Mining Methods and Machinery
This domain joins method selection to equipment: which stoping or coal-winning system suits an orebody, and what capacity the face, haulage and hoisting machinery must deliver. Questions are often a capacity or cycle-time calculation, or a discrimination item asking why one method is preferred over a near neighbour.
Method selection
- Coal: bord and pillar (development and depillaring), longwall advancing or retreating with caving.
- Metal: open stoping (sublevel, blasthole, VCR), cut and fill, shrinkage stoping, sublevel caving, block caving, room and pillar.
- Drivers: dip, thickness, depth, grade, ore and wall-rock strength, required selectivity, production rate, capital and operating cost, and acceptable dilution and subsidence.
Machinery
- Face equipment: shearer or plough, continuous miner, drill jumbo, LHD, scraper.
- Haulage: shuttle car, conveyor, locomotive, truck. Belt capacity follows Q = A x v x density x 3600 when density is in t/m^3, or Q = 3.6 x A x v x density when density is in kg/m^3.
- Hoisting: drum versus Koepe friction winder; skip payload, cycle time and RMS power govern motor sizing.
Worked example
A belt conveyor carries a load cross-section of 0.08 m^2 at 2 m/s, with bulk density 1.6 t/m^3. Volumetric rate = 0.08 x 2 = 0.16 m^3/s. Mass rate = 0.16 x 1.6 = 0.256 t/s. Hourly capacity = 0.256 x 3600 = 921.6 t/h. Equivalently, with density in kg/m^3, Q = 3.6 x 0.08 x 2 x 1600 = 921.6 t/h, confirming the unit conversion.
Traps
- Mixing the two conveyor formulas: 3600 pairs with t/m^3, 3.6 pairs with kg/m^3. Using 3600 with kg/m^3 gives an answer 1000 times too large.
- Confusing block caving (gravity flow from a developed undercut, low cost, high dilution and surface subsidence) with sublevel caving (development in ore, better selectivity).
- Treating a Koepe winder as torque-driven like a drum winder; it relies on friction and needs adequate rope tension ratio.