tonnage measurements. inquire now. methods of calculating tonnage in mining. download. of coal and tonnage factor of overburden material are 320 kg/cm. 2 and 0.8 m. 3 general view of a room-and-pillar mining method application is given.,methods for calculating the minimum amortization,mining methods may be equally applicable ( each . with . different recoveries and costs) and that the absolute maximum mining rate for each method is not necessarily the best, then the complexity of the problem becomes calculate a . minimum amortization . tonnage, or gives . a .