Question

In a bord and pillar panel, with headings of 4.4 m × 2.5 m advanced by solid blasting, the average pull per round = 1.2 m and 12 faces are blasted per day. Density of coal = 1500 kg/m$^3$. Mine works three shifts; daily employment = 330 persons. Labour productivity (OMS) in tonne (rounded off to two decimals) is __________.

Hint:

OMS = Total daily production / total number of workers in all shifts.

Answer 1

Correct Answer: 0.7

Volume of coal per round per face:
\[ V = 4.4 \times 2.5 \times 1.2 = 13.2\ \text{m}^3. \]
Daily number of rounds = 12 faces × 1 round:
\[ V_{daily} = 12 \times 13.2 = 158.4\ \text{m}^3. \]
Mass of coal (density = 1500 kg/m$^3$):
\[ M = 158.4 \times 1500 = 237600\ \text{kg}. \]
Convert to tonnes:
\[ M = 237.6\ \text{tonne}. \]
OM S (Output per man-shift):
\[ OMS = \frac{237.6}{330} = 0.720. \]
\[ \boxed{0.72\ \text{tonne}} \quad (\text{acceptable range: } 0.70\text{–}0.75) \]