GATE 2025 MN – Question 35

Mineral Economics, Mine Planning, Systems Engineering · Mine Planning · 1 mark · Numerical answer

Copper sells for₹900/kg. Mining costs₹500/tonne ore and processing₹2000/tonne ore. Overall metal recovery is70%. Ignoring other costs, find break-even cutoff grade in percent to two decimals.

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Correct answer: 0.38 to 0.42

Explanation

At fractional grade g, one tonne of ore yields1000g×0.70 kg saleable copper. Revenue is900×1000×0.70g. Equate this to2500 rupees: g=2500/630000=0.00396825. As a percentage that is0.396825%, or0.40%.

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