In a room-and-pillar stope, bench blasting is conducted using ANFO having density of 800 kg/m3. The specific gravity of rock is 2.5, hole diameter is 100 mm and spacing to burden ratio is 1.3. The charge length of each blast hole is 80% of the hole length. For a desired powder factor of 0.48 kg/tonne, the spacing and burden of the blast pattern in m respectively are
A. 2.0, 2.6
B. 2.3, 1.8
C. 5.2, 4.0
D. 1.3, 1.0
Answer: Option B
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