Question

In a surface mine, blasting is carried out using electronic detonator and cartridge emulsion explosive with the following details: Burden = 3.5 m, Spacing = 4.5 m, Bench height = 10.0 m, Subgrade drilling = 1.0 m, Stemming = 4.0 m, Linear charge concentration = 16 kg/m, Cost of one detonator = Rs. 800, Cost of explosive = Rs. 30/kg. The cost of blasting material per cubic meter of blasted rock, in Rs., is ________ (rounded off to 2 decimal places).

Hint:

Cost per unit volume = \( \frac{{Total cost of blasting material}}{{Volume of rock blasted}} \)

Answer 1

Step 1: Calculate the volume of the blast. \[ {Volume} = {Burden} \times {Spacing} \times {Bench height} = 3.5 \times 4.5 \times 10 = 157.5 \; {m}^3 \] Step 2: Calculate total charge length = Bench height + subgrade drilling - stemming. \[ {Charge length} = 10 + 1 - 4 = 7 \; {m} \] Step 3: Total explosive used = Linear charge concentration × Charge length. \[ {Explosive mass} = 16 \times 7 = 112 \; {kg} \] Step 4: Total cost = Cost of explosive + cost of one detonator. \[ {Cost} = (112 \times 30) + 800 = 3360 + 800 = 4160 \; {Rs} \] Step 5: Cost per cubic meter = Total cost / Volume. \[ {Cost/m}^3 = \frac{4160}{157.5} \approx 22.00 \; {Rs} \]