Technical Information

 

Every drilling application is different, so we cannot say that there are particular breakpoints where you should transition between drilling methods.  Rotary drilling is still the predominant method of drilling 230 mm (9 in) diameter or greater. This is driven primarily by the current limitations of tophammer units and rig air systems.  Tricone bits also become more cost effective as the larger bits are equipped with larger bearings which in turn can handle higher loads. These higher loads translate to improved drill rates. Another advantage of rotary rigs is the length of the drill rods that can be carried on board. Longer rods mean fewer connections. Smaller rotary blasthole machines utilize 9.1 meter (30 ft) length rods, while larger units are capable of running 10.7 meter (35 ft) or 12.2 meter (40 ft) rods.