Drilling

                           The major action of the quarry operation was drilling (Annex -06/P I). The all actions were depended on drilling process. In the site this was done manually, by using jackhammer, with the help of compressed air which was providing by screw compressors. In Neboda site there were two compressors and those have five outlets and five hammers could be worked at same time.

                                                                                      There are so many types of drilling according to machinery type used such as Mechanical, Hydraulic, and Thermal etc. Those types have hand drilling, track drilling, drilling by jumbos etc. The selection of the drilling equipment is based on several factors. That is type of rock, field, scale, blasting parameters etc. Other than the type drilling is also affected by the rock properties like Hardness, Strength, Plasticity, Elasticity, Structure etc. Anyway action produces more dust, noise, and little amount of ground vibration when compared with blasting as well. At the site drilling is done by using jack hammers (Annex-06/PIII). It has three major part are, the drill, the drill steel and the drill bit.

                                 Y26 Jack hammers were used in Neboda quarry. Normally five hammers were run continuously and remains were used as standby. Sub contract drillers and company drillers were worked in Neboda quarry for drilling.  

                                 Mechanical drills can have three types. Those are Rotary Percussion, Percussion, and Rotary. Y26 hammer is a Rotary Percussion type. That generates the driving percussion forces (vibrating action/ impact produced by repeated blows) and rotation, which are transmitted through the rod and the bit, to the rock surface. A load should be applied on the Jack Hammer; otherwise it will jump on hole without effective drilling.