Mining Methods and Machinery · Mining Methods · 2 marks · Numerical answer
Twelve 4.4×2.5 m bord-and-pillar headings are blasted per day with average pull 1.2 m and coal density 1500 kg/m³. The mine works three shifts and average daily employment is 330. Find output per manshift (OMS) in tonnes to two decimals.
Daily coal volume is 12×4.4×2.5×1.2=158.4 m³, giving 237.6 tonnes at 1.5 tonnes/m³. Daily employment already counts the day’s manshifts, so OMS=237.6/330=0.72 tonne per manshift. Multiplying the stated daily output or employment by three again would double-count the shift information.