... over 5 4.core diameter from 220~250mm KY-250D Rotary Blasthole Drilling RigParameterSpecificationsBorehole dia (mm) 250Hole depth (m)17.5Hole direction ... ,Uranium,Cobblestone,Marble Stone,Gyratory,Calcite,Clay, Dolomite KY-250D Rotary Blast hole Drilling Rig