What does the term 'stoping' refer to in underground mining?
A
The process of blasting ore
B
Extraction of ore from underground openings
Analysis & Theory
Stoping is the process of extracting ore from the ore body in an underground mine.
Which of the following is a classification of stoping based on ore body orientation?
C
Horizontal and vertical stoping
Analysis & Theory
Stoping methods can be classified based on ore body orientation—horizontal, vertical, or inclined.
Which stoping method is most suitable for steeply dipping ore bodies?
Analysis & Theory
Sublevel stoping is ideal for steep ore bodies with competent walls.
Shrinkage stoping is typically applied in:
A
Narrow, flat ore bodies
B
Weak ore and weak host rock
C
Steep, strong ore bodies
D
Highly fractured ground
Analysis & Theory
Shrinkage stoping suits steep ore bodies with strong ore and wall rocks.
Which stoping method allows early access to ore during development?
Analysis & Theory
Cut and fill stoping allows progressive extraction with backfilling, enabling early ore access.
Which is a primary advantage of cut and fill stoping?
C
Suitable for irregular ore bodies
D
Not suitable for weak ground
Analysis & Theory
Cut and fill is flexible and suited for irregular or variable ore geometries.
What is the main drawback of shrinkage stoping?
C
Delayed ore recovery until end of stope
D
Requires timber support
Analysis & Theory
Shrinkage stoping stores broken ore in the stope, delaying full recovery.
Sublevel caving is best applied where:
A
Ore and wall rocks are weak
B
Ore body is narrow and strong
C
Ground conditions are very stable
D
Backfill is not available
Analysis & Theory
Sublevel caving is used in weak ground where controlled caving is desired.
Which stoping method results in the most dilution?
Analysis & Theory
Sublevel caving causes significant dilution due to mixing of broken ore and waste.
In which stoping method are rooms and pillars systematically developed?
Analysis & Theory
Room and pillar mining develops a grid of open rooms separated by ore pillars for support.
A major limitation of room and pillar mining is:
C
Low recovery due to residual pillars
Analysis & Theory
Room and pillar leaves ore in the pillars, reducing recovery unless secondary recovery is done.
Which method is generally not applicable to flat lying deposits?
Analysis & Theory
Shrinkage stoping requires a steep dip for gravity ore flow.
Which stoping method offers good ground control in weak strata?
Analysis & Theory
Cut and fill allows backfilling after each cut, offering ground stability in weak rock.
Sublevel stoping generally requires:
B
Strong hanging and foot walls
D
Dilute blasting techniques
Analysis & Theory
It needs competent walls to maintain sublevel integrity and reduce dilution.
A key merit of room and pillar method is:
B
Low initial cost and simple layout
C
Very high recovery rate
Analysis & Theory
Room and pillar is simple, cost-effective, and often used in flat tabular deposits.
Which method is best for thin, steep ore bodies with strong walls?
Analysis & Theory
Shrinkage stoping suits narrow, steeply dipping bodies with good rock conditions.
What is one disadvantage of sublevel caving?
C
High ore loss and dilution
D
Requires extensive timbering
Analysis & Theory
Sublevel caving results in significant dilution and ore loss due to uncontrolled caving.
What is the advantage of using long-hole open stoping?
C
Highly mechanized and safe
Analysis & Theory
Long-hole stoping is fully mechanized, safe, and efficient for large ore bodies.
Why is cut and fill considered an expensive method?
B
Requires continuous backfilling
Analysis & Theory
Cut and fill requires filling after each cut, increasing labor and material cost.
Which stoping method is most suitable for irregular and variable ore bodies?
Analysis & Theory
Cut and fill allows adaptability to ore body shape and irregular geometry.