Four identical districts of a mine are ventilated with a quantity of 3500 m3/min at a fan drift pressure of 1.15 kPa. When one of the districts is sealed off, the change in resultant resistance is 0.072 Ns2m-8. If the fan is stopped, keeping a district sealed, the quantity through the mine becomes 850 m3/min. The natural ventilation pressure in Pa, is
- 72.12
- 82.28
- 105.56
- 144.56
The Correct Option is B
Solution and Explanation
Top Questions on Determination of mine size and mine life
The grade-tonnage distribution for the ultimate pit of a mine is given below.
\[ \begin{array}{|c|c|} \hline \text{Cu grade (\%)} & \text{Cumulative million tonnes below the grade} \\ \hline 0.1 & 0 \\ 0.4 & 15.0 \\ 0.5 & 17.0 \\ 0.6 & 18.0 \\ 0.7 & 19.0 \\ 0.9 \text{ and above} & 23.0 \\ \hline \end{array} \]
The mill cut-off grade is 0.5% Cu. The annual mining capacity (ore + waste) is 4.5 million tonne and milling capacity is 1.0 million tonne. Excavation is planned in such a way that either the mine or the mill runs at full capacity throughout. The planned life of the mine, in years, is \(\underline{\hspace{1cm}}\). (round off to one decimal place)
- GATE MN - 2021
- Mine Planning
- Determination of mine size and mine life
Questions Asked in GATE MN exam
Reciprocal levelling is performed for points P and Q by placing the same levelling instrument at A and B. The observations of staff readings are tabulated as below.
If the Reduced Level (RL) of P is 115.246 m, then the true RL of Q, in m, is _______ (rounded off to 3 decimal places)
- GATE MN - 2025
- Surveying
- SO$_2$ is emitted at a rate of 20 kg/s from a 10 km $\times$ 10 km airshed in an industrial area. Wind blows at a speed of 4 m/s from one direction in that area. Radiation inversion restricts the mixing height to 1200 m. Neglect SO$_2$ concentration in the incoming air. Assuming emitted SO$_2$ to be conservative, the steady state SO$_2$ concentration in the airshed, in $\mu g/m^3$, is _______ (rounded off to 2 decimal places).
- GATE MN - 2025
- Environmental Engineering
- In a longwall panel, air flows at a velocity of 1.2 m/s through a 900 m long gate road of 2.5 m height and 3 m width. The coefficient of friction is 0.022 Ns$^2$m$^{-4}$. The frictional pressure drop, in Pa, between two ends of the gate road is _______ (rounded off to 3 decimal places).
- GATE MN - 2025
- Fluid Mechanics
The information of a mining project for a life of three years is given below:
Additional data: Applicable tax rate = 30%
Discount rate = 10%
Depreciation method: Straight line with zero salvage value- GATE MN - 2025
- Mine planning and its components
Data from a borehole log with collar elevation at 590 mRL are given below. Composite grade is calculated using cores of 5 m above and below the reference bench at 580 mRL. The composite grade, in %, is:
- GATE MN - 2025
- Mine planning and its components