Screw Extruder Drill

a drill for stoping shallow seams of minerals (coal, rock salt, and so on) by drilling large-diameter (0.5-2.7 m) holes. The working tool of the screw extruder drill is a bit attached to a screw conveyor that removes the drilled mineral from holes 40-70 m deep; loading of the mineral into means of transportation is done automatically by the drill itself. The machine mechanizes the extraction processes, increases labor productivity and the safety of stoping and, since it is a means of automated coal mining, permits the selective stripping of minerals from mixed-composition seams, thus minimizing depletion (as opposed to mining by excavation), and the recovery of coal from the edges of an open-pit mine, which are inaccessible for excavation stoping. During the stripping of a seam with a screw extruder drill, sections of the mineral (up to 0.3 m wide) that were not taken up are left behind between drill holes, resulting in large mineral losses (up to 40-50 percent). Screw extruders are being improved to allow for an increase in drilling speed and drill-hole depth, a reduction in the time for auxiliary operations, and the utilization of remote control. Higher productivity could be provided by electrically driven self-propelled gang screw extruder drills.