Controller of Mines • 2026 • Technical Paper-III
Explain the difference between Net Present Value (NPV) and Internal Rate of Return (IRR).
Controller of Mines • 2026 • Technical Paper-III
Find the odd one out
A)
AK
B)
CM
C)
EP
D)
DN
Convert letters to positions: A=1, K=11; C=3, M=13; E=5, P=16; D=4, N=14. In (a), (b), and (c), the second letter is obtained by adding 10, 10, and 11 respectively, but more importantly the pairs follow the pattern of increasing first letters by 2: A, C, E and second letters by 2: K, M, P except the last one breaks the sequence because D does not continue the odd progression. A clearer view is that the first letters form A, C, E, D, where D is out of order and does not fit the alternating progression. Hence DN is the odd one out.
Controller of Mines • 2026 • Technical Paper-III
Explain the process of crushing in mineral processing. Differentiate between open-circuit and closed-circuit crushing with the help of a neat flow diagram.
Controller of Mines • 2026 • Technical Paper-III
Which measure of central tendency is most affected by extreme values (outliers) in a sampling dataset?
A)
Median
B)
Mode
C)
Arithmetic Mean
D)
Range
The arithmetic mean uses every value in the dataset, so very large or very small outliers can pull it up or down significantly. The median is resistant to extreme values, and the mode depends only on the most frequent value. Range is not a measure of central tendency; it is a measure of dispersion.
Controller of Mines • 2026 • Technical Paper-III
Find the odd number out in the following set: 8, 27, 64, 100, 125, 216.
A)
8
B)
27
C)
125
D)
100
The numbers 8, 27, 64, 125, and 216 are perfect cubes: 2³, 3³, 4³, 5³, and 6³. But 100 is not a cube. Therefore, 100 is the odd one out.
Controller of Mines • 2026 • Technical Paper-III
If the “Coefficient of Variation” of ore grade in two different blocks is 15% and 30% respectively, which block has higher relative variability?
A)
The block with 15%
B)
The block with 30%
C)
Both have equal variability
D)
Coefficient of variation does not measure variability
The coefficient of variation (CV) measures relative variability: a higher CV means greater dispersion relative to the mean. Since 30% is greater than 15%, the block with 30% has higher relative variability. Option (a) is incorrect because 15% is lower variability, (c) is incorrect because the values are not equal, and (d) is incorrect because CV is specifically used to measure relative variability.
Controller of Mines • 2026 • Technical Paper-III
Heavy Media Separation (HMS) is primarily based on the difference in ________ of the minerals.
Answer: specific gravity
Heavy Media Separation (HMS) separates minerals based on differences in specific gravity (relative density). In a suitable heavy medium, lighter particles float and heavier particles sink. It is not primarily based on size, shape, or magnetic property, so the correct fill is "specific gravity".
Controller of Mines • 2026 • Technical Paper-III
Briefly explain the working principle of a Ball Mill. Why is it preferred for fine grinding compared to a Rod Mill?
Controller of Mines • 2026 • Technical Paper-III
100 students appeared for two examinations, 60 passed the first, 50 passed the second and 30 passed both. The probability that a student selected at random has failed in both the examination, is:
A)
0.3
B)
0.2
C)
0.4
D)
0.1
Let A = passed the first examination and B = passed the second examination. Given: |A| = 60, |B| = 50, and |A ∩ B| = 30. So, the number who passed at least one exam is |A ∪ B| = 60 + 50 - 30 = 80. Therefore, the number who failed in both exams is 100 - 80 = 20. Hence, the required probability = 20/100 = 0.2. Since the options include 0.2, the correct option is (b).
Controller of Mines • 2026 • Technical Paper-III
According to the Metalliferous Mines Regulations, a “Reportable Injury” means any injury which involves the enforced absence of the injured person from work for a period of:
A)
24 hours or more
B)
48 hours or more
C)
72 hours or more
D)
7 days or more
Under the Metalliferous Mines Regulations, a ‘reportable injury’ is one that causes the injured person to be absent from work for 24 hours or more. Therefore, option (a) is correct. The other options (48 hours, 72 hours, 7 days) do not match the regulatory definition.
