GATE Mining Engineering Mining Methods and Machinery Syllabus

Mining Methods and Machinery syllabus — full chapter and topic list

Expand any chapter to see its topics and sub-topics. This is the whole examinable outline for Mining Methods and Machinery in GATE Mining Engineering, not a summary of it.

1. 1

   Mining Methods

   5 topics

   • Surface Mining
     • Layout
     • Development
     • Loading
     • Transportation
     • Mechanization
   • Continuous Surface Mining Systems
   • Highwall Mining
   • Underground Coal Mining
     • Bord and Pillar Systems
     • Room and Pillar Mining
     • Longwall Mining
     • Thick Seam Mining Methods
   • Underground Metal Mining
     • Open, Supported and Caved Stoping Methods
     • Stope Mechanization
     • Ore Handling Systems
2. 2

   Mining Machinery

   3 topics

   • Generation and Transmission of Mechanical, Hydraulic and Pneumatic Power
   • Materials Handling
     • Wire Ropes
     • Haulages
     • Conveyors
     • Face and Development Machinery
     • Hoisting Systems
     • Pumps
   • Comminution Methods and Machinery

Mining Methods and Machinery flashcards for GATE Mining Engineering

21 of 52 cards from the Mining Methods and Machinery deck — real questions with worked answers.

1. In surface mining, what is the definition of "stripping ratio" and how is it commonly expressed?

   The stripping ratio is the amount of overburden (waste) that must be removed to extract a unit of ore or coal. It is expressed as a volume ratio ($\mathrm{m^{3}/m^{3}}$, waste to ore) or as $\frac{\text{tonnes (or }\mathrm{m^3}\text{) of overburden}}{\text{tonne of mineral}}$ (e.g., $\mathrm{m^{3}/t}$ for coal).

2. Define the "break-even stripping ratio" (BESR) in surface mining.

   The break-even stripping ratio is the maximum stripping ratio at which surface mining is still economical, i.e. the ratio at which revenue equals the total cost of mining. $$BESR = \frac{\text{Value of ore} - \text{Cost of ore mining}}{\text{Cost of stripping per unit waste}}$$ Mining proceeds while the actual stripping ratio is below the BESR.

3. What are the principal advantages of surface mining over underground mining?

   Higher productivity and output; lower cost per tonne; better recovery (low ore loss/dilution); greater safety; better grade control; ability to use very large equipment; and less skilled labour requirement. Limitations: restricted to shallow deposits and large environmental footprint.

4. In open-pit/opencast layout, define "bench height," "bench width (berm)," and "overall pit slope angle."

   Bench height is the vertical distance between two successive bench levels. Bench width (berm) is the horizontal flat area left between benches for safety/haulage. The overall pit slope angle is the angle measured from horizontal to a line joining the toe of the lowest bench to the crest of the uppermost bench, accounting for all berms and bench faces.

5. What is the formula relating the overall pit slope angle to bench geometry?

   For uniform benches, $$\tan\theta = \frac{H}{\sum(B + H\cot\alpha)}\cdot n \quad\text{or more simply}\quad \theta = \arctan\!\left(\frac{n H}{n(B + H\cot\alpha)}\right)$$ where $H$ = bench height, $B$ = berm width, $\alpha$ = bench face angle, and $n$ = number of benches. The overall slope is flatter than the individual bench face angle due to the berms.

6. What are the three main stages of surface mine development?

   (1) Box-cut excavation to expose the seam/ore and establish the first working face; (2) Development of haul roads, ramps and benches to access the deposit; (3) Establishment of dumps/spoil banks, drainage and infrastructure. The box cut is the initial opening trench made through overburden.

7. What is a "box cut" in opencast mining?

   A box cut is the first excavation made into a deposit to remove overburden and expose the mineral seam, creating the initial working face and providing space (void) into which subsequent overburden can be cast or dumped.

8. List the four basic unit operations of surface mining production cycle.

   (1) Drilling, (2) Blasting, (3) Loading (excavation), and (4) Hauling (transportation). In overburden removal, this is often followed by dumping/spreading of spoil.

9. Compare a power shovel and a dragline as primary loading/stripping machines.

   A power shovel digs above its track level, crowds into the bank, has high digging force, and is used for loading trucks and hard material. A dragline digs below its standing level using a bucket suspended from a boom and dragged toward the machine; it has a long reach and is mainly used for overburden casting (side-casting into the de-coaled void) rather than truck loading.

