🔹 1. Introduction

Mine planning is the foundation of every surface mining operation.
Proper planning ensures:

• Safe operations
  
• High productivity
  
• Lowest cost per tonne
  
• Efficient equipment deployment
  
• Optimum recovery of ore
  
• Compliance with DGMS regulations
  

Surface mine planning includes design of:

• Benches
  
• Haul roads
  
• Pit slopes
  
• Waste dumps
  
• Production scheduling
  

                   🔹 2. Phases of Mine Planning

Surface mine planning involves three primary stages:

2.1 Long-Term Planning

• Final pit design
  
• Ultimate pit limit (UPL)
  
• Stripping ratio (SR) analysis
  
• Equipment selection
  
• Life-of-mine (LOM) planning
  

2.2 Medium-Term Planning

• Annual production targets
  
• Scheduling of benches
  
• Haul road optimization
  
• Waste dump planning
  

2.3 Short-Term Planning

• Daily/weekly planning
  
• Blast scheduling
  
• Shift-wise equipment allocation
  

🔹 3. Bench Geometry in Surface Mines

Bench design is the backbone of safe and efficient surface mining.
Key parameters:
3.1 Bench Height (H)Typically: 8–15 m
Depends on:

• Rock hardness
  
• Shovel reach
  
• Stability
  

3.2 Bench WidthMinimum Bench Width=3H\text{Minimum Bench Width} = 3HMinimum Bench Width=3HEnsures safe movement of machinery.
3.3 Bench Face Angle

• Hard rock: 70°–80°
  
• Soft rock: 55°–65°
  

3.4 Overall Slope AngleDepends on:

• Rock mass rating (RMR)
  
• Hydrogeology
  
• Height of pit
  

3.5 Catch BermsSafety berms placed between benches to stop falling rocks.

🔹 4. Pit Layout Design

Designing the pit involves:

• Selecting the pit shape
  
• Designing benches
  
• Determining slope angles
  
• Placement of haul roads
  
• Determining final pit depth
  

4.1 Ultimate Pit Limit (UPL)
UPL is determined using Lerchs–Grossmann algorithm or floating cone method.
Defines economic limit of pit.
4.2 Pit Shape

• Square/rectangular for stable slopes
  
• Circular/oval for deep pits
  
• Spiral ramps for trucks
  

4.3 Haul Road DesignGradient:

 8–10% (max)Width:

Road Width=3×truck width\text{Road Width} = 3 \times \text{truck width}Road Width=3×truck widthCurves: Superelevation includedDrainage: Must prevent water accumulation

🔹 5. Stripping Ratio (SR)

SR=Overburden VolumeOre VolumeSR = \frac{\text{Overburden Volume}}{\text{Ore Volume}}SR=Ore VolumeOverburden VolumeLow SR → profitable
High SR → uneconomic
🔹 6. Dump Design

Key dump parameters:

• Dump height: 30–60 m (depends on stability)
  
• Dump slope angle: 30°–37°
  
• Berm width: 8–12 m
  
• Bottom drainage required
  

🔹 7. Slope Stability

Controlled by:

• Rock mass properties
  
• Water pressure
  
• Bench design
  
• Load distribution
  

Slope failures can cause huge production loss.
DGMS mandates regular slope monitoring.
🔹 8. Diagrams (Text Format)Bench Geometry

 Haul Road _ / \ | Catch Berm | |---- Bench ----| | | |____Ore Zone___|

Pit Layout (Top View)
___________________________| || Spiral Haul Road || \ || \ || \__ Working Pit ||___________________________|
Cross Section
Bench 1 ________ \ \Bench 2 \______\____ Ore

🔥25 MCQs with Answers (DGMS Pattern)
1) Bench height in surface mines typically —

a) 2–4 m
b) 4–6 m
c) 8–15 m
d) 20–30 m
e) None
Answer: c
2) Bench width generally equals —

a) 1 × height
b) 2 × height
c) 3 × height
d) 5 × height
e) None
Answer: c
3) Ultimate pit limit is based on —

a) Truck size
b) Drill diameter
c) Economic cutoff & SR
d) Vibration
e) None
Answer: c
4) Haul road gradient typically —

a) 1%
b) 4%
c) 8–10%
d) 15%
e) 20%
Answer: c
5) Catch berm is used to —

a) Increase tonnage
b) Stop falling rocks
c) Enhance fragmentation
d) Increase burden
e) None
Answer: b
6) Stripping ratio formula —

a) Ore/OB
b) OB/Ore
c) Density × volume
d) Burden × spacing
e) None
Answer: b
7) Overall pit slope angle depends on —

a) Truck tyre
b) Rock mass strength
c) Diesel price
d) Temperature
e) None
Answer: b
8) Spiral ramps used for —

a) Drill stability
b) Dragline walking
c) Truck access to pit
d) Explosive loading
e) None
Answer: c
9) Dump slope angle typically —

a) 5°
b) 30°–37°
c) 60°
d) 90°
e) None
Answer: b
10) Higher SR means —

a) More profit
b) Less OB
c) More OB per tonne of ore
d) High ore grade
e) None
Answer: c
11) Slope monitoring is required because —

a) DGMS requires it
b) Safety
c) Prevent failures
d) Production continuity
e) All of these
Answer: e
12) Bench face angle in hard rock —

a) 20°
b) 45°
c) 70°–80°
d) 90°
e) None
Answer: c
13) Dump height in Indian mines —

a) 5 m
b) 10 m
c) 20 m
d) 30–60 m
e) 100 m
Answer: d
14) Haul road width —

a) 1 × truck width
b) 3 × truck width
c) 5 × truck width
d) 10 m fixed
e) 20 m fixed
Answer: b
15) Good pit layout reduces —

a) Truck size
b) Cycle time
c) Ore quality
d) Blasting
e) None
Answer: b
16) Water accumulation causes —

a) Better loading
b) More trucks
c) Slope failure
d) High VOD
e) None
Answer: c
17) Bench width helps in —

a) Ventilation
b) Safe machine movement
c) Fuel reduction
d) Blasting cost
e) None
Answer: b
18) Economic feasibility depends on —

a) Weather
b) Truck colour
c) Stripping ratio
d) Hole diameter
e) None
Answer: c
19) Ultimate pit depth depends on —

a) Diesel price
b) Profitability limits
c) Wind speed
d) Vibration
e) None
Answer: b
20) Slopes fail due to —

a) Wet conditions
b) Poor blasting
c) Weak rock
d) Overloading
e) All of these
Answer: e
21) Dump design includes —

a) Haulage
b) Ore grade
c) Drainage
d) Drilling
e) VOD
Answer: c
22) Proper bench alignment helps —

a) Safety
b) Stability
c) Better excavation
d) Productivity
e) All of these
Answer: e
23) Surface mine design starts with —

a) Blasting
b) Truck selection
c) Crusher design
d) Geological mapping
e) None
Answer: d
24) Steeper slopes give —

a) High safety
b) Low waste removal cost
c) More benches
d) Poor blasting
e) None
Answer: b
25) The main purpose of mine planning is —

a) Drill
b) Load
c) Optimize production & safety
d) Reduce coal quality
e) None
Answer: c
                              🔚 Conclusion

Mine planning and pit design are essential for safe, efficient, and economical surface mining operations.
Proper bench geometry, pit layout, slope design, and SR optimization ensure long-term productivity and DGMS compliance.

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