Controller of Mines • 2026 • Technical Paper-III
Washing is normally performed after:
A)
Grinding
B)
Flotation
C)
Primary crushing
D)
Smelting
Washing is generally a preliminary mineral processing step used to remove clay, mud, and other adhering impurities from run-of-mine ore. It is normally done after primary crushing, when the ore has been broken into smaller pieces but before finer processing stages like grinding and flotation. Grinding comes later in the flow sheet, flotation is a separate concentration process, and smelting is a metallurgical extraction step after beneficiation.
Controller of Mines • 2026 • Technical Paper-III
Which explosive is most commonly used in open-cast metalliferous mines due to its safety and cost-effectiveness?
A)
Dynamite
B)
Gunpowder
C)
ANFO (Ammonium Nitrate Fuel Oil)
D)
TNT
ANFO is the most commonly used explosive in open-cast metalliferous mines because it is cheap, relatively safe to handle compared with high explosives, and suitable for large-volume blasting. Dynamite and TNT are more powerful but costlier and less commonly used for routine open-pit production blasting. Gunpowder is outdated and largely unsuitable for modern metalliferous mining.
Controller of Mines • 2026 • Technical Paper-III
Primary crushers are mainly classified into:
A)
Jaw and Cone crusher
B)
Jaw and Gyratory crusher
C)
Roll and Hammer crusher
D)
Cone and Roll crusher
Primary crushers are the first stage of size reduction for run-of-mine ore. The commonly used primary crushers are **jaw crushers** and **gyratory crushers** because they can handle large feed sizes and very hard material.
- **Jaw crusher**: widely used for primary crushing due to simple design and high reduction ratio.
- **Gyratory crusher**: also used in primary crushing, especially for very large capacities.
Why others are incorrect:
- **Cone crusher** is generally used as a secondary or tertiary crusher, not primary.
- **Roll crusher** is usually secondary or fine crushing.
- **Hammer crusher** is mainly for softer materials and is not a standard primary crusher classification in mineral processing.
Therefore, the correct answer is **Jaw and Gyratory crusher**.
Controller of Mines • 2026 • Technical Paper-III
Selection of crusher is done on the basis of particle:
A)
Shape
B)
Specific gravity
C)
Size
D)
Percentage of mineral in ore
Crusher selection in mineral processing is primarily based on the size of the feed particles and the required product size. The type of crusher is chosen to achieve the desired reduction ratio and capacity for a given particle size range. Shape, specific gravity, and percentage of mineral in ore are not the main criteria for selecting a crusher.
Controller of Mines • 2026 • Technical Paper-III
Under the Oilfields (Regulation and Development) Act, 1948, “mineral oils” include:
A)
Coal bed methane only
B)
Natural gas and petroleum
C)
Edible oils extracted near mines
D)
Synthetic lubricants
Under the Oilfields (Regulation and Development) Act, 1948, the term “mineral oils” is understood to include petroleum and natural gas. Therefore, option (b) is correct. The other options are incorrect because coal bed methane is not the standard statutory meaning here, edible oils are unrelated to mining law, and synthetic lubricants are manufactured products, not mineral oils under the Act.
Controller of Mines • 2026 • Technical Paper-III
Under Section 5 of the Explosive Substances Act, 1908, possession of explosives under suspicious circumstances may lead to imprisonment up to:
A)
5 years
B)
10 years
C)
14 years
D)
Life imprisonment.
Under Section 5 of the Explosive Substances Act, 1908, any person in possession of explosives under circumstances giving rise to a reasonable suspicion that they are intended for an unlawful object may be punished with imprisonment which may extend to 10 years, and also be liable to fine. Hence, the correct answer is 10 years. The other options are incorrect because Section 5 does not prescribe 5 years, 14 years, or life imprisonment for this offence.
