Question

Economic depth of surface mining primarily depends on

• A. Seam gradient
• B. Seam thickness
• C. Break-even stripping ratio
• D. Overburden volume

Hint:

Surface mining is economical as long as \[ \boxed{ \text{Actual Stripping Ratio} \le \text{Break-even Stripping Ratio}. } \]

Answer 1

The Correct Option is C

Step 1: Recall the concept of economic depth. The economic depth of surface mining is the maximum depth at which mining remains profitable.

Step 2: Identify the governing factor. This depth is controlled by the break-even stripping ratio, where the cost of removing overburden equals the economic value of the mineral. Hence, \[ \boxed{\text{Break-even stripping ratio}} \] is the correct answer. Therefore, \[ \boxed{(C)} \] is the correct answer.