Mining Geology, Mine Development and Surveying · Mine Development · 2 marks · Numerical answer
A surface-mine blast has burden3.5 m,spacing4.5 m,bench height10 m,subgrade drilling1 m,stemming4 m and charge concentration16 kg/m. One detonator costs₹800 and explosive₹30/kg. Find material cost per cubic metre of rock to two decimals.
Hole length is10+1=11 m and charged length11−4=7 m. Explosive mass is7×16=112 kg. Material cost is112×30+800=4160 rupees per hole. Rock volume credited to the hole is3.5×4.5×10=157.5 m³. Unit cost=4160/157.5=26.41 rupees/m³; subgrade is not extra recovered bench volume.
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