Controller of Mines • 2026 • Technical Paper-III
The percentage of the mineral occurring as a free particle in the ore in relation to the total content is known as:
A)
Degree of freedom
B)
Degree of bondage
C)
Degree of liberation
D)
Degree of integration
In mineral processing, the percentage of a mineral present as free particles in an ore relative to its total content is called the degree of liberation. It indicates how completely the valuable mineral is separated from the gangue. The other options are not standard terms in this context: degree of freedom is unrelated, degree of bondage is not a mineral processing term, and degree of integration is not used for this definition.
Controller of Mines • 2026 • Technical Paper-III
Jigging is a process of separating particles based on their density using:
A)
A constant horizontal flow of air.
B)
A vertical pulsating column of water.
C)
High-tension electrical wires.
D)
Chemical reagents.
Jigging is a gravity concentration process used in mineral processing. It separates particles mainly on the basis of density difference by applying repeated upward and downward pulsating water currents through a bed of particles. Heavier particles settle faster, while lighter particles are carried upward. Option (a) describes air flow used in some pneumatic separation methods, not jigging. Option (c) refers to electrostatic separation, and option (d) refers to flotation or chemical separation methods.
Controller of Mines • 2026 • Technical Paper-III
Under the provisions of the Mines and Minerals (Development and Regulation) Amendment Act, 2015, what is the standard period for which a mining lease for major minerals is now granted?
A)
20 years
B)
30 years
C)
50 years
D)
99 years
Under the Mines and Minerals (Development and Regulation) Amendment Act, 2015, the standard period of a mining lease for major minerals was changed to 50 years. Earlier, leases were generally granted for 30 years. After the 2015 amendment, the lease period was made 50 years, and upon expiry it is generally granted for further periods of 20 years. Therefore, the correct option is (c) 50 years.
Controller of Mines • 2026 • Technical Paper-III
District Mineral Foundation (DMF) is guided by which scheme for benefit devolution?
A)
National Mineral Exploration Trust (NMET)
B)
PMKKKY
C)
MCDR 2017
D)
Fifth Schedule
District Mineral Foundation (DMF) funds are used for the welfare of people affected by mining, and the guiding framework for benefit devolution is the Pradhan Mantri Khanij Kshetra Kalyan Yojana (PMKKKY). PMKKKY lays down the norms for spending DMF funds for the benefit of mining-affected persons and areas. NMET is for mineral exploration, MCDR 2017 regulates mineral development, and the Fifth Schedule relates to scheduled areas, not DMF benefit devolution.
Controller of Mines • 2026 • Technical Paper-III
What is the minimum No. of persons to be employed when the Owner, Agent or Manager shall constitute a Safety Committee for promoting safety in the mines?
A)
100
B)
200
C)
300
D)
500
Correct option A: 100
Controller of Mines • 2026 • Technical Paper-III
Explain the general safety provisions under Coal Mines Regulations, 2017.
Controller of Mines • 2026 • Technical Paper-III
Discuss the role of Indian Bureau of Mines under MCDR, 2017.
Controller of Mines • 2026 • Technical Paper-III
Explain the key objectives of National Mineral Policy, 2019.
Controller of Mines • 2026 • Technical Paper-III
The District Mineral Foundation (DMF) was introduced through an amendment to which of the following Acts?
A)
The Mines Act, 1952
B)
The MMDR Act, 1957
C)
The Mineral Concession Rules, 1960
D)
National Mineral Policy, 2019
The District Mineral Foundation (DMF) was introduced by the Mines and Minerals (Development and Regulation) Amendment Act, 2015, which amended the MMDR Act, 1957. DMFs are statutory trusts set up in mining-affected districts. The other options are incorrect because the Mines Act, 1952 deals with labour and safety in mines, the Mineral Concession Rules, 1960 are subordinate rules under the MMDR framework, and the National Mineral Policy, 2019 is only a policy document, not the parent law that created DMF.
