Dust conveying and collection system

A drill cuttings conveying and collection system (50) for handling drill cuttings produced by an earth drilling rig (20). A generally tubular head member (52) is adapted to be extendable with respect to the rig deck (38) into engagement with the ground around the drillhole (35) for conducting a bailing air flowstream laden with drill cuttings to an enclosure (70) wherein coarse cuttings are separated from the flowstream by gravitational and inertia forces and deposited on the ground at a point remote from the drillhole. Relatively fine cuttings are conveyed from the coarse cuttings separating enclosure (70) to a filter and dust collection unit (88) to provide total collection of entrained particles utilizing inertial and impingement separation techniques. The system efficiency is such that a variable capacity suction pump on the dust collection unit (88) is required to operate at only 1.0 to 1.5 times the volumetric flow rate of bailing air injected into the drillhole.