Underground Mining Methods: Long hole Stoping vs. Cut-and-Fill Mining

Author: [Ramadhani Santoso - ramadhani@meta-mineral.com ]
Category:  underground mining, metalliferous mining, long hole stopping, cut-and-fill mining, underground mine design, mining methods, ore recovery, backfill, narrow vein mining, underground mine engineering

Underground mining presents unique engineering challenges, especially when extracting valuable minerals from narrow, steeply dipping orebodies. Choosing the right mining method is critical to maximizing ore recovery, maintaining worker safety, controlling dilution, and ensuring economic viability.

Among the most widely used underground mining techniques are Longhole Stoping (LHS) and Cut-and-Fill (CAF) Mining. Although both are designed for underground metalliferous deposits, they serve different geological conditions and operational objectives.

Understanding Underground Metalliferous Orebodies

Metalliferous underground mines commonly target vein-type ore deposits, which are typically:

• Narrow, ranging from 0.5 to 3.0 meters in width

• Steeply dipping, often exceeding 50°

• High in economic value

• Located deep beneath the surface

These characteristics require mining methods capable of extracting ore efficiently while minimizing waste rock dilution and maintaining ground stability.

Longhole Stoping (LHS): High Productivity Through Bulk Mining

Longhole stoping is a bulk underground mining method designed for competent rock masses and relatively continuous ore bodies.

How It Works

The mining process generally follows these steps:

1. Development of access drifts and sublevels.

2. Drilling long blast holes using production drills.

3. Charging the holes with explosives.

4. Blasting large sections of ore (stopes).

5. Recovering broken ore through drawpoints using Load-Haul-Dump (LHD) machines.

6. Backfilling the stope when required.

This method enables large volumes of ore to be extracted rapidly with relatively low operating costs.

Advantages

• High production rates

• Lower mining cost per tonne

• Excellent equipment productivity

• Suitable for mine automation

• Reduced labor requirements

Limitations

Longhole stoping performs best only when:

• Rock conditions are stable

• Orebody geometry is relatively regular

• Dilution can be controlled

If the surrounding rock is weak or the orebody is highly irregular, excessive dilution and ore losses may occur.

Cut-and-Fill (CAF) Mining: Precision for Complex Orebodies

Cut-and-fill mining is a selective underground mining method developed for challenging geological conditions.

Instead of blasting an entire stope at once, miners excavate the ore in horizontal slices, beginning at the bottom and progressing upward.

After each slice is removed, the void is immediately filled with engineered backfill before mining continues to the next level.

Mining Sequence

A typical cut-and-fill cycle includes:

• Drill

• Blast

• Muck ore

• Install ground support if required

• Place backfill

• Repeat for the next lift

This cyclic process provides continuous ground support while allowing miners to selectively recover valuable ore.

Advantages

• Excellent ore recovery

• Minimal dilution

• Suitable for irregular orebody shapes

• Increased worker safety

• Better control of ground stability

Limitations

The increased selectivity comes with trade-offs:

• Higher operating costs

• Lower production rates

• Greater labor intensity

• Longer mining cycle times

The Role of Backfill in Underground Mining

One of the defining features of cut-and-fill mining is the extensive use of backfill.

Backfill serves several important purposes:

• Supports surrounding rock

• Prevents stope collapse

• Enables mining beneath previously excavated areas

• Reduces surface subsidence

• Improves overall mine stability

Modern mines commonly use:

• Cemented paste backfill

• Hydraulic fill

• Rock fill

• Cemented rock fill

Backfill technology has become an essential component of safe and sustainable underground mining operations.

Longhole Stoping vs. Cut-and-Fill Mining

FeatureLonghole StopingCut-and-Fill MiningMining styleBulk miningSelective miningProductivityVery highModerateOre recoveryGoodExcellentDilution controlModerateExcellentOperating costLowerHigherGround stabilityRequires competent rockSuitable for weak groundBackfill requirementOptional or delayedImmediate after each liftBest orebody typeRegular, steep, continuousNarrow, irregular, complex

Which Mining Method Is Better?

Neither method is universally superior. The optimal choice depends on several technical and economic factors, including:

• Orebody geometry

• Rock mass quality

• Desired production rate

• Ore grade distribution

• Dilution tolerance

• Ground support requirements

• Overall project economics

Operations focused on maximizing production often favor Longhole Stoping, while mines targeting high-value, narrow veins with complex geology typically achieve better results using Cut-and-Fill Mining.