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Mining Engineering Mining Geology Difficulty: Medium

What is the term for a horizontal underground opening made at the lowest level to drain water? 'T'h'e' 't'e'm'p'e'r'a't'u'r'e' 'o'f' 't'h'e' 'w'h'i't'e' 'm'e't'a'l' 'w'h'e'n' 'p'o'u'r'e'd' 'i'n' 'a' 's'o'c'k'e't' 's'h'a'l'l' 'n'o't' 'e'x'c'e'e'd' '.' '.' '.' '.' '.' '.' '.' '.' 'd'e'g'r'e'e' 'c'e'n't'i'g'r'a'd'e' The line joining the point of intersection of the cross wires of the diaphragm to optical centre of objective and its imaginary continuation called . . . . . . . . Specific gravity of calcite In a room-and-pillar stope, bench blasting is conducted using ANFO having density of 800 kg/m 3 . 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