Comparison of Respirable Dust Generation by New Polycrystalline Diamond Compact and Tungsten Carbide Drill Bits in Wet and Dry Drilling

Abstract

Abstract U.S. Bureau of Mines field test results show that polycrystalline diamond compact bits used for coal-mine roof bolting, can last 200 to 600 times longer than tungsten carbide bits. During these tests it was also noted that the cutting edges of polycrystalline diamond compact bits remained sharp, they did not show any decrease in penetration rate, and it appeared that they generated less airborne dust. During these tests, however, it was not possible to measure the amount of respirable dust generated under controlled conditions. Laboratory tests were subsequently conducted to compare the respirable dust generated by new tungsten carbide and polycrystalline diamond compact bits. These tests were performed using a rotary drill test facility at the Rock Mechanics and Explosives Research Center, University of Missouri at Rolla. Respirable dust, as defined by a lognormal particle penetration curve with 50 percent penetration of 3.5-μm aerodynamic diameter, and a geometric standard deviation of [sgrave]...