Longwall mining is one of the most talked-about topics in coal mining exams, and also one of the easiest places to lose marks if you only memorise names without understanding how the face actually works. The cutting machine, the powered supports, the conveyor, the gate roads and the goaf all fit together in one moving system.
This is Part 1 of our Longwall Mining MCQ series. It has 15 questions that cover the basics, useful for GATE, DGMS exams, Overman, Mining Sirdar and mining engineering university papers. Try each question yourself first, then tap Show Answer to check it and read the short explanation.
Quick refresher before you start
- In longwall mining, a long face of coal is cut by a shearer (or a plough) while powered roof supports protect the people working at the face.
- The cut coal falls onto an armoured face conveyor (AFC), which carries it to the maingate side.
- As the face advances, the supports move forward and the roof behind them is allowed to cave. The caved area is called the goaf.
- Most longwalls work on the retreat system, meaning the face moves back towards the main roadways.
Longwall Mining MCQs: Part 01
1. Longwall mining is best suited to which type of seam?
- A. Steeply dipping seams
- B. Flat to gently inclined seams of fairly uniform thickness
- C. Heavily faulted and disturbed seams
- D. Small, discontinuous coal pockets
Show Answer
Answer: BLongwall needs a continuous, fairly regular seam with few major faults, because the equipment moves along a long straight face.
2. Which machine is mainly used to cut coal on a longwall face?
- A. Dragline
- B. Roadheader
- C. Scooptram
- D. Shearer
Show Answer
Answer: DA shearer, with rotating cutting drums, travels along the face and cuts the coal. A dragline is a surface mining machine.
3. What carries the cut coal along the longwall face?
- A. Armoured face conveyor (AFC)
- B. Rope haulage
- C. Tippler
- D. Skip
Show Answer
Answer: AThe AFC runs along the face. The shearer rides on it, and it moves the coal towards the maingate, where it passes on to the gate conveyor.
4. Which of the following is a type of powered roof support used on longwall faces?
- A. Steel arch
- B. Wooden prop
- C. Chock-shield support
- D. Roof bolt
Show Answer
Answer: CPowered supports come mainly as chocks, shields and chock-shields. They are hydraulic and self-advancing. Arches, props and bolts are other kinds of support.
5. What are the roadways at the two ends of a longwall face called?
- A. Shaft and incline
- B. Maingate and tailgate
- C. Drift and cross-cut
- D. Winze and rise
Show Answer
Answer: BThese are the gate roads. The maingate usually carries the coal conveyor and fresh air, while the tailgate usually carries return air and supplies.
6. What is the "goaf" in a longwall panel?
- A. The coal face being cut
- B. The main intake airway
- C. The area where the shearer is parked
- D. The worked-out area behind the supports where the roof caves in
Show Answer
Answer: DAs the supports move forward, the roof behind them is allowed to collapse. This caved area is the goaf, and it needs careful monitoring.
7. In a retreating longwall, in which direction does the face move?
- A. From the far boundary back towards the main roadways
- B. From the main roadways towards the far boundary
- C. Sideways across the panel
- D. Vertically upwards
Show Answer
Answer: AIn the retreat system the gate roads are developed first up to the boundary, and then the face is extracted while retreating back towards the main roadways.
8. What is the main purpose of chain pillars between longwall panels?
- A. To store coal
- B. To house the shearer
- C. To protect the gate roads and separate adjacent panels
- D. To supply fresh air to the goaf
Show Answer
Answer: CChain pillars take the abutment load, keep the gate roads stable and isolate one panel from the next.
9. In a U-type ventilation arrangement on a longwall face, how does the air flow?
- A. In through the tailgate, out through the maingate, bypassing the face
- B. In through the maingate, along the face, out through the tailgate
- C. Straight through the goaf only
- D. The face has no air flow
Show Answer
Answer: BThe air travels in a "U" shape: intake along the maingate, across the face and back along the tailgate as return air.
10. Which type of fluid is generally used in hydraulic powered supports underground?
- A. Water-based fire-resistant emulsion
- B. Petrol
- C. Diesel
- D. Ordinary lubricating oil only
Show Answer
Answer: AUnderground, fire-resistant fluids are used, typically a high-water-content emulsion. Petrol and diesel are fire and explosion hazards.
11. Which cutting machine is generally preferred in thin seams on a longwall face?
- A. Draglines
- B. Bucket wheel excavator
- C. Surface miner
- D. Plough
Show Answer
Answer: DPlough systems work well in relatively thin seams, because the plough is low and cuts a thin web of coal as it moves along the face.
12. What does the "setting load" of a powered support mean?
- A. The weight of the support in tonnes
- B. The load carried by the conveyor
- C. The initial load with which the support is pressed against the roof when set
- D. The final load at which the support fails
Show Answer
Answer: CA good setting load pre-stresses the roof strata and reduces roof separation. After setting, the support yields at its rated working resistance if the roof load rises.
13. Which hazard is especially associated with the goaf of a longwall panel?
- A. Spontaneous heating and gas accumulation
- B. Only noise
- C. Rail derailment
- D. No hazard at all
Show Answer
Answer: ABroken coal left in the goaf can heat up spontaneously, and methane can build up there. That is why monitoring and sealing practices are important.
14. What is the main advantage of longwall mining over bord and pillar mining?
- A. Lower capital cost
- B. Higher extraction and concentrated, high-output production
- C. Suitable for every kind of geology
- D. No need for ventilation
Show Answer
Answer: BLongwall recovers a large share of the seam and concentrates production on one face. Its drawbacks are the high capital cost and the need for suitable geology.
15. On what does the productivity of a longwall face depend?
- A. Seam thickness and face length
- B. Equipment availability and efficiency
- C. Roof conditions and face advance rate
- D. All of the above
Show Answer
Answer: DAll of these matter. A longwall is a system, so a weak link such as a stopped conveyor or poor roof stops the whole face.
Answer key
| Q | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |
|---|---|---|---|---|---|---|---|---|
| Ans | B | D | A | C | B | D | A | C |
| Q | 9 | 10 | 11 | 12 | 13 | 14 | 15 | |
| Ans | B | A | D | C | A | B | D |
How to get the most out of these MCQs
- Cover the answer, answer all 15 first, and only then check your score.
- For every wrong answer, read the explanation and write one line in your notes.
- Draw a simple sketch of a longwall panel (face, maingate, tailgate, chain pillars, goaf). Most of these questions become easy once you can picture the layout.
- Repeat the set after a week to see what has stuck.
Note: these questions are for practice and revision. For statutory provisions on longwall working, refer to the Coal Mines Regulations and the latest DGMS circulars.
Longwall Mining MCQ Series
This series is designed to build a deeper understanding of longwall mining and to help with exam preparation.
Next: Part 02
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