10. Define "reach" and "dumping radius" for a dragline.

    Reach (digging reach) is the maximum horizontal distance from the dragline's center to where the bucket can dig. Dumping radius is the horizontal distance from the machine center to the point where spoil is dumped. Both are governed by the boom length and boom angle of the walking dragline.

11. What is the duty cycle of a shovel and what are its components?

    The shovel duty (cycle) time is the time for one complete loading cycle: $$t_{cycle} = t_{dig} + t_{swing\,loaded} + t_{dump} + t_{swing\,empty}$$ Typical cycle times are about 25–35 s. The number of cycles per truck load determines shovel-truck matching.

12. State the formula for theoretical output (production rate) of a shovel.

    $$Q = \frac{3600}{t_{cycle}} \cdot C \cdot F \cdot \frac{E}{S}$$ where $Q$ = production ($\mathrm{m^3/h}$ bank), $t_{cycle}$ = cycle time (s), $C$ = bucket capacity, $F$ = bucket fill factor, $E$ = job/operating efficiency, and $S$ = swell factor that converts loose to bank volume.

13. What is the "swell factor" and how does it relate bank volume to loose volume?

    The swell factor accounts for the volume increase of material when excavated (loosened). $$\text{Loose volume} = \text{Bank volume} \times (1 + \text{Swell \%})$$ The bank-to-loose conversion is the load factor $LF = \frac{1}{1+S}$, where $S$ is the fractional swell. Typical rock swell is 25–45%.

14. In shovel-truck systems, what is the "match factor" and what value is ideal?

    The match factor balances truck arrival rate against shovel loading rate: $$MF = \frac{N_{trucks}\times t_{load}}{N_{shovels}\times t_{cycle\,truck}}$$ A match factor of $\approx 1$ is ideal: $MF>1$ means trucks queue (shovel-bound), $MF<1$ means the shovel waits (truck-bound).

15. What are the main mechanized transportation systems used in surface mines?

    (1) Rear-dump/off-highway trucks (most flexible); (2) Belt conveyors (continuous, for crushed material, low cost over distance); (3) Rail (for long, flat hauls and large tonnages); (4) In-pit crushing and conveying (IPCC); and (5) aerial ropeways/skips in special terrain.

16. Compare truck haulage and conveyor (belt) transport in surface mines.

    Trucks: flexible, low capital, suited to variable routes/short life, but high operating cost, fuel/tyre intensive, discontinuous, and steep-grade limited (~10%). Conveyors: continuous, low operating cost, high capacity, can climb steeper grades, automatable, but high capital cost, inflexible routing, and require crushing of material first.

17. What is In-Pit Crushing and Conveying (IPCC), and why is it adopted?

    IPCC places a (semi-mobile or fully mobile) crusher inside the pit so blasted material is crushed near the face and transported out by conveyor instead of trucks. It is adopted to cut haulage (diesel/tyre) costs, reduce emissions, handle deepening pits, and provide continuous high-capacity transport, at the expense of higher capital cost and reduced flexibility.

18. What characterizes a Continuous Surface Mining (CSM) system?

    A CSM system extracts material continuously without drilling and blasting, using machines such as bucket-wheel excavators (BWEs), continuous surface miners (drum-type rock cutters), and bucket-chain excavators feeding belt conveyors. It suits soft to medium-strength, flat-lying deposits (lignite, soft coal, phosphate) and gives steady output, selective mining, and reduced ground vibration.

19. Describe a bucket-wheel excavator (BWE) and its role.

    A BWE is a large continuous digging machine with a rotating wheel carrying a ring of buckets at the end of a boom. As the wheel rotates and the boom slews, the buckets cut and discharge material onto a boom conveyor feeding a belt system. BWEs are used in large soft-rock/lignite operations for continuous overburden removal and mineral extraction.

20. What is a "surface miner" (continuous miner of the drum type) and its key advantage?

    A surface miner is a self-propelled machine with a central cutting drum studded with picks that cuts, crushes, and (often) loads material in one pass without drilling and blasting. Key advantages: selective/clean mining of thin seams, no blasting (no vibration/flyrock, suitable near habitation), uniform product size, and direct loading onto trucks/conveyors.

21. What is highwall mining and when is it used?

    Highwall mining recovers coal from the exposed highwall of a terminated opencast pit (or contour mine) by driving a series of parallel, unmanned entries into the seam using a remotely operated continuous miner with an auger/conveyor train. It is used to recover coal economically beyond the final highwall where the stripping ratio becomes uneconomic for further opencasting, without going fully underground.

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