Drilling Method for Hard and Slipping Formation in Western Hubei

In host strata of phosphate rock,lead-zinc mine,silver and vanadium ore and overlying strata of western Hubei,there is common existence of hard rocks.Sinian dolomite contains a large amount of silicon horizon and "chalcedony" layer formed by chemical vapor deposition,silicon content is more than 80% with dense structure,low abrasiveness and drillability of Ⅸ～Ⅹ level.By the test in drilling field,the paper described the diamond bit selection,artificial bit conditioning and diamond drilling process parameters selection;summed up the successful experience in construction practice for further resolving drilling slipping difficulty.