Evaluation of the Effect of Rock Strength on Drilling Penetration Rate and Index of Rotation Energy–A Case Study

Proper knowledge of the rocks and properties of rock will allow proper selection of the bit and speed of rotation of the drill for fast penetration and reduce the cost of drilling. Since the rock fragmentation process requires the drilling of small diameter holes for the placement of explosive material, this makes the evaluation of rock properties' effect on this operation important. This study focus on evaluating the effect of rock properties and drill parameters on drill bit penetration rate, specific energy, and index of rotational energy. Two case studies mine in southwest Nigeria were considered for this study. Rock properties, penetration rate, and index rotation energy of the drill quarry machines were determined. The obtained parameters for different drilling operations were used to develop datasets for different observations. The uniaxial compressive strength, point load, and hardness values of the case study granite have an average value of 90.56-121.43 MPa, 6.8-8.54 MPa, and 45.648.01 respectively. Prediction models were developed for the prediction of the drill penetration rate, specific energy, and index of rotation energy as a function of the rock properties. The developed regression models show a very high correlation having R2 value close to unity. Hence the proposed regression models can reasonably predict drill penetration rate, specific energy, and index of rotation energy for practical purposes.