PDC coal mine roof bolt,Mining Tool Expert 1.drill ... 56mm 4.best rice, long use life PDC coal mine roof boltIntroductionPDC bit uses PDC as main cutting components ... edges.PDC bit is mainly used for geological prospecting,coal exploration,water conservancy and power engineering,etc. Features1. ... It has a low cost Technical Parameter of PDC coal mine roof bolt Colliery Drilling Tools Main Standard(mm) DHLM ...