Method and apparatus for controlling dust in a rotary drilling operation

Claim 1

IN A ROCK-DRILLING OPERATION WHEREIN A TUBULAR DRILL STRING, WHICH INCLUDES A BIT OF THE TYPE HAVING CONES AND BEARINGS ROTATABLY MOUNTING THE CONES, ROTATES WITHIN A DRILL HOLE WHILE THE CONES ENGAGE A DRILLING FACE AT THE BOTTOM OF THE HOLE AND PRODUCE CUTTINGS WHICH INCLUDE DUST, A METHOD OF CONTROLLING THE DUST COMPRISING INJECTING AN AIR STREAM THROUGH THE DRILL STRING, DISCHARGING A MAJOR PORTION OF THE AIR THROUGH THE BIT INTO THE DRILL HOLE TO BLOW CUTTINGS FROM THE DRILLING FACE AND OUT THE HOLE, DISCHARGING A MINOR PORTION OF THE AIR INTO THE BEARINGS TO FLUSH AWAY FOREIGN PARTICLES, CONDUCTING A WATER STREAM THROUGH THE DRILL STRING, MAINTAINING THE WATER STREAM SEPARATE FROM THE AIR STREAM FROM THE UPPER END OF THE DRILL STRING TO THE BIT, AND DISCHARGING THE WATER INTO THE DRILL HOLE SEPARATELY FROM THE MINOR PORTION OF THE AIR WHERE THE WATER WETS THE CUTTING WITHOUT CONTACTING THE BEARINGS.