars of coal are left to support the roof, and coal is extracted through a network of roadways (bords).
It is economical, simple, and safe when properly designed. The method allows good ventilation and mechanization. Pillar design and support systems are regulated by DGMS under CMR 2017.
Its success depends on proper pillar sizing, adequate roof support, and systematic depillaring.

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🎯 25 MCQs – Bord and Pillar Mining

Q1. In the Bord and Pillar method, “bords” are:
A. Coal blocks left for support
B. Roadways or galleries driven in coal seam
C. Crosscuts in metal mines
D. Inclined shafts
E. Airways
Answer: B.
Solution: Bords are the galleries driven in the seam.

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Q2. The main purpose of pillars in Bord and Pillar mining is:
A. To provide ventilation
B. To store coal
C. To support the roof
D. To facilitate haulage
E. To control gas
Answer: C.
Solution: Pillars are left to support the overlying strata.

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Q3. Typical extraction ratio in Bord and Pillar mining is:
A. 10–20%
B. 25–35%
C. 40–60%
D. 70–90%
E. 100%
Answer: C.
Solution: Usually, 40–60% of coal is extracted.

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Q4. The method is best suited for:
A. Thick seams at shallow to moderate depth
B. Thin seams at great depth
C. Steep seams
D. Ore bodies with irregular shape
E. Alluvial deposits
Answer: A.
Solution: Ideal for thick seams with strong roof.

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Q5. Barrier pillars are left to:
A. Divide panels
B. Support the roof locally
C. Protect surface structures or roads
D. Separate ventilating circuits
E. Store equipment
Answer: C.
Solution: Barrier pillars ensure protection against collapse near important structures.

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Q6. The Bord and Pillar method is also known as:
A. Longwall
B. Shrinkage stoping
C. Room and Pillar
D. Cut and Fill
E. Open stoping
Answer: C.
Solution: Alternate name is Room and Pillar.

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Q7. The factor determining pillar size is:
A. Manager’s choice
B. Gradient
C. Depth and roof condition
D. Ventilation pressure
E. Temperature
Answer: C.
Solution: Deeper seams and weak roofs require larger pillars.

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Q8. Which of the following is used for roof support?
A. Timber props
B. Roof bolts
C. Steel supports
D. All the above
E. None
Answer: D.
Solution: Combination of supports used based on strata.

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Q9. The network of bords and pillars forms:
A. Stopes
B. Panels
C. Drifts
D. Raises
E. Levels
Answer: B.
Solution: Panels are formed by a group of pillars.

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Q10. Who issues regulations for safe pillar design?
A. IBM
B. DGMS
C. GSI
D. CIL
E. CMPDI
Answer: B.
Solution: DGMS under CMR 2017 governs design and safety.

Q11. Which operation is carried out after full development in Bord and Pillar mining?
A. Drilling
B. Depillaring
C. Surveying
D. Shaft sinking
E. Roof bolting
Answer: B.
Solution: Depillaring (pillar extraction) is done after full development is complete.

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Q12. The process of extracting coal from pillars is known as:
A. Bord formation
B. Caving
C. Depillaring
D. Room creation
E. Stripping
Answer: C.
Solution: Pillar extraction = depillaring.

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Q13. Ventilation in Bord and Pillar workings is maintained by:
A. Natural air flow
B. Auxiliary fans and regulators
C. Stopes and raises
D. Surface wind pressure
E. Cooling fans
Answer: B.
Solution: Auxiliary fans and regulators control ventilation through bords.

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Q14. Which of the following layouts gives the best ventilation control?
A. Random layout
B. Checkerboard layout
C. Diagonal layout
D. Modified room layout
E. Irregular pattern
Answer: B.
Solution: Checkerboard layout ensures efficient air distribution.

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Q15. Main roof fall risk occurs during:
A. Development
B. Drivage
C. Depillaring
D. Panel formation
E. Surveying
Answer: C.
Solution: Depillaring disturbs pillar support, leading to roof falls.

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Q16. A “split and fender” method is associated with:
A. Development
B. Depillaring
C. Ventilation
D. Transport
E. Survey
Answer: B.
Solution: Used for systematic extraction of pillars in depillaring stage.

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Q17. Which machine is used in mechanized Bord and Pillar mining?
A. Dragline
B. Shovel
C. Continuous Miner (CM)
D. Jack hammer
E. Shuttle car only
Answer: C.
Solution: Continuous Miner is the key machine in mechanized B&P mining.

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Q18. The extraction ratio in depillaring can reach up to:
A. 25%
B. 40%
C. 70–90%
D. 100%
E. None
Answer: C.
Solution: During depillaring, recovery improves to 70–90%.

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Q19. Pillar collapse can be prevented by:
A. Larger pillar size and good support
B. Narrow bords
C. Poor roof support
D. Over extraction
E. Irregular drilling
Answer: A.
Solution: Proper pillar design and roof support prevent collapse.

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Q20. DGMS regulations on pillar design are given under:
A. CMR 2017 Regulation 99
B. CMR 2017 Regulation 107–110
C. MMR 1961 Regulation 86
D. Mines Act 1952 Section 23
E. DGMS Circular 03/2015
Answer: B.
Solution: CMR 2017 Reg. 107–110 deals with working and pillar stability.

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Q21. The barrier pillar width depends on:
A. Mine manager’s choice
B. Production target
C. Depth of cover and seam thickness
D. Ventilation pressure
E. Temperature
Answer: C.
Solution: Greater depth requires wider barrier pillars.

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Q22. Roof bolting is mainly used for:
A. Transport
B. Roof support
C. Drainage
D. Lighting
E. Coal sampling
Answer: B.
Solution: Roof bolts prevent strata separation and roof falls.

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Q23. The main function of a panel barrier is to:
A. Divide haulage roadways
B. Separate two panels and restrict air flow
C. Store material
D. Block haul roads
E. None
Answer: B.
Solution: Panel barriers isolate panels to maintain stability and ventilation control.

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Q24. Which of the following is a DGMS Circular relevant to roof support and depillaring?
A. DGMS Tech Circular 02 of 2010
B. DGMS Circular 03 of 2007
C. DGMS Circular 05 of 2018
D. DGMS General Circular 04 of 2015
E. DGMS Safety Circular 07 of 2019
Answer: A.
Solution: Tech Circular 02/2010 covers roof support and slope safety guidelines.

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Q25. What is the main risk during depillaring in gassy seams?
A. Dust
B. Fire and explosion
C. Flooding
D. Low productivity
E. Noise
Answer: B.
Solution: Gassy seams may ignite due to friction and air leakage during extraction.

The Bord and Pillar method remains the most adaptable underground mining system in India, balancing safety, efficiency, and productivity.
For DGMS exams, aspirants must focus on layout design, pillar dimensions, and regulatory guidelines under CMR 2017.

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