Drilling operations in mining involve creating holes in rock formations for blasting, exploration, or sampling. These operations are essential for breaking rock, accessing mineral deposits, and ensuring efficient and safe mining activities.
In this article:
Drilling Operations in Mining
Drilling is a critical operation in mining, used to create holes in rock for exploration, blasting, sampling, and excavation. Unlike manufacturing drilling, mining drilling deals with hard rock, large depths, and rough environments.
1. Purpose of Drilling in Mining
Mining drilling is carried out to:
- Locate and evaluate mineral deposits
- Create holes for blasting (rock fragmentation)
- Extract samples for analysis
- Provide access for ventilation, drainage, and supports
- Create shafts, raises, and tunnels
2. Main Types of Drilling Operations in Mining
Exploration Drilling
Description:
Used to find and evaluate mineral deposits before actual mining begins.
Objectives:
- Determine mineral type
- Estimate ore quantity and quality
- Define depth and direction of ore body
Methods Used:
- Core drilling
- Reverse circulation (RC) drilling
Output:
- Rock samples
- Core samples
Applications:
- Gold, coal, iron ore, copper exploration
2. Core Drilling
Description:
A cylindrical core sample of rock is extracted using a hollow drill bit.
Features:
- Provides continuous rock sample
- High geological accuracy
Equipment:
- Diamond core drill
- Core barrel
Applications:
- Geological mapping
- Mineral analysis
- Structural study of rock
3. Reverse Circulation (RC) Drilling
Description:
Uses dual-wall drill rods where compressed air pushes cuttings to the surface.
Features:
- Faster than core drilling
- Less contamination
- Dry drilling method
Applications:
- Mineral exploration
- Grade control drilling
4. Blast Hole Drilling
Description:
Drilling holes for placing explosives to break rock.
Features:
- Large diameter holes
- Pattern-based drilling
Hole Diameter:
- 75 mm to 400 mm (or more)
Applications:
- Open-pit mining
- Quarrying
5. Production Drilling
Description:
Drilling carried out during active mining for daily rock breaking.
Purpose:
- Fragment ore and waste rock
- Maintain production cycle
Used In:
- Open-pit mines
- Underground mines
6. Rotary Drilling
Description:
Uses rotary motion and heavy downward force to crush rock.
Equipment:
- Rotary drill rigs
- Tricone bits
Applications:
- Large-diameter blast holes
- Coal and iron ore mining
7. Percussion Drilling
Description:
Rock is broken by repeated hammering action.
Types:
- Top hammer drilling
- Down-the-hole (DTH) drilling
(a) Top Hammer Drilling
- Hammer located above the drill string
- Energy transmitted through drill rods
Applications:
- Shallow holes
- Hard rock mining
(b) Down-the-Hole (DTH) Drilling
- Hammer located directly above the drill bit
- High efficiency and straight holes
Applications:
- Deep blast holes
- Hard and abrasive rocks
8. Raise Boring
Description:
Used to create vertical or inclined shafts between underground levels.
Process:
- Pilot hole drilled
- Reamer head enlarges hole from bottom to top
Applications:
- Ventilation shafts
- Ore passes
- Escape routes
9. Auger Drilling
Description:
Uses a helical screw (auger) to remove material.
Applications:
- Soft rock
- Overburden
- Coal mining
10. Underground Drilling
Description:
Drilling performed inside underground tunnels.
Purpose:
- Face drilling
- Roof bolting
- Blasting
Equipment:
- Jumbo drill rigs
- Hand-held rock drills
3. Drilling Patterns in Mining
Common Blast Hole Patterns:
- Square pattern
- Rectangular pattern
- Staggered pattern
Purpose:
- Efficient rock fragmentation
- Controlled blasting
4. Drilling Equipment Used in Mining
- Rotary drill rigs
- DTH hammers
- Tricone bits
- Diamond core bits
- Jumbo drilling machines
- Compressors
5. Factors Affecting Mining Drilling
- Rock hardness
- Rock abrasiveness
- Hole depth and diameter
- Drill bit type
- Drilling method
- Ground conditions
6. Advantages of Drilling in Mining
✔ Enables efficient blasting
✔ Accurate ore body evaluation
✔ Increases safety and productivity
✔ Reduces mining cost
7. Challenges in Mining Drilling
❌ Tool wear due to hard rock
❌ Deviation in deep holes
❌ High operational cost
❌ Environmental concerns (dust, noise)
Summary Table
| Drilling Type | Main Purpose |
|---|---|
| Exploration drilling | Find minerals |
| Core drilling | Geological analysis |
| RC drilling | Fast sampling |
| Blast hole drilling | Rock fragmentation |
| Production drilling | Daily mining |
| DTH drilling | Deep hard rock holes |
| Raise boring | Shafts & ventilation |
Conclusion:
Drilling in mining is used to explore minerals, collect samples, and break rock for extraction.
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